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. 2021 Jan 18;26(2):488. doi: 10.3390/molecules26020488

Chemical Diversity and Bioactivities of Monoterpene Indole Alkaloids (MIAs) from Six Apocynaceae Genera

Afrah E Mohammed 1, Zainab H Abdul-Hameed 2, Modhi O Alotaibi 1,*, Nahed O Bawakid 2, Tariq R Sobahi 2, Ahmed Abdel-Lateff 3,4, Walied M Alarif 5,*
Editor: John C D’Auria
PMCID: PMC7831967  PMID: 33477682

Abstract

By the end of the twentieth century, the interest in natural compounds as probable sources of drugs has declined and was replaced by other strategies such as molecular target-based drug discovery. However, in the recent times, natural compounds regained their position as extremely important source drug leads. Indole-containing compounds are under clinical use which includes vinblastine and vincristine (anticancer), atevirdine (anti-HIV), yohimbine (erectile dysfunction), reserpine (antihypertension), ajmalicine (vascular disorders), ajmaline (anti-arrhythmic), vincamine (vasodilator), etc. Monoterpene Indole Alkaloids (MIAs) deserve the curiosity and attention of researchers due to their chemical diversity and biological activities. These compounds were considered as an impending source of drug-lead. In this review 444 compounds, were identified from six genera belonging to the family Apocynaceae, will be discussed. These genera (Alstonia, Rauvolfia, Kopsia, Ervatamia, and Tabernaemontana, and Rhazya) consist of 400 members and represent 20% of Apocynaceae species. Only 30 (7.5%) species were investigated, whereas the rest are promising to be investigated. Eleven bioactivities, including antibacterial, antifungal, anti-inflammatory and immunosuppressant activities, were reported. Whereas cytotoxic effect represents 47% of the reported activities. Convincingly, the genera selected in this review are a wealthy source for future anticancer drug lead.

Keywords: Apocynaceae, monoterpene, alkaloids, cytotoxicity, anti-inflammatory, antimicrobial

1. Introduction

Alkaloids are basic nitrogenous natural metabolites with structural diversity and molecular conformity. They displayed interesting bioactivities and are known to perform an important role in plant protection. The majority of them were discovered from plants and recently recorded Ca 21,000 [1,2]. The alkaloids are generally derived from amino acids that are containing one or more nitrogen atoms. These precursors are playing a rule in their classification. Also, the biosynthetic pathway of alkaloids can be named according the amino acid source [3]. Thus, they can be categorized into several groups based on associated moieties, including piperidine, pyrrolidine, pyrrole, pyridine, quinolone, isoquinoline, indole, quinolizidine, pyrrolizidine, tropane, benzylisoquinoline, purine, β-carboline, indolinics and quinolizidine.

Terpenoids are considered to be interesting natural products that have chemical diversity and different bioactivities. Common terpenoids have been reported from marine sources [4]. Whereas, the plants were listed as an important source of such metabolites. Terpenoids include several subclasses according to the number of carbo-skeleton; monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), sesterterpenes (C25), triterpenes (C30), and tetraterpenes (C40).

Monoterpene indole alkaloids (MIAs) are metabolites containing a bicyclic structure of a benzene ring fused to a five-membered pyrrole ring. It is a noteworthy that the occurrence of multipart alkaloids is largely restricted to limited number of plant families. (e.g., Apocynaceae, Loganiaceae, and Rubiaceae) [5,6,7,8]. These families are closely taxonomically related. Also, on the chemical aspect, they are recognized to have apparent uniformity in the building blocks of these alkaloids. MIAs have been proposed to be sourced from strictosidine, which originates from the condensation of tryptophan with secologanin (C10 or C9 part), which can be divided into linear six carbon (6 C), one carbon (1 C) and three carbon (3 C) units (Figure 1). The connection between them requires proving. The nine-carbons fragment may be formed by the loss at certain stage of one of the carbons from the 3 C unit, and there are also a few indole bases which appear to have ended up without the 3 C or the 1 C units. Three hypothetical building blocks, Types I, II and III. It is nevertheless a useful way of dividing indole alkaloids into groups based on their sub­ architecture. Since Type I alkaloids are by far the most numerous, they may be the source of Type II and III. It was suggested by LeMen and Tylor that the convention be extended to cover Type II and III alkaloids as illustrated in Figure 1. On these hypothetical bases, the MIAs categorized according to their biogenic pathway in three main groups, corynanthe, aspidosperma and iboga [9].

Figure 1.

Figure 1

Biogenetic numbering rule as adopted from LeMen and Tylor.

Recently, strictosidine has been considered as the building block of MIAs biosynthesis [10]. MIAs have been proposed to arise from strictosidine, which itself originates from the condensation of tryptophan with secologanin in a 1:1 ratio. Strictosidine has been elaborated to give an impressive array of structural variants. This type of alkaloids possess 18 (or 19) carbon atoms on its skeleton. Additionally, the MIAs could be produced from tryptophan and secologanin in 1:2 or 2:1 ratio. According to this arrangement, three types (classes) of monoterpenes were constructed, including, corynanthe (e.g., ajmalicine), aspidosperma (e.g., tabersonine) and iboga (e.g., catharanthine) [11,12,13].

Apocynaceae contains about 250 genera and 2000 species [14]. Five sub-families are classified under Apocynaceae, including, Apocynoideae, Asclepiadoideae, Periplocoideae, Rauvolfioideae, and Secamonoideae. Apocynaceae species ranged from shrubs to trees. The characteristic features of these plants include colorful flowers and opposite leaves. Traditionally, species of this family have been used for the treatment of fever, malaria, gastrointestinal ailments, diabetes, and pain [15]. Additionally, some species have shown antiplasmodial and anticancer activities [14]. Several Apocynaceae MIAs have been used as anticancer, analgesic, anti-inflammatory and anti-spasmodic agents. For example, vinblastine, vinorelbine, vincristine, and vindesine were utilized as anticancer agents, whereas ajmalicine and ajmaline were used in the treatment of cardiovascular disorders (Figure 2) [2]. Catharanthus roseus and Rauvolfia serpentine are members of Apocynaceae and are known as sources of bioactive indole alkaloids [16]. Reserpine has been used as a tranquillizer, whereas vinblastine and vincristine have been used as anti-leukemic agents [17]. Vincristine and vinblastine were among the earliest anti-tumor agents, and since 1965 have been used as tubulin polymerization inhibitors. They have been used in combination for the treatment of acute lymphoblastic leukemia and also against both Hodgkin’s and non- Hodgkin lymphoma. Additionally, strychnine is potent muscle contracting agent whereas, yohimbine has been used for the treatment of sexual dysfunction and investigated as a remedy for type-2 diabetes in animal and human models.

Figure 2.

Figure 2

Examples of well-known biologically active terpene indole alkaloids.

There are several publications interested in the terpene indole alkaloids of individual species of the family Apocynaceae. The current review organizes the reported MIAs considering the historical aspect in each selected genus. Moreover, these MIAs were biosynthetically classified according to the tepenoidal fragment, i.e., corynanthe, aspidosperma, or iboga. Also, it focuses on the origin, structural diversity and biological activities exerted by 444 (Table 1) monoterpene indole alkaloids which have been reported from selected six genera of the family Apocynaceae (Alstonia, Kopsia, Ervatamia, Rauvolfia, Tabernaemontana and Rhazya), in the period between 2010 and December 2020. The listed metabolites are categorized under 26 subclasses, ajmaline, akuamiline, akuammidine, akuammicine, apparicine, aspidofractinine, aspidospermatan, eburnane, flabelliformide, kopsine, macroline, macroline oxindole, macroline-akuammiline, methyl chanofruticosinate, nareline, paucidactine, picrinine, pleiocarpamine, sarpagine, scholaricine, secodine, strictosidine, strychnos, vincamine, vincorine and vobasine (Figure 3 and Figure 4).

Table 1.

Monoterpenoid indole alkaloids from the six species of Apocynaceae.

Comp No Compound Name Class Type Source Part Country Activities
1 (14a,15a)-14,15-Epoxy Aspidofractinine Aspidofractinine Alstonia mairei Leaves and twigs China Cytotoxicity
2 Maireine A Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
3 Maireine B Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
4 Venalstonine Aspidofractinine Alstonia mairei Leaves and twigs China Cytotoxicity
5 (−)-Minovincinine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
6 (−)-11-Methoxymino Vincinine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
7 (−)-Echitovenine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
8 Echitovenaldine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
9 Echitovenidine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
10 11-Methoxyechitovenidine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
11 Echitoveniline Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
12 11-Methoxyechitoveniline Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
13 Echitoserpidine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
14 11-Methoxyechitoserpidine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
15 Vindolinine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
16 Lochnericine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
17 Tabersonine Aspidosperma Alstonia mairei Leaves and twigs China Cytotoxicity
18 Perakine Ajmaline Alstonia mairei Leaves and twigs China Cytotoxicity
19 Picrinine Picrinine Alstonia mairei Leaves and twigs China Cytotoxicity
20 Deacetylpicraline 3,4,5-Trimethoxybenzoate picraline Alstonia mairei Leaves and twigs China Cytotoxicity
21 Picralinal picraline Alstonia mairei Leaves and twigs China Cytotoxicity
22 Rhazimol Akummidine Alstonia mairei Leaves and twigs China Cytotoxicity
23 Alsmaphorazines A Scholaricine Alstonia pneumatophore Leaves Malysia Anti-inflammatory
24 Alsmaphorazine B Scholaricine Alstonia pneumatophore Leaves Malysia Anti-inflammatory
25 Alstrostine A Strictosidine Alstonia rostrata Leaves and twigs China Cytotoxicity
26 Alstrostine B Strictosidine Alstonia rostrata Leaves and twigs China Cytotoxicity
27 Alstrostine C Akummicine Alstonia rostrata Leaves and twigs China Cytotoxicity
28 Alstrostine D Akummicine Alstonia rostrata Leaves and twigs China Cytotoxicity
29 Alstrostine E Akummicine Alstonia rostrata Leaves and twigs China Cytotoxicity
30 Alstrostine F Corynanthe Alstonia rostrata Leaves and twigs China Cytotoxicity
31 11-Hydroxy-6,7-Epoxy-8-Oxo-Vincadifformine Aspidosperma Alstonia yunnanensis Whole plant China Cytotoxicity
32 14-Chloro-15-Hydroxyvinca Difformine Aspidosperma Alstonia yunnanensis Whole plant China Cytotoxicity
33 Perakine N4-Oxide Ajmaline Alstonia yunnanensis Whole plant China Cytotoxicity
34 Raucaffrinoline N4-Oxide Ajmaline Alstonia yunnanensis Whole plant China Cytotoxicity
35 Vinorine N1,N4-Dioxide Ajmaline Alstonia yunnanensis Whole plant China Cytotoxicity
36 Oxovincadifformine Aspidosperma Alstonia yunnanensis Whole plant China Cytotoxicity
37 Vinorine N4-Oxide Ajmaline Alstonia yunnanensis Whole plant China Cytotoxicity
38 Vinorine Ajmaline Alstonia yunnanensis Whole plant China Cytotoxicity
39 Alsmaphorazine C Octahydropyrrolo[2,3-b]pyrrole and 2-azabicyclo[3.3.1]nonane units Alstonia pneumatophore Leaves Malaysia Cytotoxicity
40 Alsmaphorazine D Octahydropyrrolo[2,3-b]pyrrole and 2,8-diazabicyclo[3.3.1]nonane units Alstonia pneumatophore Leaves Malaysia Cytotoxicity
41 Alsmaphorazine E Octahydropyrrolo[2,3-b]pyrrole and 2,8-diazabicyclo[3.3.1]nonane units Alstonia pneumatophore Leaves Malaysia Cytotoxicity
42 Scholarisin I picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory Antifungal
43 Scholarisin II picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory Antifungal
44 Scholarisin III picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
45 Scholarisin IV picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
46 Scholarisin V picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
47 Scholarisin VI picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
48 Scholarisin VII picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
49 (3R,5S,7R,15R,16R,19E)-Scholarisine F picrinine Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
50 3-Epi-Dihydrocorymine Vincorine Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
51 (E)-16-Formyl-5α-Methoxystrictamine picraline Alstonia scholaris Leaves China Cytotoxicity,
Anti-inflammatory, Antifungal
52 Alstolactine A Corynanthe Alstonia scholaris Leaves China Antibacterial
53 Alstolactine B Corynanthe Alstonia scholaris Leaves China Antibacterial
54 Alstolactine C Corynanthe Alstonia scholaris Leaves China Antibacterial
55 Alistonitrine A Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
56 6,7-Epoxy-8-Oxo-Vincadifformine Aspidosperma Alstonia rupestris Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
57 11-Acetyl-6,7-Epoxy-8-Oxo-Vincadifformine Aspidosperma Alstonia rupestris Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
58 11-Hydroxy-14-Chloro-15-Hydroxyvincadifformine Aspidosperma Alstonia rupestris Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
59 Perakine N1,N4-Dioxide Ajmaline Alstonia rupestris Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
60 11-Hydroxy-6,7-Epoxy-8-Oxovincadifformine Aspidosperma Alstonia rupestris Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
61 N(4)-Methyl-Talpinine Sarpagine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
62 N(4)-Meth-Yl-N(4),21-Secotalpinine Macroline Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
63 Alstonerinal Macroline Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
64 Alstonerine Macroline Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
65 Macrocarpine B Macroline Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
66 Affinisine Sarpagine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
67 Villalstonine Macroline-Pleiocarpamine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
68 Villalstonine N(4)-Oxide Macroline-Pleiocarpamine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
69 Villalstonidine D Macroline-Pleiocarpamine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
70 Villalstonidine E Macroline-Pleiocarpamine Alstonia angustifolia Stem
bark
Vietnam Anti-inflammatory, Anti-Leishmanial
71 Normavacurine-21-One Pleiocarpaman Alstonia scholaris Leaves China Antibacterial
72 5-Hydroxy-19,20-E-Alschomine Corynanthe Alstonia scholaris Leaves China Antibacterial
73 5-Hydroxy-19,20-Z-Alschomine Corynanthe Alstonia scholaris Leaves China Antibacterial
74 Alstoniascholarine A Corynanthe Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
75 Alstoniascholarine B Corynanthe Alstonia scholaris Leaves China Antibacterial, Anti- Fungal
76 Alstoniascholarine C Corynanthe Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
77 Alstoniascholarine D Corynanthe Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
78 Alstoniascholarine E Corynanthe Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
79 Alstoniascholarine F Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
80 Alstoniascholarine G Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
81 Alstoniascholarine H Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
82 Alstoniascholarine I Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
83 Alstoniascholarine J Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
84 Alstoniascholarine K Scholarisine Alstonia scholaris Leaves China Antibacterial,
Anti- Fungal
85 Alstoniascholarine L Corynanthe Alstonia scholaris Leaves China Cytotoxicity
86 Alstoniascholarine M Corynanthe Alstonia scholaris Leaves China Cytotoxicity
87 Alstoniascholarine N Corynanthe Alstonia scholaris Leaves China Cytotoxicity
88 Alstoniascholarine O Scholarisine Alstonia scholaris Leaves China Cytotoxicity
89 Alstoniascholarine P Scholarisine Alstonia scholaris Leaves China Cytotoxicity
90 Alstoniascholarine Q Scholarisine Alstonia scholaris Leaves China Cytotoxicity
91 Scholarisine H Corynanthe Alstonia scholaris Leaves China Antibacterial
92 Scholarisine I Nareline Alstonia scholaris Leaves China Antibacterial
93 Scholarisine J Nareline Alstonia scholaris Leaves China Antibacterial
94 Scholarisine K Corynanthe Alstonia scholaris Leaves China Antibacterial
95 Scholarisine L Corynanthe Alstonia scholaris Leaves China Antibacterial
96 Scholarisine M Corynanthe Alstonia scholaris Leaves China Antibacterial
97 Scholarisine N Corynanthe Alstonia scholaris Leaves China Antibacterial
98 Melosline A Corynanthe Alstonia scholaris Leaves and twigs China Cytotoxicity
99 Melosline B Secodine Alstonia scholaris Leaves and twigs China Cytotoxicity
100 1-[2-[2-(Carboxymethyl) Indole-3-Yl] Ethyl]-3-Ethylpyridinium Hydroxide Inner Salt Secodine Alstonia scholaris Leaves and twigs China Cytotoxicity
101 Alstiyunnanenine A Sarpagine Alstonia Yunnanensis Aerial
parts
China Cytotoxicity
102 Alstiyunnanenine B Picraline Alstonia Yunnanensis Aerial
parts
China Cytotoxicity
103 Alstiyunnanenine C Akummiline Alstonia Yunnanensis Aerial
parts
China Cytotoxicity
104 Alstiyunnanenine D Scholaricine Alstonia Yunnanensis Aerial
parts
China Cytotoxicity
105 Alstiyunnanenine E Scholaricine Alstonia Yunnanensis Aerial
parts
China Cytotoxicity
106 Alstomairine A Scholaricine Alstonia Mairei Leaves China Cytotoxicity
107 Alstomairine B Scholaricine Alstonia Mairei Leaves China Cytotoxicity
108 Alstomairine C Scholaricine Alstonia Mairei Leaves China Cytotoxicity
109 Alpneumine A Scholaricine Alstonia Mairei Leaves China Cytotoxicity
110 Alstrostine G Corynanthe Alstonia rostrata Bark and trunks China Cytotoxicity
111 Alstrostine H Corynanthe Alstonia rostrata Bark and trunks China Cytotoxicity
112 Alstrostine I Scholarisine Alstonia rostrata Bark and trunks China Cytotoxicity
113 Alstrostine J Secodine Alstonia rostrata Bark and trunks China Cytotoxicity
114 Alstrostine K Corynanthe Alstonia rostrata Bark and trunks China Cytotoxicity
115 Scholarisine T Nareline Alstonia scholaris Leaves China Antibacterial
116 Scholarisine U Nareline Alstonia scholaris Leaves China Antibacterial
117 Scholarisine V Nareline Alstonia scholaris Leaves China Antibacterial
118 Scholarisine W Nareline Alstonia scholaris Leaves China Antibacterial
119 Scholarisine A Nareline Alstonia scholaris Leaves China Antibacterial
120 Scholarisine P Nareline Alstonia scholaris Leaves China Anti-inflammatory
121 Scholarisine Q Akuammiline Alstonia scholaris Leaves China Anti-inflammatory
122 Scholarisine R Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
123 Scholarisine S Nareline Alstonia scholaris Leaves China Anti-inflammatory
124 (16R)-E-Isositsnikine Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
125 Nareline Nareline Alstonia scholaris Leaves China Anti-inflammatory
126 5-Methoxystrictamine Akuammiline Alstonia scholaris Leaves China Anti-inflammatory
127 Leuconolam Aspidosperma Alstonia scholaris Leaves China Anti-inflammatory
128 Epileuconolam Aspidosperma Alstonia scholaris Leaves China Anti-inflammatory
129 Nb-Demethylalstogustine Scholarisine Alstonia scholaris Leaves China Anti-inflammatory
130 19-Epischolaricine Scholarisine Alstonia scholaris Leaves China Anti-inflammatory
131 Scholaricine Scholarisine Alstonia scholaris Leaves China Anti-inflammatory
132 Vallesamine Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
133 Akuammidine Akuammidine Alstonia scholaris Leaves China Anti-inflammatory
134 17-Nor-Excelsinidine Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
135 Strictosamide Corynanthe Alstonia scholaris Leaves China Anti-inflammatory
136 Vincamaginine A Ajmaline Alstonia penangiana Leaves Malaysia Cytotoxicity
137 Vincamaginine B Ajmaline Alstonia penangiana Leaves Malaysia Cytotoxicity
138 Alstonisinine A Macroline Oxindole Alstonia penangiana Leaves Malaysia Cytotoxicity
139 Alstonisinine B Macroline Oxindole Alstonia penangiana Leaves Malaysia Cytotoxicity
140 Alstonisinine C Macroline Oxindole Alstonia penangiana Leaves Malaysia Cytotoxicity
141 Alstonoxine F Macroline Oxindole Alstonia penangiana Leaves Malaysia Cytotoxicity
142 Angustilongine A Macroline-Akuammiline Alstonia penangiana Leaves Malaysia Cytotoxicity
143 Angustilongine B Macroline-Akuammiline Alstonia penangiana Leaves Malaysia Cytotoxicity
144 Angustilongine C Macroline-Akuammiline Alstonia penangiana Leaves Malaysia Cytotoxicity
145 Angustilongine D Macroline-Akuammiline Alstonia penangiana Leaves Malaysia Cytotoxicity
146 Winphyllines A Vincorine Alstonia rostrata Twigs China Cytotoxicity
147 Winphyllines B Scholarisine Alstonia rostrata Twigs China Cytotoxicity
148 Nb-Demethylechitamine Vincorine Alstonia rostrata Twigs China Cytotoxicity
149 17-O-Acetylnorechitamine Vincorine Alstonia rostrata Twigs China Cytotoxicity
150 12- Methoxyechitamidine Scholarisine Alstonia rostrata Twigs China Cytotoxicity
151 N(4)-Demethylastogustine Scholarisine Alstonia rostrata Twigs China Cytotoxicity
152 17-Formyl-10-Demethoxyvincorine N(4)-Oxide Vincorine Alstonia scholaris Leaves China _
153 10-Methoxyalstiphyllanine H Ajmaline Alstonia scholaris Leaves China _
154 10-Demethoxyvincorine N(4)-Oxide Vincorine Alstonia scholaris Leaves China _
155 Alstoscholactine Corynanthe Alstonia scholaris Leaves Malaysia Vasorelaxation
Cytotoxicity
156 Alstolaxepine Corynanthe Alstonia scholaris Leaves Malaysia Vasorelaxation
Cytotoxicity
157 Alstobrogaline Corynanthe Alstonia scholaris Leaves Malaysia Cytotoxicity
158 Kopsiyunnanines G Aspidosperma Kopsia arbora Aerial
parts
China _
159 Kopsiyunnanines H Aspidosperma Kopsia arbora Aerial
parts
China _
160 Kopsihainin A Aspidosperma Kopsia hainanensis Stems China Antitussive
161 Kopsihainin B Aspidofractinine Kopsia hainanensis Stems China Antitussive
162 Kopsihainin C Aspidofractinine Kopsia hainanensis Stems China Antitussive
163 Kopsinine Aspidofractinine Kopsia hainanensis Stems China Antitussive
164 Methyl Demethoxycarbonylchanofruticosinate Methyl Chanofruticosinate Kopsia hainanensis Stems China Antitussive
165 Singaporentine A Aspidofractinine Kopsia singapurensis Barks and leaves Malaysia _
166 N(1)-Formylkopsininic Acid Aspidofractinine Kopsia singapurensis Barks and leaves Malaysia _
167 N(1)-Formylkopsininic Acid-N(4)-Oxide Aspidofractinine Kopsia singapurensis Barks and leaves Malaysia _
168 15-Hydroxykopsamine Aspidofractinine Kopsia singapurensis Barks and leaves Malaysia _
169 14α-Hydroxy-N(4)-Methylcondylocarpine Aspidosoermata Kopsia singapurensis Barks and leaves Malaysia _
170 Singaporentinidine Corynanthe Kopsia singapurensis Barks and leaves Malaysia _
171 Kopsininate Aspidofractinie Kopsia hainanensis Leaves and stems China Antifungal, Antibacterial
172 N1-Decarbomethoxy Chanofruticosinic Acid Methyl Chanofruticosinate Kopsia hainanensis Leaves and stems China Antifungal, Antibacterial
173 Methyl N1- Decarbomethoxy Chanofruticosinate N(4)-Oxide Methyl Chanofruticosinate Kopsia hainanensis Leaves and stems China Antifungal, Antibacterial
174 Methyl Chanofruticosinate N(4)-Oxide Methyl Chanofruticosinate Kopsia hainanensis Leaves and stems China Antifungal, Antibacterial
175 5,6-Secokopsinine Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
176 5β-Hydroxykopsinine Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
177 16-Epi-Kopsinilam Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
178 5-Oxokopsinic Acid Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
179 Na-Demethoxycarbonyl-12-Methoxykopsine Kopsine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
180 14(S)-Hydroxy-19(R)- Methoxytubotaiwine Strychnos Kopsia jasminiflora Stem barks Thailand Cytotoxicity
181 19-Oxo-(−)-Eburnamonine Vincamine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
182 19(S)-Hydroxy-Δ14-Vincamone Vincamine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
183 Kopsinilam Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
184 Kopsinic Acid Aspidofractinine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
185 12-Methoxykopsine Kopsine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
186 Kopsanone Kopsine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
187 19(R)- Methoxytubotaiwine Strychnos Kopsia jasminiflora Stem barks Thailand Cytotoxicity
188 (−)-Eburnamonine Vincamine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
189 19-OH-(−)-Eburnamonine Vincamine Kopsia jasminiflora Stem barks Thailand Cytotoxicity, Acetylcholinesterase inhibitor
190 Δ14-Vincamone Vincamine Kopsia jasminiflora Stem barks Thailand Cytotoxicity
191 Phutdonginin Eburnane Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
192 Melodinine E Aspidosperma Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
193 Kopsilongine Aspidofractinine Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
194 Kopsamine Aspidofractinine Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
195 (−)-Methylenedioxy-11,12-Kopsinaline Aspidofractinine Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
196 Decarbomethoxykopsiline Kopsine Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
197 Vincadifformine Aspidosperma Kopsia arborea Twigs Thailand Antibacterial, Acetylcholinesterase inhibition
198 Arboridinine Corynanthe Kopsia arborea _ Malaysia Relaxation Effect
199 Kopsiyunnanines J1 and J2 Aspidosoermata Kopsia arborea Aerial
parts
China _
200 Paucidirinine Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
201 Paucidirisine Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
202 Paucidactinine Aspidosperma Kopsia pauciflora Stem bark Malaysia Cytotoxicity
203 Pauciduridine Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
204 Paucidactine D Paucidactine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
205 Paucidactine E Paucidactine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
206 Paucidisine Kopsine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
207 (−)-19-Oxoisoeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
208 (−)-19(R)-Hydroxyeburnamenine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
209 (−)-19(R)-Hydroxy-O-Ethylisoeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
210 Larutienine B Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
211 Paucidactine A Paucidactine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
212 Paucidactine B Paucidactine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
213 Paucidactine C Paucidactine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
214 5, 22-Dioxokopsane Kopsine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
215 (+)-Eburnamonine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity,
216 Eburnamenine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
217 (−)-Eburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
218 (+)-Isoeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
219 (+)-19-Oxoeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
220 (−)-19(R)-Hydroxyisoeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
221 (+)-19(R)-Hydroxyeburnamine Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
222 Larutienine A Eburnane Kopsia pauciflora Stem bark Malaysia Cytotoxicity
223 (−)-Norpleiomutine Eburnane- Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
224 (+)-Kopsoffinol Eburnane- Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
225 (−)-Demethylnorpleiomutine Eburnane- Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
226 (+)-Kopsoffine Vincamine- Aspidofractinine Kopsia pauciflora Stem bark Malaysia Cytotoxicity
227 Kopsiyunnanine M Scholarisine- Corynanthe Kopsia arborea Aerial
partss
China _
228 Arborisidine Pericine Kopsia arborea Whole plant Malayan Cytotoxicity
229 Arbornamine Arbornane Kopsia arborea Whole plant Malayan Cytotoxicity
230 Kopsinidine C Kopsine Kopsia officinalis$ Twigs and leaves China Immunosuppressive activity
231 Kopsinidine D Kopsine Kopsia officinalis$ Twigs and leaves China Immunosuppressive activity
232 Kopsinidine E Kopsine Kopsia officinalis$ Twigs and leaves China Immunosuppressive activity
233 11,12-Methylenedioxychanofruticosinic Acid Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
234 12-Methoxychanofruticosinic Acid Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
235 N(4)-Methylkopsininate Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
236 Chanofruticosinic Acid Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
237 Kopsinine Methochloride Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
238 Demethoxycarbonylkopsin Kopsine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
239 Methyl Chanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
240 Methyl 11,12-Methylenedioxychanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
241 Methyl 12-Methoxychanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
242 Methyl 11,12-Methylenedioxy-N1-Decarbomethoxychanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Twigs and leaves China Immunosuppressive activity
243 Kopsininic Acid Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
244 (−)-11,12-Methylenedioxykopsinaline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
245 (−)-N-Methoxycarbonyl-11,12-Methylenedioxykopsinaline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
246 (−)-N-Methoxycarbonyl- 12-Methoxykopsinaline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
247 N-Carbomethoxy-11-Hydroxy-12- Methoxykopsinaline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
248 Kopsinoline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
249 (−)-12-Methoxykopsinaline Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
250 11,12-Methylenedioxykopsinaline N(4)- Oxide Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
251 Kopsinine B Aspidofractinine Kopsia officinalis Twigs and leaves China Immunosuppressive activity
252 Rhazinilam Aspidosperma Kopsia officinalis Twigs and leaves China Immunosuppressive activity
253 Pleiocarpamine Methochloride Corynanthe Kopsia officinalis Twigs and leaves China Immunosuppressive activity
254 Kopsioffine A Aspidosperma Kopsia officinalis Leaves and stems China Yeast α-glucosidase inhibitory
255 Kopsioffine B Aspidosperma Kopsia officinalis Leaves and stems China Yeast α-glucosidase inhibitory
256 Kopsioffine C Aspidosperma Kopsia officinalis Leaves and stems China Yeast α-glucosidase inhibitory
257 Kopsifoline G Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
258 Kopsifoline H Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
259 Kopsifoline I Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
260 Kopsifoline J Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
261 Kopsifoline K Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
262 Kopsifoline A Aspidosperma Kopsia fruticose Aerial
parts
China Cytotoxicity, Antifungal, Antibacterial
263 Kopsiarborine A Aspidofractinine Kopsia arborea Aerial parts China Cytotoxicity
264 Kopsiarborine B Methyl Chanofruticosinate Kopsia arborea Aerial
parts
China Cytotoxicity
265 Kopsiarborine C Aspidosperma Kopsia arborea Aerial parts China Cytotoxicity
266 Kopsiaofficine A Aspidofractinine Kopsia officinalis Aerial parts China Cytotoxicity
267 Kopsiaofficine B Paucidactine Kopsia officinalis Aerial parts China Cytotoxicity
268 Kopsiaofficine C Aspidofractinine Kopsia officinalis Aerial parts China Cytotoxicity
269 Kopsiofficine H Eburnane Kopsia officinalis Stems China Anti-inflammatory
270 Kopsiofficine I Eburnane Kopsia officinalis Stems China Anti-inflammatory
271 Kopsiofficine J Eburnane Kopsia officinalis Stems China Anti-inflammatory
272 Kopsiofficine K Eburnane Kopsia officinalis Stems China Anti-inflammatory
273 Kopsiofficine L Kopsine Kopsia officinalis Stems China Anti-inflammatory
274 (+)-O-Methyleburnamine Eburnane Kopsia officinalis Stems China Anti-inflammatory
275 (−)-O-Methylisoeburnamine Eburnane Kopsia officinalis Stems China Anti-inflammatory
276 16-Isoeburnamine Eburnane Kopsia officinalis Stems China Anti-inflammatory
277 20-Oxoeburnamenine Eburnane Kopsia officinalis Stems China Anti-inflammatory
278 Methyl 11, 12-Methylenedioxychanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Stems China Anti-inflammatory
279 Methyl N-(Decarbomethoxy)-11,12-(Methylenedioxy) Chanofruticosinate Methyl Chanofruticosinate Kopsia officinalis Stems China Anti-inflammatory
280 O-Methylleuconolam Aspidosperma Kopsia officinalis Stems China Anti-inflammatory
281 Leuconodine D Aspidosperma Kopsia officinalis Stems China Anti-inflammatory
282 Oxayohimban-16-Carboxylic Acid Corynanthe Kopsia officinalis Stems China Anti-inflammatory
283 19, 20-Dihydroisositsirikine Corynanthe Kopsia officinalis Stems China Anti-inflammatory
284 Rauvomine A Sarpagine Rauvolfia vomitoria Aerial
parts
China Anti-inflammatory
285 Rauvomine B Sarpagine Rauvolfia vomitoria Aerial parts China Anti-inflammatory
286 Peraksine Sarpagine Rauvolfia vomitoria Aerial parts China Anti-inflammatory
287 Alstoyunine A Sarpagine Rauvolfia vomitoria Aerial parts China Anti-inflammatory
288 11-Hydroxyburnamine Picraline Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
289 Rauvoyunnanine A Sarpagine Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
290 Rauvoyunnanine B Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
291 Lochnerine Sarpagine Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
292 Serpentinic Acid Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
293 Reserpine Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
294 (−)-Yohimbine Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
295 Ajmaline Ajmaline Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
296 Mauiensine Ajmaline Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
297 Ajmalicine Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
298 Sitsirikine Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
299 Strictosidinic Acid Strictosidine Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
300 Caboxine B Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
301 Isocaboxine B Corynanthe Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
302 Spegatrine Sarpagine Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
303 19(S),20(R)-Dihydroperaksine Sarpagine Rauvolfia yunnanensis Whole plant China Cytotoxicity Immunosuppressive
304 Ervataine Iboga Ervatamia yunnanensis Stems China _$
305 Ibogaine Iboga Ervatamia yunnanensis Stems China _$
306 Coronaridine Iboga Ervatamia yunnanensis Stems China Acetylcholinesterase Inhibition
307 Heyneanine Iboga Ervatamia yunnanensis Stems China _
308 Voacangine Hydroxyindolenine Iboga Ervatamia yunnanensis Stems China _
309 Coronaridine Hydroxyindolenine Iboga Ervatamia yunnanensis Stems China _
310 10-Hydroxycoronaridine Iboga Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
311 Voacangine Iboga Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
312 19(S)-Heyneanine Iboga Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
313 19(R)-Heyneanine Iboga Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
314 Heyneanine Hydroxyindolenine Iboga Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
315 Vobasine Vobasine Ervatamia hainanensis Stems China Acetylcholinesterase inhibition
316 Ervachinine E Iboga Ervatamia chinensis Whole plants China Cytotoxicity
317 Rutaecarpine Corynanthe Ervatamia chinensis Whole plants China Cytotoxicity
318 Ervahainine A Iboga Ervatamia hainanensis Leaves and twigs China Cytotoxicity
319 Ervaoffine A Iboga Ervatamia officinalis Leaves and twigs China _
320 Ervaoffine B Iboga Ervatamia officinalis Leaves and twigs China _
321 Ervaoffine C Iboga Ervatamia officinalis Leaves and twigs China _
322 Ervaoffine D Iboga Ervatamia officinalis Leaves and twigs China _
323 (7S)-3-Oxoibogaine Hydroxyindolenine Iboga Ervatamia officinalis Leaves and twigs China _
324 Ibogaine- 5,6-Dione Iboga Ervatamia officinalis Leaves and twigs China _
325 19-Epi-5-Oxovoacristine Iboga Ervatamia officinalis Leaves and twigs China _
326 Iboluteine Ervatamia officinalis Leaves and twigs China _
327 (7S)- Ibogaine Hydroxyindolenine Iboga Ervatamia officinalis Leaves and twigs China _
328 Ibogaline Iboga Ervatamia officinalis Leaves and twigs China _
329 Conopharyngine Iboga Ervatamia officinalis Leaves and twigs China _
330 Voacristine Iboga Ervatamia officinalis Leaves and twigs China _
331 19S -Hydroxyibogamine Iboga Ervatamia officinalis Leaves and twigs China _
332 Ibogaine N4-Oxide Iboga Ervatamia officinalis Leaves and twigs China _
333 3-Oxo-7r-Coronaridine Hydroxyindolenine Iboga Ervatamia hainanensis Leaves and twigs China _
334 3S-Cyano-7S-Coronaridine Hydroxyindolenine Iboga Ervatamia hainanensis Leaves and twigs China _
335 3R-Hydroxy-7S-Coronaridine Hydroxyindolenine Iboga Ervatamia hainanensis Leaves and twigs China _
336 3S -(24S-Hydroxyethyl)-Coronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
337 3S -(24R-Hydroxyethyl)-Coronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
338 5-Oxo-6S-Hydroxycoronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
239 5-Oxo-6S -Methoxy-Coronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
340 7S-coronaridine hydroxyindolenine Iboga Ervatamia hainanensis Leaves and twigs China _
341 3-Oxo-7S-Coronaridine Hydroxyl Indolenine Iboga Ervatamia hainanensis Leaves and twigs China _
342 5-Oxocoronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
343 3-Oxocoronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
344 Pseudoindoxyl Coronaridine Iboga Ervatamia hainanensis Leaves and twigs China _
345 Ervaoffine E Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
346 Ervaoffine f Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
347 Ervaoffine G Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
348 Lirofoline A Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
349 Lirofoline B Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
350 6-Oxo-Ibogaine Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
351 8-Oxo-Ibogaine Lactam Iboga Ervatamia officinalis Leaves and twigs China Neuroprotective
352 Erchinine A Iboga Ervatamia chinensis Roots China Antibacterial, Antifungal
353 Erchinine B Iboga Ervatamia chinensis Roots China Antibacterial, Antifungal
354 Ervapandine A Iboga Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
355 3R-Hydroxyibogaine Iboga Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
356 12-Hydroxyakuammicine N4-Oxide Akuammicine Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
357 19-Epi-Voacristine Iboga Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
358 Taberdivarine I Iboga Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
359 12-Hydroxyakuamicine Akuammicine Ervatamia pandacaqui Leaves and twigs China Cytotoxicity
360 Ervadivamine A Vobasine-Iboga-Vobasine Ervatamia divaricate Roots China Cytotoxicity
361 Ervadivamine B Vobasine-Iboga-Vobasine Ervatamia divaricate Roots China Cytotoxicity
362 19,20-Dihydroervahanine A Vobasine-Iboga Ervatamia divaricate Roots China Cytotoxicity
363 Ibogamine Iboga Ervatamia divaricate Roots China Cytotoxicity
364 Ervatamine Flabelliformide Ervatamia yunnanensis Stems China _
365 20-Epi-Ervatamine Flabelliformide Ervatamia yunnanensis Stems China _
366 Dregamine Vobasine Ervatamia yunnanensis Stems China _
367 Tabernaemontanine Vobasine Ervatamia yunnanensis Stems China _
368 Apparicine Iboga Ervatamia yunnanensis Stems China _
369 Isovoacangine Apparicine Ervatamia yunnanensis Stems China _
370 Conodusine A Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
371 Conodusine B Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
372 Conodusine C Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
373 Conodusine D Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
374 Conodusine E Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
375 Apocidine A Aspidosperma Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
376 Apocidine B Aspidosperma Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
377 Conoduzidine A Vincamine Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
378 Tabernamidine A Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
379 Tabernamidine B Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
380 (+)-Catharanthine Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
381 Tabernamine Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
382 19′(S)-Hydroxytabernamine Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
383 19′(R)-Hydroxytabernamine Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
384 16′-Decarbomethoxyvoacamine Vobasine-Iboga Tabernaemontana corymbosa Stem bark Malaysia Cytotoxicity
385 Isoakuammiline Corynanthe Tabernaemontana litoralis Fruits USA _
386 18-Hydroxypseudovincadifformine Iboga Tabernaemontana litoralis Fruits USA _
387 3,19-Oxidocoronaridine Iboga Tabernaemontana litoralis Fruits USA _
388 Strictosidine Strictosidine Tabernaemontana litoralis Fruits USA _
389 $Tabervarine A Iboga Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
390 $Tabervarine B Iboga Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
391 Vobasidine C Vobasine Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
392 Ervadivaricatine B Vobasine-Iboga Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
393 Pedunculine Aspidosperma- Aspidosperma Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
394 Polyervine Aspidosperma- Aspidosperma Tabernaemontana divaricate Leaves and twigs China Cytotoxicity
395 Flabellipparicine Flabelliformide-Apparicine Tabernaemontana divaricate Stems China Cytotoxicity
396 19,20-Dihydrovobparicine Vobasine-Apparicine Tabernaemontana divaricate Stems China Cytotoxicity
397 10′- Demethoxy-19,20-Dihydrovobatensine D Vobasine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
398 3′-(2-Oxopropyl)Ervahanine A Sarpagine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
399 Ervahanine A Sarpagine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
400 Vobparicine Vobasine-Apparicine Tabernaemontana divaricate Stems China Cytotoxicity
401 19,20-Dihydrotabernamine Vobasine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
402 19,20-Dihydrotabernamine A Vobasine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
403 Taberdivarines E Vobasine-Iboga Tabernaemontana divaricate Stems China Cytotoxicity
404 Tubotaiwine Strychnos Tabernaemontana divaricate Stems China Cytotoxicity
405 Hydroxy-3-(2-Oxopropyl) Coronaridine Indolenine Iboga Tabernaemontana divaricate Stems China Cytotoxicity
406 Deoxytubulosine Corynanthe bisindole Tabernaemontana divaricate Stems China Cytotoxicity
407 (3R,7S,14R,19S,20R)-19-Hydroxypseudovincadifformine Iboga Tabernaemontana bufalina Branches and leaves China Cytotoxicity
408 17-Demethoxy-Hydroisorhyn Chophylline Corynanthe Tabernaemontana bufalina Branches and leaves China Cytotoxicity
409 17-Demethoxy-Isorhynchophylline Corynanthe Tabernaemontana bufalina Branches and leaves China Cytotoxicity
410 Voachalotine Akuammidine Tabernaemontana bufalina Branches and leaves China Cytotoxicity
411 12-Methoxyl-Voaphylline Aspidosperma Tabernaemontana bufalina Branches and leaves China Cytotoxicity
412 Conophylline Aspidosperma- Aspidosperma Tabernaemontana bufalina Branches and leaves China Cytotoxicity
413 5,6-Dioxo-11-Methoxy Voacangine Iboga Tabernaemontana contorta Fruits Cameroon Anti-inflammatory
414 (−)-Apparicin-21-One Apparicine Tabernaemontana contorta Fruits Cameroon Anti-inflammatory
415 Tabernabovine A Corynanthe bisindole Tabernaemontana bovina Leaves China Anti-inflammatory
416 Tabernabovine B Aspidosperma Tabernaemontana bovina Leaves China Anti-inflammatory
417 Tabernabovine C Iboga Tabernaemontana bovina Leaves China Anti-inflammatory
418 Secopleiocarpamine A Corynanthe Rhazya stricta Aerial parts Pakistan Antifungal
419 16,17-Epoxyisositsirikine Corynanthe Rhazya stricta Aerial parts Pakistan Antifungal
420 2-Ethyl-3[2-(3-Ethyl-1,2,3,6-Tetrahydropyridine)Ethyl]-Indole Secodine Rhazya stricta Aerial parts Pakistan Antifungal
421 2-Ethyl-3[2-(3-Ethylpiperidine)Ethyl]-Indole Secodine Rhazya stricta Aerial parts Pakistan Antifungal
422 Tetrahydrosecodine Secodine Rhazya stricta Aerial parts Pakistan Antifungal
423 16,17-Dihydrosecodine Secodine Rhazya stricta Aerial parts Pakistan Antifungal
424 Deacetylakuammilin Akuammiline Rhazya stricta Aerial parts Pakistan Antifungal
425 Rhazimal Akuammiline Rhazya stricta Aerial parts Pakistan Antifungal
426 Strictamine-N-Oxide Akuammiline Rhazya stricta Aerial parts Pakistan Antifungal
427 Rhazinaline Akuammiline Rhazya stricta Aerial parts Pakistan Antifungal
428 Rhazinaline Nb-Oxide Akuammiline Rhazya stricta Aerial parts Pakistan Antifungal
429 Akuammicine Akummicine Rhazya stricta Aerial parts Pakistan Antifungal
430 16R-E-Isositsirikine Corynanthe Rhazya stricta Aerial parts Pakistan Antifungal
431 Dihydrositsirikine Corynanthe Rhazya stricta Aerial parts Pakistan Antifungal
432 Antirhine Corynanthe Rhazya stricta Aerial parts Pakistan Antifungal
433 Vincadifformine N(4)-Oxide Aspidosperma Rhazya stricta Aerial parts Pakistan Antifungal
434 Eburenine Aspidosperma Rhazya stricta Aerial parts Pakistan Antifungal
435 Winchinine B Aspidosperma Rhazya stricta Aerial parts Pakistan Antifungal
436 Quebrachamine Aspidosperma Rhazya stricta Aerial parts Pakistan Antifungal
437 Strictanol Aspidosperma Rhazya stricta Aerial parts Pakistan Antifungal
438 16-Epi-Stemmadenine-N-Oxide Corynanthe Rhazya stricta Leaves Saudi Arabia Cytotoxicity
439 Stemmadenine-N-Methyl Corynanthe Rhazya stricta Leaves Saudi Arabia Cytotoxicity
440 20-Epi-Antirhine Corynanthe Rhazya stricta Leaves Saudi Arabia Cytotoxicity
441 Isopicrinine Picrinine Rhazya stricta Leaves Saudi Arabia Cytotoxicity
442 Epirhazyaminine Rhazya stricta Aerial parts Saudi Arabia Cytotoxicity
443 20-Epi-sitsirikine Rhazya stricta Aerial parts Saudi Arabia Cytotoxicity
444 Strictamine Rhazya stricta Aerial parts Saudi Arabia Cytotoxicity

Figure 3.

Figure 3

The types of the structures identified monoterpenoid alkaloids from the six genera.

Figure 4.

Figure 4

Common monoterpenoid indole alkaloidal skeletons of the six genera.

Additionally, the future prospective and emphasizing the research gaps and highlighting the roadmap to discover the potent bioactive monoterpenoid alkaloids, which could be a drug lead from the six genera. Also, this review will discuss the reported structural activity relationships.

2. Alstonia

Plants of the genus Alstonia are grown in Africa and Asia. It includes 60 species, which were recognized as rich source of heterocyclic monoterpene indole alkaloids. It has different names according to the geographical sources, including Devil tree, Australian fever bush, dita bark, Australian quinine, fever bark and palimara. Alstonia bark shows potent therapeutic effects including anti-inflammatory, antirheumatic, analgesic, antidiabetic, antimalarial, antipyretic, antihelminthic, antibiotic, antimicrobial, anticancer, antibacterial and antitussive effects [18,19,20].

Three monoterpene indole alkaloids (MIAs) derivatives, (14α,15α)-14,15-epoxyaspidofractinine (1) and maireines A (2) and B (3) have been isolated from the leaves and twigs of A. mairei [21]. Additionally, venalstonine (4) [22], (−)-minovincinine (5) [23], (−)-11-methoxyminovincinine (6) [24], (−)-echitovenine (7) [25], echitovenaldine (8) [26], echitovenidine (9), 11-methoxyechitovenidine (10) [27], echitoveniline (11), 11-methoxyechitoveniline (12) [24], echitoserpidine (13) [28],11-methoxyechitoserpidine (14) [29], (19S)-vindolinine (15) [22], lochnericine (16), tabersonine (17) [30], perakine (18) [31], picrinine (19) [32], F (20) [33], picralinal (21) [34] and rhazimol (22) [35] were isolated from the same species (Figure 5). These compounds were elucidated through the interpretation of different spectroscopic measurements including 1D and 2D NMR and MS. Interesting in compound (1) was the interpretation of the Rotating Frame Overhauser Enhancement Spectroscopy (ROSY) spectrum led to the establishment of the α-orientation of the epoxy moiety. Compounds 122 were evaluated against five human cancer cells, hepatocellular carcinoma (SMMC-7721), breast (SK-BR-3), pancreatic (PANC-1), human myeloid leukemia (HL-60), and lung (A-549) with IC50 values > 40 μM [21].

Figure 5.

Figure 5

Compounds 122.

The majority of reported alkaloids from A. scholaris, were of the picrinine type whereas, those isolated from A. yunnanensis were either picrinine or aspidospermine types.

Alsmaphorazines A (23) and B (24) (Figure 6) were identified from the leaves of malaysian A. pneumatophore. The chemical structures were determined on the basis of 2D NMR and MS spectral analysis. These compounds had an unprecedented skeleton containing an 1,2-oxazine (six-member ring) and an isoxazolidine (five-member ring) [36]. The absolute configuration of alsmaphorazine B was determined using CD spectral analysis. The absolute configuration of alsmaphorazine B (24) was studied by comparing its experimental CD spectrum with the calculated CD spectrum, with the CD calculations performed by Turbomole 6.1using the Time-Dependent Density Functional Theory (TD-DFT-B3LYP/TZVPP) level of theory on RI-DFTBP386LYP/TZVPP optimized geometries. Compound 23 inhibited the production of nitric oxide (NO) in an LPS-stimulated J774.1 cell with an IC50 value = 49.2 μM, without affecting the cell viability, whereas compound 24 showed no inhibitory effect at 50.0 μM. Compound 23 was more potent as an anti-inflammatory agent due to the presence of a hydroxyl group at C-12 [36].

Figure 6.

Figure 6

Compounds 2330.

Alstrostines A (25) and B (26) were determined as derived from the condensation of tryptophan and secologanin in a ratio of 1:2. They were isolated from Alstonia rostrata [37]. The structures were established by measuring 1H, 13C, HSQC, HMBC, 1H-1H COSY and ROESY. Compounds, 25 and 26, exhibited a weak cytotoxicity against five human cancer cells, hepatocellular carcinoma (SMMC-7721), breast (MCF-7), colon (SW480), myeloid leukemia (HL-60) and lung (A-549), with IC50 values > 40 μM [37].

Alstrostines C-F (2730) (Figure 6) were isolated from the leaves and twigs of Chinese A. rostrata [38]. Compounds 2730 showed a characteristic UV absorption at 326, 275 and 214 nm, which indicated the presence of an indole alkaloid with a β-anilineacrylate system. The chemical structure elucidation was confirmed by 1D and 2D NMR. Compounds 2730 showed weak cytotoxicity against five human cancer cells, breast (SK-BR-3), human myeloid leukemia (HL-60), pancreatic (PANC-1), hepatocellular carcinoma (SMMC-7721) and lung (A-549) cells, with IC50 values > 40 μM [38].

Five MIAs, 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (31), 14-chloro-15-hydroxyvinca difformine (32), perakine N4-oxide (33), raucaffrinoline N4-oxide (34), and vinorine N1,N4-dioxide (35) (Figure 7) have been reported from A. yunnanensis. Additionally, three compounds, 11-methoxy-6,7-epoxy-8-oxovincadifformine (36), vinorine N4-oxide (37) and vinorine (38) have also been found from the same plant [39]. The chemical structures were established based on 1D and 2D (1H-1H-COSY, HMQC, HMBC, and ROESY) NMR spectroscopy. Compounds 33, 34, and 37 showed cytotoxicity against astrocytoma and glioma cells (CCF-STTG1, CHG-5, SHG-44 and U251) with IC50 values ranging from 9.2 to 17.4 μM. Adriamycin was used as positive control and showed cytotoxicity with an IC50 value ranging from 21.8 to 33.7 μM. These compounds exhibited a cytotoxic effect against breast cancer (MCF-7) and human skin cancer (SK-MEL-2) with IC50 values ranging from 28.1 to 35.5 μM. Adriamycin was used as positive control and exhibited a cytotoxic effect with IC50 values ranging from 14.1 to 37.6 μM [39]. Alkaloids 35 and 38 displayed no cytotoxic activities or selective inhibition of COX-2 comparable to those of 33, 34 and 37 although they possess the same monoterpene indole skeleton. The observations indicated that a N4-oxide functionality was essential for cytotoxic and anti-inflammatory properties, while a N1-oxide maybe weaken the cytotoxic activities for this type of alkaloids. The observations indicated that the presence of oxide in N4 was essential for cytotoxic and anti-inflammatory activities, while the presence of the oxide on N1-oxide led to decreasing the cytotoxicity.

Figure 7.

Figure 7

Compounds 3138.

Alsmaphorazines (C) (39), (D), (40), and (E) (41) (Figure 8) were elucidated from A. pneumatophore [40]. The planar structure of 39 was elucidated by 2D NMR and MS. This alkaloid possesses a novel ring skeleton containing an octahydropyrrolo[2,3-b]pyrrole unit. The absolute configuration of (39) was determined by the modified Mosher’s method and also confirmed by measuring the CD spectrum, which fully agreed with the CD calculations. Compounds 3941 showed no cytotoxicity and also weak anti-melanogenesis activity against HL-60 and B16F10 cells with IC50 values >100 μM [40].

Figure 8.

Figure 8

Compounds 3951.

New scholarisins I-VII (4248), and (3R,5S,7R,15R,16R,19E)-scholarisine F (49) [41], along with three known indoles: 3-epi-dihydrocorymine (50), and (E)-16-formyl-5α-methoxystrictamine (51) were identified from the leaves of Alstonia rupestris (Figure 8) [42]. Compounds 42, 47, and 51 showed significant cytotoxicity against cancer cells, A-549, BGC-823, HepG2, HL-60, MCF-7, SMMC-7721, and SW480 with IC50 values < 30 μM. These compounds exhibited selective inhibition effect of COX-2 with IC50 values ranging between 92.0 and 96.4 μM, while compounds 43, 44, and 4850 displayed a weak cytotoxicity towards the tested tumor cells with IC50 values > 40 μM. Furthermore, alkaloids 45 and 46 showed a weak cytotoxicity with IC50 values > 80 μM. Doxorubicin was used as a positive control and showed with IC50 value < 35 µM. These activities of 45 and 46, indicated that the bond connection between C-5 and N-4 was essential for the cytotoxicity [41]. Compounds 42, 43, 44 and 49 showed antifungal activity against Gibberella pulicaris (KZN 4207) and Colletotrichum nicotianae (SACC-1922) with MIC values of 0.64 and 0.69 mM; 1.37 and 1.44 mM; 1.80 and 1.91 mM and 1.55 and 1.71 mM, respectively. Nystatin was implemented as a positive control and showed MIC values of 0.007 and 0.006 mM. These bioactivities may be due to the presence of a formyl group at C-16 in the alkaloids subclasses picrinine in 42, vincorine in 47, and akuammiline in 51, respectively and also may play a role in anti-inflammatory activity [41].

Alstolactines A (52), B (53), and C (54) (Figure 9) were isolated from the leaves of chines A. scholaris [43]. The structures were identified by extensive spectroscopic data analyses and X-ray diffraction analyses. The absolute stereochemistry was deduced from crystal X-ray diffraction. These compounds are biosynthetically originated from picrinine, which is the main metabolite in A. scholaris. Compounds 5254 exhibited no effects against four bacterial strains: Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus [43].

Figure 9.

Figure 9

Compounds 5260.

Moreover, Alistonitrine A (55) (Figure 9) had an unprecedented caged carbon skeleton with a unique 6/5/6/5/5/6 ring system and also contained three nitrogen atoms. It was isolated from the same species [12]. Its structure and absolute configuration were established by extensive spectroscopic analyses and electron circular dichroism calculations. Compound 55 exhibited no activity as an anti-inflammatory in both NF-κB and HIF-α models [12].

The MIAs, 6,7-epoxy-8-oxo-vincadifformine (56), 11-acetyl-6,7-epoxy-8-oxo-vincadifformine (57), 11-hydroxy-14-chloro-15-hydroxyvincadifformine (58) and perakine N1,N4-dioxide (59) were identified from the aerial parts of A. rupestris. Additionally, 11-hydroxy-6,7-epoxy-8-oxovincadifformine (60) and 35 were isolated from the same species [44].

Compounds 56, 57 and 60 exhibited potent cytotoxic effects against head and neck squamous cancer (SCL-1, Detroit-562, UMSCC-1, CAL-27, TCA-83, HepG2 and SCC-PKU) cells, with IC50 values < 20 μM. Doxorubicin was implemented as a positive control and showed cytotoxicity, with IC50 values ≤ 35.4 µM. Compound 56 exhibited potent effect, with IC50 values ≤ 13.7 μM. This may be due to the absence of any substitution at the phenolic ring. This can be explained by the fact that the attachment of electron-donating groups (OH and OAc) led to a reduction in the cytotoxicity [44]. Compounds 56, 57, and 60 displayed significant antifungal activities against Alternaria alternata and Phytophthora capsici, with MIC values = 0.66 & 0.99 mM, 0.87 & 1.10 mM and 1.53 & 1.64 mM, respectively. Nystatin was implemented as positive control and showed effect with MIC values 0.007 and 0.061 mM. Compounds 56, 57, and 60 displayed moderate activity against Staphylococcus aureus, with MIC values of 15.72, 16.33 and 14.91 mM. Meanwhile, compounds 59 and 35 exhibited potent effects against Staphylococcus aureus, with MIC values of 0.49 and 0.83 mM. Rifampicin was used as a positive control and showed an effect at MIC valued = 0.003 mM for bacteria. Additionally, compound 59 showed higher antibacterial effects toward S. aureus than compound 35. The present of a formyl group at the C-20 position might increase the activities for ajmaline indole alkaloids [44].

The bioassay-guided fractionation of the stem bark of Vietnamese Alstonia angustifolia using the HT-29 human colon cancer cells, led to the reporting of six MIAs, N(4)-methyl-talpinine (61) [45], N(4)-meth-yl-N(4),21-secotalpinine (62) [46], alstonerinal (63) [47], alstonerine (64) [48], macrocarpine B (65) [46], affinisine (66) [49], from the stem bark of A. angustifolia. Additionally, villalstonine (67), villalstonine N(4)-oxide (68) [50], villalstonidine D (69) and villalstonidine E (70) [51] (Figure 10) were identified from the same plant.

Figure 10.

Figure 10

Compounds 6170.

Compounds 61 and 66 are sarpagine-type and compounds 6265 are macroline-derived alkaloids whereas macroline-pleiocarpamine bisindole alkaloids are present in compounds 6770.

Compound 61 showed significant inhibitory activity toward NF-κB (p65), with an ED50 value = 1.2 μM. Rocaglamide was employed as a positive control, with ED50 value = 0.9 μM. Compounds 6164, 66 and 6870 showed anti-leishmanial activity toward the promastigotes of Leishmania Mexicana, with IC50 values < 183.5 μM. Compound 62 exhibited a potent effect, with IC50 value = 57.8 μM. Amphotericin B was employed as a positive control and exhibited potent effect against L. mexicana promastigote, with an IC50 value = 0.09 μM. The dimeric compounds 6870, which contain quaternary ammonium cation at N(4), exhibited potent effect than compound 67. Additionally, compound 67 has not function group at N(4) [45]. Also, the presence of formyl and acetyl groups in 6264. These moieties may enhance the effects of compounds belonging to macroline indole alkaloids compared with 65.

Normavacurine-21-one (71), 5-hydroxy-19, 20-E-alschomine (72), and 5-hydroxy-19, 20-Z-alschomine (73) (Figure 11), were isolated from the leaves of Alstonia scholaris cultivated in Kunming, China [52]. Compound 71 exhibited a significant antimicrobial effect against Enterococcus faecalis ATCC 10541, with an MIC = 0.78 μg/mL, whereas compound 73 showed a significant effect against Pseudomonas aeruginosa ATCC 27853, with an MIC value = 0.781 μg/mL. Cefotaxime was used as a positive control, with an MIC = 0.19 μg/mL [52]. Alstoniascholarines A-Q (7490), were identified from the leaves of A. scholaris collected from Yunnan [53,54]. Compounds 79 and 83 showed a potent antibacterial activity against Pseudomonas aeruginosa ATCC 27853, with MIC value = 3.13 mg/mL. Gentamycin was applied as a Positive control and showed an inhibitory effect, with an MIC value = 0.78 mg/mL. Additionally, compounds 77, 80, and 83 exhibited moderate antifungal activities toward Epidermophyton floccosum CBS 566.94, with MIC value s= 31.25 mg/mL. Griseofulvin was applied as a positive control and showed an inhibitory effect, with an MIC value = 7.81 mg/mL [53]. Compounds 8590 showed no cytotoxicity against five tumor cell: MCF-7, A-549, HL-60, SW-480, and SMMC-7721[54].

Figure 11.

Figure 11

Compounds 7190.

Scholarisines H-O (9197) (Figure 12) were isolated from the leaves of the Chinese A. scholaris [55]. The chemical structures were elucidated on the basis of comprehensive spectroscopic data and X-ray diffraction. Compounds 9197 showed weak antibacterial activities against five strains: Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25922, Escherichia coli ATCC 11775, Providencia smartii ATCC 29916, and Enterococcus faecalis ATCC 10541), with MIC values = 100 μg/mL. Gentamycin was used as a positive control, with an MIC value < 2.00 μg/mL [55].

Figure 12.

Figure 12

Compounds 9197.

A further study on the leaves and twigs of A. scholaris [56] led to identification of melosline A (98), B (99) and 1-[2-[2-(carboxymethyl) indole-3-yl] ethyl]-3-ethylpyridinium hydroxide inner salt (100) (Figure 13) [57]. Melosline A (98) was an unprecedented indole alkaloid, with a 6/5/6/6 tetracyclic ring skeleton. The structures were established by spectroscopic analyses. The absolute configuration of 98 was confirmed by the comparison of experimental data with the calculated electronic circular dichroism (ECD). Compound 98 showed a moderate cytotoxic activity against breast cancer (MCF-7), with an IC50 value = 39.78 μM. Cisplation was employed as a positive control [56].

Figure 13.

Figure 13

Compounds 98109.

Alstiyunnanenines A-E (101105) (Figure 13) and alstoniascholarine I (82) (Figure 11), were isolated from A. yunnanensis [54,58]. Compounds 104, 105, and 82 displayed potent cytotoxicity against human gastric carcinoma (BGC-823 cells), human hepatocellular, (HepG2 cells), human myeloid leukemia (HL-60), human breast cancer (MCF-7), and osteosarcoma (SOSP-9607, MG-63, Saos-2, M663), with IC50 values ranging between 3.2 and 5.8 μM. Adriamycin was used as a positive control and exhibited cytotoxicity, with an IC50 value < 0.04 μM [58]. Three monoterpenoid indoles, alstomairines A-C (106108) [59], together with alpneumine A (109) [60] were identified from the leaves of the chines A. mairei. Compounds 107 and 108 showed potent cytotoxic effects against osteosarcoma cells (U2-OS, Mg-63, Saos-2, and SOSP-9607) with IC50 values ranging from 9.2 to 13.0 μM, whereas compounds 106 and 109 had IC50 values < 15.0 μM. The presence of the methyl group on N-4 indicate increasing the cytotoxicity in that scholaricine-type (Figure 4) than the presence of N(4)-oxide moiety. Doxorubicin was used as Positive control and showed cytotoxicity, with an IC50 value < 0.03 μM [59].

Alstrostine G-K (110114) (Figure 14), were identified from the Chinese A. rostrata [61]. Compounds 110114 showed no cytotoxicity against HeLa, SGC-7901 gastric cancer, and A-549 lung cancer at 20 µM [61].

Figure 14.

Figure 14

Compounds 110114.

Six nareline-type indoles including three cage-like skeletons, scholarisines T-V (115117) [62] (Figure 15), and three previously identified analogues scholarisine W (118), scholarisine A (119), and scholarisine I (92) [55], were isolated from the leaves of the Chinese A. scholaris [56]. Compounds 115117 displayed anti-bacterial effects against Escherichia coli ATCC 8739, with an MIC value = 0.78 μg/mL. Additionally, compound (116) inhibited the growth of Bacillus subtilis ATCC 6633 bacterium with an MIC value = 3.12 μg/mL and was referenced with cefotaxime as a positive control. The absence of the ethyl group at C-20 position indicated an increase in the anti-bacterial activities as in 116, compared with compounds (115 and 117) [63]. Cefotaxime was used as a positive control and exhibited an inhibitory effect, with an MIC value of 0.39 μg/mL. There were scholarisines P-S (120123), (16R)-E-isositsnikine (124) [64], nareline (125) [65], 5-methoxystrictamine (126), leuconolam (127), epileuconolam (128) [66], and Nb-demethylalstogustine (129) [67]. Also, 19-epischolaricine (130), scholaricine (131), vallesamine (132) [68], akuammidine (133) [69], 17-nor-excelsinidine (134) [70], strictosamide (135) [71,72] and compounds 19 and 21, were isolated from the same species. Compounds 123, 19, 21, 130 and 133 exhibited significant NF-κB inhibitory activity with IC50 < 25 μM. Furthermore, compounds 19, 126 and 130 inhibited TNFα-induced NF-κB activation in the same dose. Three nareline-type MIAs, compounds (120, 123 and 125) were identified from A. scholaris [73].

Figure 15.

Figure 15

Compounds 115135.

Two ajmaline type MIAs, vincamaginine A (136), and vincamaginine B (137); four macroline oxindole- alstonisinines A (138) and B (139), alstonisinine C (140), and alstonoxine F (141); four bisindole compounds of macroline-akuammiline type; angustilongine A–D (142145) (Figure 16) were reported from Malaysian Alstonia penangiana [73]. The structures of these alkaloids were determined by the interpretation of spectroscopic data and compounds 141142, were confirmed by X-ray diffraction analysis. Compounds 142 and 143 showed growth inhibitory activity against human prostate carcinoma (LNCaP and PC-3), human breast adenocarcinoma (MDA-MB-231 and MCF7), human colorectal carcinoma (HCT 116 and HT-29) and human lung carcinoma (A549). Furthermore, the potent effects of 142 and 143 against HT-29 cells were evaluated, with IC50 values = 0.7 ± 0.1 μM and 0.3 ± 0.0 μM, respectively (Cisplatin, IC50 >10 μM). Compound 143 exhibited an effect against vincristine-resistant KB cells, with an IC50 value of 0.7 ± 0.3 μM (Vincristine 0.3 ± 0.1 μM) [73].

Figure 16.

Figure 16

Compounds 136145.

Winphyllines A (146), B (147) [74], Nb-demethylechitamine (148) [75], 17-O-acetylnorechitamine (149) (Figure 17) [76], 12-methoxyechitamidine (150) [67], and N(4)-demethylastogustine (151) [77] were isolated from the collected twigs of the Chinese A. rostrata. Compounds 146151 exhibited cytotoxicity against cancer cells (HL-60, SMMC-7721, A-549, MCF-7, and SW480), with IC50 values = 40 μM [74]. A vincorine-type, 17-formyl-10-demethoxyvincorine N(4)-oxide (152), an ajmaline-type 10-methoxyalstiphyllanine H (153), and 10-demethoxyvincorine N(4)-oxide (154) were obtained from the leaves of A. scholaris [78]. The phytochemical investigation of A. scholaris led to the publication of alstoscholactine (155) and alstolaxepine (156) [79]. A further investigation on the leaves of Malaysian A. scholaris led to the reporting of alstobrogaline (157) [80]. Compounds 155 and 156 exhibited no cytotoxic effects, whereas 156 induced marked vasorelaxation in reported rat aortic rings precontracted with phenylephrine, with EC50 = 6.58 ± 3.66 μM and Emax = 93.9 ± 4.3% (cf. verapamil, EC50 = 0.55 ±0.19 μM and Emax = 106.4 ± 3.4%) [74]. Compound 157 showed weak cytotoxic activity against breast cancer cells MDA-MB-231 and MCF7, with IC50 values = 25.3 and 24.1 μM, respectively [80].

Figure 17.

Figure 17

Compounds 146157.

The scaffold of the reported monoterpene indole compounds from A. scholaris is affected by the geographical environment. Indian, Pakistanian and Thai. A. scholaris are rich with picrinine-type indole compounds, whereas, those identified from Indonesia and the Philippine, are rich in angustilobine-type [81]. Genus Alstonia was addressed as a source of angustilongines A (142) and B (143). These compounds showed more potent anticancer activities than those recognized from A. penangiana, although all of them belong to macroline- and akuammiline-type bisindole alkaloids.

A review entitled "Alstonia scholaris and Alstonia macrophylla: A comparative review on traditional uses, phytochemistry and pharmacology" was published in 2014 and mentioned the compounds obtained from A. scholaris from 1976 to 2009, and from A. macrophylla from 1987 to 2013 [82]. A review published in 2018 entitled "The alstoscholarisine compounds: isolation, structure determination, biogenesis, biological evaluation and synthesis" studied the alstoscholarisine compounds obtained from A. scholaris [83]. Furthermore, a review published in 2016 called "An overview phytochemistry and chromatographic analysis of Alstonia scholaris used as a traditional medicine" discussed A. scholaris compounds which were reported between 1965 and 2009 [84].

The identified metabolites from Alstonia were categorized under two main classes: corynanthe and aspidosprma. Corynanthe contains eight subclasses: ajmaline-type (18, and 3335), picrinine-type (1921 and 4244), akummiline-type (22), vincorine-type (47, 50 and 148149), sarpagine-type (61, 66 and 101), macroline-type (6265), scholaricine-type (104109) and macroline oxindole-type (138141). Meanwhile,, aspidosprmia contains six subclasses: aspidosprma-type (31 and 32) vincamine-type (8284 and 8890), aspidofractinine-type (1 and 4), bisindole alkaloids macroline-pleiocarpamine-type (6770), and macroline- akuammiline-type (142145). Ajmaline derivatives with formyl group and/or a quaternary ammonium cation N(4) showed an interesting bioactivity.

3. Kopsia

Kopsia (Family Apocynaceae) contained 30 species with a distribution in China, India, Southeast Asia, and Australia. Sixteen species were grown in Malaysia [85], and five species were grown in Thailand [86]. These plants are considered as rich sources of indole-containing compounds. Traditionally, some of the species have been used for the treatment of tonsillitis, dropsy and rheumatoid arthritis. Several species have been reported to have antitumor, antimanic, antitussive and antileishmanial effects [87,88,89]. A review published in 2017 was interested in reporting indole alkaloids from genus kopsia plants regarding reversing multidrug resistance in vincristine-resistant KB cells for example, kopsirensine B, arboloscine A [90], grandilodines A and C, and lapidilectine B [91,92].

Kopsiyunnanines G (158) and kopsiyunnanines H (159) (Figure 18) with an aspidosperma-containing skeleton were isolated from the aerial part of the Chinese Kopsia arborea [93]. Kopsihainins A (160), B (161), and C (162) were isolated as new compounds from K. hainanensis [89], along with the known compounds, kopsinine (163) [87] and methyl demethoxycarbonylchanofruticosinate (164) [94] were isolated from the stems of Chinese K. hainanensis. Compounds 163 and 164 showed significant antitussive activity, these compounds are within the aspidofractinine-type and methyl chanofruticosinate-type indoles, respectively. Compounds 163 and 164 inhibited coughing by 88% and 76%, respectively [83]. Compound 163 was more active, with an ID50 value = 0.11 mmoL/kg, whereas compound 164 exhibited an effect, with an ID50 value = 0.45 mmol/kg, (Codeine, ID50 = 0.1 mmol/kg) [90]. The link from C-2 to C-20 in compound 163 and the attachment of the methoxy carbonyl group at C-16 position promote the antitussive activity.

Figure 18.

Figure 18

Compounds 158170.

Four alkaloids of aspidofractinine-type, singaporentine A (165), N(1)-formylkopsininic acid (166), N(1)-formylkopsininic acid-N(4)-oxide (167), and 15-hydroxykopsamine (168), along with an aspidospermatan-type, 14α-hydroxy-N(4)-methylcondylocarpine (169), and singaporentinidine (170) (Figure 18) were identified from the barks and leaves of Malaysian K. singapurensis [95].

From the leaves and stems of the Chinese medicinal plant K. hainanensis, four compounds, kopsininate (171), N1-decarbomethoxy chanofruticosinic acid (172), methyl N1- decarbomethoxy chanofruticosinate N(4)-oxide (173) and methyl chanofruticosinate N(4)-oxide (174) (Figure 19) were reported [96]. Compound 172 was the most effective against Erwinia carotovora bacterium, with an MIC of 7.8 mg/mL. Furthermore, compound 172 showed antifungal activities against four plant pathogenic fungi: Penicillium italicum, Fusarium oxysporum f. sp. Niveum, Rhizoctonia solani and Fusarium oxysporum. Cubense had an EC50 = from 15.2 to 43.8 μg/mL dose values. Compound 172 showed a potent effect towards F. oxysporum f. sp. Cubense, with an EC50 = 15.2 mg/mL. A comparison of this result with the positive control Midlothian, with an EC50 = 57.0 mg/mL showed compound 172 to be more active. The presence of carboxylic group attached to the C-2 position in 172 is important for antifungal activity, particularly, in methyl chanofruticosinate-type indoles [96].

Figure 19.

Figure 19

Compounds 171197.

Three aspidofractinie-type compounds, 5,6-secokopsinine (175), 5β-hydroxykopsinine (176), 16-epi-kopsinilam (177) [97], two kopsine-type metabolites, 5-oxokopsinic acid (178), and Na-demethoxycarbonyl-12-methoxykopsine (179) [97], a strychnos-type, 14(S)-hydroxy-19(R)- methoxytubotaiwine (180), and vincamine-type, and strychnos type 19-oxo-(−)-eburnamonine (181), 19(S)-hydroxy-Δ14-vincamone (182) [97], along with ten known compounds, 163 [87], kopsinilam (183) [98], kopsinic acid (184), 12-methoxykopsine (185) [99], kopsanone 186), 19(R)- methoxytubotaiwine (187) [88], (−)-eburnamonine (188), 19-OH-(−)-eburnamonine (189), and Δ14-vincamone (190) [97] were yielded from the stem bark of the Thai Kopsia jasminiflora (Figure 19). Compounds 163, 183, and 184 belong to aspidofractinie-type, 185 and 186 belong to Kopsine-type, 187 belongs to strycno-type, 188190 belonging to the vincamine- type MIAs.

The vincamine-type compound 182 showed a potent inhibitory activity against HT29, HCT116, and A549 cancer cells, with IC50 values = 0.36, 0.40, and 0.51 μM, respectively. Meanwhile, compounds 188 and 189 showed moderate activities with IC50 values ranging from 2.00 to 2.61 μM (Docetaxel, IC50 < 0.0005 μM). These results indicated the structural features that are necessary for the presence of a vincamine-type carbonyl group at the C-16 position, forming an amide function group, and a methylene group or hydroxyl methine at C-19 position in 182, 188, and 189 [97]. The presence of a double bond in the piperidine ring between C-15 and C-16 may be responsible for increasing the activity of compound 182.

A study on the content of twigs of K. arborea grown in Thailand revealed the isolation of a new MIA, phutdonginin (191) [100], an eburnane-type compound, together with eight known compounds, among them, 164 [87], 189 [88] melodinine E (192) [101], kopsilongine (193), kopsamine (194) [94], (−)-methylenedioxy-11,12-kopsinaline (195) [87], decarbomethoxykopsiline (196) [102], and vincadifformine (197) [103]. Only 194 and 196 displayed AChE inhibition activity with MIR values 12.5 and 6.25 μg, respectively, compared with reference drug galanthamine MIR = 0.004 μg. In addition, compounds 194 and 198 also displayed the weak acetylcholinesterase (AChE) inhibition of 23.3% and 45.7% in a microplate test at 1 mM. Compounds 191 and 189 showed moderate inhibition of bacterium toward Escherichia coli TISTR 780 with MIC = 32 μg/mL, with vancomycin and gentamycin references drugs with MIC values 0.125–0.25 μg/mL [100].

Malaysian Kopsia arborea was investigated and arboridinine (198) [85] was reported (Figure 20). The further investigation of the aerial parts of K. arborea led to the isolation of kopsiyunnanines J1 and J2 (199a and 199b) [104]. Compound 198 exhibited a moderate relaxation effect that was dependent on the contraction of phenylephrine-induced in the rat aortic rings, with an EC50 of 4.98 μM, and an Emax 60.6 ± 7.8% with the reference control isoprenaline with an EC50 value = 0.08 μM, and an Emax 79.7 ± 4.2% [85].

Figure 20.

Figure 20

Compounds 198227.

Seven aspidofractinine -type alkaloids, paucidirinine (200), paucidirisine (201), paucidactinine (202), pauciduridine (203), paucidactine D (204), paucidactine E (205), and paucidisine (206), along with Additionally, four eburnane skeleton, (−)-19-oxoisoeburnamine (207), (−)-19(R)-hydroxyeburnamenine (208), (−)-19(R)-hydroxy-O-ethylisoeburnamine (209), and larutienine B (210) were isolated from Kopsia pauciflora [91]. Moreover, twelve compounds, paucidactine A (211), paucidactine B (212) [105], paucidactine C (213) [88], 5, 22-dioxokopsane (214) [98], (+)-eburnamonine (215) [94], (+)-eburnamenine (216) [106], (−)-eburnamine (217), (+)-isoeburnamine (218) [94], (+)-19-oxoeburnamine (219) [105], (−)-19(R)-hydroxyisoeburnamine (220), (+)-19(R)-hydroxyeburnamine (221) [87], and larutienine A (222) [90] were published. Furthermore, three bisindole compounds have been identified, (−)-norpleiomutine (223), (+)-kopsoffinol (224) [107], and (−)-demethylnorpleiomutine (225) [87] and (+)-kopsoffine (226) (Figure 20) [107], were identified from the same species. A bisindole alkaloid were isolated by Kitajima at et from Yunnan Kopsia arborea, named Kopsiyunnanine M (227) [108].

Compounds 223 and 224 exhibited growth inhibitory activity against MCF-7, PC-3, A549, and HCT-116, with IC50 values ranging between 11.5 and 25.1 μM (Cisplatin, IC50 value in the range of 5.0–14.3 μM). The obliteration of the biological activity in 225 may be due to the presence of a carboxylic group in C-16, instead of a methoxycarbonyl group in 223 [91]. Arborisidine (228) and arbornamine (229) were isolated from a Malaysian K. arborea. Compound 228 represented a unique skeleton [109]. Compounds 228 and 229 exhibited no activities against KB, PC-3, HCT116, A549 and HT-29 cells [109].

Six new Kopsinidine C-E (230232), 11,12-methylenedioxychanofruticosinic acid (233), 12-methoxychanofruticosinic acid (234), and N(4)-methylkopsininate (235), in addition to chanofruticosinic acid (236) as new natural compound [110], along with compounds 163, 164, 178, 183, 179, and 215 (Figure 21) were isolated from K. officinalis. Additionally, Kopsinine methochloride (237), demethoxycarbonylkopsin (238) [111], methyl chanofruticosinate (239), methyl 11,12-methylenedioxychanofruticosinate (240) [94], methyl 12-methoxychanofruticosinate (241), methyl 11,12-methylenedioxy-N1-decarbomethoxychanofruticosinate (242) [112], kopsininic acid (243), and (−)-11,12-methylenedioxykopsinaline (244) [98] were identified from the same species. Furthermore, (−)-N-methoxycarbonyl-11,12-methylenedioxykopsinaline (245) [98], (−)-N-methoxycarbonyl- 12-methoxykopsinaline (246), N-carbomethoxy-11-hydroxy-12- methoxykopsinaline (247) [113], kopsinoline (248) [114], (−)-12-methoxykopsinaline (249) [98], 11,12-methylenedioxykopsinaline N(4)- oxide (250) [87], kopsinine B (251) [115], rhazinilam (252) [66], and pleiocarpamine methochloride (253) [116] were all isolated from the twigs and leaves of chines K. officinalis. Compound 252 displayed a significantly inhibition effect of the human T cell proliferation, which was activated by using anti-CD3/anti-CD28 antibodies, with an IC50 = 1.0 μM, showing stimulation, with an IC50 = 1.1 μM [110]. Compound 252 was indicated to have the highest cytotoxic effect due to the presence of a hydroxyl group in C-14 and C-15 position [110].

Figure 21.

Figure 21

Compounds 228253.

Kopsioffines A-C (254256) [117] (Figure 22) were isolated from the leaves and stems of K. officinalis. These compounds possess a relatively novel ten-membered lactam ring [117]. Additionally, five MIAs, Kopsifolines G-K (257261) were identified from the same plant [118]. Moreover, kopsifoline A (262) was isolated from the aerial parts of an unidentified Kopsia sp. [119]. Compounds 259261 exhibited cytotoxic effects against dermatoma (HS-1, A431, SCL-1, HS-4), gastric carcinoma (BGC-823), breast cancer (MCF-7), and colon cancer (SW480), with IC50 values in a range between 11.8 and 13.8; between 10.3 and 12.5; between 7.3 and 9.5 μM, respectively (Adriamycin, IC50 < 34 nM). Compound 261 showed a potent cytotoxic effect that may be due to the presence of two hydroxyl groups in the C-14 and C-15 positions, instead of one hydroxyl group at C-15 position in compounds 259 and 260. Compounds 257, 258 and 262 exhibited a weak cytotoxic effect with IC50 values > 20 μM. This may be due to the absence of a hydroxyl group in that position [118]. Compounds 254256 exhibited weak inhibitory effects on yeast α-glucosidase in vitro with IC50 values > 50 μM [118]. Compounds 259260 exhibited interesting antifungal and antimicrobial activities toward five pathogen bacteria Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Shigella dysenteriae and Klebsiella pneumoniae), and also exhibited an antibacterial effect on the oral pathogens Streptococcus viridans and Streptococcus mutans. Netilmicin was used as a reference drug, with MIC values < 0.18 mm. 5-Flucytocine was used as a positive control with MIC values < 0.09 mM. Alkaloid 261 displayed the highest antimicrobial activity toward the tested pathogens, with an MIC value of 0.15–1.14 mM, while compounds 259 and 260 showed significant activities, with MIC values of 0.77–3.09 and 0.72–1.37 mM. Compounds 257, 258 and 262 were inactive. The present of a hydroxyl group at the piperidine ring enhanced the anticancer and antimicrobial activity in this subtype of indoles [118]. The investigation of the aerial parts of K. arborea led to the isolation of three compounds: kopsiarborines A-C (263265) [120]. Meanwhile, the study of the aerial parts of K. officinalis led to the reporting of three MIAs, kopsiaofficines A–C (266268) (Figure 22) [121]. Compounds 263 and 264 showed significant cytotoxic activities against H446, H292, A549, H460, ATCC, and 95-D, with IC50 values < 20 μM, (Doxorubicin, IC50 value = 0.06 μM). Compound 264 exhibited a potent activity with IC50 values < 9.5 μM, and compound 265 was inactive [120]. Compound 268 exhibited a potent cytotoxicity against H446, A549, ATCC, 95-D, H460, H292, SPCA-1, and lung cancer cells, with IC50 values < 10 mM, while compound 266 showed some cytotoxic activity with IC50 value < 20 μM (Doxorubicin, IC50 = 13.7–33.7 nM) [121].

Figure 22.

Figure 22

Compounds 254268.

Kopsiofficines H–L (269273) [122] (Figure 23), together with fourteen compounds, 164, 208, 239, 241, (+)-O-methyleburnamine (274) [93], (−)-O-methylisoeburnamine (275) [123], 16-isoeburnamine (276) [124], 20-oxoeburnamenine (277) [125], methyl 11, 12-methylenedioxychanofruticosinate (278) [99], methyl N-(decarbomethoxy)-11, 12-(methylenedioxy) chanofruticosinate (279) [126], O-methylleuconolamm (280) [127], leuconodine D (281) [128], oxayohimban-16-carboxylic acid (282) [129], and 19, 20-dihydroisositsirikine (283) [130] (Figure 23), were identified from the stems of K. officinalis plant [122]. Compounds 164, 241, 270, 271, 274, 275, 279, and 281 exhibited significant anti-inflammatory activity towards IL-1β, PGE2 and TNF-α at 5 μg/mL. Deametasona was used as a positive control at 10 μg/mL [122].

Figure 23.

Figure 23

Compounds 269283.

Table 1 methyl chanofruticosinate-type (164, 173175), aspidosoermatan-type (169, 199), kopsine-type (179, 185186), strychnos-type (180, 187), vincamine-type (181, 188, 189), paucidactine-type (204, 205) and eburnane-type (207210), all these subtypes belongs to the main class aspidospirma, and very few compounds belong to the main class of corynanthe-type indoles (Figure 4). Vincamine and methyl chanofruticosinate derivatives showed interesting biological activity.

4. Rauvolfia

Rauvolfia (family Apocynaceae) contains 60 species. It contains trees or shrubs that are distributed in Africa, America, and Asia [131]. Rauvolfia serpentine is one of the most important medicinal plant that has been considered as a drug lead for a long time [132]. Rauvolfia has been used traditionally for the treatment of several diseases, such as high blood pressure (hypertensive), fever (malaria), arrhythmia, cancer, oxidative stress, microbial problems, intestinal spleen ailments, and various mental disorders [133]. Therapeutically, it is a source of monoterpenoid indoles, including ajmaline (antiarrhythmic), ajmalicine, yohimbine, reserpine (antihypertensive), and serpentine [133].

A review entitled "Rauvolfia serpentina L. Benth. ex Kurz. phytochemical, pharmacological and therapeutic aspects" was published in 2013 and evaluated various bioactive compounds as ajmaline, ajmalicine, deserpidine, reserpine, reserpiline, serpentine, rescinnamine and yohimbine [132]. A review entitled "Chemical and Biological Perspectives of Monoterpene Indole Compounds from Rauwolfia species" mentioned the compounds obtained until 2016 [134]. Another review described the structures and pharmacological potentials of the plant species Rauvolfia tetraphylla L. (Apocynaceae) [135].

Two normonoterpenoid indole compounds were isolated from the aerial parts of Rauvolfia vomitoria, rauvomines A (284) and B (285) [136] along with two known compounds peraksine (286) (Figure 24) [137] and alstoyunine A (287) [42]. Compound 285 displayed significant anti-inflammatory effects against murine macrophages (RAW 264.7), with an IC50 value = 39.6 μM, whereas, compounds 284, 286 and 287 displayed moderate anti-inflammatory effects with IC50 values = 55.5, 65.2, and 75.3 μM, respectively, (Celecoxib, IC50 = 34.3 μM) [136]. Compound 285 showed a potent activity which maybe double the number of connections linking C-20 to C-16 in sarpagine-type indoles, compared with compound 284 [63].

Figure 24.

Figure 24

Compounds 284303.

Three compounds, 11-hydroxyburnamine (288) and rauvoyunnanines A and B (289290) were identified from Chinese R. yunnanensis [138]. Additionally, fourteen compounds 135 [139], lochnerine (291) [140], serpentinic acid (292) [141], reserpine (293) [142], (−)-yohimbine (294) [143], ajmaline (295) [143], mauiensine (296) [144], ajmalicine (297) [145], sitsirikine (298) [146], strictosidinic acid (299) [147], caboxine B (300) [148], isocaboxine B (301) [148], spegatrine (302) [149], and 19(S),20(R)-dihydroperaksine (303) [150] (Figure 24) were isolated also from chines R. yunnanensis. Compound 293 displayed a weak cytotoxicity against HT-29 and SW480, with IC50 values = 35.2 and 45.3 μM, respectively. Auranofin was used as a positive control and showed cytotoxicity with IC50 values = 2.5 and 3.9 μM, respectively. Compounds 294 and 299 displayed immunosuppressive activities on human T cell proliferation, with IC50 values = 5.9 and 5.0 μM, respectively. All compounds except 294 and 299 showed weak activities with IC50 values > 50 μM [138]. The metabolites were identified from genus Rauvolfia and were categorized under the corynanthe-type. The compounds were also classified under three subclasses including: sarpagine-type 284285, picraline-type 288 and ajmaline-type 295296 and 298 [138].

5. Ervatamia

The genus Ervatamia contains 120 species. It is distributed in Asia and Australian. Of which, fifteen species and five varieties are grown in south China. Ervatamia is a rich source of iboga-type MIAs, which is characterized by structural novelty and biological diversity including neuroprotective, anti-tumor, and anti-addiction activities [151,152,153].

Six Iboga-type compounds: ervataine (304) [151], ibogaine (305) [154], coronaridine (306) [49], heyneanine (307) [155], voacangine hydroxyindolenine (308) [156,157] and coronaridine hydroxyindolenine (309) [158,159] (Figure 25), were obtained from the Chinese Ervatamia yunnanensis [151].

Figure 25.

Figure 25

Compounds 304318.

Compound 306 exhibited significant protective effects toward MPP+ (1-methyl-4-phenylpyridinium) and induced damage in primary cortical neurons with an IC50 = 12.5 μM. Parkinson’s disease (PD) is caused by MPP+ a toxic agent that interferes with the function of mitochondria, thus causing neuronal damage and death. Brain-derived neurotrophic factor (BDNF) was used as a positive control and showed an inhibitory effect, with an IC50 value = 200 ng/mL [49].

Eight compounds, coronaridine (306) [49], coronaridine hydroxyindolenine (309) [158,159], 10-hydroxycoronaridine (310) [160], voacangine (311) [153], 19(S)-heyneanine (312) [160], 19(R)-heyneanine (313) [161], heyneanine hydroxyindolenine (314) [162], and vobasine (315) [163], were identified from the stems of E. hainanensis. Compounds 306, 309315 displayed acetylcholinesterase inhibitory activities. Compounds 306 and 311 displayed a potent cholinesterase inhibitory effect, with IC50 values = 8.6 and 4.4 μM, respectively. Galantamine was used as a reference drug, with an IC50 = 3.2 μM, that is used for Alzheimer’s disease [164]. Compound 310 possessed a hydroxyl group at the phenyl moiety, which was replaced by proton in compound 306. This led to a decrease in the inhibitory activity of AChE in 306 compared to 310. The methoxy group at the phenyl moiety in 311, led to an improvement in the activity. This indicated that the electron-donor substituents attached at the phenyl group were important for the improvement of AChE inhibition [164].

Ervachinine E (316) [165] and rutaecarpine (317) [166] were isolated from E. chinensis [165]. It displayed moderate antitumor activities against HL-60, SMMC-7721, A-549, and SW480 cancer cells, with values of IC50 ranging between 6.59 and 14.70 μM. (Cisplatin, IC50 values between 1.00 and 26.75 μM) [165].

The compound Ervahainine A (318), an oxindole derivative that is cyano-substituted, was identified from the twigs and leaves of E. hainanensis [167]. Compound 318 showed growth inhibitory activities toward HepG2 and HepG2/ADM cells with IC50 values of 12.47 ± 0.24 and 17.68 ± 0.31 μM [167].

Seven new iboga-type derivatives: ervaoffines A–D (319322), (7S)-3-oxoibogaine hydroxyindolenine (323), ibogaine-5,6-dione (324), and 19-epi-5-oxovoacristine (325), along with ten compounds, 305, 307, 311, iboluteine (326) [168], (7S)- ibogaine hydroxyindolenine (327) [157], ibogaline (328) [169], conopharyngine (329) [170], voacristine (330) [171], 19S-hydroxyibogamine (331) [172], and ibogaine N4-oxide (332) [173,174] (Figure 26), were isolated from the twigs and leaves of E. officinalis.

Figure 26.

Figure 26

Compounds 319332.

Seven compounds, 3-oxo-7R-coronaridine hydroxyindolenine (333), 3S-cyano-7S-coronaridine hydroxyindolenine (334), 3R-hydroxy-7S-coronaridine hydroxyindolenine (335), 3S-(24S-hydroxyethyl)-coronaridine (336), 3S-(24R-hydroxyethyl)-coronaridine (337), 5-oxo-6S-hydroxycoronaridine (338) and 5-oxo-6S-methoxy-coronaridine (339) [175], along with six others, 306, 7S-coronaridine hydroxyindolenine (340) [176], 3-oxo-7S-coronaridine hydroxylindolenine (341) [177], 5-oxocoronaridine (342) [177], 3-oxocoronaridine (343) [178] and pseudoindoxyl coronaridine (344) [177], (Figure 27) from identified from twigs and leaves of E. hainanensis [175].

Figure 27.

Figure 27

Compounds 333–353.

Another study on the twigs and leaves of E. officinalis led to the reporting of three MIAs, ervaoffines E–G (345347) [179], and six compounds 306, 342, lirofoline A (348), lirofoline B (349) [172], 6-oxo-ibogaine (350) [180], and 8-oxo-ibogaine lactam (351) [179,180,181]. Compound 347 showed a significant neuroprotective effect towards damage induced by oxygen-glucose deprivation (OGD) of the cortical neurons cultured of ischemic stroke in vitro, with an IC50 = 100 μM, Neuroserpin was used as a reference drug, with an IC50 = 20 ng/mL [179]. Two compounds were obtained from the roots of E. chinensis, erchinines A and B (352,353) [63]. Both compounds 352 and 353 displayed a potent significant antibacterial activity toward Bacillus subtilis which was better than that of the antibacterial drugs fibraurtine with an MIC = 25 μM and berberine with an MIC = 12.5 μM that are derived from plant. Additionally, compound 352 displayed an equal antifungal effect against (Trichophyton rubrum) to the reference drug griseofulvin, with an MIC = 6.25 μM.

Ervapandine A (354) [182], 3R-hydroxyibogaine (355) [182], and 12-hydroxyakuammicine N4-oxide (356) [182], along with four known ones, 313, 305, 19-epi-voacristine (357) [183], taberdivarine I (358) [184] and 12-hydroxyakuamicine (359) [185], (Figure 28) were identified from the leaves and twigs of Chinese E. pandacaqui [182].

Figure 28.

Figure 28

Compounds 354369.

Liu et al. (2018) [186] studied the roots of E. divaricate and identified two unprecedented trimeric MIAs, Ervadivamines A (360) and B (361), together with the dimeric compound, 19,20-dihydroervahanine A (362), (Figure 29) and two monomeric ones, ibogaine (305) and Ibogamine (363) [187]. Compound 359 displayed a moderate cytotoxic effect against MCF-7, with an IC50 value = 33.61 μM [182]. Compound 360 showed a significant positive cytotoxicity against MCF-7, A-549, HT-29 and HepG2/ADM and showed potent effect against HepG2/ADM, with an IC50 value = 12.55 ± 0.54 μM (Adriamycin, IC50 = 45.70 ± 2.15 μM) [186].

Figure 29.

Figure 29

Compounds 370384.

Two pair of MIAs epimers composed of, ervatamine (364), [188] 20-epi-ervatamine (365), [188] dregamine (366), and [188] tabernaemontanine (367) [188] and two compounds, apparicine (368) [189] and isovoacangine (369) [190], were isolated from E. yunnanensis [191].

The Ervatamia genus is known to produce iboga-type indole derivatives, which contain two subclasses, flabelliformide-type (364, 365) and apparicine-type (368) (Figure 28), with compounds belongonging to the main class corynathe. The iboga-type showed an interesting bioactivity in the nervous system.

6. Tabernaemontana

The Genus Tabernaemontana (subfamily Rauvolfioideae) contains 110 species, which are distributed throughout tropical and subtropical regions. Thirty species are grown in Brazil, whereas, 44 species were grown in America and the rest in different places around the world. Traditionally, the plants of this genus have been used for the treatment of hypertension, sore throat, and abdominal pain [6,192]. A review article entitled “Brazilian Tabernaemontana genus: indole compounds and phytochemical activities” activities was published in 2016 [6]. It concerned in the monomeric and dimeric MIAs reported from the genus. A review article entitled: A review on tabernaemontana spp.: Multipotential medicinal plant, shows the MIAs reported from this genus until 2015 [6].

Conodusine A-E (370374), apocidine A (375) and B (376), conoduzidine A (377), tabernamidine A (378) and B (379) (Figure 29) were isolated from the Malaysian stem-bark of Tabernaemontana corymbose malaysian [193]. Additionally, thirty-two compounds were also identified from the same plant, including 307, 314, 338, (+)-catharanthine (380), tabernamine (381) [194], 19′(S)-hydroxytabernamine (382) [195], and 19′(R)-hydroxytabernamine (383) [195]. 16′-decarbomethoxyvoacamine (384) [180] (Figure 29). The chemical structures were determined based on analysis of the NMR and MS spectral data. However, compounds 370, 372, 374, 375 and 377 were confirmed by X-ray diffraction analyses. 371 and 371 belong to iboga alkaloids and tabernamidine B is an iboga-containing bisindole. Tabernamidine B (379) is notable for the presence of an α-substituted acetyl group at C-20 of the iboga carbon skeleton. The absolute configuration of (+)-conodusine E was based on an analysis of the ECD data in correlation with (−)-heyneanine and X-ray analysis. Compounds 381384 exhibited growth inhibitory effects against drug-sensitive KB/S, with an IC50 value < 4.7 μM and vincristine-resistant (KB/VJ300) cells with an IC50 value < 4.2 μM. For that type of human oral cancer cell lines, vincristine was used as a reference drug with an IC50 value < 1.8 nM [193].

Two compounds, isoakuammiline (385) and 18-hydroxypseudovincadifformine (386) [196], have been reported from the American fruits of T. litoralis. Additionally, five compounds 3,19-oxidocoronaridine (387) [196], strictosidine (388) [196], 306, heyneanine 307, and tabersonine (17), have been identified from the same species [196]. Strictosidine is the major alkaloid in fruit arils, however in the capsule strictosidine it was converted to mainly iboga and pseudoaspidosperma alkaloids. However, in seeds, strictosidine was converted to both iboga and aspidosperma alkaloids, but the only major iboga alkaloid, coronaridine, was not substituted, whereas in fruit capsule coronaridine was oxidized to form heyneanine and 3,19-oxidocoronaridine.

Tabervarines A (389) and B (390) [197], 311, 369, vobasidine C (391) [198], 311, 368, ervadivaricatine B (392) [187], pedunculine (393) [199], tabernaemontanine (367) [198] and polyervine (394) [200] were published from the twigs and leaves of the Chinese T. divaricate (Figure 30). Compounds 388 and 389 exhibited a weak cytotoxic effect against cancer MCF-7, SMMC-7721, HL-60, A-549, and SW480 cells at a value > 40 μM [197].

Figure 30.

Figure 30

Compounds 385394.

Four new bisindole compounds, flabellipparicine (395), 19,20-dihydrovobparicine (396), 10′- demethoxy-19,20-dihydrovobatensine D (397) and 3′-(2-oxopropyl)ervahanine A (398) [201], together with ten known compounds, 381, 368, ervahanine A (399) [202], vobparicine (400) [203], 19,20-dihydrotabernamine (401) [204], 19,20-dihydrotabernamine A (402) [205], taberdivarine E (403) [184], tubotaiwine (404) [206], hydroxy-3-(2-oxopropyl)coronaridineindolenine (405) [204], and deoxytubulosine (406) [201] (Figure 31) were identified from the stems of T. divaricate. Compounds 368, 395403 and 406 exhibited cytotoxic activities against MCF-7 and A-549 with IC50 values < 8.1 μM. Compound 406 exhibited the highest effects against MCF-7 and A-549 with IC50 values of 0.1 and 0.2 nM, respectively. 7-ethyl-10-hydroxycamptothecin (SN38) was employed as a positive control and showed cytotoxic effect, with an IC50 value < 2 nM [201]. The presence of β-carboline benzoquinolizidine nucleus played an important role in increasing the cytotoxicity in 406, whereas, compounds (368 and 395403) possessed two NH indolic group [201].

Figure 31.

Figure 31

Compounds 395406.

(3R,7S,14R,19S,20R)-19-hydroxypseudovincadifformine (407) [207], 17-demethoxy-hydroisorhyn chophylline (408) [208], 17-demethoxy-isorhynchophylline (409) [208], voachalotine (410) [171], 12-methoxyl-voaphylline (411) [209], and conophylline (412) [209] (Figure 32) were isolated from the branches and leaves of Chinese T. bufalina. Compound 412 showed potent cytotoxic activities against B16 and MDA-MB-231 cells with IC50 values of 0.13 and 8.9 μM, respectively. Gambogic acid was used as a positive control with IC50 values 22.1 and 13.5 μM, respectively [207].

Figure 32.

Figure 32

Compounds 407417.

Two compounds, 5,6-dioxo-11-methoxy voacangine (413), and (−)-apparicin-21-one (414), and heyneanine (307), were identified from the fruits of cameroonean T. contorta [210] lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophage cells. BAY 11-7082 was used as positive control with 10 μM [210]. Tabernabovines A–C (415417) were isolated from T. bovina [211]. Compound 415 displayed potent inhibitory activity of NO production in LPS-stimulated RAW 264.7 macrophages with IC50 value 44.1 value μM. l-NMMA was used as a positive control and showed an inhibitory effect with IC50 value = 48.6 μM [211].

Previous studies have proven that various bisindole compounds have more effect than monomeric indole compounds, including the dimeric indoles such as (euburnane–aspidospermatan, euburnane–ibogan, akuammidine–ibogan, aspidospermatan– aspidospermatan and vobasine–strychnan) type compounds. Interestingly, dimeric indoles showed more cytotoxicity than the monomeric units.

The Tabernaemontana genus produced iboga type indoles, which contained four subclasses, such as vincamine-type, apparicine-type and akuammidine, these compounds which belongs to the main class aspidosperma and corynanthe, respectively.

7. Rhazya

Rhazya comprises two species, Rhazya stricta (R. stricta) and Rhazya orientalis (R. stricta) [212]. R. orientalis grown in western Thrace and northeastern Turkey [213] whereas, R. stricta is grown in South Asia (Afghanistan, Pakistan and India) and on the Arabian Peninsula (Saudi Arabian, Qatar, UEA, Iraq) and Iran. Rhazya is a rich source of indole-containing compounds. Traditionally, it is has been used to cure various diseases, such as fever, rheumatism, inflammation, skin infections, sore throat, diabetes, and stomach disorders. For example, strictanol, sewarine, tetrahydrosecamine vallesiachotamine and tetrahydrosecaminediol exhibit anticancer properties [213,214,215,216,217,218]. A recent study on the aerial parts of R. stricta by Ahmad et al. [215], several MIAs were isolated including, three new, secopleiocarpamine A (418), 16,17-Epoxyisositsirikine (419), and 2-Ethyl-3[2-(3-ethyl-1,2,3,6-tetrahydropyridine)ethyl]-indole (420) [215] (Figure 33), five previously reported compounds from other Apocynaceae genera (126, 127, 133, 298 and 404), and a number of previously isolated MIAs from the same species: 2-ethyl-3[2-(3-ethylpiperidine)ethyl]-indole (421), tetrahydrosecodine (422), 16,17-dihydrosecodine (423) [216], deacetylakuammilin (424) [217], rhazimal (425), strictamine-N-oxide (426) [218], rhazinaline (427) [212], rhazinaline Nb-oxide (428) [219], akuammicine (429) [220], 16R-E-isositsirikine (430) [221], dihydrositsirikine (431) [222], antirhine (432) [129], vincadifformine N(4)-oxide (433) [223], eburenine (434) [93], winchinine B (435), quebrachamine (436) [224] and strictanol (437) (Figure 33) [215,225] were isolated from R. stricta. Furthermore, 16-epi-stemmadenine-N-oxide (438) (Figure 33), stemmadenine-N-methyl (439), and 20-epi-antirhine (440) were reported from R. stricta [226]. Additionally, isopicrinine (441) was isolated from the leaves of R. stricta, collected from Bahra, Saudi Arabia [227]. Abdul-Hameed et al. (2021) [228] identified two new indole alkaloids named, epirhazyaminine (442) and 20-epi-sitsirikine (443), together with five known compounds, 430, 432, 434, 437 and strictamine (444) were obtained from the aerial parts of R. stricta, collected from AL-Madinah city, Saudi Arabia [228]. Compounds 418, 422, 428, 432, 434, and 436 exhibited moderate growth inhibitory activities toward Candida strains (C. guilliermondii, C. albicans, C. krusei, C. lusitaniae and C. glabrata) with MIC values ranging from 3.125 to 50 μg/mL. (Amphotericin B, MIC value < 1 μg/mL) [213]. Compound 438 displayed a cytotoxic effect against HCT-116, PC-3, and HepG2, with IC50 values = 2.20, 2.25, and1.9 μM, respectively, (Cisplatin, IC50 values ≤ 0.90 μM). Furthermore, compound 439 significantly hindered of the cancer cells to migration and preventing the wound healing at 24 and 48 h (from 81 and 77% to 68 and 46%, respectively). It also inhibited proliferation and prevented cell migration of all cancer cell was evaluated, with an IC50 = 70 μM [223]. Compound 441 displayed a potent cytotoxic effect towards MCF-7, with an IC50 value = 240 μM [224]. Compounds 430, 432, 434, 437, and 442444 displayed weak activities against three cancer cell lines (HCT-116, PC-3, and HepG2), with IC50 in the range of 45.0 ± 0.012 and 85.0 ± 0.068 μM against HCT-116, IC50 in the range 39.0 ± 0.012 and 87.0 ± 0.068 μM against PC-3, and IC50 in the range 72.0 ± 0.164 and 87.0 ± 0.032 μM against HepG-2μM) against HepG-2 [225]. The Rhazya genus contains many MIAs subclasses, such as secodine-type (420424), akuammiline-type (426), akummicine-type (428) and picrinine-type (441), (Figure 3), with compounds belonging to the main classes aspidosperma and corynanthe.

Figure 33.

Figure 33

Compounds 418444.

8. Biosynthesis of Monoterpenoid Indole Alkaloids

Monoterpenoidal indoles are obtained from the reaction of tryptamine with secologanin terpenoid. Condensation of tryptamine with Secologanin produces strictosidine by the Mannich-link reaction. The deglycosylation of strictosidine converts it to a hemiacetal. Opening the hemiacetal led to forming an aldehyde group, which then reacts with the (N-4) secondary amine of strictosidine to form 4,21-dehydrocorynanthenine. Allylic isomerization moves the double bond of vinyl to a conjugation with iminium nitrogen that generates dehydrogeissoschizine, which is then cyclized to form cathenamine. The reduction of cathenamine in the presence of NADPH forms ajmalicine (corynanthe-type) [229].

The formation of Preakuammicine occurs from dehydrogeissoschizine. Preakuammicine intermediate (strychnos-type) is the common precursor of the strychnos, aspidosperma and iboga indole alkaloids. Preakuammicine reduced to form stemmadenine, then rearranged to form the acrylic ester dehydrosecodine, which is a common intermediate for iboga and aspidosperma skeletons. Tabersonine (aspidosperma type) and catharanthine (iboga type) are formed the Diels-Alder reaction (Scheme 1) [229].

Scheme 1.

Scheme 1

Biosynthesis of corynanthe, aspidosperma and iboga indoles.

Polyneuridine aldehyde (sarpagan type) is an intermediate compound of the ajmaline pathway. The possibility of a mechanism where the sarpagan bridge enzyme converts an isomer of 4,21-dehydrogeissoschizine to polyneuridine aldehyde is shown (Scheme 2). Polyneuridine aldehyde methyl ester is hydrolyzed by polyneuridine aldehyde esterase, generating an acid which decarboxylates, to yield epi-vellosamine. Epi-vellosamine transforms to the ajmaline alkaloid vinorine. The hydroxylation of vinorine to vomilene is caused by the vinorine hydroxylase enzyme. After formation of vomilene, two step reduction occurs. First, the indolenine bond is reduced by an NADPH enzyme to yield 1,2-dihydrovomilenene. The second step, reducing the 1,2-dihydrovomilenene to acetylnorajmaline by a 1,2-dihydrovomilenene reductase enzyme. The acetyl linkage of acetylnorajmaline is hydrolyzed by acetylesterase to yield norajmaline. Finally, the production of ajmaline by N-methyl transferase of a methyl group at the indole nitrogen of norajmaline occurs (Scheme 2) [229,230].

Scheme 2.

Scheme 2

Biosynthesis of ajmaline indole alkaloids. (SB) Sarpagan bridge enzyme; polyneuridine aldehyde reductase (PNAE), vinorine synthase (VS), vinorine hydroxylase (VH), vomilenine reductase (VR), dihydrovomilenine reductase (DHVR) 17-O-acetyl-ajmalanesterase (AAE), norajmaline-N-methyltransferase (NMT).

It is noteworthy to mention that, sarpagine, ajmaline, and macroline alkaloids are biosynthetically similar or all derived from the same origin. Whereas, sarpagine can be converted into macroline by means of Michael addition [231], on the other hand macroline can be converted into sarpagine by through a retro-Michael reaction [231,232,233]. Similarly, some sarpagine-containing alkaloids can be converted into ajmalines under strong acidic conditions, which refers to the great similarity between them [233].

9. Conclusions and Future Prospectives

Natural products have an unprecedented molecular conformity with a diversity of functionalities. These characteristics enable them to produce biological effects, which validates the initial step for a drug lead. In recent years, the majority of new drugs reported have been natural or originated from natural sources. Alkaloids are an important source of drugs. It is noteworthy that, many alkaloids displaying fascinating molecular structures with diverse physiological and pharmacological effects have been isolated from plant families. The Apocynaceae family has been noted as a unique producer of biologically active natural metabolites such as vincristine, vinblastine, reserpine and yohimbine. This review is interested in discussing the metabolites produced from six genera belong to the family Apocynaceae. These six genera contain 400 species, which represent 20% of the Apocynaceae family. Only 30 species, which represent 7.5% of the total species of the six genera were studied. Chemical investigation of these genera led to the reporting of 444 MIAs, in the period between 2010 until December 2020, which were discussed in this review.

Figure 34 illustrates the number of compounds isolated from the six species; there are 157 (35.4%), 126 (28.4%), 66 (14.9%), 48 (10.8%), 27 (6.1%), and 20 (4.4 %), from Alstonia, Kopsia, Ervatamia, Tabernaemontana, Rhazya and Rauvolfia, respectively. We believe that the six genera are interesting candidate for further investigation. This record coincided with the data illustrated in Figure 35. For example, Alstonia scholaris is a species that belongs to the genus Alstonia that has produced the highest number of MIAs (71 compounds) and represents 45.2 % of the MITs identified from the same genus between 2010 and 2020. The second and third most interesting species are Kopsia officinalis and Kopsia pauciflora which produced 45 and 27 compounds, respectively. These two species represent 35.7% and 21.4% of the total compounds produced from the genus Kopsia. The fourth most interesting species belong to the genus Alstonia (Alstonia mairei), which produced 26 compounds and represents 16.5 % of the MITs identified from the genus Alstonia.

Figure 34.

Figure 34

Number of compounds isolated from the six genera.

Figure 35.

Figure 35

Percentage of reported compounds from the species.

It is interesting that the majority of compounds were isolated from twigs and leaves as illustrated in Figure 36. Additionally, the majority of the examined species belonging to the selected six genera were Chinese species and led to the identification of 360 compounds.

Figure 36.

Figure 36

Number of compounds identified from different organs.

Figure 37 presents the biological activities of the compounds. The prominent activity was cytotoxicity followed by anti-inflammatory and antimicrobial activities. Thus, these compounds could be a source of anticancer drugs.

Figure 37.

Figure 37

Number of compounds versus biological activities.

The family of terpene indole alkaloids has been discovered for over a century. There are numbers of total syntheses studies of these intricate scaffolds have been achieved. Additionally, several reviews and book chapters, as well as the references therein, are interested in the synthetic efforts have been reported.

Acknowledgments

The authors acknowledge with thanks Deanship of Scientific Research at Princess Nourah bint Abdulrahman University, for funding through the Fast-track Research Funding Program.

Author Contributions

Conceptualization, W.M.A., A.A.-L. and Z.H.A.-H.; resources, A.E.M., M.O.A. and N.O.B.; data curation, Z.H.A.-H., W.M.A. and A.A.-L.; writing—original draft prepa-ration, Z.H.A.-H., W.M.A. and A.A.-L.; writing—review and editing, Z.H.A.-H., W.M.A. and A.A.-L.; supervision, T.R.S.; funding acquisition, A.E.M. and M.O.A. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Deanship of Scientific Research at Princess Nourah Bint Abdulrahman University through the Fast-track Research Funding Program.

Conflicts of Interest

The authors declare no conflict of interest.

Footnotes

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Abbreviations

A431 Dermatoma cancer
A-549 Lung cancer
AChE Acetylcholinesterase
B16F10 Melanogenesis activity
BEN-MEN-1 Meningioma
BGC-823 Human gastric carcinoma
CAL-27 Head and neck squamous cell carcinomas
CCF-STTG1 Astrocytoma
CHG-5 Glioma
CI Confidence intervals
Detroit-562 Head and neck squamous cell carcinomas
ED50 Median effective dose
F.sp. Forma specialis, abbreviated f. sp., is an informal taxonomic grouping allowed by the International Code of Nomenclature for algae, fungi, and plants
HCT 116 Human colorectal carcinoma
HeLa Human Gastric cancer
Hep-2 Head and neck squamous cell carcinomas
HepG2 Human hepatocellular
HIF-α Hypoxia-inducible factor
HL-60 Human myeloid leukemia
HS-1 Dermatona cancer
HS-4 Dermatona cancer
HT-29 Human colorectal carcinoma
IC50 Half maximal inhibitory concentration
ID50 Median infective dose
IL-1β Interleukin 1 beta
LNCaP Human prostate carcinoma
M663 Osteosarcoma cells
MCF-7 Human breast cancer
MDA-MB-231 Human breast adenocarcinoma
MG-63 Osteosarcoma cells
MIAs Terpenoid indole compounds
MIAs Monoterpenoid indole compounds
MIC Minimum inhibitory concentration
NF-kB Nuclear factor k-light-chain-enhancer of activated B cells
NO Nitric oxide
PANC-1 Pancreatic cancer
PC-3 Human prostate carcinoma
PGE2 Prostaglandin E2
SAOS-2 Osteosarcoma cell lines
SCC-PKU Head and neck squamous cell carcinomas
SCL-1 Head and neck squamous cell carcinomas
SGC-7901 Gastric cancer
SHG-44 Human glioma cancer
SK-BR-3 Human breast cancer
SK-MEL-2 Human skin cancer
SMMC-7721 Hepatocellular carcinoma
SOSP-9607 Human Osteosarcoma cell lines
SW480 Human Colon cancer
TCA-83 Head and neck squamous cell carcinomas
TNF-α Tumor necrosis factor-α
U251 Human glioma cancer
U2-OS Osteosarcoma cell lines
UMSCC-1 Head and neck squamous cell carcinomas

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