The Ethnopharmacological Uses, Metabolite Diversity, and Bioactivity of Rhaponticum uniflorum (Leuzea uniflora): A Comprehensive Review

Abstract

Rhaponticum uniflorum (L.) DC. (syn. Leuzea uniflora (L.) Holub) is a plant species of the Compositae (Asteraceae) family that is widely used in Asian traditional medicines in China, Siberia, and Mongolia as an anti-inflammatory and stimulant remedy. Currently, R. uniflorum is of scientific interest to chemists, biologists, and pharmacologists, and this review includes information from the scientific literature from 1991 to 2022. The study of the chemodiversity of R. uniflorum revealed the presence of 225 compounds, including sesquiterpenes, ecdysteroids, triterpenes, sterols, thiophenes, hydroxycinnamates, flavonoids, lignans, nucleosides and vitamins, alkanes, fatty acids, and carbohydrates. The most studied groups of substances are phenolics (76 compounds) and triterpenoids (69 compounds). Information on the methods of chromatographic analysis of selected compounds, as well as on the quantitative content of some components in various organs of R. uniflorum, is summarized in this work. It has been shown that the extracts and some compounds of R. uniflorum have a wide range of biological activities, including anti-inflammatory, antitumor, immunostimulatory, anxiolytic, stress-protective, actoprotective, antihypoxic, anabolic, hepatoprotective, inhibition of PPARγ receptors, anti-atherosclerotic, and hypolipidemic. Published research on the metabolites and bioactivity of R. uniflorum does not include clinical studies of extracts and pure compounds; therefore, an accurate study of this traditional medicinal plant is needed.

1. Introduction

Rhaponticum Vaill. is a small genus from the tribe Cynareae of the Asteraceae family that is distributed mainly in tropical and subtropical regions of Europe, Asia, and Africa. In total, more than 20 species belong to the genus and are distributed in a narrow strip in the Northern hemisphere from the Atlantic coast to the Pacific Ocean [1]. Close to Rhaponticum are the Mediterranean monotypic genus Leuzea and the small Asian genus Stemmacantha, which, combined, include approximately 10 species. Many species of Rhaponticum are of economic importance, and some have been introduced into cultivation as ornamental or medicinal plants. R. carthamoides (also known as Maral root) is widespread from Central Asia to Siberia and Xinjiang; it is a medicinal plant and a source of ecdysteroids; it is recommended as part of combination therapy for asthenia, physical and mental overwork, impotency, and during convalescence [2]. North African endemic species R. acaule is used as an aperitif, cholagogue, depurative, digestive, stomachic, and tonic in North and Central Tunisia [3]. Creeping knapweed or R. repens is a traditional medicine in Central Asia; it is applied as an emetic, antiepileptic, and anti-malaria remedy [4].

One-flowered leuzea or Rhaponticum uniflorum (L.) DC. (synonyms—R. dauricum Turcz., R. monanthum (Georgi) Worosch., Centaurea monanthos Georgi, C. grandiflora Pall., C. membranaceae Lam., Serratula uniflora Spreng., Leuzea daurica Bge., and L. uniflora (L.) Holub.) has received considerable attention in recent years. There are some scientific study reviews dedicated to R. carthamoides [2] and the genus Rhaponticum [5]; however, the issues of R. uniflorum are not fully covered. Therefore, the aim of this work is to summarize scientific information about R. uniflorum regarding the chemical composition of the herb and roots, as well as methods of analysis and biological activity.

Botanically, R. uniflorum is a low- or medium-height plant (20–60-cm tall) with straight, simple, felted stems [1,2]. Its leaves are rough on both sides, with adpressed cobwebby pubescence, pinnately divided into 8–12 pairs of dentate or entire obtuse lobes. The basal and lower leaves are petiolate, and the upper ones are sessile. Single inflorescences (3–5-cm wide) have outer and middle leaflets that are adpressed, leathery, light-brown, bare, broadly ovate, contain shiny appendages, and are split at the top into uneven lobes. Flower corolla is slightly funnel-shaped and has a coloration ranging from pale pink to red. The rhizome is thick, long, and vertical, with a loose, tuberous-fibrous surface and a few thin roots. Flowers are collected in late spring and early summer, and the roots are dug up in early autumn (Figure 1). In nature, R. uniflorum is scattered on meadow-steppe mountain slopes, along sandy riverbanks, and in the forests of Eastern Siberia and the Russian Far East, as well as in Northern Mongolia, Northeastern China, and Korea [6].

Figure 1.

Rhaponticum uniflorum (L.) DC. (one-flowered leuzea) in its natural habitat (Republic Buryatia, Ivolginskii District, Kluchi vicinity, mountain slope; (a)), and dried roots (qizhou loulu; (b)) and flowers (louluhua, spyang-tser; (c)).

2. Review Strategy

To produce a relevant review, international databases (e.g., Scopus, Web of Science, PubMed, and Google Scholar) were used. Because most studies have been performed by Chinese and Russian scientists, national electronic resources (e.g., Chinese research databases (Wanfang and CNKI Journals) and the Russian scientific database (eLibrary)) were included in the search. These resources contain relevant articles that are not indexed by international databases. Only original papers written in English, Chinese, and Russian, and published in journals prior to October 2022, were considered. An exception was made for the ethnopharmacological data collected from books. The search keywords used included plant names (e.g., “Rhaponticum uniflorum”, “Leuzea uniflora”, “Stemmacantha uniflora”, “Fornicium uniflorum”) and metabolite names. The list of R. uniflorum compounds includes secondary metabolites mostly correlated with ethnopharmacological uses and bioactivities of the plant, and, for a more complete picture, information about primary metabolites is also mentioned in this manuscript.

3. Ethnopharmacology

Ethnopharmacological uses of roots, flowers, and the herb of R. uniflorum were found in Asian traditional medicines (Table 1).

Table 1.

Traditional medical uses of R. uniflorum.

Plant Part	Locality	Traditional Use	Ref.
Roots	China	Anti-inflammatory, antipyretic, detoxifier, antitumor, lactation remedy	[7]
Flowers	China	Relieving burning pain, clearing heat, detoxifying remedy	[9]
	Buryatia	Anti-inflammatory remedy at stomach deseases, gastroenteritis, pneumonia, bronchitis, tuberculosis	[10,11]
	Tibet	Remedy for cleansing wounds and ulcers, indigestion, stomach and lung diseases, to treat skin diseases (boils, carbuncles), mastitis, rheumatoid arthritis	[12,13,14]
Herb	Mongolia	Anti-inflammatory remedy, increasing the vitality of the body	[15]
Buds	Korea	Anti-inflammatory, detoxifier, antipyretic, and analgesic agent	[8]

In traditional Chinese medicine, the roots of R. uniflorum (qizhou loulu) have been used as an anti-inflammatory, antipyretic, detoxifier, antitumor, and lactation agent [7], while flowers (louluhua) have the functions of relieving burning pain, clearing ‘heat’ (or ‘fire’), and as a detoxifying remedy [8]. In the Buryatia Republic, in addition to R. uniflorum [9], under the name spyang-tser, flowers of R. carthamoides, as well as the flowers and roots of Carduus crispus, Guirão ex Nyman, and Cirsium esculentum (Siev.) C.A.Mey., are used to treat stomach inflammations, gastroenteritis, pneumonia, bronchitis, and tuberculosis [10]. In Tibetan medicine, spyang-tser plants are prescribed for cleansing wounds and ulcers, indigestion, and other diseases of the stomach [11], lung diseases [12], and to treat skin diseases (boils, carbuncles), mastitis, and rheumatoid arthritis [13]. In Mongolian folk medicine, the R. uniflorum herb (khonkhor zul, spyang-tser, spyang-tser-dmar-po) is used as a water decoction, as an anti-inflammatory remedy, and to increase the vitality of the body [14]. In Korea, young buds of R. uniflorum are a food product, and the roots (nuro) are used to treat chronic gastritis as an anti-inflammatory, detoxifier, antipyretic, and analgesic agent [15]. Roots and flowers of R. uniflorum are traditional Chinese remedies recorded in the Chinese pharmacopeia and the “Drug Standard of the Ministry of Public Health of the People’s Republic of China” [16].

4. Metabolite Diversity

More than 200 compounds (1–225) have been detected in various organs of R. uniflorum, including sesquiterpenes (1–14), diterpenes (15–17), triterpenes (18–86), thiophenes (87–98), hydroxycinnamates (99–108), flavonoids (109–162), lignans (163–170), various phenolics (171–174), amino acids (175–187), nucleosides and vitamins (188–195), alkanes (196–199), fatty acids (200–217), and carbohydrates (218–225) (Table 2).

Table 2.

Compounds 1–225 found in R. uniflorum.

No	Compound	Formula	MW *	Herb	Leaves	Flowers	Seeds	Roots
	Sesquiterpenes
1	Rhaponticol	C15H24O3	252					[17]
2	Parthenolide	C15H20O3	248			[9]
3	Cynaropicrin	C19H22O6	364	[18]	[19]	[19]	[19]	[19]
4	Cynaropicrin, desacyl-	C15H18O4	262		[19]
5	Cynaropicrin, 4′-deoxy- (aguerin B)	C19H22O5	330	[18]	[19]	[19]	[19]	[19]
6	Repin	C19H22O7	362		[19]
7	Repin, 15-desoxy- (salograviolide C)	C17H20O6	320	[18]	[19]			[19]
8	Repin, 8-desacyl-	C15H18O5	278		[19]
9	Janerin	C19H22O7	362		[19]
10	Janerin, 19-desoxy-	C19H22O6	346		[19]
11	Janerin, chloro-	C19H23ClO7	398.5		[19]
12	Repdiolide	C19H22O6	346		[19]
13	Chlorohyssopifolin A (centaurepensin, hyrcanin)	C19H24Cl2O7	435		[19]			[20]
14	Chlorohyssopifolin E	C19H25ClO8	416		[19]
	Diterpenes
15	Diosbulbin B	C19H20O6	344					[21]
16	Abietic acid	C20H30O2	302			[9]
17	Phytol	C20H40O	296	[6]
	Triterpenes
18	Ajugasteron C	C27H44O7	480	[6]	[22]			[23,24,25]
19	Ajugasteron C 20,22-acetonide	C30H48O7	520		[22]			[23,24,25]
20	Ajugasteron C 2,3;20,22-diacetonide	C33H52O7	560		[22]			[23,24,26]
21	5-Deoxycaladasterone (dacryhainansterone)	C27H42O6	462		[22]	[27]
22	5-Deoxycaladasterone (dacryhainansterone) 20,22-acetonide	C30H46O6	502		[22]	[27]		[16,17]
23	2-Deoxyecdysone	C27H44O5	448		[22]
24	25-Deoxyecdysone	C27H44O5	448		[22]
25	2-Deoxy-20-hydroxyecdysone	C27H44O6	464	[28]	[22]		[29]	[28]
26	Ecdysone	C27H44O6	464	[6]
27	11α-Hydroxyecdysone	C27H44O7	480					[23]
28	20-Hydroxyecdysone	C27H44O7	480	[7,28,30]	[22]	[27]	[29]	[7,23,24,25,31,32]
29	20-Hydroxyecdysone 2-O-acetate	C29H46O8	522		[22]
30	20-Hydroxyecdysone 3-O-acetate	C29H46O8	522		[22]	[27]
31	20-Hydroxyecdysone 25-O-acetate (viticosterone E)	C29H46O8	522	[6]
32	20-Hydroxyecdysone 20,22-acetonide	C30H48O7	520	[6]	[22]	[27]
33	20-Hydroxyecdysone 2,3;20,22-diacetonide	C33H52O7	560		[22]
34	20-Hydroxyecdysone 3-O-glucoside	C33H54O12	642					[6]
35	20-Hydroxyecdysone 25-O-glucoside	C33H54O12	642					[6]
36	20-Hydroxyecdysone 2-O-cinnamate	C36H50O8	610		[33]
37	29-Hydroxy-24(28)-dehydromakisterone C	C29H46O8	522		[22]
38	Inokosterone (callinecdysone A)	C27H44O7	480		[22]	[27]
39	Inokosterone 20,22-acetonide	C30H48O7	520		[22]
40	Inokosterone 20,22-acetonide 25-O-acetate	C32H50O8	562		[22]
41	Integristerone A	C27H44O8	496	[28]	[22]			[28]
42	Integristerone A 20,22-acetonide	C30H48O8	536		[22]	[27]
43	Makisterone C (podecdysone A, lemmasterone)	C29H48O7	508		[22]
44	Makisterone C 20,22-acetonide	C32H52O7	548		[27]	[27]
45	Polypodine B	C27H44O8	496		[22]
46	Polypodine B 20,22-acetonide	C30H48O8	536		[27]
47	Polypodine B 2-O-cinnamate	C36H50O9	626		[33]
48	Ponasterone A	C27H44O6	464		[22]
49	Rapisterone C	C29H48O7	508					[23]
50	Rhapontisterone (punisterone)	C27H44O8	496	[7]	[22]			[7,23,31,32]
51	Rhapontisterone R1	C29H42O9	534					[32]
52	Rubrosterone	C19H26O5	334	[6]
53	Turkesterone	C27H44O8	496	[7,30]	[22]			[7,31]
54	Turkesterone 20,22-acetonide	C30H48O8	536		[22]
55	Turkesterone 2-O-cinnamate	C36H50O9	626		[33]
56	Uniflorsterone	C27H44O7	480					[34]
57	Roburic acid	C30H48O2	440			[9]
58	Urs-12-en-3-one (α-amyrenone)	C30H48O	424					[35]
59	Urs-12-en-3β-ol (α-amyrin)	C30H50O	426	[35]				[35]
60	3-Oxo-urs-12-en-24-oic acid methyl ester	C31H48O3	468	[35]
61	3β-Hydroxy-urs-12-en-28-oic acid (ursolic acid)	C30H48O3	456	[35]				[25,36,37]
62	3β-Hydroxy-urs-12,18(19)-dien-28-oic acid 28-O-glucoside	C36H56O8	616					[25]
63	3β-Hydroxy-urs-12,18(19)-dien-28-oic acid 3-O-arabinoside-28-O-glucoside	C41H64O12	748					[25]
64	3β-Hydroxy-urs-12,18(19)-dien-28-oic acid 3,28-di-O-glucoside	C42H66O13	778					[38]
65	3β-Hydroxy-urs-9(11),12-dien-28-oic acid 3-O-arabinoside-28-O-glucoside (unifloroside)	C41H64O12	748					[39]
66	3β-Hydroxy-urs-12,19(29)-dien-28-oic acid 28-O-glucoside	C36H56O8	616					[25]
67	3β-Hydroxy-urs-12,19(29)-dien-28-oic acid 3,28-di-O-glucoside	C42H66O13	778					[38]
68	3β,19α-Dihydroxy-urs-12-en-28-oic acid (pomolic acid)	C30H48O4	472					[25,40]
69	Pomolic acid 28-O-glucoside	C36H58O9	634					[25,39]
70	Pomolic acid 3-O-arabinoside-28-O-glucoside (ziyuglycoside I)	C41H66O13	766					[25,39]
71	Pomolic acid 3-O-arabinoside (ziyuglycoside II)	C35H56O8	604					[25,39]
72	3-Oxo-19α-hydroxy-urs-12-en-28-oic acid	C30H46O4	470					[25,36,40]
73	2α,3β,19α-Trihydroxy-urs-12-en-28-oic acid (tormentic acid)	C30H48O5	488					[36]
74	Tormentic acid 28-O-glucoside (rosamutin, rosamultin)	C36H58O10	650					[25,39]
75	2α,3β,19α-Trihydroxy-urs-12-en-23,28-dioic acid 28-O-glucoside (sauvissimoside R1)	C36H56O12	680					[25,39]
76	2α,3α,19α-Trihydroxy-urs-12-en-28-oic acid	C30H48O5	488					[18,29]
77	2α,3α,19α,25-Tetrahydroxy-urs-12-en-28-oic acid	C30H48O6	504					[40]
78	2α,3α,19α,25-Tetrahydroxy-urs-12-en-23,28-dioic acid	C30H46O8	534					[25]
79	Olean-12-en-3β-ol (β-amyrin)	C30H50O	426	[35]				[35]
80	3β-Hydroxy-olean-12-en-28-oic acid (oleanolic acid)	C30H48O3	456					[41]
81	2α,3β,19α-Trihydroxy-olean-12-en-28-oic acid (arjunic acid)	C30H48O5	488					[36]
82	β-Sitosterol	C29H50O	414	[35]				[40,41]
83	β-Sitosterol 28-O-glucoside (daucosterol)	C35H60O6	576					[25]
84	Stigmasterol	C29H48O	412	[35]				[41]
85	Stigmastan-3,5-diene	C29H48	396	[35]				[35]
86	Stigmast-4-en-3-on	C29H48O	412					[35]
	Thiophenes
87	Arctinal	C12H8OS2	232					[17,41]
88	Arctinone b	C13H10OS2	246					[17,41,42]
89	Arctinone b, 7-chloro-	C13H9ClOS2	280.5					[41,42]
90	Arctinol b	C13H12O2S2	264					[17]
91	Arctic acid	C12H8O2S2	248					[17,25,40]
92	2,2′-Dithiophene, 5-methoxy-	C9H8OS2	196					[41]
93	2,2′-Dithiophene, 5-methoxy-5′-(1-propynyl)-	C12H10OS2	234					[41]
94	2,2′-Dithiophene, 5-(4-acetoxy-1-butynyl)-	C14H12O2S2	276					[41]
95	Rhaponthienylenol	C13H14O3S2	282					[6]
96	Rhapontiynethiophene A	C11H7ClS2	238.5					[42]
97	Rhapontiynethiophene B	C13H10O2S	230					[42]
98	Thiophene, 2-(pentadiynyl-1,3)-5-(3,4-dihydroxy-butynyl-1)-	C13H10O2S	230					[17]
	Hydroxycinnamates
99	Cinnamic acid	C9H8O2	148			[9]
100	Cinnamaldehyde	C9H8O	132			[9]
101	4-O-Caffeoylquinic acid	C16H18O9	354	[43]			[29]
102	5-O-Caffeoylquinic acid	C16H18O9	354	[43]		[9]	[29]
103	1,3-Di-O-caffeoylquinic acid	C25H24O12	516	[43]
104	1,5-Di-O-caffeoylquinic acid	C25H24O12	516	[43]
105	3,4-Di-O-caffeoylquinic acid	C25H24O12	516	[43]			[29]
106	3,5-Di-O-caffeoylquinic acid	C25H24O12	516	[30]		[9]	[29]
107	4,5-Di-O-caffeoylquinic acid	C25H24O12	516				[29]
108	Isoferuoyl serotonin	C20H20N2O4	352				[29]
	Flavonoids
109	Apigenin	C15H10O5	270		[33]	[16]
110	Apigenin 7-O-glucoside (cosmosiin)	C21H20O10	432		[33]	[16]
111	Apigenin 7-O-glucuronide	C21H18O11	446		[33]	[16]
112	Apigenin 6-C-glucoside (isovitexin)	C21H20O10	432		[33]
113	Apigenin 8-C-glucoside (vitexin)	C21H20O10	432		[33]	[9]
114	Apigenin 6,8-di-C-glucoside (vicenin-2)	C27H30O15	594			[16]
115	6-Methoxyapigenin (hispidulin)	C16H12O6	300		[33]
116	Luteolin	C15H10O5	286			[16]	[29]
117	Luteolin 7-O-glucoside (cynaroside)	C21H20O11	448		[33]
118	Luteolin 7-O-(6″-O-cinnamoyl)-glucoside	C30H26O12	578		[33]		[29]
119	Luteolin 7-O-(2″-O-caffeoyl)-glucoside (rhaunoside G)	C30H26O14	610		[33]
120	Luteolin 7-O-(6″-O-caffeoyl)-glucoside	C30H26O14	610		[33]
121	Luteolin 7-O-glucuronide	C21H18O12	462		[33]
122	Luteolin 7-O-rutinoside (scolymoside)	C27H30O15	594		[33]
123	Luteolin 3′-O-glucoside (dracocephaloside)	C21H20O11	448		[33]
124	Luteolin 4′-O-glucoside	C21H20O11	448		[33]
125	Luteolin 6-C-glucoside (isoorientin)	C21H20O11	448		[33]
126	Luteolin 8-C-glucoside (orientin)	C21H20O11	448		[33]
127	Luteolin 6,8-di-C-glucoside (lucenin-2)	C27H30O16	610		[33]
128	3′-Methoxyluteolin (chrysoeriol)	C16H12O6	300		[33]	[30]
129	6-Hydroxyluteolin	C15H10O6	302		[33]
130	6-Hydroxyluteolin 7-O-glucoside	C21H20O12	464		[33]		[29]
131	6-Hydroxyluteolin 7-O-(6″-O-cinnamoyl)-glucoside (rhaunoside B)	C30H26O13	594		[33]		[29]
132	6-Hydroxyluteolin 7-O-(2″-O-caffeoyl)-glucoside (rhaunoside A)	C30H26O15	626
133	6-Hydroxyluteolin 7-O-(6″-O-caffeoyl)-glucoside (spicoside A)	C30H26O15	626		[33]
134	6-Hydroxyluteolin 7-O-rutinoside	C27H30O16	610		[33]
135	6-Hydroxyluteolin 4′-O-glucoside (rhaunoside C)	C21H20O12	464		[33]
136	6-Methoxyluteolin (nepetin)	C16H12O7	316		[33]
137	6-Methoxyluteolin 7-O-glucoside (nepitrin)	C22H22O12	478		[33]
138	6-Methoxyluteolin 7-O-(6″-O-cinnamoyl)-glucoside (rhaunoside E)	C31H28O13	608		[33]
139	6-Methoxyluteolin 7-O-(6″-O-caffeoyl)-glucoside (rhaunoside D)	C31H28O15	640		[33]
140	6-Methoxyluteolin 7-O-rutinoside	C28H32O16	624		[33]
141	6-Methoxyluteolin 3′-O-glucoside (rhaunoside F)	C22H22O12	478		[33]
142	6-Methoxyluteolin 4′-O-glucoside	C22H22O12	478		[33]
143	6,8-Dihydroxyluteolin 7-O-glucoside (zeravschanoside)	C21H20O13	480		[33]
144	5,6,7,4′-Tetrahydroxy-3′-methoxyflavone (nodifloretin)	C16H12O7	316		[33]
145	5,6,7,3′-Tetrahydroxy-4′-methoxyflavone	C16H12O7	316		[33]
146	Kaempferol	C15H10O6	286			[30]
147	Kaempferol 3-O-rhamnoside (quercitrin)	C21H20O11	448			[30]
148	6-Hydroxykaempferol	C15H10O7	302		[33]
149	6-Hydroxykaempferol 7-O-glucoside	C21H20O12	464		[33]
150	6-Hydroxykaempferol 7-O-(6″-O-caffeoyl)-glucoside	C30H26O15	626		[33]
151	6-Methoxykaempferol 7-O-glucoside	C22H22O12	478		[33]
152	Quercetin	C15H10O7	302			[30]
153	Quercetin 3-O-rhamnoside (quercitrin)	C21H20O11	448			[9]
154	Quercetin 3-O-glucoside (isoquercitrin)	C21H20O12	464			[9]
155	Quercetin 3-O-rutinoside (rutin)	C27H30O16	610			[9]
156	6-Hydroxyquercetin (quercetagetin)	C15H10O8	318		[33]
157	6-Hydroxyquercetin 7-O-glucoside (quercetagitrin)	C21H20O13	480		[33]
158	6-Hydroxyquercetin 7-O-(6″-O-caffeoyl)-glucoside	C30H26O16	642		[33]
159	6-Methoxyquercetin 7-O-glucoside (patulitrin)	C22H22O13	494		[33]
160	3′-Methoxyquercetin (isorhamnetin)	C16H12O6	300		[33]	[9]
161	4′-Methoxyquercetin (diosmetin)	C16H12O6	300			[30]
162	Catechin	C15H14O6	190					[25]
	Lignans
163	Hemislin B					[30]
164	Hemislin B O-glucoside					[30]
165	Arctigenin	C21H24O6	372			[9]
166	Arctigenin O-glucoside (arctiin)	C27H34O11	534			[9]
167	Carthamogenin	C21H22O6	370				[29]
168	Carthamoside	C27H32O11	532				[29]
169	6″-O-Acetyl carthamoside	C29H34O12	574				[29]
170	Tracheloside	C27H34O12	550				[29]
	Other phenolics
171	3,5-Dimethoxy-4-hydroxybenzaldehyde (syringaldehyde)	C9H10O4	182			[9]
172	3,3′,4-Tri-O-methyl-ellagic acid	C17H12O8	344					[25]
173	Coumarin	C9H6O2	146			[9]
174	Ligustilide	C12H14O2	190			[9]
	Amino acids
175	Alanin	C3H7NO2	89	[44]				[44]
176	Arginin	C6H14N4O2	174	[44]				[44]
177	Glycine	C2H5NO2	75	[44]				[44]
178	Histidin	C6H9N3O2	155					[44]
179	Lysine	C6H14N2O2	146	[44]				[44]
180	Leucin	C6H13NO2	131	[44]
181	Methionine	C5H11NO2S	149					[44]
182	Phenylalanine	C9H11NO2	165	[44]				[44]
183	Proline	C5H9NO2	115	[44]				[44]
184	Serine	C3H7NO3	105	[44]				[44]
185	Tyrosine	C9H11NO3	181	[44]				[44]
186	Threonine	C4H9NO3	119	[44]				[44]
187	Valin	C5H11NO2	117					[44]
	Nucleosides and vitamins
188	Cordycepin (3′-deoxyadenosine)	C10H13N5O3	251			[9]
189	Thiamine (vitamin B1)	C12H17N4OS+	265	[45]				[45]
190	Riboflavine (vitamin B2)	C17H20N4O6	376	[45]				[45]
191	Pantothenic acid (vitamin B5)	C9H17NO5	219	[45]				[45]
192	Nicotinic acid (niacin, vitamin B3)	C6H5NO2	123	[45]				[45]
193	Nicotinamide	C6H6N2O	122			[9]
194	Pyridoxine (vitamin B6)	C8H11NO3	169	[45]				[45]
195	Folic acid (vitamin B9)	C19H19N7O6	441					[45]
	Alkanes
196	Pentacosane	C25H52	352	[35]
197	Heptacosane	C27H56	380	[35]
198	Octacosane	C28H58	394	[35]
199	Nonacosane	C29H60	408	[35]
	Fatty acids
200	Tetradecanoic acid (myristic acid; 14:0)	C14H28O2	228	[35]				[35]
201	Pentadecanoic acid (15:0)	C15H30O2	242	[35]				[35]
202	Hexadecanoic acid (palmitic acid; 16:0)	C16H32O2	256	[35]				[35]
203	Heptadecanoic acid (margaric acid; 17:0)	C17H34O2	270	[35]				[35]
204	Octadecanoic acid (stearic acid; 18:0)	C18H36O2	284	[35]				[35]
205	Icosanoic acid (arachic acid; 20:0)	C20H40O2	312	[35]				[35]
206	Heneicosanoic acid (21:0)	C21H42O2	326	[35]
207	Docosanoic acid (behenic acid; 22:0)	C22H44O2	340	[35]				[35]
208	Tricosanoic acid (23:0)	C23H46O2	354	[35]				[35]
209	Tetracosanoic acid (lignoceric acid; 24:0)	C24H48O2	368	[35]				[35]
210	Pentacosanoic acid (25:0)	C25H50O2	382	[35]				[35]
211	Hexacosanoic acid (cerotic acid; 26:0)	C26H52O2	396	[35]
212	Octacosanoic acid (montanic acid; 28:0)	C28H56O2	424	[35]
213	Triacontanoic acid (melissic acid; 30:0)	C30H60O2	452	[35]
214	Hexadec-7-enoic acid (16:1n9)	C16H30O2	254	[35]				[35]
215	Octadec-9-enoic acid (oleic acid; 18:1n9)	C18H34O2	282					[35]
216	Octadeca-9,12-dienoic acid (linoleic acid; 18:2n6)	C18H32O2	280	[35]				[35]
217	Octadeca-9,12,15-trienoic acid (linolenic acid; 18:3n3)	C18H30O2	278	[35]		[9]		[35]
	Carbohydrates
218	Glucose	C6H12O6	180		[46]	[46]	[46]	[46]
219	Fructose	C6H12O6	180		[46]	[46]	[46]	[46]
220	Sucrose	C12H22O11	342		[46]	[46]	[46]	[46]
221	Kestose (1F-β-fructofuranosyl sucrose)	C18H32O16	504		[46]			[46]
222	Nystose (di-(1F-β-fructofuranosyl) sucrose)	C24H42O21	666		[46]			[46]
223	1F-β-Fructofuranosyl nystose	C30H52O26	828		[46]			[46]
224	Di-(1F-β-fructofuranosyl) nystose	C36H62O31	990		[46]			[46]
225	Tri-(1F-β-fructofuranosyl) nystose	C42H72O36	1152		[46]			[46]

* MW—Molecular weight.

4.1. Sesquiterpenes

Fourteen sesquiterpenes (1–14) have been identified in R. uniflorum, including eudesmane 1, germacranolide 2, and guaianes 3–14 [17,18,19,20] (Figure 2). Rhaponticol {7α,8α,12-trihydroxy-eudesma-4(15)-11(13)-diene, 1}, isolated from roots of R. uniflorum [17], is the only eudesmane found in the Rhaponticum genus, and it is non-typical for the Rhaponticum group (Centaureinae subtribe). This sesquiterpene type is characteristic of other members of the tribe, including the genus Centaurea (Centaurea group) and, less commonly, for the Mediterranean species Cheirolophus and Phonus (Carthamus group) [20].

Figure 2.

Sesquiterpenes 1–14 and diterpenes 15–17.

Parthenolide (2), a typical feverfew component, has been found in Centaurea and Stizolophus genera [20], but it is the only germacranolide in the Rhaponticum group. Unlike eudesmanes and germacranolides, guaianes are widely distributed in Rhaponticum species, especially cynaropicrine (3), and are identified in R. uniflorum [18] and in R. carthamoides (Willd.) Iljin, R. exaltatum (Willk.) Greuter, R. pulchrum Fisch. & C.A.Mey., R. scariosum subsp. Rhaponticum (L.) Greuter, and R. serratuloides (Georgi) Bobrov [20]. Structurally similar to 3, sesquiterpenes 4–12 have been isolated from the herb and roots of R. uniflorum [18,19], as well as two chlorinated sesquiterpenes, i.e., chlorohyssopifolins A (13) and E (14) [19,20].

4.2. Diterpenes

The member of furanoid norditerpenes diosbulbin B (15) was found in R. uniflorum roots (Figure 2) [21]. This compound, first isolated from Dioscorea bulbifera L. [47], is a hepatotoxic agent that causes oxidative damage to hepatocyte membranes [48]. Additionally, abietane diterpenoid abietic acid (16) and acyclic diterpene alcohol phytol (17) have been detected in the flowers and herb of R. uniflorum.

4.3. Triterpenes

Various types of triterpenes were found in R. uniflorum, including ecdysteroids, triterpene acids, alcohols, ketones, and sterols. Ecdysteroids were first discovered in R. uniflorum in the early 1990s [31]. Since then, 39 compounds (18–56) of this group have been identified in the plant, of which 33 are in the herb (18–26, 28–33, 36–48, 50, 52–55) and 15 in the roots (18–20, 22, 25, 27, 28, 34, 35, 41, 49–51, 53, 56) (Figure 3). Almost all compounds contain a full side chain, except rubosterone (16). The number of hydroxyl groups in ecdysteroid structures can be 3 (52), 4 (23, 24), 5 (21, 22, 25, 26, 48), 6 (18–20, 27–36, 38–40, 43, 44, 49, 51, 56), and 7 (37, 41, 42, 45–47, 50, 53–55), indicating the dominance of polyhydroxy compounds. The most common derivatives are 20-hydroxyedysone (28–36), ajugasterone C (18–20), inokosterone (38–40), polypodine B (45–47), and turkesterone (53–55). For individual components, acetates (29–31), acetonides (19, 22, 32, 39, 42, 44, 46, 54), diacetonides (20, 33), and acetonide-acetates (40) can be formed. Glycosides are a rare group of derivatives for R. uniflorum because only two compounds (22 and 23) have been identified in the roots of this species [6]. Ecdysteroids cinnamoyl esters 36, 47, and 55 found in the leaves of the plant deserve special attention [33]. Previously known compounds (36 and 47) were isolated only from the fern Dacrydium intermedium Kirk (Lepidothamnus intermedius (Kirk) Quinn, Podocarpaceae) [49,50]. The unusual structural compounds include rapontisteron R₁ (51) (which contains a furan ring in the side chain [32]) and uniflorsterone (56) (which contains a hydroxyl group in the atom C-23 [34]).

Figure 3.

Ecdysteroids 18–56. Ac–acetyl; Cin–cinnamoyl; β-D-Glcp–β-D-glucopyranose.

Comparing the chemodiversity of the ecdysteroids in R. uniflorum with that of the more-studied species R. carthamoides (in which more than 50 compounds of this class have been identified so far [20]), it can be assumed that there are many more compounds in the composition of the steroid metabolome of R. uniflorum.

Different organs of R. uniflorum are the sources of 25 non-ecdysteroid triterpenoids (57–81), including 23 compounds isolated from the roots and five components detected in the herb (57, 59–61, 79) (Figure 4). The only tetracyclic triterpene roburic acid (57), typical for Gentiana roots [51], was detected in the flowers of R. uniflorum [9]. The remaining compounds (58–81) were pentacyclic triterpenes. Ursans are the dominant structural type of R. uniflorum triterpenes (21 compounds), as opposed to oleanans, represented by fewer components (3 compounds). Triterpenoids of R. uniflorum can contain unsaturated bonds at C₉–C₁₁, C₁₂–C₁₃, C₁₈–C₁₉, C₁₉–C₂₉, hydroxyl groups at C₂, C₃, C₁₉, and C₂₅ and carboxyl groups at C₂₃ and C₂₈. Eleven compounds have been identified as mono- and di-glycosides, including fragments of β-D-glucose and/or α-L-arabinose at C₃ and/or C₂₈. Two alcohols, α- (59) and β-amyrins (79) [35], as well as two acids, 3-oxo-ursus-12-en-24-oic acid (as methyl ether, 60) [35] and ursolic acid (61) [30], have been detected in the R. uniflorum herb. Triterpenoids of R. uniflorum roots are notable for their large structural diversity of the primary ursan skeleton, as well as their ability to form glycosides identified only in this part of the plant. The basic triterpene aglycones are 3β-hydroxy-urs-12,18(19)-dien-28-oic acid as glycosides 62–64 [25,39], 3β-hydroxy-urs-12,19(29)-dien-28-oic acid as glycosides 66 and 67 [25,39], pomolic acid (3β,19α-dihydroxy-urs-12-en-28-oic acid, 68) [25,41] and tormentic acid (2α,3β,19α-trihydroxy-urs-12-en-28-oic acid, 73) [36]. Of note, the 3β-hydroxy functional group is typical for R. uniflorum triterpenoids, except in three compounds with a 3α-hydroxy functional group, including 76 [25,41], 77 [41], and 76 [25], isolated from the roots of R. uniflorum growing in China. A few oleanan derivatives include β-amyrin (79) [35], oleanolic acid (80) [40], and arjunic acid (81) [36]. Five stigmastane derivatives have been found in the R. uniflorum herb and roots, including β-sitosterol (82) and its glucosides daucosterol (83) [25,35,40,41], stigmasterol (84) [35,41], stigmastan-3,5-diene (85) [35], and stigmast-4-en-3-one (86) [35].

Figure 4.

Triterpenes 57–86. A-L-Arap–α-L-arabinopyranose; β-D-Glcp–β-D-glucopyranose.

4.4. Thiophenes

Twelve thiophenes (87–98) have been isolated from the roots of R. uniflorum, including monomers (97, 98) and dimeric derivatives of 2,2′-dithiophene (87–96) (Figure 5). Typical thiophenes of R. uniflorum are derivatives of 5′-(1-propynyl)-2,2′-dithiophene, with various substituents at position C₅, such as arctinal (87) [17,41], arctinone b (88) [17,41,42], and arctic acid (91) [17,25,40]. Two chlorinated thiophenes, 7-chloroarctinone b (89) [41,42] and rhapontiynethiophene A (96) [42], have been isolated from the roots of Chinese origin.

Figure 5.

Thiophenes 87–98 and hydroxycinnamates 99–108. Caf–caffeoyl.

4.5. Hydroxycinnamates

Cinnamic acid (99) and cinnamaldehyde (100) have been found in the R. uniflorum flowers [9], while seven caffeoylquinic acids (101–107) were found to be components of the herb and seeds (Figure 5) [29,30,43]. Feruloyl serotonin (108) was isolated from the seeds of R. uniflorum [29] and was previously found in R. carthamoides [52].

4.6. Flavonoids

Flavonoids are the largest group of R. uniflorum metabolites containing 53 compounds (109–161), including 37 flavones (101–145), 16 flavonols (146–161) and one catechin (162) (Figure 6) [9,16,29,30,33]. Flavone derivatives are present in most O- and C-glucosides of apigenin (6 compounds), luteolin (12 compounds), 6-hydroxyluteolin (7 compounds), and 6-methoxyluteolin (7 compounds). Glycoside moieties of flavone glycosides contain glucose, glucuronic acid, rutinose, and acylated carbohydrates as cinnamoyl/caffeoyl-glucose attached mainly at C₇ (18 compounds) and at C_3′/C_4′ (5 compounds). Glycosides of kaempferol, 6-hydroxykaempferol, quercetin, and 6-hydroxy/methoxy-quercetin are the main flavonols of R. uniflorum. The general structural patterns are very similar to flavones (carbohydrate nature, 7-O-glycosylation), and 3-O-glycosides have also been detected. The known data indicate that the greatest flavonoid diversity is specific to leaves, which contain 43 compounds [33], followed by the flowers (15 compounds) [9,30] and seeds (4 compounds) [29].

Figure 6.

Flavonoids 109–162. Caf–caffeoyl; Cin–cinnamoyl; β-D-Glcp–β-D-glucopyranose; β-D-GlcAp–β-D-glucuronopyranose; α-L-Rhap–α-L-rhamnopyranose.

4.7. Lignans

Four lignans have been identified in the herbal part of R. uniflorum, which include those widely distributed in Asteraceae arctigenin (164), arctiin (165) [9], hemislin B (162), hemislin B O-glucoside (163) [30], found only in Hemistepta lyrata (Bunge) Bunge (Asteraceae) (Figure 7) [52]. Later, carthamogenin (166) and carthamoside (167), which are isomeric to 162 and 163 in the α-position of hydrogen at C_8′ [53], were isolated from the seeds of R. uniflorum together with the acetyl ester of 167 and tracheloside (169) [29].

Figure 7.

Lignans 163–170 and various phenolics 171–174. Ac–acetyl; β-D-Glcp–β-D-glucopyranose.

4.8. Other Compounds

Among other phenolic components, catechin (171) and 3,3′,4-tri-O-methyl-ellagic acid (172) in the roots [13] and 3,5-dimethoxy-4-hydroxybanzaldehyde (170), coumarin (173), and ligustilide (174) in the flowers have been identified in R. uniflorum [9]. The presence of 13 amino acids (175–187), including essential amino acids, was found in R. uniflorum organs [44]. The main components of the free amino acids were alanine and glycine, while lysine and valine dominated among the bound amino acids. 3′-Deoxyadenosine (cordycepin, 188) and nicotinamide (193) were detected in the flowers [9], and some vitamins (189–192, 194, 195) have been quantified in the herb and roots of R. uniflorum [45]. Additionally, four alkanes (196–199) and fatty acids (200–217) have been described as components of the whole plant [35]. The main components of the lipid fraction of R. uniflorum herb are linolenic acid (19.6%), palmitic acid (18.0%), and linoleic acid (13.4%). Root lipids of R. uniflorum are similar to the herb profile; however, the highest content was noted for linoleic acid (41.2%) and lower for palmitic acid (1.8%) and linolenic acid (8.3%). There is also information about essential oil composition in the flowers [54] and roots of R. uniflorum [55], including free carbohydrates (218–225) and polysaccharides [46].

5. Chromatographic Analysis of R. uniflorum

Despite the widespread use of R. uniflorum as a medicinal plant, only few methods for the quantitative analysis of this plant material using liquid chromatography are known (Table 3). To separate the main ecdysteroids of the herb and roots of R. uniflorum (28, 25, 41, 50, 53), six variants of high performance liquid chromatography analysis on reversed-phase sorbents have been proposed, i.e., using the columns Ultrasphere ODS [7], Zorbax ODS [28], ProntoSIL 120-5 C18 [56], YMC-Pack C18 [57], GLC Mastro C18 [43], and Waters Acquity UPLC HSS T3 C18 [9] with 100–250-mm length [7,9,28] or 60-mm microcolumns [56]. Mixtures of methanol, acetonitrile, water, perchlorate buffer, and formic acid have been used as eluents to achieve separation in isocratic and gradient modes. The total duration of the analysis varied from 15 to 70 min. Analysis of the dominant components of R. uniflorum flowers has also been performed under reversed phase HPLC conditions using a mixture of phosphoric acid and acetonitrile [57]. The chosen analysis conditions allowed separation of six compounds, including 28, 109, 116, 128, 147, and 163.

Table 3.

HPLC analysis conditions used for the separation of selected R. uniflorum metabolites.

Compounds	Column	Elution Mode (I—Isocratic; G—Gradient), Eluents, Gradient Programm; Flow Rate (ν)	Column Temperature (T), Detector 1 (D), Analysis Duration (t)	Ref.
28, 50, 53	Ultrasphere ODS (250 × 4.6 mm, 5 μm; Hichrom Ltd., Lutterworth, UK)	I; MeOH-H2O 40:60; ν 1.5 mL/min	T 20°C; D: UV (λ 242 nm); t 15 min	[7]
25, 28, 41	Zorbax ODS (250 × 4.6 m, 5 μm; Agilent Technologies, Santa-Clara, CA, USA)	I; MeCN-H2O 20:80; ν 2 mL/min	T 55 °C; D: UV; t 20 min	[28]
25, 28, 41, 53	ProntoSIL 120-5 C18 AQ (60 × 1 mm, 1 μm; Knauer, Berlin, Germany)	G; A: 4.1 M LiClO4-0.1 M HClO4 5:95, B: MeCN; 0–15 min 5–58% B; ν 0.15 mL/min	T 35 °C; D: UV (λ 248 nm); t 15 min	[56]
28, 109, 116, 128, 147, 163	YMC-Pack C18 (250 × 4.6 mm, 5 μm; YMC Co. Ltd., Kyoto, Japan)	G; A: 0.2% H3PO4, B: MeCN; 0–15 min 20–25% B, 15–50 min 25–40% B; ν 0.8 mL/min	T 35 °C; D: UV (λ 254 nm); t 50 min	[57]
28, 38, 101–107, 111, 121	GLC Mastro C18 (150 × 2.1 mm, 3 μm; Shimadzu, Kyoto, Japan)	G; A: 0.5% HCOOH in water, B: 0.5% HCOOH in MeCN; 0–2 min 5–6% B, 2–9 min 6–11% B, 9–15 min 11–25% B, 15–20 min 25–55% B, 20–25 min 55–5% B	T 35 °C; D: PDA (λ 254 nm), MS; t 25 min	[43]
2, 16, 57, 99, 100, 102, 106, 113, 153–155, 160, 164, 165, 170, 173, 174, 188, 193, 217	Waters Acquity UPLC HSS T3 C18 (100 × 2.1 mm, 1.8 μm)	G; A: MeCN, B:0.1% HCOOH; 0–10 min 100% B, 10–20 min 100–70% B, 10–25 min 70–60% B, 25–30 min 60–50% B, 30–40 min 50–30% B, 40–45 min 30–0% B, 45–60 min 0% B, 60–60.1 min 0–100% B, 60.1–70min 100% B; ν 0.2 mL/min	T 30 °C; D: DAD (λ 254 nm), MS; t 70 min	[9]

¹ Detectors: DAD–diode array; MS–mass spectrometric; PDA–photodiode array; UV–ultraviolet.

According to the quantitative analysis of R. uniflorum, the content of individual compounds in different organs may vary (Table 4). The concentration of the dominant ecdysteroid 20-hydroxyecdysone (28) in raw materials collected in Russia was 0.02–1.06% [28,56]. Plants growing in China are characterized by a higher content of 28 in the leaves (up to 1.35%) than in the roots (0.45%) [7,57]. The level of other ecdysteroids (25, 41, 50, and 53) was characterized as trace. The concentration of the basic phenolic compounds in R. uniflorum flowers varied from 0.03–0.05% for 128 to 0.42–2.26% for 163 [57].

Table 4.

Content of selected metabolites in R. uniflorum organs, % of dry plant weight.

Origin	Compound
	25	28	41	50	53	109	116	128	147	163
Roots
China [7]		0.12–0.45		0.01–0.06	0.01–0.07
Russia [28,56]	Tr.–0.02	0.09–0.85	Tr.	0.16
Flowes
China [7]		0.78		0.02	Tr.
Russia [28]		0.03
Leaves
China [7,41]		0.27–1.35		Tr.–0.09	Tr.	0.08–0.24	0.19–0.60	0.03–0.05	0.66–1.26	0.42–2.26
Russia [28]	Tr.–0.06	0.02–0.85	Tr.–0.02
Stems
China [7]		0.62		0.05	0.02
Russia [28]	Tr.	0.03–0.47	Tr.
Herb
Russia [56]	0.24	1.06		0.10	0.21

Tr.—trace content.

6. Bioactivities

The known literature data on bioactivity of R. uniflorum are primarily related to the preparation of plant roots in the form of extracts and decoctions, as well as the bioactivity of the leaf, herb, and flower extracts (Table 5).

Table 5.

Bioactivity data of R. uniflorum.

Extract, Compound	Assay, Model	Dose a	Positive Control	Result b	Ref.
Anti-inflammatory activity
In vitro study
Roots ethanol extract	LPS-stimulation of murine macrophage RAW 264.7 cells	10–100 μg/mL	Dexamethasone (10 μg/mL)	Inhibition NO, TNF-α, IL-6, IL-1β, iNOS, COX-2, HO-1, NF-κB, phospho-IκBα, IκBα, ERK1/2, p38, JNK	[58]
Roots hexane, chloroform, ethyl acetate, butanol, water extracts	LPS-stimulation of murine macrophage RAW 264.7 cells	5–100 μg/mL	NG-monomethyl-L- arginine monoacetate (10 μM)	Inhibition NO, PGE2, IL-1β, IL-6, iNOS	[8]
Flower ethanol extract	Doxorubicin-initiated cardiotoxicity of embryonic rat cardiomyocytes H9c2	12.5–800 μg/mL	Dexrazoxane (7.5 μg/mL)	Inhibition ROS, Bax, cleaved-caspase-3, cleaved-caspase-9, cleaved-PARP, NF-κB	[16]
In vivo study
Flower ethanol extract	Oropharyngeal aspirational LPS induced acute lung injury of male BALB/c mice	100–400 mg/kg	Dexamethasone (5 mg/kg)	Inhibition TNF-α, IL-6, NO, p-p38, p-JNK, p-ERK, TLR4, Myd88, p-IκB, p-p65, Keap1; stimulation Nrf2, HO-1, NQO1	[9]
Antitumor activity
In vitro study
Root ethanol extract	AGS human gastric adenocarcinoma cell	50–150 μg/mL	5-Fluorouracil (5 mg/kg)	Inhibition of tumor cells grow	[59]
Roots ethyl acetate extract	Cell carcinoma cell line SCC15	50 μg/mL	5-Fluorouracil (5 μg/mL)	Inhibition tumor grow, ETS1, Prx1	[60]
Root methylene chloride, ethyl acetate, butanol extracts	Human lung adenocarcinoma cells A549 and H1299	10–500 μg/mL	5-Fluorouracil (5 mg/kg)	Inhibition of tumor cells grow	[61]
In vivo study
Roots ethanol extract	Mice bearing H22 hepatoma cells	100–400 mg/kg p.o.	5-Fluorouracil (5 mg/kg)	Anti-angiogenic and pro-apoptotic effects against H22 hepatoma cells	[62]
Roots ethyl acetate extract	Human OSCC cell line SCC15	12.5–100 μg/mL	5-Fluorouracil (5 mg/kg)	Induction of apoptosis; suppression of cell invasion and migration; inhibition Prx1, vimentin, Snail	[63]
Roots water extract	Mice bearing H22 hepatoma cells	100–400 mg/kg p.o.	5-Fluorouracil (5 mg/kg)	Inhibition tumor grow, TNF-α	[64]
Immune-stimulating activity: in vivo study
Roots ethanol extract	Erythrocyte immune function of rats	3–15 mg/kg; i.p.	-	Enhancement of erythrocyte immune function	[65]
Leaf ethanol extract	Cyclophosphamide-induced immunodeficiency of CBA×C57Bl/6 mice	100 mg/kg; i.p.	Echinacea extract (200 mg/kg)	Increasing of the cellular, humoral, and macrophage immunity	[66]
Nervous system effects: in vivo study
Roots ethanol extract	Elevated plus maze test and dark/light chamber of Wistar rats	100–300 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Anti-anxiety effect	[67]
Roots ethanol extract	D-galactose-induced aging of mice	20–100 mg/kg; p.o.	-	Anti-aging effect	[68]
Roots ethanol extract	Passive avoidance test of mice	20–100 mg/kg; p.o.	-	Improving memory impairment	[69]
Leaf ethanol extract	Passive avoidance test of mice	50–200 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Anxiolytic effect	[70]
Leaf ethanol extract	Hypoxia/reoxygenation of Wistar rats	100–200 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Neuroprotective effect	[71]
Stress-protective activity: in vivo study
Roots ethanol extract	Immobilization stress and psycho-emotional stress tests of Wistar rats	100–300 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Stress-protective effect	[67,72]
Actoprotective and anabolic activity: in vivo study
Roots ethanol extract	Physical endurance test of Wistar rats	100–300 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Increasing of overall physical endurance, working capacity, ATP in muscles, skeletal muscle mass; decrease metabolic acidosis	[67,68]
Antihypoxic and anti-ischemic activity: in vivo study
Roots ethanol extract	Hypercapnic, hemic, histotoxic hypoxia of Wistar rats	50–200 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Antihypoxic effect	[67]
Leaf ethanol extract	Bilateral carotid artery occlusion of Wistar rats	50–200 mg/kg; p.o.	Rhaponticum carthamoides extract (100 mg/kg)	Decrease mortality, neurological deficit, severity of cerebral edema	[73]
Hepatoprotective activity
In vitro study
Root ethanol extract	H2O2-induced liver cells damage	12.5–400 μg/mL	-	Icreasing cell viability; reduction LDH, ALT, AST, MDA; increasing GSH	[74]
Root ethanol extract	H2O2-induced HepG2 cells damage	25–400 μg/mL	-	Icreasing cell viability, SOD, GSH; reduction LDH, ALT, AST, MDA, caspase-3, 8, 9, cytoplasmic cytochrome C, p-JNK, nuclear NF-κB	[75]
In vivo study
Roots water extract	Carbon tetrachloride-induced acute liver injury of mice	50–200 mg/kg; i.p.	Bifendate (10 mg/kg)	Reduction serum ALT, AST, liver level of LOOH, MDA; increasing liver CAT, GSH-Px, SOD, Mn-SOD, Na+-K+-ATPase and Ca2+-Mg2+-ATPase; DNA damage of hepatocyte	[76]
Anti-aterosclerotic and hypolypidemic activity: in vivo study
Root ethanol, water extract	Hypercholesterol diet of mice	100–400 mg/kg; p.o.	-	Decreasing total cholesterol, total glycerides, LDL-C; icreasing HDL-C	[77]
Root ethanol extract	Oleic acid-induced fat accumulation in HepG2 cells	10–500 μg/mL; p.o.	-	Decreasing total cholesterol, total glycerides, LDL-C; icreasing HDL-C	[78]
Inhibition of PPARγ receptors: in vitro study
Roots ethanol extract; 7-chloroarctinone b	Cell-based transactivation assay	1.18–10 μM	-	Inhibition of rosiglitazone-induced transcriptional activity of PPARγ	[79]
Antioxidant activity: in vitro study
Root water extract	Total antioxidant activity, hydroxyl radical scavenging, Fe2+-induced lipid peroxidation in liver mitochondria	0–100 μg/mL	Ascorbic acid	Antioxidant activity	[80]
Root butanol extract	Total antioxidant activity, hydroxyl radical scavenging, Fe2+-induced lipid peroxidation in liver mitochondria	0–100 μg/mL	Ascorbic acid	Antioxidant activity	[81]
Herb ethanol extract	Radical-scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radicals; 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid cation-radicals; superoxide radicals; Fe2+-chelating activity	5–1000 μg/mL	Ascorbic acid	Antioxidant activity	[43]
Antibacterial activity: in vitro study
Root water extract	Inhibition of Gardnerella vaginalis	0–20 mg/mL	Ampicillin	Bacterial grow inhibition	[82]
Diuretic activity: in vivo study
Root water extract	3-Month application of extract solution by Wistar rats	100–500 mg/mL; p.o.	-	Moderarte increase of diuresis	[58]
Antidiabetic activity: in vitro study
Seed water extract, flavonoids, lignans	Inhibition of pancreatic α-amylase	0–100 μg/mL	Acarbose	Moderarte inhibition of α-amylase	[29]

^a p.o.–per os, oraly; i.p.–intraperitonealy. ^b ALT–alanine transaminase; AST–aspartate transaminase; Bax–Bcl-2-associated X protein; CAT–catalase; COX-2–cyclooxygenase-2; ERK–extracellular signal-regulated kinase 1/2; ETS1–protein C-ets-1; GSH–glutathione reduced; HDL–high-density lipoprotein; HO-1–heme oxygenase 1; IL-6–interleukin-6; IL-1β–interleukin-1β; iNOS–inducible nitric oxide synthase; IκBα–nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha; JNK–c-Jun N-terminal kinase; Keap1–Kelch-like ECH-associated protein 1; LDH–lactate dehydrogenase; LDL–low-density lipoprotein; LOOH–lipid hydroperoxide; MDA–malondialdehyde; Myd88–myeloid differentiation primary response 88; NF-κB–nuclear factor kappa B; NO–nitric oxide (II); NQO1–NAD(P)H dehydrogenase [quinone] 1; Nrf2–nuclear factor erythroid 2-related factor 2; PARP–poly ADP ribose polymerase; PGE2–prostaglandin E2; Prx1–peroxiredoxin-1; p38–mitogen-activated protein kinase p38; ROS–reactive oxygen species; SOD–superoxide dismutase; TNF-α–tumor necrosis factor-alpha; and TLR4–toll-like receptor 4. “-”–no data.

6.1. Anti-Inflammatory Activity

The study of the anti-inflammatory mechanisms of R. uniflorum roots and flowers demonstrated their effectiveness in in vitro and in vivo studies [8,9,16,19,58]. Ethanol extract of R. uniflorum roots significantly inhibited the secretion of nitric oxide (NO) and inflammatory cytokines in the culture of RAW 264.7 mouse macrophages and peritoneal macrophages without the manifestation of cytotoxicity [58]. The extract significantly suppressed the expression of inducible NO synthase (iNOS) and cyclooxygenase 2 while simultaneously inducing the expression of heme oxygenase 1 [58]. The inhibition of phosphorylation and degradation of the IκBα factor led to the prevention of nuclear translocation of the NF-κB transcription factor, which, in turn, controls the expression of immune response, apoptosis, and cell cycle genes. A pronounced ability of the R. uniflorum root extract to suppress mitogen-activated protein kinases (MAPKs), such as ERK1/2, p38, and JNK, was revealed in a culture of lipopolysaccharide (LPS)-stimulated macrophages [8]. The lipophilic components of the hexane and chloroform fractions of R. uniflorum had a greater inhibitory effect on NO production in a culture of LPS-stimulated macrophages and suppressed the transcription of the iNOS messenger RNA [8]. The butanol and ethyl acetate fractions reduced the synthesis of prostaglandin PGE2, while the hexane and ethyl acetate fractions led to the suppression of interleukin-1β [8]. Overall, these facts demonstrate the effectiveness of the R. uniflorum root extract as an anti-inflammatory agent acting through the activation of NF-κB and MAPK signaling pathways. Investigation of the anti-inflammatory activity of the R. uniflorum flower extract demonstrated its facilitating potential after doxorubicin-initiated cardiotoxicity of embryonic rat cardiomyocytes H9c2 [16]. In in vivo experiments, R. uniflorum flower extract prevented LPS-induced pathological alterations of lung bronchoalveolar lavage fluid (BALF) [9]. Downregulation of F4/80 antigen expression in lungs and suppression of LPS-induced elevations in BALF and lung tissue levels of myeloperoxidase were observed with the simultaneous reduction of expression of proteins p-p38, p-JNK, p-ERK (mitogen-activated protein kinase signaling pathway), TLR4, Myd88, p-IκB, and p-p65 (Toll-like receptor 4 and NF-κB signaling pathway) [9]. The abovementioned results indicated that the R. uniflorum flower extract ameliorated LPS-induced acute lung injury by suppressing the inflammatory response and enhancing antioxidant capacity.

6.2. Antitumor Activity

The root extracts of R. uniflorum in in vitro studies reduced the proliferation of AGS human gastric adenocarcinoma cells [59], SCC 15 oral cancer cells [60], and human lung adenocarcinoma cells A549 and H1299 tumor cells [61]. The extracts inhibited messenger RNA (mRNA) and expressed transcription factors protein C-ets-1 (ETS1), and peroxiredoxin 1 (Prx1) resulted in the suppression the growth and proliferation of SCC 15 cells [60]. Animal experiments with H₂₂ hepatoma cells demonstrated reduction of transplanted tumor grow caused by reducing DNA fragmentation and microvascular density and worsening the expression of signaling proteins, such as vascular endothelial growth factors (VEGF) and hypoxia-inducible factor 1α (HIF-1α), indicating an antiangiogenic and proapoptotic effect on H₂₂ cells [62]. Root ethyl acetate extract affected the growth of SCC15 epidermoid carcinoma cells, reducing their viability and inducing their apoptosis. Treatment of cells with this fraction promoted the expression of messenger RNA and E-cadherin, while reducing the expression of peroxiredoxin 1, vimentin, and the SNAI1 protein influenced the program of the epithelial-mesenchymal transition, significantly reducing tumor growth [63]. The aqueous extract of R. uniflorum roots (100–400 mg/kg) slowed tumor growth by 27–38% in mice with transplanted H22 tumors, improving the immune system and antioxidant status of the organism [64].

6.3. Immune-Stimulating Activity

The immunostimulatory effect of the R. uniflorum root extract has been described for the experimental immune suppressions caused by azathioprine, owing to the increasing activity of the cellular, humoral, and macrophage components of the body′s immune system [65]. The extract from the leaves of R. uniflorum is an effective immune stimulant in cyclophosphamide-induced immunodeficiency [66].

6.4. Nervous System Effects

A study on the anti-anxiety effect of R. uniflorum showed that animals treated with dry root extract (200–300 mg/kg) had higher overall locomotor activity compared to control animals. Administration of the R. uniflorum extract had a pronounced anti-anxiety effect under conditions of unpunished behavior. An increase in exploratory activity and a decrease in the feeling of fear and anxiety in animals was explained by a decrease in their level of emotionality [67]. The administration of the extract stimulated cognitive functions, accelerated the development of conditioned reflexes, and ensured the long-term preservation of memory. The use of the R. uniflorum root extract in mice with galactose-induced aging contributed to the prevention of mitochondrial degeneration, increased the level of succinate dehydrogenase and superoxide dismutase in brain tissues, and decreased the level of MDA, monoamine oxidase, and lactate dehydrogenase activity [68]. Finally, it led to a decrease in the concentration of lipoperoxides and lipofuscin in brain tissues, positively affecting the learning and memory processes [69]. The leaf extract of R. uniflorum (50–200 mg/kg) resulted in the adaptation of animals to unfamiliar conditions, an increase in orienting-exploratory activity, and the formation of a conditioned reflex with positive reinforcement, which has generally indicated a pronounced anti-anxiety effect [70]. After 30 min hypobaric hypoxia and 3 h reoxygenation, the use of R. uniflorum leaf extract (100 mg/kg) limited the formation of pyknotic neurons, sharply hypochromic neurons, and “shadow cells” in the cortex of cerebral hemispheres, indicating a neuroprotective effect during hypoxia/reoxygenation [71].

6.5. Stress-Protective Activity

In models of 18 h immobilization stress and psycho-emotional stress, it was found that extracts from the herb and roots of R. uniflorum (100 mg/kg) had a pronounced stress-protective effect, reducing the involution of immunocompetent organs (adrenals, thymus, spleen), delaying the development of deep destruction of the gastric mucosa, reducing the level of MDA, and increasing the concentration of reduced glutathione and the activity of catalase and superoxide dismutase [67]. After administration of R. uniflorum extracts, there was a decrease in blood concentration of adrenaline, norepinephrine, adrenocorticotropic hormone, corticosterone, and aldosterone [72]. The positive effect of extracts is due to the limitation of hyperactivation of sympathetic–adrenal and hypothalamic–pituitary–adrenal stress-realizing systems.

6.6. Actoprotective and Anabolic Activity

Administration of the R. uniflorum root extract (100 mg/kg) led to an increase in overall physical endurance in experimental animals, which affected the increase in working capacity, improved energy supply of working tissues, and increased ATP content in skeletal muscles [68]. A decrease in the severity of metabolic acidosis and the intensity of free radical processes also prolonged the possibility of performing physical work. An increase in the animal body weight, up to 16% compared with the control after application of the R. uniflorum root extract (100 mg/kg), occurred owing to an increase in the skeletal muscle mass [67]. An increase in the muscle protein synthesis and DNA and RNA concentrations was observed without a noticeable effect on blood glucose and somatotropic hormone levels, which indicated an anabolic effect of the R. uniflorum root extract.

6.7. Antihypoxic and Anti-Ischemic Activity

Dry extracts of R. uniflorum (50–200 mg/kg) demonstrated pronounced antihypoxic effect, while the effectiveness of root extract was higher in models of hypercapnic and hemic hypoxia, and the herb extract was more effective in histotoxic hypoxia [67]. Intragastric administration of R. uniflorum leaf extract (50–200 mg/kg, 14 days) before bilateral carotid artery occlusion led to a decrease in the total mortality of experimental animals, a decrease in neurological deficit, and a decrease in the severity of cerebral edema [73].

6.8. Hepatoprotective Activity

Root ethanol extract of R. uniflorum increased cell viability at H₂O₂-induced liver cell damage in in vitro models [74,75]. Pre-treatment of mice with an aqueous R. uniflorum root extract attenuated CCl₄-induced liver damage, decreased the activity of alanine aminotransferase and aspartate aminotransferase in serum, reduced the concentration of hydroperoxides and malondialdehyde in the liver, increased the level of catalase, glutathione peroxidase, and superoxide dismutase, and reduced glutathione [76]. A decrease in the activity of Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase in liver mitochondria and a decrease in the hepatocyte DNA damage indicated a pronounced hepatoprotective effect of the extract on the function of the damaged organ.

6.9. Anti-Aterosclerotic and Hypolypidemic Activity

In a hypercholesterol diet model in birds, the R. uniflorum root extract was found to reduce the incidence and severity of atherosclerotic vascular lesions while protecting the ultra-microstructural integrity of cells [77]. The ethanol R. uniflorum root extract reduced the levels of triglycerides and the low- and high-density lipoproteins in the blood of mice with experimental hyperlipidemia and prevented lipid accumulation in hepatocytes [78].

6.10. Other Activities

Peroxisome activator-activated receptors (PPARs) are a group of nuclear receptors that play an essential role in the regulation of metabolism. Gamma-type receptors (PPARγ) are expressed in all tissues of the body and are a therapeutic target for the treatment of obesity, diabetes, cancer, and other diseases. The R. uniflorum root extract, as well as its component 7-chloroarctinone b (89), inhibited the rosiglitazone-induced transcriptional activity of PPARγ [79]. Plasmon resonance indicated that 89 binds to PPARγ receptors, blocking the ability of PPARγ agonists to interact with the ligand-binding domains of the receptors (PPARγ-LBD). The ability of 89 to inhibit hormonal and rosiglitazone-induced adipocyte differentiation was confirmed using the Gal4/UAS model and two hybrid yeast methods, indicating its potential efficacy for the treatment of metabolic diseases.

There is also evidence that the aqueous R. uniflorum root extract has an antioxidant and membrane-stabilizing activity [43,80,81], an antibacterial effect against Gardnerella vaginalis [82], a moderate diuretic effect [58], and a pancreatic α-amylase-inhibiting potential [29].

7. Toxicity

The study of acute toxicity of R. uniflorum dry extracts from the herb and roots at doses of 3.5–10 g/kg demonstrated no death of animals after intragastric administration [83]. After intraperitoneal administration, the LD₅₀ values were 5.8 (herb extract) and 9.5 g/kg (root extract). Long-term administration of the extracts had no negative effect on the morpho-functional parameters of the central nervous, cardiovascular, and urinary systems, organs of the gastrointestinal tract, metabolism, peripheral blood parameters, and the hemostasis system of laboratory animals [83]. Application of the extract as single injection at doses of 100 and 1000 mg/kg did not have local irritating or mutagenic effects. These results indicate that R. uniflorum extracts belong to the practically non-toxic group.

8. Conclusions

This review summarizes the scientific literature concerning the chemical composition, methods of analysis, and biological activity of traditional medicine Rhaponticum uniflorum. The presented data indicate a good degree of knowledge of the metabolites of the roots and herb of R. uniflorum. Of particular interest are the anti-inflammatory components of R. uniflorum, such as sesquiterpenes [84], ecdysteroids [85], triterpenes [86], thiophenes [87], and flavonoids [88]. Owing to the confirmed presence of these compounds in the plant, we understand its ethnopharmacological use as an anti-inflammatory agent. Despite promising information on the chemical and pharmacological composition of R. uniflorum and its extracts, biological studies of individual compounds are still insufficient. We note a lack of studies on metabolites (e.g., sesquiterpenes, triterpenes, and thiophenes) in aboveground organs. The composition of phenolic compounds of the whole plant has not been fully studied to date. Carbohydrates remain an unexplored class of compounds for R. uniflorum and the genus Rhaponticum in general. It is necessary to expand our knowledge about the organ-specific distribution of substances in the plant, as well as the influence of the environmental conditions of R. uniflorum growth on its chemical profile. Owing to the current level of scientific interest in R. uniflorum and its extracts, new data on the pharmacological efficacy of pure compounds in various pathologies should be expected in the near future. Therefore, we believe that this review is a starting point for future research on the health benefits of consuming products containing R. uniflorum, especially modern dosage forms (e.g., nanoformulations), which will contribute to a wider inclusion of this natural component in new pharmacological products.

9. Patents

Available patent information suggests that R. uniflorum extracts were registered as components of complex antihypoxic and adaptogenic remedy [89], cosmetic composition with a purpose of lipometabolism promoter [90], soy sauce [91], and granulated insecticide [92], as well as an independent medicine with stress-protective [93] or anxiolytic activity [94].

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data is contained within the article.

Conflicts of Interest

The author declares no conflict of interest. The funders had no role in the design of the study, in the collection, analyses, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.

Funding Statement

This research was funded by the Ministry of Education and Science of Russia, grant number 121030100227-7.