Naturally Occurring Chromone Glycosides: Sources, Bioactivities, and Spectroscopic Features

Abstract

Chromone glycosides comprise an important group of secondary metabolites. They are widely distributed in plants and, to a lesser extent, in fungi and bacteria. Significant biological activities, including antiviral, anti-inflammatory, antitumor, antimicrobial, etc., have been discovered for chromone glycosides, suggesting their potential as drug leads. This review compiles 192 naturally occurring chromone glycosides along with their sources, classification, biological activities, and spectroscopic features. Detailed biosynthetic pathways and chemotaxonomic studies are also described. Extensive spectroscopic features for this class of compounds have been thoroughly discussed, and detailed ¹³C-NMR data of compounds 1–192, have been added, except for those that have no reported ¹³C-NMR data.

1. Introduction

Chromone glycosides are a class of secondary metabolites with various medicinal properties. They are widely distributed in many plant genera and, to a lesser extent, in some fungal species and other sources [1]. Several biological activities have been reported for various chromone glycosides. For example, aloesin and its analogues, from Aloe, are used in cosmetic preparations to treat hyperpigmentation induced by UV radiation, owing to their role in inhibition of tyrosinase enzyme [2,3]. Additionally, 8-[C-β-d-[2-O-(E)-cinnamoyl]glucopyranosyl]-2-[(R)-2-hydroxypropyl]-7-methoxy-5-methylchromone), isolated from certain Aloe species, was reported to have potent topical anti-inflammatory activity comparable to the effect of hydrocortisone without affecting thymus weight [3]. Macrolobin, from Macrolobium latifolium, has a remarkable acetylcholinesterase inhibitory activity with an IC₅₀ value of 0.8 µM. Uncinosides A and B, isolated from the Chinese herbal medicine Selaginella uncinata, showed potent anti-RSV (respiratory syncytial virus) activity with IC₅₀ values of 6.9 and 1.3 µg/mL. Taking into consideration the broad biological activities of chromone glycosides, this review summarizes the naturally occurring chromone glycosides and categorizes these compounds on their structural basis, in addition to their sources, bioactivities and spectroscopic features. Importantly, this review will shed more light toward the NMR features of chromone glycosides to help natural product researchers in the identification of various chemical structures. Scientific databases as SciFinder, PubMed, and Google Scholar were used to collect the relevant literature data.

2. Biosynthesis

Chromones are biosynthesized through the acetic acid pathway by the condensation of five acetate molecules. These compounds, generally, have a methyl group at C-2 and are oxygenated at C-5 and C-7 [4]. Pentaketide Chromone Synthase (PCS) is a key enzyme in the biosynthesis process that catalyzes the formation of a pentaketide chromone (5,7-dihydroxy-2-methylchrome) from five-step decarboxylative condensations of malonyl-CoA, followed by the Claisen cyclization reaction to form an aromatic ring. However, it is unclear whether the heterocyclic ring closure of the pentaketide chromone is enzymatic or not, because the ring closure can take place due to spontaneous Michael-like ring closure, as in the case of flavanone formation from chalcone in vitro. PCS also accepts acetyl-CoA, resulting from decarboxylation of malonyl-CoA, as a starter substrate, but it is a poor substrate for PCS [5].The pentaketide chromone has been isolated from several plants and is known to be the biosynthetic precursor of the chromone derivatives with additional heterocyclic rings (e.g., furano-, pyrano- and oxepino-chromone glycosides). Scheme 1 ([6] with modifications) shows the sequence of steps utilized in the biosynthesis of these compounds, fully consistent with the biosynthetic rationale developed above. The key intermediate is 5,7-dihydroxy-2-methylchromone [5,6]. For many years, the cyclization had been postulated to involve an intermediate epoxide, such that nucleophilic attack of the phenol onto the epoxide group might lead to formation of either five-membered furan, six-membered pyran or the seven-membered oxepin heterocycles, as commonly encountered in natural products [6].

Scheme 1.

Proposed mechanisms for the enzymatic formation of 5,7-dihydroxy-2-methylchromone and its derivatives.

Aloesone Synthase (ALS) (Scheme 2, [5] with modifications) is a key enzyme in the biosynthesis of heptaketide chromone aloesone derivatives, such as aloesone 7-O-β-d-glucopyranoside (53) in rhubarb and anti-inflammatory aloesone 8-C-β-d-glucopyranoside (aloesin, 98) in Aloe (A. arborescens). ALS efficiently catalyzes the formation of a heptaketide aromatic pyrone 6-(2-(2,4-dihydroxy-6-methylphenyl)-2-oxoethyl)-4-hydroxy-2-pyronechromone from acetyl-CoA and six molecules of malonyl-CoA through an aldol cyclization. The unstable heptaketide pyrone (or acid form) would then undergo subsequent spontaneous isomerization to the β-ketoacid chromone, which is followed by decarboxylation to produce the heptaketide aloesone [5].

Scheme 2.

Proposed mechanisms for the enzymatic formation of aloesone and its derivatives.

3. Taxonomy

We have reviewed the literature concerning the occurrence of chromone glycosides, and we have found that 192 different chromone glycosides have been isolated from different natural sources, including angiosperms, ferns, lichens, fungi and actinobacteria (Table 1). The occurrence of chromone glycosides is mostly confined to botanical families: Apiaceae, Fabaceae, Myrtaceae, Asphodelaceae, Ranunculaceae, Rubiaceae, Hypericaceae, Ericaceae, Amaryllidaceae, Polygonaceae and Araceae. However, few chromone glycosides are also present in Asteraceae, Eucryphiaceae, Saxifragaceae, Smilacaceae, Pentaphylaceae, Salicaceae, Meliaceae, Euphorbiaceae, Staphyleaceae, Amaranthaceae, Aquifoliaceae, Rosaceae, Bignoniaceae, Olacaceae, Pinaceae, Selaginellaceae, Gentianaceae, Cannabaceae, Euphorbiaceae, Cucurbitaceae, Thymelaeaceae and Poaceae. Many of the naturally occurring chromone-8-C-glycosides such as the well-known chromone glycoside aloesin (98) were reported from genus Aloe. Until now, chromone glycosides with additional heterocyclic moieties such as pyrano-, oxepino- and pyrido-chromone glycosides were only isolated from Saposhnikovia divaricate, Eranthis species and Schumanniophyton magnificum, respectively. Another interesting category comprises hybrids of furano-chromones with cycloartane triterpenes, which were reported from Cimicifuga foetida. Actinobacteria also constitute an important source of the chromone alkaloid aminoglycosides, which are isolated from Streptomyces, Saccharothrix and Actinomycete species.

Table 1.

The distribution of chromone glycosides reported through this review.

		Family	Genus	Species	Compounds
Plants (Angiosperms)	1	Ericaceae	Rhododendron	ovatum	2
				spinuliferum	3
				collettianum	55
			Calluna	vulgaris	13
	2	Rubiaceae	Schumanniophyton	magnificum	7, 25, 156
			Knoxia	corymbosa	20, 24, 35, 36
			Adina	rubescens	20
			Neonauclea	sessilifolia	26, 166
	3	Amaryllidaceae	Gethyllis	ciliaris	10
			Pancratium	biflorum	20, 66
				maritimum	20, 47
	4	Polygonaceae	Polygonum	capitatum	15
			Rheum	austral	50
				sp.	52, 53
	5	Apiaceae	Ammi	visnaga	20, 140, 146
			Peucedanum	austriacum	20
				japonicum	149
			Cnidium	monnieri	57, 58, 123–130
				juponicum	123, 124
			Bupleurum	chinense	58
			Angelica	archangelica	125
				genuflexa	146, 149
				japonica	146, 149
			Archangelica	litoralis	125
			Saposhnikovia	divaricata	143–146, 149, 150
			Ledebouriella	seseloides	144
			Diplolophium	buchananii	144, 146, 151
			Sphallerocarpus	gracilis	144
			Glehnia	littoralis	149
	6	Hypericaceae	Hypericum	henryi	22, 23
				erectum	22, 38
				sikokumontanum	38, 39, 60, 61
				japonicum	82, 83
	7	Ranunculaceae	Delphinium	hybridum	28
			Cimicifuga	heracleifolia	141
				foetida	146, 147, 157–165
			Eranthis	hyemalis	131, 132, 152, 153, 154
				cilicica	133, 134, 153, 155
	8	Myrtaceae	Myrtus	communis	34
			Syzygium	aromaticum	66, 71, 80, 86
			Baeckea	frutescens	66, 67, 70, 72, 85, 87
			Kunzea	ambigua	67, 70, 72–74, 80, 85, 88, 89
			Eucalyptus	globulus	80
				maidenii	82, 83
				grandis	83
				urograndi	83
	9	Fabaceae	Cassia	multijuga	51, 77
				siamea	59
				obtusifolia	68, 69
				spectablis	78
				obtusifolia	84
			Macrolobium	latifolium	64
			Aspalathus	linearis	65
			Abrus	mollis	80
			Ononis	vaginalis	135
	10	Asphodelaceae	Aloe	vera	75, 76, 90–98, 103, 104–110, 112–117, 120–122
				barbadensis	97, 98, 103, 107, 108
				rupestris	99
				cremnophila	101
				nobilis	111, 118, 119
	11	Araceae	Scindapsus	officinalis	18–20, 29, 31, 32, 56, 57
	12	Asteraceae	Mutisia	acuminate	1
	13	Eucryphiaceae	Eucryphia	cordifolia	4
	14	Saxifragaceae	Astilbe	thunbergii	4
15	Smilacaceae	Smilax	glabra	4
16	Pentaphylaceae	Eurya	japonica	5
17	Salicaceae	Salix	matsudana	6
18	Meliaceae	Dysoxylum	binectariferum	7
19	Euphorbiaceae	Acalypha	fruticose	7
20	Staphyleaceae	Staphylea	bumalda	7
21	Amaranthaceae	Salicornia	europaea	12
22	Aquifoliaceae	Ilex	hainanensis	13
23	Rosaceae	Dasiphora	parvifolia	16, 17
24	Bignoniaceae	Tecomella	undulata	20, 27
25	Olacaceae	Scorodocarpus	borneensis	26
26	Pinaceae	Pseudotsuga	sinensis	37
27	Selaginellaceae	Selaginella	uncinata	46, 48
28	Gentianaceae	Swertia	punicea	54
29	Cannabaceae	Humulus	lupulus	62
30	Euphorbiaceae	Chrozophora	prostrata	79
31	Cucurbitaceae	Cucumis	melo	136
32	Thymelaeaceae	Aquilaria	sinensis	137, 139
33	Poaceae	Imperata	cylindrical	138
Ferns	1	Polypodiaceae	Drynaria	fortunei	7, 28, 30, 32, 33, 57
	2	Dryopteridaceae	Dryopteris	fragrans	20, 21
	3	Onocleaceae	Matteuccia	intermedia	49
Lichens			Roccellaria	mollis	41, 42, 45
			Schismatomma	accedens	41, 42, 45
			Roccella	galapagoensis	41, 42, 45
			Lobodirina	cerebriformis	44
Fungi			Armillaria	tabescens	11
			Orbiocrella	sp.	40, 43
			Stemphylium	botryosum	63
Actinobacteria			Streptomyces	phaeoverticillatus var. takatsukiensis	168
				pluricolorescens	169–171
				sp.	172–178, 180
				griseoruber	179
			Saccharothrix	sp.	181–183
			Actinomycete		184–192

4. Chromone Glycosides

Chromone glycosides belong to a group of oxygen-containing heterocyclic compounds with a benzo-γ-pyrone skeleton. Naturally occurring chromone glycosides can be either O-glycosides or C-glycosides. For O-glycosides, the most frequently encountered group is the 7-O-glycosides; however, 2-, 3-, 5-, 8-, 11- and 13-O-glycosides also exist but to a lower extent. For an example, only one 6-O-glycoside 11 has been reported from nature, and from fungi, not higher plants [1]. Glycosylation can also be detected at side chains for chromones, at C-11 and C-12 as in compounds 56–59, at the hydroxyprenyl and hydroxyisoprenyl side chains as in 123 and 128, respectively, or at the phenyl ethyl moiety as 139. The most abundant among chromone glycosides is the glucoside from. However, other sugar moieties such as xylose, arabinose and rhamnose were also detected in 3-, 7- and 11-O-glycosides.

4.1. Chromone O-glycosides

4.1.1. 2-O-Glycosides

This category includes compound 1 (Figure 1), 2-hydroxy-5-methylchromone-β-d-glucopyranoside, isolated from the aerial parts of Mutisia acuminata var. hirsuta, a member of family Asteraceae [7]. The authors did not report biological activity for this compound.

Figure 1.

Structure of compound 1.

4.1.2. 3-O-Glycosides

This category includes compounds 2–5. They share the same aglycone nucleus but with different sugar moieties at C-3. Eucryphin 4 was reported as a new compound in 1979 [8]; however, it was reported again in 1996 as a new compound under the name smiglanin [9]. In addition, 3,5,7-trihydroxychromone 3-O-β-d-xylopyranoside 2 was first reported in 2005 from Rhodadendron ovatum [10], but it was reported again as a new compound in 2013 [11]. Compounds 2–5 are shown in Figure 2. The sources and the reported biological activities are summarized in Table 2.

Figure 2.

Structures of compounds 2–5.

Table 2.

3-O-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
2	3,5,7-trihydroxychromone-3-O- β-d-xylopyranoside	Rhododendron ovatum roots [10] Eurya japonica stems [11]	Inhibitory effects on LPS (Lipopolysaccharide)-induced NO (Nitric Oxide) production with inhibition rate 36.24 ± 1.29% at 20 μg/mL [11]
3	3,5,7-trihydroxylchromone-3-O- α-l-arabinopyranoside	Rhododendron spinuliferum aerial parts [12]	Inhibition of NO production in LPS-stimulated RAW 264.7 cells with an IC50 value more than 100 mM [12]
4	Eucryphin (5,7-dihydroxy-3-(α-O-l-rhamnopyranosyl)- 4H-l-benzopyran-4-one)	Eucryphia cordifolia bark [8] Astilbe thunbergii rhizomes [13]	Norepinephrine-enhancing lipolytic effect 6.432 ± 0.014 FFA µmol/mL at 1000 µg [13] Enhancing effect on burn wound repair at 100 mg ointment per mouse [14]
	Smiglanin (3,5,7-trihydroxychromone-3-O- α-l-rhamnopyranoside)	Smilax glabra roots [9]	No reported biological activity
5	5,7-Dihydroxy-4H-chromen-4-one- 3-O-β-d-glucopyranoside	Eurya japonica stems [11]	Inhibitory effects on LPS-induced NO production with inhibition rate 53.79 ± 1.78% at 20 μg/mL [11]

4.1.3. 5-O-Glycosides

Among the naturally occurring 5-O-glycosides, Staphylosides A and B (8–9), isolated from Staphylea bumalda, are characterized by a presence of a disaccharide moiety attached to C-5. The disaccharide chain in 8 is β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside while in 9, is α-d-glucopyranosyl-(1→6)-β-d-glucopyranoside. Compounds 6–10 are shown in Figure 3. The sources and the reported biological activities (if any) are summarized in Table 3.

Figure 3.

Structures of compounds 6–10.

Table 3.

5-O-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
6	Matsudoside A (5-β-d-glucosyloxy-7- hydroxychromone)	Salix matsudana leaves [15]	No reported biological activity
7	Schumaniofioside A (2-methyl-5,7-dihydroxychromone 5-O-β-d-glucopyranoside)	Schumanniophyton magnificum root bark [16] Dysoxylum binectariferum fruits [17]. Acalypha fruticose aerial parts [18,19] Drynaria fortune rhizomes [13]	Inhibition of proinflammatory cytokines TNF-α (39.51 ± 1.21%) and IL-6 (22.21 ± 0.58%) at 5 μM [17] Inhibition of NF-kB transcriptional activity and iNOS with IC50 value of 29.5 ± 6.5 µg/mL [19]
8	Staphyloside A	Staphylea bumalda leaves [20]	No reported biological activity
9	Staphyloside B
10	Isoeugenitol glucoside	Gethyllis ciliaris underground parts [21]	No reported biological activity

4.1.4. 6-O-Glycosides

Compound 11 (Figure 4) has a unique structure for bearing 4-O-methylglucopyranosyl unit. Chemically, it is 6-O-(4-O-methyl-β-d-glucopyranosyl)-8-hydroxy-2,7-dimethyl-4H-benzopyran-4-one, isolated from the rice culture of the fungus Armillaria tabescens [1]. Although such compounds are not common in higher plants, several of them have previously been isolated from fungi [1].

Figure 4.

Structure of compound 11.

4.1.5. 7-O-Glycosides

This subclass is characterized by the presence of sugar at C-7. Hyperimone A is the same as Urachromone A (22), reported at nearly the same time from different co-authors from the genus Hypericum. Takanechromone A (38) is the same as Hyperimone B, isolated from the same genus by different co-authors. They were reported each time as new compounds. We preferred to add only ¹³C-NMR data of one set of these compounds (Table 23). Several biological activities have been reported to some members of this subclass. Compounds 12–53 are shown in Figure 5. The sources and the reported biological activities (if any) are summarized in Table 4.

Figure 5.

Structures of compounds 12–53.

Table 4.

7-O-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
12	7-O-β-d-glucopyranosyl-6-methoxychromone	Salicornia europaea leaves and stems [25]	No reported biological activity
13	5,7-dihydroxychromone 7-O-β-d-glucopyranoside	Ilex hainanensis leaves [26] Calluna vulgaris flowers [27]	No reported biological activity
14	5,7-dihydroxychromone 7-O-β-d-glucuronide methyl ester	Davallia mariesii rhizomes [28]	No reported biological activity
15	7-O-(6′-galloyl)-β-d-glucopyranosyl-5-hydroxychromone	Polygonum capitatum aerial parts [29]	No reported biological activity
16	5-hydroxy-7-O-(6-O-p-cis-coumaroyl-β-d-glucopyranosyl)-chromone	Dasiphora parvifolia aerial parts [30]	No reported biological activity
17	5-hydroxy-7-O-(6-O-p-trans-coumaroyl-β-d-glucopyranosyl)-chromone	Dasiphora parvifolia aerial parts [30]	No reported biological activity
18	Officinaliside A	Scindapsus officinalis stems [31]	No reported biological activity
19	7-O-α-l-rhamnosyl-nereugenin	Scindapsus officinalis stems [31]	No reported biological activity
20	Undulatoside A (2-methyl-5,7-dihydroxychromone 7-O-β-d-glucopyranoside)	Scindapsus officinalis stems [31] Ammi visnaga fruits [32] Knoxia corymbosa [33] Pancratium biflorum roots [34] Panacratium biflorum flowering bulbs [35] Pancratium maritimum L. fresh bulbs [36] Peucedanum austriacum [37] Tecomella undulata bark [38] Adina rubescens leaves [39] Dryopteris fragrans [40] Staphylea bumalda leaves [20]	Immunomodulatory activity inhibited the proliferation of murine B lymphocytes in vitro at 10−5 M [33] Inhibition of nitric oxide production in lipopolysaccharide induced RAW 264.7 macrophages with an IC50 value of 49.8 μM [40] Weak antimigratory activity against human metastatic prostate cancer cells (PC-3M) at 50 µM [36]
21	Frachromone C (5-hydroxy-2-ethylchromone-7-O-β-d-glucopyranoside)	Dryopteris fragrans whole plant [40]	Inhibition of nitric oxide production in lipopolysaccharide induced RAW 264.7 macrophages with an IC50 value of 45.8 μM [40]
22	Urachromone A (5-hydroxy-2-isopropylchromone-7-O-β-d-glucopyranoside)	Hypericum henryi aerial parts [41] Hypericum erectum [42]	No reported biological activity
	Hyperimone A
23	Urachromone B	Hypericum henryi aerial parts [41]	No reported biological activity
24	Corymbosin K2 (7-O-β-d-6- acetylglucopyranosyl-5-hydroxy-2-methylchromone)	Knoxia corymbosa [33]	Immunomodulatory activity inhibited the proliferation of murine B lymphocytes in vitro at 10−5 M [33]
25	Schumanniofioside B	Schumanniophyton magnificum root bark [16]	No reported biological activity
26	5-hydroxy-2-methylchromone-7-O-β-d-apiofuranosyl-(1→6)- β-d-glucopyranoside	Neonauclea sessilifolia roots [43] Scorodocarpus borneensis leaves [44] Staphylea bumalda leaves [20]	No reported biological activity
27	Undulatoside B	Tecomella undulata [45]	No reported biological activity
28	2-methyl-chromone-5,7-diol 7-O-α-l-rhamnopyranosyl-(1-6)-β-d-glucopyranoside	Delphinium hybridum aerial parts [46] Drynaria fortunei rhizomes [22]	No reported biological activity
29	Officinaliside C (7-O-[β-d-glucopyranosyl-(1-2)-α-l-rhamnopyranosyl]-5-hydroxy-2-methyl-4H-1-benzopyran-4-one)	Scindapsus officinalis stems [31]	No reported biological activity
30	Drynachromoside C (5-hydroxy-2-methyl chromone-7-O-β-d-glucopyranosyl (1-3)-α-l-rhamnopyranoside)	Drynaria fortunei rhizomes [22]	Inhibitory activity on triglyceride accumulation at 10 μM [22]
31	Officinaliside B (7-O-[6-acetyl-β-d-glucopyranosyl-(1-3)-α-l-rhamnopyranosyl]-5-hydroxy- 2-methyl-4H-1-benzopyran-4-one)	Scindapsus officinalis stems [31]	Inhibition of NO production in LPS-stimulated RAW 264.7 cells with an IC50 value of 16.1 μM [31]
32	Drynachromoside A (5-hydroxy-2-methyl-4H-benzopyran-4-one-7-O-β-d-glucopyranosyl-(1-4)-α-l-rhamnopyranoside)	Scindapsus officinalis stems [31] Drynaria fortunei rhizomes [47]	Proliferative activity 10.1% on MC3T3-E1 (Mouse osteoblast) cells at 25 μg/mL [47]
33	Drynachromoside D (5-hydroxy-2-methyl chromone-7-O-α-l-arabinopyranosyl(1-2)-β-d-glucopyranosyl(1-4)-α-l-rhamnopyranoside)	Drynaria fortunei rhizomes [22]	Inhibitory activity on triglyceride accumulation (inhibited PPARγ, C/EBPα and aP2 expression by 50%, 43% and 37% at 10 mM) [22]
34	Undulatoside A 6′-O-gallate	Myrtus communis leaves [48]
35	Corymbosin K3 (7-O-[6-O-(4-O-trans-caffeoyl-β-d-allopyranosyl)]-β-d-glucopyranosyl-5-hydroxy-2- methylchromone)	Knoxia corymbosa [33]	Immunomodulatory activity inhibited the proliferation of murine B lymphocytes in vitro at 10−5 M [33]
36	7-O-[6-O-(4-O-trans-feruloyl-β-d-allopyranosyl)]- β-d-glucopyranosyl-5-hydroxy-2-methylchromone	Knoxia corymbosa [33]	No reported biological activity
37	5-hydroxy-6-methylchromone-7-O-β-d-glucopyranoside	Pseudotsuga sinensis [49]	No reported biological activity
38	Takanechromone A (5,7-dihydroxy-3-methylchromone- 7-O-β-d-glucopyranoside)	Hypericum sikokumontanum aerial parts [50] Hypericum erectum [42]	No reported biological activity
	Hyperimone B
39	Takanechromone B (5,7-dihydroxy-3-ethylchromone- 7-O-β-d-glucopyranoside)	Hypericum sikokumontanum aerial parts [50]	No reported biological activity
40	7-O-(4-O-Methyl-β-d-glucopyranosyl)eugenitol	The scale-insect pathogenic fungus Orbiocrella sp. [23]	No reported biological activity
41	Mollin	Lichens (Roccellaria mollis, Schismatomma accedens, Roccella galapagoensis) [51]	No reported biological activity
42	Roccellin	Lichens (Roccellaria mollis, Schismatomma accedens, Roccella galapagoensis) [51]	No reported biological activity
43	7-O-(4-O-Methyl-β-d-glucopyranosyl)isoeugenitol	The scale-insect pathogenic fungus Orbiocrella sp. [23]	No reported biological activity
44	Lobodirin	Lobodirina cerebriformis lichen [51]	No reported biological activity
45	Galapagin	Lichens (Roccellaria mollis, Schismatomma accedens, Roccella galapagoensis) [51]	No reported biological activity
46	Uncinoside A (5-hydroxy-2,6,8- trimethylchromone 7-O-β-d-glucopyranoside)	Selaginella uncinate Herb [24]	Antiviral activity against respiratory syncytial virus (RSV) with an IC50 value of 6.9 μg/mL, against parainfluenza type 3 virus (PIV 3) with an IC50 value of 13.8 μg/mL [24]
47	Pancrichromone	Pancratium maritimum L. fresh bulbs [36]	No reported biological activity
48	Uncinoside B (5-acetyoxyl-2,6,8-trimethylchromone 7-O-β -d-glucopyranoside)	Selaginella uncinate herb [24]	Antiviral activity against respiratory syncytial virus (RSV) with an IC50 value of 1.3 μg/mL, against parainfluenza type 3 virus (PIV 3) with an IC50 value of 20.8 μg/mL [24]
49	Matteuinterin B	Matteuccia intermedia rhizomes [52]
50	2,5-dimethylchromone-7-O-β-d-glucopyranoside	Rheum austral D. Don underground parts [53] Rumex gmelini Turcz. roots [54]	Anti-oxidant activity (DPPH radical scavenging capacity with an IC50 value of 66.9 ± 1.3 μM) [53]
51	5-acetonyl-7-β-d-glucopyranosyl-2-methylchromone	Cassia multijuga leaves [55,56]	No reported biological activity
52	2-methyl-5-(2′-oxo-4′-hydroxyphenyl)-7-hydroxychromone 7-O-β-d-glucopyranoside	Chinese rhubarb (Rhei Rhizoma) [57]	No reported biological activity
53	Aloesone 7-O-β-d-glucopyranoside	Chinese rhubarb (Rhei Rhizoma) [57]	No reported biological activity

Drynachromosides C (30) and D (33) exhibited inhibitory activity on triglyceride accumulation [22]. The effects of these compounds on mRNA expression of the three adipogenesis-related marker genes, PPARγ, C/EBPα and Ap2, in 3T3-L1 were investigated. The mRNA expression levels of PPARγ, C/EBPα and Ap2 were found to be dramatically downregulated. Compounds 40 and 43, having a unique sugar unit of 4-O-methyl-β-d-glucopyranose, were isolated from the scale-insect pathogenic fungus Orbiocrella sp. BCC 33248 [23]. Uncinosides A (46) and B (48) [24], isolated from the Chinese herbal medicine Selaginella uncinata, showed potent anti-RSV (respiratory syncytial virus) activity with IC₅₀ values of 6.9 and 1.3 µg/mL, respectively. Uncinoside B (48) was found to have a TI value of 64.0, a large therapeutic index comparable to that of ribavirin with a TI value of 24.0, which is an approved drug for the treatment of RSV infection in humans. They also showed moderate antiviral activities against PIV 3 (parainfluenza type 3 virus) with IC₅₀ values of 13.8 and 20.8 µg/mL and TI values of 6.0 and 4.0, respectively.

4.1.6. 8-O-Glycosides

Only two compounds 54–55 were reported in nature. They are shown in Figure 6. The sources and the reported biological activities (if any) are summarized in Table 5.

Figure 6.

Structures of compounds 54–55.

Table 5.

8-O-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
54	8-O-β-d-Glucopyranosyl-2-methylchromone	Swertia punicea whole herb [58]	No reported biological activity
55	8-O-β-d-Glucopyranosyl-6-hydroxy-2-methyl-4H-1-benzopyrane-4-one	Rhododendron collettianum aerial parts [59]	Inhibitory activity against tyrosinase enzyme with an IC50 value of 256.97 μM [59]

4.1.7. 11- and 13-O-Glycosides

Compound 57 was reported in 2012 as Monnieriside A [60] and was then reported as Drynachromoside B [22,31,47]. Compounds 56–59 are shown in Figure 7. The sources and the reported biological activities (if any) are summarized in Table 6.

Figure 7.

Structures of compounds 56–59.

Table 6.

11, 13-O-chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
56	Officinaliside D (2-hydroxymethyl-5,7-dihydroxy-4H-benzopyran-4- one-1′-O-α-l-arabinopyranoside)	Scindapsus officinalis stems [31]	Inhibition of NO production in LPS-stimulated RAW 264.7 cells with an IC50 value of 19.1 µM [31]
57	Drynachromoside B	Drynaria fortune rhizomes [22,47] Scindapsus officinalis stems [31]	Mild inhibitory activity against MC3T3-E1 (mouse osteoblast) cells at 3.125 to 100 μg/ml [47] Triglyceride accumulation inhibitory effect at 0.1 to 10 μM [22]
	Monnieriside A	Cnidium monnieri fruits [60]	No reported biological activity
58	Saikochromoside A	Bupleurum chinense [61] Cnidium monnieri fruits [60]	No reported biological activity
59	2-Methyl-5-propyl-7,12- dihydroxychromone-12-O-β-d-glucopyranoside	Cassia siamea stem [62]	No reported biological activity

4.1.8. Chromanone Glycosides

Chromanone glycosides or 2,3-dihydrochromone glycosides are not abundant in nature. Reviewing the literature, we encountered only four examples 60, 61, 62 and 63. Their structures are shown in Figure 8. The sources and biological activities (if any) of these compounds are summarized in Table 7.

Figure 8.

Structures of compounds 60–63.

Table 7.

Chromanone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
60	Takanechromanone A	Hypericum sikokumontanum aerial parts [50]	Anti-Helicobacter pylori at 100 µg/disc [50]
61	Takanechromanone B
62	5-β-d-glucopyranosyloxy-7-hydroxy-2-isopropyl-chromanone	Humulus lupulus L. bracts [63]	No reported biological activity
63	Stemphylin (3-hydroxy-2, 2-dimethyl-5-α-d-glucopyranoside-2, 3-dihydrochromone)	The liquid culture of the fungus Stemphylium botryosum [64]	Phytotoxic activity [64]

4.2. Chromone C-Glycosides

In contrast to chromone O-glycosides, which are widely distributed and of common occurrence, C-glycoside derivatives are rarely found out.

4.2.1. 3-C-Glycosides

This subclass includes the unusual 5,7-dihydroxychromone-3α-d-C-glucoside, named macrolobin, isolated from the aerial parts of Macrolobium latifolium [65]. Its structure is shown in Figure 9. Its source and biological activities are summarized in Table 8.

Figure 9.

Structure of compound 64.

Table 8.

3-C-Chromone glycoside with its source and biological activities.

No.	Compound	Source	Biological Activity
64	Macrolobin (5,7-dihydroxychromone- 3α-d-C-glucoside)	Macrolobium latifolium aerial parts [65]	Inhibition of acetylcholinesterase enzyme with an IC50 value of 0.8 μM Antimicrobial activity against P. aeruginosa and Salmonella at 0.73 and 0.44 μM, respectively [65]

4.2.2. 6-C-Glycosides

Compounds 65–79 are shown in Figure 10. The sources and the reported biological activities (if any) are summarized in Table 9.

Figure 10.

Structures of compounds 65–79.

Table 9.

6-C-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
65	5,7-dihydroxy-6-C-glucosyl-chromone	Aspalathus linearis fermented rooibos (red-brownish dry leaves) [66]	No reported biological activity
66	Biflorin (6-β-C-glucopyranosyl-5,7-dihydroxy-2-methylchromone)	Pancratium Biflorum roots [34] Syzygium aromaticum L. flower buds [67,68] Baeckea frutescens leaves [69,70]	Inhibitory activity to phosphodiesterase and spared cyclic nucleotides at 10−9 M [34] Inhibition of LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7 macrophages with IC50 values of 51.7 and 37.1 μM, respectively [67]
67	6-β-C-glucopyranosyl- 5,7-dihydroxy-2-isopropylchromone	Baeckea frutescens leaves [69,70] Kunzea ambigua leaves [71]	Inhibitory activity 70.4% against EBV-EA (Epstein–Barr virus early antigen) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) at 500 mol ratio/TPA [71]
68	Obtusichromoneside C	Cassia obtusifolia seeds [72]	Weak inhibitory activity against human organic anion/cation transporters (OATs/OCTs) and organic anion transporting polypeptides (OATPs) at 50 μM [72]
69	Obtusichromoneside A
70	Kunzeachromone C	Kunzea ambigua leaves [71] Baeckea frutescens leaves [70]	Inhibition of copper-induced LDL oxidation with an IC50 value of 3.35 ± 0.36 μM [70]
71	6-C-β-d-(6′-O-galloyl)glucosylnoreugenin	Syzygium aromaticum flower buds [68,73]	Cytotoxicity against human ovarian cancer cells (A2780) with an IC50 value of 66.78 ± 5.49 μM [68] Prolyl endopeptidase inhibitory effects with an IC50 value of 1.74 ± 0.03 μM [73]
72	6-β-C-(2′-O-galloylglucopyranosyl)-5,7-dihydroxy- 2-isopropylchromone	Baeckea frutescens leaves [69,70] Kunzea ambigua leaves [71]	Inhibitory activity 68.4% against EBV-EA activation induced by TPA at 500 mol ratio/TPA [71] Inhibition of copper-induced LDL oxidation with an IC50 value of 3.90 ± 0.24 μM [70]
73	Kunzeachromone D	Kunzea ambigua leaves [71]	No reported biological activity
74	Kunzeachromone A
75	Aloeveraside B	Aloe vera resin [74,75,76]	Inhibition of urease enzyme (55% and 62%, respectively) at 1 mg/mL concentration, significant growth inhibition (70.5 and 76.4%) of the breast cancer cell line MDA-MB-231 at 100 μM, and antioxidant (80% and 60%) at 1 mg/mL [74] Anti-lipid peroxidation activity with IC50 values of 432.1 ± 0.6 and 469.5 ± 0.4 µmol/L, respectively [75]
76	Aloeveraside A
77	Acetonyl-6-glycosyl -7-hydroxy -2-methylchromone	Cassia multijuga leaves [55,56]	No reported biological activity
78	5-acetonyl-7-hydroxy-6-C-glucopyranosyl-2-methyl chromone 2″-O-glucopyranoside	Cassia spectablis seeds [77]	No reported biological activity
79	2-acetonyl-5-methyl-7-hydroxy-6-C-glucopyranosyl chromone 2″-O-glucopyranoside	Chrozophora prostrata roots [78]	No reported biological activity

4.2.3. 8-C-Glycosides

Many of the naturally occurring chromone-8-C-glycosieds can be found in genus Aloe. Approximately 26 chromone-8-C-glycosides were reported in the perennial plant Aloe vera, which is a well-known pharmaceutical herb used in traditional Chinese medicine [76]. Some significant bioactive chromone-8-C-glycosides were isolated and identified in Aloe vera, including Aloesin (98), aloeresin E (109), isoaloeresin D (110), aloeresin A (114) and other derivatives. For instance, aloeresin A (114) exhibited a promising therapeutic activity toward α-glucosidase enzyme [79], while the compound isobiflorin (80), isolated from the flower buds of Syzygium aromaticum, had the capacity to inhibit LPS-induced production of nitric oxide (NO) and prostaglandin E₂ (PGE2) in RAW 264.7 macrophages [67]. A chromone-8-C-glycoside, 5,7-dihydroxy-2-isopropylchromone-8-β-d-glucoside, reported in Hypericum japonicum, showed an activity against Epstein–Barr virus [71]. Additionally, BACE1 (β-secretase), which is a possible potential target in the treatment of Alzheimer’s disease, was inhibited by some compounds as aloesin (98) [80], 7-O-methyl-aloeresin A (115) [81] and 2′-feruloyl-7-O-methylaloesin (119) [80]. Furthermore, tyrosinase, which is the key enzyme for controlling the production of melanin, was inhibited by aloeresin E (109) and isoaloeresin D (110) [82]. The compounds 80–122 are shown in Figure 11, Figure 12 and Figure 13. The sources and the reported biological activities (if any) are summarized in Table 10.

Figure 11.

Structures of compounds 80–89.

Figure 12.

Structures of compounds 90–115.

Figure 13.

Structures of compounds 116–122.

Table 10.

8-C-Chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
80	Isobiflorin	Abrus mollis Hance. aerial parts [83] Syzygium aromaticum L. flower buds [67] Kunzea ambigua (SM.) Druce. leaves [71] Eucalyptus globulus leaves [84,85] Eugenia caryophyllata flower buds [86]	Inhibition of LPS-induced production of nitric oxide (NO) with an IC50 > 60 μM and prostaglandin E2 (PGE2) ) with an IC50 value of 46.0 μM [67]
81	7-methoxy-isobiflorin	Zhuyeqing Liquor; a famous traditional Chinese functional health liquor [87]	No reported biological activity
82	5,7-Dihydroxy-2-isopropylchromone- 8-β-d-glucoside	Hypericum japonicum aerial parts [71,88,89] Eucalyptus maidenii bark [84]	Inhibit Epstein–Barr virus early antigen induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) in Raji cells (70.4%) at 500 mol ratio/TPA [71]
83	5,7-Dihydroxy-2-(1-methylpropyl) chromone-8-β-d-glucoside	Hypericum japonicum aerial parts [71,88] Eucalyptus grandis, Eucalyptus urograndi, and Eucalyptus maidenii bark [90]	No reported biological activity
84	Obtusichromoneside B	Cassia obtusifolia seeds [72]	Inhibitory activity against human organic anion/cation transporters (OATs/OCTs) and organic anion transporting polypeptides (OATPs) at 50 μM [72]
85	Kunzeachromone E [8-β-C-(2′-galloylglucopyranosyl)- 5,7-dihydroxy-2-methylchromone]	Kunzea ambigua leaves [71] Baeckea frutescens leaves [70]	Inhibition activity toward copper-induced LDL oxidation with IC50 value of 3.98 ± 0.24 µM [70]
86	8-C-β-d-(6′-O-galloyl)glucosylnoreugenin [2-Methyl-5,7-dihydroxy-chromone-8-β-d-(6′-O-galloyl)-glucopyranoside]	Syzygium aromaticum L. leaves [91] Syzygium aromaticum L. flower buds [68,73]	Cytotoxicity against human ovarian cancer cells (A2780) with an IC50 value of 87.50 ± 1.56 µM [68] Significant inhibition capacity against Prolyl Endopeptidase with IC50 value of 1.48 ± 0.02 µM [73]
87	8-β-C-(2′-galloylglucopyranosyl)-5,7-dihydroxy-2-isopropylchromone	Baeckea frutescens leaves [70]	Active against copper-induced LDL oxidation with an IC50 value of 3.91 ± 0.18 µM [70]
88	Kunzeachromone F [2-Methyl-5,7-dihydroxy-chromone-8-β-d-(2’,3′-di-O-galloyl)-glucopyranoside]	Kunzea ambigua leaves [71]	No reported biological activity
89	Kunzeachromone B [2-Isopropyl-5,7-dihydroxy-chromone-8-β-d-(2’,3′-di-O-galloyl)-glucopyranoside]	Kunzea ambigua leaves [71]	No reported biological activity
90	2,5-dimethyl-8-C-β-d-glucopyranosyl-7-hydroxy-chromone	Aloe vera [92]	No reported biological activity
91	2-(E)-propenyl-7- methoxy-8-C-β-d-glucopyranosyl-5-methylchromone	Aloe vera [76,80]	BACE1 (β-secretase) inhibitory activity with an IC50 value of 20.5 µM [80]
92	8-C-β-d-glucosyl-(R)-aloesol	Aloe vera [76,80]	BACE1 (β-secretase) inhibitory activity (39.2%) at 100 μM [80]
93	8-C-β-d-glucosyl-7-O-methyl-(R)-aloesol	Aloe vera [76,80] and anerobic incubation of aloesin with bacterial mixture [93]	BACE1 (β-secretase) inhibitory activity (26.8%) at 100 μM [80]
94	8-C-β-d-glucosyl-(S)-aloesol	Aloe vera [76] and anerobic incubation of aloesin with bacterial mixture [93]	No reported biological activity
95	8-C-β-d-glucosyl-7-O-methyl-(S)-aloesol	Aloe vera [76] and anerobic incubation of aloesin with bacterial mixture [93]	No reported biological activity
96	8-C-β-d-glucosyl-7-O-methylaloediol	Aloe vera [76,80]	No reported biological activity
97	Neoaloesin A	Aloe vera [76] Aloe barbadensis leaves [94]	No reported biological activity
98	Aloesin	Aloe vera [76,80] Aloe barbadensis leaves [95]	Antioxidant activity (50 ± 1 μM trolox equivalent) at 100 mg of soluble solid/L solution [95] BACE1 inhibitory activity (37.5%) at 100 μM [80] Suppresses hyperpigmentation (40%) at 100 mg⁄g polyethylene glycol [2]
99	7-O-methylaloesin	Aloe rupestris leaves exudate [96]	No reported biological activity
100	Aloesin-2″,3″,4″,6″-tetra-O-acetate	Anerobic incubation of aloesin with bacterial mixture [93]	No reported biological activity
101	2″-O-tigloylaloesin	Aloe cremnophila leaves exudate [97]	No reported biological activity
102	8-C-β-d-glucopyranosyl-7-hydroxy-5-methylchromone-2-carboxylic acid	Herbal tea “muti” [98]	No reported biological activity
103	8-[C-β-d-[2-O-(E)-cinnamoyl]glucopyranosyl]-2-[(R)-2-hydroxypropyl]-7-methoxy-5-methylchromone	Aloe vera [76] Aloe barbadensis leaves [99]	Topical anti-inflammatory activity at 200 µg/ear [99]
104	Aloeresin D	Aloe vera [76]	No reported biological activity
105	Rabaichromone	Aloe vera [76]	No reported biological activity
106	Allo-aloeresin D	Aloe vera [76]	No reported biological activity
107	Aloeresin K	Aloe vera [76] Aloe barbadensis leaf skin [100]	No reported biological activity
108	Aloeresin J	Aloe vera [76] Aloe barbadensis leaf skin [100]	No reported biological activity
109	Aloeresin E	Aloe vera leaves [76,82]	Inhibition of tyrosinase enzyme (40% and 80% at 50 and 100 ppm, respectively) [82]
110	Isoaloeresin D	Aloe vera leaves [76,82]	Inhibition of tyrosinase enzyme (20% and 40% at 50 and 100 ppm, respectively) [82] Antiviral activity against Pepper mild mottle virus; PMMoV (37.5 ± 6.5% at 1.5 mg/mL) [81]
111	2′-O-[p-methoxy-(E)-cinnamoyl]-(S)-aloesinol	Aloe nobilis leaves [12]	BACE1 inhibitory activity (34.1%) at 100 μM [80]
112	Iso-rabaichromone	Aloe vera [76,82]	No reported biological activity
113	8-C-glucosyl-(2′-O-cinnamoyl)-7-O-methylaloediol B	Aloe vera leaves [76]	No reported biological activity
114	Aloeresin A	Aloe vera [76]	Antioxidant activity [101] α-glucosidase inhibitory activities, with IC50 values of 11.94 and 2.16 mM against rat intestinal sucrase and maltase [79]
115	7-O-methyl-aloeresin A	Aloe vera [76]	Tyrosinase inhibitory activity with an IC50 value of 9.8 μM [81]
116	6′-O-coumaroyl-aloesin	Aloe vera [76]	Anti-lipid peroxidation activity with an IC50 value of 476.4 ± 0.9 µM [75]
117	7-Methoxy-6′-O-coumaroyl-aloesin	Aloe vera [76]	Weak anticancer activity against breast cancer cell line, MDA-MB-231 (induce 30% decline in cell survival at 25 μM ) [102]
118	2′-Feruloylaloesin	Aloe nobilis leaves [80]	Inhibition activity against β-secretase (36.4%) at 100 μM [80] Inhibition effect against mushroom tyrosinase (27 ± 0.57%) at 0.4 μM [103]
119	2′-Feruloyl-7-O-methylaloesin	Aloe nobilis leaves [80]	Inhibition activity against BACE1 (β-secretase) (48.7%) at 100 μM [80]
120	9-Dihydroxyl-2′-O-(Z)-cinnamoyl-7-methoxy-aloesin	Aloe vera [76]	Inhibition of tyrosinase enzyme (9.5 ± 9.0%) at 100 μM Antiviral against Pepper mild mottle virus; PMMoV (31.5 ± 4.2% inhibition at 1.5 mg/mL) [81]
121	4′-O-β-d-glucosyl-isoaloeresin DI	Aloe vera [76]	No reported biological activity
122	4′-O-β-d-glucosyl-isoaloeresin DII	Aloe vera [76]	No reported biological activity

4.3. Phenyl and Isoprenyl Chromone Glycosides

This category is characterized by a hydroxyl prenyl moiety at C-6 or C-8, or a hydroxyl isoprenyl moiety at C-6 only. The sugar moiety can be either situated at C-7 hydroxyl of the chromone nucleus or C-4’ of the hydroxyl prenyl or C-2’ of the hydroxyl isoprenyl moiety. Most of the compounds in this category were reported from the genus Cnidium, belonging to family Apiaceae. The reported biological activity associated with several compounds in this category is their significant inhibition of fat accumulation in differentiated adipocytes employing 3T3-L1 preadipocyte cells as an assay system [60]. The compounds 123–134 are shown in Figure 14. The sources and the reported biological activities (if any) are summarized in Table 11.

Figure 14.

Structures of compounds 123–134.

Table 11.

Prenyl and isoprenyl chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
123	Cnidimoside A	Cnidium Juponicum whole plant [104,105] Cnidium monnieri fruits [60,106]	Significant inhibition of fat accumulation at 300 μM in differentiated adipocytes [60] Antitumor and antimetastatic actions at 0.1–100 μM (in vitro) and 20, 50 mg/kg, twice daily (in vivo) [105]
124	Cnidimoside B	Cnidium Juponicum whole plant [104] Cnidium monnieri fruits [60]	Significant ihibition of fat accumulation at 300 μM in differentiated adipocytes [60]
125	2-methyl-5-hydroxy-6-(2- butenyl-3-hydroxymethyl)-7-(β-d-glucopyranosyloxy)-4H- 1-benzopyran-4-one	Cnidium monnieri fruits [60] Angelica archangelica [107] Archangelica litoralis [107]	No reported biological activity
126	Hydroxycnidimoside A	Cnidium monnieri fruits [60,106]	Significant inhibition of fat accumulation at 300 μM in differentiated adipocytes [60]
127	Monnieriside B	Cnidium monnieri fruits [60,106]
128	Monnieriside C	Cnidium monnieri fruits [60]	No reported biological activity
129	Monnieriside D
130	Monnieriside E
131	7,8-Secoeranthin-β-d-glucopyranoside (8-{(2E)-4-[β-d-glucopyranosyl)oxy]-3-methylbut-2-enyl}-5,7- dihydroxy-2-methyl-4H-l-benzopyran-4-one)	Eranthis hyemalis tubers [108]	No reported biological activity
132	2-C-Hydroxy-7,8-seroeranthipn-β-d-glucopyranoside (8-{(2E)-4-[β-d-glucopyranosyl)oxy]-3-methylbut-2-enyl}-5,7- dihydroxy-2-(hydroxymethyl)-4H-1-benzopyran-4-on2)
133	7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one	Eranthis cilicica tubers [109]	No reported biological activity
134	7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-2-hydroxymethyl-8- [(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one

4.4. Phenyl Ethyl Chromone Glycosides

Reviewing the literature, we encountered five phenyl ethyl chromone glycosides. The phenyl ethyl moiety is usually located at C-2 of the chromone nucleus. The sugar moiety is attached to C-7 of the chromone skeleton in compounds 135–137, while in compound 138, the sugar is attached to C-8. In compound 139, the sugar is not attached directly to the basic chromone skeleton. Compounds 135–139 are shown in Figure 15. Their sources are summarized in Table 12. There are no reported biological activities of these compounds.

Figure 15.

Structures of compounds 135–139.

Table 12.

Phenyl ethyl chromone glycosides with their sources.

No.	Compound	Source
135	Ononin glucoside	Ononis vaginalis whole plant [110]
136	7-Glucosyloxy-5-hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone	Cucumis melo seeds [111]
137	Aquilarinoside C (6,4′-dimethoxy-3′-hydroxy-2- (2-phenylethyl)chromone 7-O-β-d-glucopyranoside)	Aquilaria sinensis stems [112]
138	2-(2-phenylethyl) chromone-8-O-β-d-glucopyranoside	Imperata cylindrical rhizomes [113]
139	2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone	Aquilaria sinensis resinous heartwood [114]

4.5. Chromone Glycosides with Additional Heterocyclic Moieties

This category of chromone glycosides is further classified based on the additional heterocyclic moiety into furano-chromone glycosides, pyrano-chromone glycosides, oxepino-chromone glycosides and pyrido-chromone glycosides.

4.5.1. Furano-Chromone Glycosides

This subclass of compounds is characterized by presence of an additional furan, or a tetrahydrofuran ring fused with the benzo-δ-pyrone. Khellol glucoside (140), isolated from Ammi visnaga, is one of the important members in this subclass. It possess potent coronary vasodilator and bronchodilator activities [115]. It was reported to have a significant hypocholesterolemic effect. It lowered low-density lipoprotein cholesterol (LDL-C) by 73%, high-density lipoprotein cholesterol (HDL-C) by 23%, and total-C by 44%, after a single oral dose of 20 mg/kg per day after two weeks [116]. Compounds 140–148 are shown in Figure 16. The sources and the reported biological activities (if any) are summarized in Table 13.

Figure 16.

Structures of compounds 140–148.

Table 13.

Furano-chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
140	Khellol glucoside (Khellinin; Khelloside)	Ammi visnaga fruits [117] Eranthhis hyernalis tubers [108]	Potent coronary vasodilator and bronchodilator [115] Hypocholesterolemic effect at 20 mg/kg per day [116]
141	Norkhelloside	Cimicifuga heracleifolia rhizomes [118]	No reported biological activity
142	7-[(O-β-d-glucopyranosyl-(1→6)- β-d-glucopyranosyl)oxy]methyl-4-hydroxy-5H-furo[3,2-g][1]benzopyran-5-one	Eranthis cilicica tubers [109]	No reported biological activity
143	4′-O-β-d-glucopyranosylvisamminol (Monnieriside G)	Cnidium monnieri fruits [60] Saposhnikovia divaricata roots [119]	Antitumor activity against SK-OV-3 with an IC50 value of 93.91 μM [120]
144	4′-O-β-d-glucopyranosyl-5-O-methylvisamminol	Ledebouriella seseloides roots and rhizomes [121] Saposhnikovia divaricata roots [119,122] Diplolophium buchananii aerial parts [123] Sphallerocarpus gracilis roots [124]	Analgesic, antipyretic, anti-inflammatory, and anti-platelet aggregation activities [125,126] Antitumor activity with against H-460 cell line with an IC50 value of 86.91 μM [120]
145	(2’S)-4′-O-β-d-apiofuranosyl- (1→6)-β-d-glucopyranosylvisamminol	Saposhnikovia divaricata roots [119]	Antitumor activities against PC-3 and SK-OV-3 cell lines with IC50 values of 48.5, 81.91 μM, respectively [120]
146	prim-O-glucosylcimifugin	Ammi visnaga fruits [127] Angelica genuflexa roots [128] Eranthis hyernalis tubers [108] Angelica japonica roots [129] Cimicifuga foetida rhizomes [130] Diplolophium buchananii aerial parts [123] Saposhnikovia divaricata roots [131]	Analgesic, antipyretic, anti-inflammatory, anti-platelet aggregation and antitumor activities [125,126,131]
147	Cimifugin-4′-O-[6″-feruloyl]-β-d-glucopyranoside	Cimicifuga foetida rhizomes [132]	No reported biological activity
148	Monnieriside F	Cnidium monnieri fruits [60]	No reported biological activity

4.5.2. Pyrano-Chromone Glycosides

This subclass of compounds is characterized by the presence of an additional pyran ring fused with the benzo-δ-pyrone. Only three compounds were reported from nature until now. Of them, 3′-O-glucopyranosylhamaudol (Sec-O-glucopyranosylhamaudol) (149) and (3’S)-3′-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranosylhamaudol (150), isolated from the Saposhnikovia divaricata, showed weak anti-cancer activity. Both compounds were screened against three cancer cell lines, namely human prostatic cancer cell (PC-3), human ovarian carcinoma cell (SK-OV-3), and human lung cancer cell (H460) using the conventional MTT assay. Compound 149 showed a weak activity against H460, with an IC₅₀ value of 94.25 ± 1.45 µM while compound 150, showed an activity against SK-OV-3 with an IC₅₀ value of 86.21 ± 1.03 µM [119]. Compounds 149–151 are shown in Figure 17. The sources and the reported biological activities (if any) are summarized in Table 14.

Figure 17.

Structures of compounds 149–151.

Table 14.

Pyrano-chromone glycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
149	3′-O-glucopyranosylhamaudol (Sec-O-glucopyranosylhamaudol)	Angelica genuflexa roots [128] Angelica japonica roots [129] Glehnia littoralis roots [133] Peucedanum japonicum roots [134] Saposhnikovia divaricata roots [119,122]	Antitumor activity against H-460 cell line with an IC50 value of 94.25 ± 1.45 μM [119]
150	(3’S)-3′-O-β-d-apiofuranosyl-(1→6)- β-d-glucopyranosylhamaudol	Saposhnikovia divaricata roots [119]	Antitumor activity against SK-OV-3 with an IC50 value of 86.21 ± 1.03 μM [119]
151	(2’S)-2′-hydroxy-7-O-methylallopeucenin 2′-O-β-d-glucopyranoside	Diplolophium buchananii aerial parts [123]	No reported biological activity

4.5.3. Oxepino-Chromone Glycosides

This subclass of compounds is characterized by the presence of an additional oxepin fused with the benzo-δ-pyrone. Only four compounds were reported from nature until now, and all of them were reported from Eranthis species. The compounds 152–155 are shown in Figure 18. The sources are summarized in Table 15. There are no reported biological activities for these compounds.

Figure 18.

Structures of compounds 152–155.

Table 15.

Oxepino-chromone glycosides with their sources.

No.	Compound	Source
152	Eranthin β-d-glucopyranoside	Eranthis hyemalis tubers [108]
153	Eranthin β-d-gentiobioside	Eranthis cilicica tubers [109] Eranthis hyemalis tubers [108]
154	2-C-Hydroxyeranthin β-d-glucopyranoside	Eranthis hyemalis tubers [108]
155	9-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-8,11-dihydro-5,9-dihydroxy-2-methyl-4Hpyrano[2,3-g][1]benzoxepin-4-one	Eranthis cilicica tubers [109]

4.5.4. Pyrido-Chromone Glycosides

This subclass includes only the chromone alkaloidal glycoside; Schumanniofoside. This compound was found to reduce the lethal effect of black cobra (Naja melanoleuca) venom in mice [135]. The authors proved that this effect is greatest when the venom is mixed and incubated with the extract or schumanniofoside. They concluded that the mode of action is by oxidative inactivation of the venom. Schumanniophyton magnificum is used extensively in African ethno-medicine for the treatment of various diseases and, most commonly, the treatment of snake bites [135]. Its structure is shown in Figure 19. Its source and biological activity are summarized in Table 16.

Figure 19.

Structure of compound 156.

Table 16.

Pyrido-chromone glycosides with its source and biological activity.

No.	Compound	Source	Biological Activity
156	Schumanniofoside	Schumanniophyton magnificum stem bark [135]	Anti-snake venom activity at 0.01–0.16 g/kg [135]

4.6. Hybrids of Chromones with Other Classes of Secondary Metabolites

This is an interesting category, as the chromone skeleton is conjugated to another high molecular weight compound, as shown in the following subclasses.

4.6.1. Hybrids of Furano-Chromones with Cycloartane Triterpenes

This subclass of compounds is a hybrid of cycloartane triterpene and chromone. The reported compounds were isolated from the rhizomes of Cimicifuga foetida. The compounds 157–165 are shown in Figure 20. The sources and the reported biological activities (if any) are summarized in Table 17.

Figure 20.

Structures of compounds 157–165.

Table 17.

Hybrids of furanochromones with cycloartane triterpenes with their sources and biological activities.

No.	Compound	Source	Biological Activity
157	Cimitriteromone A	Cimicifuga foetida rhizomes [130]	No reported biological activity
158	Cimitriteromone B	Cimicifuga foetida rhizomes [130]	Anti-proliferative activity with an IC50 value of 15.73 ± 0.59 μM [130]
159	Cimitriteromone C	Cimicifuga foetida rhizomes [130]	No reported biological activity
160	Cimitriteromone D	Cimicifuga foetida rhizomes [130]	Anti-proliferative activity with an IC50 value of 24.21 ± 0.61 μM [130]
161	Cimitriteromone E	Cimicifuga foetida rhizomes [130]	No reported biological activity
162	Cimitriteromone F	Cimicifuga foetida rhizomes [130]	No reported biological activity
163	Cimitriteromone G	Cimicifuga foetida rhizomes [130]	No reported biological activity
164	Cimitriteromone H	Cimicifuga foetida rhizomes [136]	No reported biological activity
165	Cimitriteromone I	Cimicifuga foetida rhizomes [136]	Anti-proliferative activity with an IC50 value of 27.14 ± 1.38 μM [136]

4.6.2. Hybrids of Chromones with Secoiridoids

There are only two compounds (Figure 21) belonging to this class, sessilifoside (166) and 7″-O-β-d-glucopyranosylsessilifoside (167). Both compounds were isolated from the roots of Neonauclea sessilifolia roots [41]. The authors did not report biological activities for these compounds.

Figure 21.

Structures of compounds 166–167.

4.6.3. Chromone Alkaloids Aminoglycosides

This category includes compounds 168–192. Compounds 168–180 were reported from a strain of Streptomyces, isolated from a soil sample. These compounds showed antimicrobial activity against Gram-positive bacteria, as well as a potent antitumor activity. Conversely, compounds 181–183 were isolated from Saccharothrix species, while compounds 184–192 were reported from Actinomycete and exhibited antitumor and antimicrobial activities [137]. Compounds 168–192 are shown in Figure 22 and Figure 23. The sources and the reported biological activities (if any) are summarized in Table 18.

Figure 22.

Structures of compounds 168–183.

Figure 23.

Structures of compounds 184–192.

Table 18.

Chromone alkaloids aminoglycosides with their sources and biological activities.

No.	Compound	Source	Biological Activity
168	Kidamycin (rubiflavin B)	Streptomyces phaeoverticillatus var. takatsukiensis [138]	Antibiotic with MIC (minimum inhibitory concentration) ranges from 0.19–1.56 μg/mL and potent antitumor activity [138]
169	Neopluramycin	Streptomyces pluricolorescens [139,140]	Antibiotics and potent antitumor activity [140]
170	14, 16-Epoxykidamycin	Streptomyces pluricolorescens [141]	Antibiotic against Gram-positive bacteria with MIC ranges from 0.5 to 10 μg/mL and antitumor activity [141]
171	Pluramycin A	Streptomyces pluricolorescens [139,140]	Antibiotic and antitumor activity [140]
172	Rubiflavin A	Streptomyces species [142]	Antibiotic and antitumor activity [142]
173	Rubiflavin C-1
174	Rubiflavin C-2
175	Rubiflavin D
176	Rubiflavin E
177	Rubiflavin F (isokidamycin)
178	PD 121,222	Streptomyces species [143]	Antibiotic and potent antitumor activity [143]
179	Hedamycin	Streptomyces griseoruber [144,145]	Antibiotic and potent antitumor activity against HeLa cells [144]
180	Ankinomycin (deangolosaminylhedamycin)	Streptomyces species [146]	Antibiotic against Gram-positive bacteria with MICs ranges from 0.39–1.56 μg/mL and potent antitumor activity [146]
181	Pluraflavin A	Saccharothrix species [147]	Antibiotic and potent antitumor activity [147]
182	Pluraflavin B
183	Pluraflavin E
184	Altromycin A	Actinomycete, AB 1246E-26 [148,149]	Antibiotic against Gram-positive bacteria and potent antitumor activity [137]
185	Altromycin B
186	Altromycin C
187	Altromycin D
188	Altromycin E	Actinomycete, AB 1246E-26 [137]
189	Altromycin F
190	Altromycin G
191	Altromycin H
192	Altromycin I

5. Spectroscopic Features

5.1. UV Features

Most of the published work on chromones show several strong bands in the range of 200–320 nm [150,151]. In contrast to chromone, the pyrone ring of 4-chromanone contains no double bond. The ultraviolet absorption spectra of chromones and chromanones are summarized in Table 19 [150].

Table 19.

UV Band maxima of chromones and chromanone in 3-methylpentane at 25 °C.

Chromones		Chromanones
Band system	λmax	λmax
A	360, 352, 345, 337, 324	363, 347 322(sh), 312 252, 246 219(sh), 213
B	301, 290, 283
C	225, 246, 239, 227, 223, 216, 202

The UV spectrum of chromones in alcohol shows two strong bands at λ_max 245 and 299 nm [152,153,154]. Some data reported three bands at λ_max 245, 303 and 297 nm [150]. 2-methyl-5,7-dihydroxy chromone shows bands at λ_max 250, 255, 295 and 325 nm, meanwhile 2-methyl-5-hydroxy-7-O-glycosyl chromone shows bands at λ_max 248, 255 and 290 nm [154]. The presence of an electron attracting group at C-2 resulted in a bathochromic shift in all bands [151]. The information gained from applying spectral shift reagents with flavonoids can be also applied to chromones. In the case of AlCl₃, a bathochromic shift of 20–70 nm, which is non-reversible with acids, indicates a free hydroxyl group at position 5. Meanwhile, a bathochromic shift with NaOAc can be diagnostic for the presence of a free 7-hydroxyl group [154,155].

5.2. IR Features

Carbonyl region: The IR carbonyl stretching frequency for a chromone is observed at 1640~1660 cm⁻¹, which is slightly higher than that of δ-pyrone (1650 cm^−l) but is much lower than that of coumarins (1720–1740 cm^−l) [25,153]. Despite that the OH group attached to C-5 of the chromone nucleus chelates strongly with the CO group, this intramolecular H-bonding has only a slight bathochromic effect on the CO stretching frequency [156]. All 5-hydroxychromones possess three significant maxima in the 1580–1700 cm⁻¹ region. The two higher frequencies are intense at 1660 and 1630 cm⁻¹, with a constant wavenumber separation of 34 ( ± 5) cm⁻¹ in both carbon tetrachloride and chloroform.

Hydroxyl region: The IR hydroxyl stretching vibration for a chromone was observed at 2500–3650 cm⁻¹. A strong chelation in 5-hydroxychromones does not produce a considerable bathochromic shifts in both the OH and CO stretching bands [156]. Chelated 5-hydroxychromones produce no absorption maxima in the 3300–3600 cm⁻¹ region, but a weak absorption envelope extends from 2400 to 3300 cm⁻¹. The entire envelope is associated with various stretching modes of the chelated 5-OH group [156]. For 7-hydroxychromones, a steric buttressing effect is observed when the 7-OH group is flanked by a bulky substituent in the ortho-position (6 or 8). The free OH band appears as a doublet centered at 3615 cm⁻¹, the separation of the components being ~26 cm⁻¹. When a prenyl moiety is located in the ortho-position to the 7-OH group, an intramolecular OH interaction occurs, resulting in two OH stretching frequencies. When a 7-OH group is flanked by an OMe group, intense intramolecularly bonded OH stretching frequencies are found at ~3513 and 3517 cm⁻¹, respectively [156]. The 2-hydroxymethyl group exhibits a free stretching frequency at ≈3615 cm⁻¹. At concentrations higher than 0.15 M, a broad-bonded OH frequency at 3400 cm⁻¹ occurs due to intermolecular H-bonding, and it consequently disappears on dilution [156].

5.3. ¹H-NMR Features

In the following text, we try to give insight about the most characteristic ¹H-NMR features of the benzo-δ-pyrone skeleton (Figure 24) and its glycosides. The δ-pyrone ring has two olefinic protons assigned as H-2 and H-3. In 2, 3 unsubstituted chromones, for example compound 12, the ¹H-NMR spectrum shows two ortho-coupled doublets (J = 6.0 Hz), located downfield at δ_H 8.19 (H-2) and upfield at δ_H 6.26 (H-3) [25]. For 2-alkyl and 2-O-glycosyl chromones (compounds 21 and 1, respectively), they are characterized by an upfield singlet proton (H-3) at δ_H 6.11 and 5.98, respectively [7,40]. Meanwhile, 3-alkyl and 3-O-glycosyl chromones (compounds 39 and 2, respectively) are characterized by a downfield singlet proton (H-2) at δ_H 7.93 and 8.07, respectively [10,50].

Figure 24.

Basic skeleton of Chromone.

Chromanone glycosides or 2,3-dihydrochromone glycosides are characterized by an oxygenated proton (H-2) at δ_H 4.12 and 5.44 as in compounds 62 [63] and 60 [50], respectively. The splitting pattern of H-2 can be either d, dd or ddd, depending on the number of neighboring protons. A small coupling constant between H-2 and H-3 (J= 2.8 Hz) can determine that they are located in the equatorial–equatorial position [50]. Further information on the detailed configuration can be clarified from observing NOESY correlations. Unsubstituted chromanones at C-3, as in 62, show two geminal protons at δ_H 2.50 and 2.70. Their splitting pattern shows geminal (J_3a-3b = 16.2 Hz) and vicinal (J_ax-eq = 2.7 Hz or J_ax-ax = 12.6 Hz ) couplings [63]. In 3-alkyl substituted chromanones, as in 60 and 61, H-3 is also detected at δ_H 2.79 [50].

Naturally occurring chromones often bear a hydroxyl or methoxy group at C-5 and/or C-7 and a methyl group at C-2 and/or C-5 [153]. The C-5 methyl is usually observed in 6-C and 8-C glycosides. In aprotic solvents such as DMSO-d₆, the chelated 5-OH is detected as a singlet at δ_H 12.57; meanwhile, the 7-OH is detected at δ_H 10.00, as in compound 56 [31]. The C-2 methyl in Schumaniofioside A 7 can be detected at δ_H 2.33 (3H, s) [17]. Meanwhile, those located at C-5, can be detected more downfield at δ_H 2.64 (3H, s) as in 79 [78].

For the phenyl part of the benzo-δ-pyrone skeleton, the protons show chemical shift and coupling constant values similar to those observed for protons in substituted benzenes.

Sugar moiety: Xylosyl, arabinosyl and glucosyl chromones show an anomeric proton signal at δ_H ~4.73 (d, J = 7–7.6 Hz) [10,11,12]. The former moieties can be differentiated by the number of the oxygenated protons at the δ_H 3-5 region, in addition to the difference in ¹³C-NMR values. Rhamnosyl chromones show a distinct signal at δ_H ~1.25 (3H, d, J = 6.0 Hz) corresponding to CH₃-6’ of α-l-rhamnose [8]. The most abundant chromone of C-glycosides is the 8-C-glycoside form, followed by 6-C-glycosides. However, we encountered a unique 3-C-glycoside named macrolobin 64 [65]. The anomeric proton in macrolobin is detected at δ_H 5.32 (d, J = 1.5 Hz), the small coupling constant being indicative of the α-anomer [65]. Biflorin 66 and isobiflorin 80, as representative for 6-C and 8-C-glycosides, respectively, show the anomeric proton signal at δ_H 4.55 (d, J = 9.8 Hz), and 4.63 (d, J = 9.8 Hz), respectively [69]. The former coupling constant value is higher than that observed in case of O-glycosides (J = 7–7.6 Hz) [11,12]. In 5-O, 7-O, 6-C, furano-, pyrano-, oxepino-chromone glycosides, the sugar moiety can be further substituted with another sugar, as in 8–9, 25–32, 78–79, 141–142, 150 and 153, respectively. In 6-C, 8-C and, to a lesser extent, 7-O-glycosides, the sugar moiety can be mono- or disubstituted with a phenolic acid moiety, commonly at C-2’ or C-6’ or C-2’ and C-3’. The most commonly occurring phenolic moiety is gallic acid, but other phenyl propanoids such as cinnamoyl, coumaroyl, feruloyl and coniferoyl moieties also exist. The galloyl moiety is characterized by a singlet aromatic signal integrated for two protons at δ_H 6.75 [27]. The cinnamoyl moiety is confirmed by two trans-coupled olefinic protons at δ_H 7.43 (d, J = 15.8 Hz) and 6.25 (d, J = 15.8 Hz), in addition to the aromatic signals of the benzene ring [30]. The presence of coumaroyl substitution is characterized by AA’ BB’ system for two pairs of ortho-coupled aromatic protons at δ_H 7.31 (2H, d, J = 8.6 Hz) and δ_H 6.74 (2H, d, J = 8.6 Hz), a trans-olefinic proton signals at δ_H 7.35 (1H, d, J = 16.1 Hz) and δ_H 6.03 (1H, d, J = 15.9 Hz) [29].

Prenyl and Isoprenyl chromone glycosides: In the case of 7-O-glycoside 127, hydroxyl prenyl moiety can be easily characterized by the allylic methylene protons at δ_H 3.53 (2H, m, H-1’), an olefinic proton at δ_H 5.39 (t, J = 6.4, H-2’), oxygenated methylene protons δ_H 4.20 and 4.46 (1H each, d, J = 12.0 Hz, H-4’), and an olefinic methyl at δ_H 1.75 (3H, d, J = 1.2, H-5″) [60]. Its isomeric 4′-O-glycoside 126 showed similar signals; however, the hydroxyl methylene protons (H-4’) were slightly downfield at δ_H 4.34 and 4.65 due to O-glycosidation [106]. Meanwhile, the hydroxyl isoprenyl group in the 7-O-glycoside 130 is characterized by the methylene protons at δ_H 2.96 (2H, m, H-1’), an oxygenated methine proton at δ_H 4.35 (H-2’, m), exomethylene protons at δ_H 4.74 and 4.91 (H-4’) and an olefinic methyl at δ_H 1.87 (3H, s, H-5’). Its isomeric 2′-O-glycoside 129 showed similar signals, but the oxygenated methine proton (H-2’) is shifted downfield at δ_H 4.74 due to O-glycosidation [60].

Phenyl ethyl chromone glycosides: The presence of the phenyl ethyl moiety in compound 136 can be detected by the methylene proton signals at δ_H 2.75 (2H each, dd, J = 14.8, 6.4 Hz, H-7’) and 3.19 (2H each, J = 14.8, 3.1 Hz, H-8’), in addition to the aromatic protons of the phenyl ring. The 8′-hydroxy phenyl ethyl moiety in 135 shows an oxygenated proton signal δ_H 5.85 (dd, J = 3.5, 5.9 Hz, H-8’) [110].

5.4. ¹³C-NMR Features

For better understanding of the differences in chemical shifts related to the substituents on the chromone moiety, we preferred to add the ¹³C-NMR data in Table 20, Table 21, Table 22, Table 23, Table 24, Table 25, Table 26, Table 27, Table 28, Table 29, Table 30, Table 31, Table 32, Table 33, Table 34, Table 35, Table 36, Table 37, Table 38, Table 39 and Table 40. For the numbering of the skeleton, the following figure (Figure 25) gives few examples for the numbering system of the skeleton with multiple substituents. Briefly, the basic chromone nucleus was assigned numbers 1–10. In the case of a substitution at C-2, numbers 11, 12…etc. were given to the substituents, followed by substitution at C-3 and so on. Sugar moiety, and substituents attached to it, were assigned numbers 1’, 2’, … and then 1″, 2″, … etc. For better understanding, the following figure shows representative examples for the numbering system. Some complicated structures have their own numbering system, shown on them within the review.

Table 20.

The ¹³C-NMR spectral data of compounds 1–14 except those which have no reported ¹³C-NMR data.

C	1	2	3	4	5	7	11	13	14
2	161.2	147.4	147.7	147.8	147.4	167.2	167.8	158.6	159.5
3	93.1	141.2	141.0	138.1	141.5	111.7	109.1	112.0	112.8
4	166.6	178.4	178.5	177.0	178.4	180.3	183.2	183.6	184.4
5	137.1	163.4	163.3	161.5	163.4	160.2	93.9	163.4	163.9
6	132.0	100.1	100.2	98.8	100.2	104.6	162.0	101.3	101.9
7	127.8	166.4	166.3	164.3	166.5	164.7	110.2	164.9	165.2
8	114.9	95.0	95.0	93.8	95.0	99.1	159.6	96.2	96.9
9	154.3	159.3	159.3	157.2	159.4	161.1	156.6	159.5	160.2
10	114.5	106.2	106.2	104.8	106.1	109.2	106.1	108.4	109.3
11	23.2	-	-	-	-	19.9	20.3	-	-
12	-	-	-	-	-	-	8.2	-	-
1′	100.1	104.6	104.4	100.6	104.2	105.0	101.7	101.6	102.1
2′	73.2	74.6	72.0	69.9	74.8	74.6	75.1	74.7	75.1
3′	77.5	77.1	73.6	70.2	77.4	77.3	78.4	77.9	77.8
4′	69.6	70.8	69.2	71.5	71.3	71.3	80.5	71.2	73.9
5′	76.7	67.1	67.1	69.7	78.5	78.7	78.1	78.4	77.5
6′	60.7	-	-	17.7	62.6	62.5	60.9	62.4	171.5
OCH3	-	-	-	-	-	-	-	-	53.8
Solvent	DMSO-d6	CD3OD	CD3OD	DMSO-d6	CD3OD	CD3OD	C5D5N	CD3OD	CD3OD
References	[7]	[10]	[12]	[9]	[11]	[17]	[1]	[27]	[28]

Table 21.

The ¹³C-NMR spectral data of compounds 15–23 except which has no reported ¹³C-NMR data.

C	15	16	17	18	20	21	22	23
2	158.1	158.4	158.5	168.9	161.6	174.3	175.5	174.6
3	110.8	111.9	112.0	108.8	108.8	107.8	106.2	106.6
4	181.8	183.6	183.6	182.5	182.5	184.3	183.3	183.1
5	161.3	163.1	163.2	161.2	157.9	163.0	162.2	162.7
6	99.8	101.2	101.2	99.8	100.3	101.0	100.6	100.7
7	162.9	164.6	164.8	163.1	168.9	164.8	164.2	164.2
8	94.6	96.2	96.2	94.9	95.0	95.9	95.3	95.3
9	157.7	159.4	159.4	157.9	163.4	159.5	158.4	158.4
10	106.8	108.5	108.5	105.5	105.5	107.0	106.5	107.4
11	-	-	-	20.5	20.5	28.3	33.3	40.4
12	-	-	-	-	-	11.2	19.9	27.6
13	-	-	-	-	-	-	19.9	17.7
14	-	-	-	-	-	-	-	11.7
1′	99.7	101.5	101.5	100.6	99.9	101.6	101.7	101.7
2′	73.1	74.7	74.7	73.3	73.5	74.7	74.8	74.8
3′	76.2	77.9	77.9	76.6	77.6	77.8	78.5	78.5
4′	69.7	71.9	72.0	69.6	70.7	71.2	71.2	71.1
5′	74.1	75.8	76.0	66.2	76.8	78.4	79.3	79.2
6′	63.4	64.2	64.7	-	61.1	62.4	62.4	62.3
1″	119.5	127.4	127.3	-	-	-	-	-
2″	108.8	133.7	131.2	-	-	-	-	-
3″	145.6	115.8	117.0	-	-	-	-	-
4″	138.6	160.0	161.4	-	-	-	-	-
5″	145.6	115.8	117.0	-	-	-	-	-
6″	108.8	133.7	131.2	-	-	-	-	-
7″	165.9	145.1	146.9	-	-	-	-	-
8″	-	116.0	115.1	-	-	-	-	-
9″	-	168.1	168.9	-	-	-	-	-
Solvent	DMSO-d6	CD3OD	CD3OD	DMSO-d6	DMSO-d6	CD3OD	C5D5N	C5D5N
References	[29]	[30]	[30]	[31]	[157]	[40]	[41]	[41]

Table 22.

The ¹³C-NMR spectral data of compounds 24–32 except which has no reported ¹³C-NMR data.

C	24	25	26	28	29	30	31	32
2	168.7	157.3	167.9	168.2	168.9	169.2	168.9	168.5
3	108.7	108.3	108.8	108.8	108.8	109.3	108.8	108.4
4	182.4	181.9	182.7	182.8	182.5	184.2	182.5	182.1
5	161.5	161.1	162.4	162.4	161.7	163.1	161.7	161.3
6	99.9 *	108.7	100.6	100.7	100.2	100.8	100.0	99.6
7	162.9	162.6	163.9	163.9	161.9	163.4	161.9	161.6
8	94.9	108.2	95.3	95.1	95.2	95.7	95.1	94.7
9	157.7	168.2	158.3	158.3	157.9	159.5	157.9	157.5
10	105.5	105.0	106.3	106.3	105.7	106.8	105.6	105.2
11	20.3	19.9	19.9	20.1	20.5	20.4	20.5	20.1
1′	99.8 *	99.3	101.9	102.0	98.8	99.6	98.5	98.1
2′	73.3	77.0	74.6	74.6	81.2	71.0	69.8	69.5
3′	76.5	75.8	78.5	78.5	70.4	82.5	82.1	70.3
4′	70.2	68.9	71.5	71.6	70.9	72.4	70.7	81.4
5′	74.1	76.0	77.4	77.5	69.4	70.9	68.7	68.5
6′	63.7	60.5	69.0	68.0	18.3	18.1	18.0	17.9
1″	-	108.7	111.2	102.7	105.0	105.9	104.8	104.4
2″	-	76.7	77.9	72.0	74.5	75.4	74.1	74.5
3″	-	79.2	80.3	72.8	77.2	77.8	76.8	77.1
4″	-	73.9	75.1	74.1	70.0	71.1	70.6	70.1
5″	-	64.1	65.8	69.8	76.7	77.7	74.8	76.7
6″	-	-	-	18.6	61.5	62.2	64.1	61.2
CH3CO	20.9, 170.5	-	-	-	-	-	21.1, 170.6	-
Solvent	DMSO-d6	CDCl3, DMSO-d6	C5D5N	C5D5N	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6
References	[33]	[16]	[44]	[46]	[31]	[22]	[31]	[47]

* Data interchangeable.

Table 23.

The ¹³C-NMR spectral data of compounds 33–41.

C	33	34	35	36	37	38	39	40	41
2	168.3	168.2	168.3	168.3	157.8	154.8	154.7	168.6	168.4
3	108.2	108.7	108.3	108.2	110.6	120.3	125.8	108.7	108.4
4	181.4	182.7	181.9	181.9	181.5	183.8	183.5	182.5	182.3
5	161.1	162.3	161.1	161.2	157.7	163.0	163.1	158.4	185.1
6	99.5	100.6	99.8	99.5	108.9	100.9	100.8	109.1	108.5
7	161.4	163.7	162.6	162.6	160.9	164.6	164.6	161.1	155.56
8	94.5	94.6	94.3	94.5	93.3	95.8	95.8	93.3	97.7 *
9	157.3	158.3	157.4	157.4	155.4	159.4	159.5	155.9	160.3
10	105.0	106.3	105.1	105.1	106.0	107.4	107.6	105.1	105.0
11	19.9	19.9	19.8	19.8	7.4	10.2	19.3	20.5	19.9
12	-	-	-	-	-	-	13.4	7.9	6.9
1′	98.0	101.6	99.5	98.1	100.1	101.6	101.6	100.2	93.1 *
2′	69.5	74.4	72.9	73.0	73.1	74.7	74.7	73.8	77.3
3′	69.8	78.1	76.1	76.2	76.4	77.8	77.8	76.5	74.5
4′	80.9	71.3	69.9	69.9	69.6	71.2	71.2	79.4	69.7
5′	68.4	75.8	73.9	73.9	77.1	78.4	78.4	76.1	73.3
6′	17.9	64.5	63.4	63.4	60.6	62.4	62.4	60.7	60.5
1″	102.3	121.0	128.5	127.9	-	-	-	-	-
2″	81.4	110.4	114.8	114.9	-	-	-	-	-
3″	76.6	147.4	146.9	148.9	-	-	-	-	-
4″	69.8	140.8	147.7	149.3	-	-	-	-	-
5″	77.6	147.4	120.7	122.5	-	-	-	-	-
6″	61.0	110.4	115.9	115.8	-	-	-	-	-
7″	-	167.1	144.6	144.7	-	-	-	-	-
8″	-	-	115.7	115.8	-	-	-	-	-
9″	-	-	166.1	166.2	-	-	-	-	-
1‴	103.5	-	99.5	99.5	-	-	-	-	-
2‴	71.2	-	70.3	71.2	-	-	-	-	-
3‴	71.7	-	71.0	71.6	-	-	-	-	-
4‴	66.4	-	67.1	67.1	-	-	-	-	-
5‴	64.2	-	75.0	74.8	-	-	-	-	-
6‴	-	-	61.0	61.0	-	-	-	-	-
OCH3	-	-	-	55.8	-	-	-	60.1	-
CH3CO	-	-	-	-	-	-	-	-	20.7, 169.6
Solvent	DMSO-d6	C5D5N	DMSO-d6	DMSO-d6	DMSO-d6	CD3OD	CD3OD	DMSO-d6	DMSO-d6
References	[47]	[48]	[33]	[33]	[49]	[50]	[50]	[23]	[51]

* Data interchangeable.

Table 24.

The ¹³C-NMR spectral data of compounds 43–52 except those which have no reported ¹³C-NMR data.

C	43	45	46	47	48	49	50	52
2	168.7	168.4	168.4	169.5	170.0	160.0	164.9	164.9
3	108.4	108.0	108.0	108.4	109.1	112.5	101.9	118.6
4	182.9	182.7	182.7	182.4	185.0	185.0	178.8	177.6
5	159.5	152.6	155.9	152.5	157.8	158.8	141.8	137.9
6	98.3	109.7	114.3	135.2	116.3	117.3	116.6	110.5
7	160.9	158.5	158.8	157.8	160.2	161.2	160.4	159.8
8	104.6	114.3	109.8	94.7	111.6	112.9	111.5	99.6
9	155.0	155.9	152.6	155.6	154.6	155.5	159.3	158.5
10	105.2	106.5	106.5	106.2	108.2	110.6	117.1	115.7
11	20.5	20.0	20.1	20.2	20.5	10.3	22.8	19.4
12	8.1	8.8	9.0	-	8.9	10.5	19.9	48.7
13	-	8.9	9.1	-	9.5	-	-	205.3
14	-	-	-	-	-	-	-	52.0
15	-	-	-	-	-	-	-	62.7
16	-	-	-	-	-	-	-	23.6
1′	100.3	104.3	104.4	100.8	105.7	106.5	100.3	102.1
2′	73.9	76.0	74.1	74.1	75.3	76.5	77.6	73.0
3′	76.5	73.9	76.3	78.0	75.6	78.5	73.6	76.3
4′	79.4	70.0	69.9	69.9	71.7	72.5	70.1	69.4
5′	76.1	73.4	77.0	77.0	77.7	76.4	76.9	77.0
6′	60.7	63.0	61.0	61.2	64.3	65.3	61.0	60.5
1″	-	-	-	-	-	173.1	-	-
2″	-	-	-	-	-	47.3	-	-
3″	-	-	-	-	-	71.4	-	-
4″	-	-	-	-	-	46.9	-	-
5″	-	-	-	-	-	176.6	-	-
6″	-	-	-	-	-	28.4	-	-
OCH3	60.1	-	-	56.7	-	-	-	-
CH3CO	-	20.4, 170.1	-	-	20.4, 172.5	-	-	-
Solvent	DMSO-d6	DMSO-d6	*	DMSO-d6	*	CD3OD	CDCl3	DMSO-d6
References	[23]	[51]	[24]	[36]	[24]	[52]	[53]	[57]

* The authors did not report the NMR solvent.

Table 25.

The ¹³C-NMR spectral data of compounds 53–64 except those which have no reported ¹³C-NMR data.

C	53	54	55	56	57	60	61	62	64
2	161.0	166.3	169.9	166.6	166.5	105.9	104.7	83.5	148.0
3	117.2	110.7	109.3	107.6	106.9	46.2	52.9	42.2	140.5
4	178.1	177.4	184.0	182.2	182.5	199.2	198.9	193.7	178.9
5	141.3	117.8	96.0	162.0	162.0	165.3	165.2	161.5	163.6
6	113.0	125.0	162.9	99.5	98.8	97.5	97.5	100.0	100.2
7	159.9	119.2	101.0	165.1	164.8	168.4	168.4	166.6	166.2
8	99.7	147.4	164.7	94.5	93.6	97.0	97.0	99.1	95.3
9	158.8	147.3	159.3	158.1	158.2	160.4	160.2	166.2	159.3
10	116.1	125.4	119.0	104.3	104.2	102.0	102.4	106.7	106.6
11	47.3	20.1	20.3	66.1	66.0	13.8	23.7	33.2	-
12	202.5	-	-	-	-	-	11.8	18.2 *	-
13	29.8	-	-	-	-	-	-	-	-
14	22.3	-	-	-	-	-	-	-	-
1’	101.3	102.4	101.6	102.8	102.7	104.1	104.1	104.0	102.1
2’	73.1	74.8	74.7	73.9	73.6	75.0	75.0	74.6	72.0
3’	76.3	78.6	78.3	76.4	76.6	77.9	77.9	77.4	74.0
4’	69.5	71.2	71.4	67.7	70.1	71.0	71.0	71.2	71.5
5’	77.0	79.2	77.8	63.6	76.8	78.0	78.0	78.5	72.4
6’	60.9	62.4	62.4	-	61.3	62.5	62.5	62.5	62.5
Solvent	DMSO-d6	C5D5N	CD3OD	DMSO-d6	CD3OD	CD3OD	CD3OD	CD3OD	CD3OD
References	[57]	[58]	[59]	[31]	[60]	[54]	[50]	[63]	[65]

* Data interchangeable.

Table 26.

The ¹³C-NMR spectral data of compounds 66–72.

C	66	67	68	69	70	71	72
2	167.3	174.7	168.3	168.4	167.8	169.4	174.4
3	107.8	105.1	108.6	108.8	107.0	109.2	105.3
4	181.8	182.2	181.8	181.8	182.0	184.3	182.2
5	160.6	160.6	160.6	160.6	160.4	162.3	160.4
6	108.7	108.7	108.6	108.8	108.1	108.9	107.0
7	163.2	163.3	163.1	163.1	162.4	165.0	163.4
8	93.3	93.4	93.3	93.3	93.9	95.2	93.7
9	156.6	156.7	156.6	156.6	157.0	159.4	156.9
10	103.0	103.3	103.2	103.2	102.9	105.1	103.1
11	19.8	32.3	43.1	66.2	20.0	20.4	32.4
12	-	19.8	64.1	46.0	-	-	19.8
13	-	19.8	23.3	63.8	-	-	19.8
14	-	-	-	43.8	-	-	-
15	-	-	-	23.5	-	-	-
1′	73.0	73.0	72.9	72.9	70.8	75.6	70.7
2′	70.1	70.2	70.0	70.0	72.0	72.6	72.0
3′	78.9	78.9	78.8	78.8	76.7	80.1	76.6
4′	70.6	70.6	70.5	70.5	70.8	71.9	70.7
5′	81.4	81.6	81.4	81.4	82.0	80.2	81.8
6′	61.4	61.5	61.4	61.4	61.6	65.2	61.5
1″	-	-	-	-	119.9	121.6	119.9
2″	-	-	-	-	108.9	110.4	108.7
3″	-	-	-	-	145.4	146.6	145.4
4″	-	-	-	-	138.2	140.0	138.1
5″	-	-	-	-	145.4	146.6	145.4
6″	-	-	-	-	108.9	110.4	108.9
7″	-	-	-	-	164.8	168.6	164.7
Solvent	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	CD3OD	DMSO-d6
References	[69]	[69]	[72]	[72]	[71]	[73]	[69]

Table 27.

The ¹³C-NMR spectral data of compounds 73–79 except those which have no reported ¹³C-NMR data.

C	73	74	75	76	79
2	167.7	174.9	162.3	163.1	160.6
3	106.3	105.3	113.2	111.0	112.4
4	182.0	182.2	181.9	181.8	178.5
5	161.1	160.9	143.1	146.1	*
6	108.1	106.4	127.0	128.3	126.5
7	163.1	163.2	160.1	161.1	160.8
8	93.4	93.4	119.4	121.1	100.6
9	157.1	157.0	161.3	157.9	159.0
10	103.0	103.1	115.8	114.3	114.6
11	19.9	32.4	48.7	48.5	47.8
12	-	19.78	204.4	204.6	202.4
13	-	19.75	29.8	30.7	29.8
14	-	-	23.3	23.3	22.5
CH3O	-	-	-	55.8	-
1′	70.7	70.7	75.5	75.6	71.4
2′	69.7	69.7	71.9	72.3	81.7
3′	77.6	77.6	80.0	79.9	78.2
4′	68.7	68.7	72.9	72.1	70.1
5′	81.8	81.7	79.8	78.5	81.1
6′	61.2	61.2	65.2	65.4	60.9
1″	119.7	119.7	133.6	128.3	105.1
2″	108.9	108.9	131.2	131.0	74.3
3″	145.5	145.4	116.8	115.3	76.1
4″	138.5	138.4	161.3	160.4	69.3
5″	145.5	145.4	116.8	115.3	76.1
6″	108.9	108.9	131.2	131.0	60.3
7″	165.3	165.4	146.2	146.2	-
8″	-	-	114.9	116.0	-
9″	-	-	169.2	169.1	-
1‴	119.1	119.0	-	-	-
2‴	108.7	108.7	-	-	-
3‴	145.3	145.3	-	-	-
4‴	138.4	138.3	-	-	-
5‴	145.3	145.3	-	-	-
6‴	108.7	108.7	-	-	-
7‴	164.6	164.4	-	-	-
Solvent	DMSO-d6	DMSO-d6	CD3OD	CD3OD	DMSO-d6
References	[71]	[71]	[74]	[74]	[78]

* The authors missed assigning this position.

Table 28.

The ¹³C-NMR spectral data of compounds 80–89.

C	80	81	82	83	84	85	86	87	88	89
2	167.0	169.3	174.4	173.0	168.2	167.6	167.2	174.8	167.7	174.5
3	107.4	108.7	105.0	106.2	108.3	107.8	107.5	105.4	108.0	105.6
4	181.9	184.3	182.2	181.9	181.9	182.2	181.9	182.4	182.2	182.4
5	160.4	149.4	160.4	160.4	160.3	160.8	160.5	160.7	161.0	161.0
6	98.4	94.5	98.5	98.7	98.3	97.6	98.3	97.8	98.0	97.9
7	162.5	162.8	162.8	164.2	162.7	162.2	162.6	162.3	162.4	162.6
8	104.3	105.2	104.1	104.7	108.4	103.9	104.0	102.8	103.9	102.1
9	156.1	164.6	156.5	156.6	158.9	157.1	156.3	157.2	157.1	157.2
10	103.5	106.3	102.0	103.3	103.8	102.8	103.5	104.0	102.0	104.0
11	19.6	20.3	32.7	39.1	42.1	11.0	19.7	33.1	20.1	33.1
12	-	-	20.0	27.0	66.5	-	-	19.8	-	20.3
13	-	-	19.5	11.4	45.8	-	-	20.3	-	20.1
14	-	-	-	17.4	64.1	-	-	-	-	-
15	-	-	-	-	23.6	-	-	-	-	-
1′	73.1	74.9	73.1	73.3	73.2	70.6	73.3	70.7	70.7	70.8
2′	71.0	72.8	71.2	71.2	70.3	72.5	70.0	72.5	70.1	70.2
3′	78.5	80.0	78.5	78.7	78.6	76.1	78.1	76.0	77.0	77.0
4′	70.3	71.7	70.8	70.9	71.0	70.8	70.7	71.2	68.5	68.9
5′	81.1	82.4	81.5	81.5	81.4	81.7	78.3	82.0	81.5	81.9
6′	61.3	62.9	61.8	61.7	61.5	61.5	63.8	61.8	61.0	61.3
1″	-	-	-	-	-	119.7	119.4	119.6	119.6	119.6
2″ , 6″	-	-	-	-	-	108.8	108.5	108.7	108.9	108.9
3″ , 5″	-	-	-	-	-	145.5	145.5	145.4	145.6	145.5
4″	-	-	-	-	-	138.8	138.3	138.3	138.7	138.7
7″	-	-	-	-	-	165.0	165.8	165.0	165.5	165.4
1‴	-	-	-	-	-	-	-	-	118.7	118.7
2‴ , 6‴	-	-	-	-	-	-	-	-	108.7	108.7
3‴ , 5‴	-	-	-	-	-	-	-	-	145.5	145.4
4‴	-	-	-	-	-	-	-	-	138.5	138.6
7‴	-	-	-	-	-	-	-	-	164.8	164.8
OCH3	-	56.8	-	-	-	-	-	-	-	-
Solvent	DMSO-d6	CD3OD	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6
References	[86]	[87]	[158]	[158]	[72]	[71]	[91]	[69]	[71]	[71]

Table 29.

The ¹³C-NMR spectral data of compounds 91–100 except which has no reported ¹³C-NMR data.

C	91	93	94	95	96	97	98	99	100
2	162.7	164.9	167.1	167.0	169.2	160.2	160.2	160.8	159.6
3	109.8	111.2	112.2	111.9	110.8	112.6	112.4	113.0	113.7
4	182.7	178.7	182.3	181.9	182.4	178.3	178.5	178.9	179.1
5	144.0	141.0	143.1	143.7	144.1	139.5	140.1	141.3	144.1
6	112.8	111.5	112.2	112.6	113.1	116.9	116.3	111.9	118.5
7	162.5	160.0	162.3	162.1	162.7	160.2	159.5	160.3	159.0
8	113.3	112.8	116.1	113.1	113.7	107.1	110.0	113.1	106.2
9	158.8	157.2	160.0	158.9	159.1	155.9	157.8	157.3	159.6
10	117.4	115.9	118.5	117.0	117.6	114.3	114.7	115.9	113.9
11	124.7	43.2	44.3	44.2	76.2	47.2	47.7	47.8	48.2
12	139.0	63.8	66.7	66.3	69.5	202.5	202.4	202.5	200.7
13	18.4	23.8	23.6	23.6	19.7	22.2	22.6	30.0	30.2
14	23.6	22.8	23.3	23.6	23.7	29.9	29.9	23.0	23.1
15	56.9	56.4	-	56.7	56.9	-	-	56.6	-
1′	75.1	73.0	76.0	74.6	74.9	80.2	73.5	72.9	68.1
2′	72.4	70.9	73.2	72.7	72.9	77.5	71.0	71.1	73.7
3′	80.3	78.8	80.1	80.0	80.3	74.8	78.7	79.1	73.7
4′	72.3	70.8	71.8	71.9	72.2	80.5	70.4	70.7	70.2
5′	82.9	81.8	82.7	82.4	82.6	68.3	81.5	81.8	76.6
6′	63.0	61.7	62.8	63.0	63.3	63.8	61.4	61.8	61.6
2 ′-OCOCH3	-	-	-	-	-	-	-	-	168.6, 20.7
3 ′-OCOCH3	-	-	-	-	-	-	-	-	169.4, 20.7
4 ′-OCOCH3	-	-	-	-	-	-	-	-	170.3, 20.7
6 ′-OCOCH3	-	-	-	-	-	-	-	-	170.6, 20.7
Solvent	CD3OD	DMSO-d6	CD3OD	CD3OD	CD3OD	DMSO-d6	DMSO-d6	CD3OD	CDCl3
References	[80]	[159]	[160]	[82]	[160]	[94]	[94]	[96]	[93]

Table 30.

The ¹³C-NMR spectral data of compounds 103–110 except which has no reported ¹³C-NMR data.

C	103	104	106	107	108	109	110
2	165.0	165.0	167.4	167.2	167.4	167.1	167.2
3	111.3	111.3	112.5	112.6	112.6	111.9	111.9
4	178.6	178.8	182.3	182.2	182.2	181.9	182.0
5	141.7	141.8	144.6	144.8	144.6	144.3	144.3
6	111.0	111.3	112.7	112.6	112.5	112.3	112.4
7	159.5	159.8	162.1	162.0	162.0	161.6	161.6
8	110.6	110.7	111.8	111.4	111.8	111.6	111.3
9	157.4	157.5	159.8	159.6	159.6	159.3	159.1
10	115.8	115.8	117.2	117.2	117.2	116.9	116.9
11	43.1	43.3	44.6	44.9	44.6	44.5	44.3
12	64.4	63.9	65.9	66.3	66.0	66.6	66.5
13	23.3	23.7	23.6	23.7	23.6	23.5	23.6
14	22.8	22.9	23.7	23.7	23.6	23.5	23.3
15	56.5	56.5	57.0	57.1	57.0	56.9	57.0
1′	70.6	70.6	72.8	72.8	72.8	71.9	71.8
2′	72.6	72.3	73.4	73.7	73.9	74.0	73.7
3′	75.7	75.9	77.7	77.7	77.9	77.6	77.4
4′	70.4	70.9	72.4	72.4	72.3	72.4	72.4
5′	81.8	82.0	83.0	80.1	82.9	82.7	82.4
6′	61.5	61.6	63.1	64.4	63.1	62.9	62.7
1″	133.9	125.0	127.0	127.0	128.2	135.3	126.7
2″	128.9	130.3	133.2	131.1	130.9	128.9	130.9
3″	128.2	115.8	115.7	116.9	115.4	129.7	116.6
4″	130.4	159.6	160.0	161.3	163.2	131.3	160.7
5″	128.2	115.8	115.7	116.9	115.4	129.7	116.6
6″	128.9	130.3	133.2	131.1	130.9	128.9	130.9
7″	144.1	144.4	145.0	146.6	146.1	146.1	146.4
8″	117.8	114.0	115.7	114.6	115.6	118.1	114.2
9″	165.0	165.4	167.6	168.0	167.8	167.2	167.8
OCH3	-	-	-	-	55.9	-	-
COCH3	-	-	-	173.0, 20.9	-	-	-
Solvent	DMSO-d6	DMSO-d6	CD3OD	CD3OD	CD3OD	CD3OD	CD3OD
References	[99]	[159]	[80]	[100]	[100]	[82]	[82]

Table 31.

The ¹³C-NMR spectral data of compounds 111–122 except which has no reported ¹³C-NMR data.

C	111	112	113	114	115	116	117	119	120	121	122
2	167.2	167.6	169.7	160.3	163.0	160.1	163.1	160.6	164.0	167.6	166.8
3	112.1	112.2	110.5	1125	113.8	112.5	111.0	112.5	112.4	112.2	112.2
4	182.2	182.3	182.4	178.6	182.1	178.4	181.8	178.6	182.0	182.3	182.3
5	143.5	144.6	144.8	141.0	144.7	140.4	146.1	141.8	144.9	144.6	144.8
6	116.3	112.6	112.7	115.8	112.2	115.7	128.3	111.5	113.1	112.6	112.7
7	161.3	162.0	162.1	159.l	162.1	159.4	161.1	159.7	162.3	161.0	162.2
8	110.0	111.9	111.8	110.2	112.0	110.7	121.1	110.8	111.6	111.9	111.9
9	160.4	159.6	159.4	158.3	159.6	157.9	157.9	157.4	159.5	159.6	159.6
10	117.0	117.3	117.5	114.8	117.1	114.8	114.3	115.6	117.6	117.2	117.3
11	44.3	44.6	75.7	48.1	49.1	47.8	48.5	47.9	98.6	44.6	44.6
12	66.7	66.8	69.2	202.4	204.7	202.3	204.6	202.1	203.7	66.8	66.8
13	23.5	23.6	19.7	30.4	29.9	29.6	30.7	29.6	23.7	23.7	24.0
14	23.5	23.6	23.7	22.7	23.7	22.6	23.3	22.7	25.0	23.6	23.5
15	-	57.1	57.1	-	57.1	-	55.8	55.5	57.2	57.1	57.1
1′	73.0	72.1	72.8	70.2	72.1	73.3	75.6	70.4	72.6	72.6	72.6
2′	74.0	74.0	74.1	72.3	73.9	70.8	72.3	72.2	74.3	74.1	73.6
3′	77.9	77.9	77.8	76.0	77.9	78.5	79.9	75.8	78.0	77.8	77.6
4′	72.1	72.7	72.3	70.2	72.6	70.4	72.1	70.6	71.9	78.3	78.1
5′	82.8	82.9	83.0	81.8	82.8	78.4	78.5	81.9	83.3	82.9	82.9
6′	63.1	63.1	63.1	61.8	63.3	64.8	65.4	61.5	63.5	63.0	63.0
1″	128.3	127.5	135.7	125 I	127.0	125.0	128.3	125.5	135.7	129.8	129.7
2″	131.0	115.1	129.2	1301	130.8	130.3	131.0	111.1	129.3	130.8	132.6
3″	116.7	149.9	130.1	115.8	116.7	115.7	115.3	147.9	130.1	118.0	116.7
4″	161.2	146.6	131.6	159.6	161.3	159.7	160.4	149.2	131.6	163.8	159.7
5″	116.7	116.6	130.1	115.8	116.7	115.7	115.3	115.5	130.1	-	-
6″	131.0	123.0	129.2	1301	130.8	130.3	131.0	122.9	129.3	-	-
7″	146.2	147.1	146.4	144.4	145.3	144.9	146.2	144.6	146.3	146.0	144.7
8″	115.8	114.5	118.4	114.1	115.1	114.0	116.0	114.2	118.5	116.5	117.6
9″	168.0	168.2	167.4	165.4	168.1	166.7	169.1	165.4	167.4	167.8	167.7
OCH3	56.1	-	-	-	-	-	-	56.3	-	-	-
1‴	-	-	-	-	-	-	-	-	-	101.9	101.7
2‴	-	-	-	-	-	-	-	-	-	74.8	74.9
3‴	-	-	-	-	-	-	-	-	-	72.1	72.6
4‴	-	-	-	-	-	-	-	-	-	71.3	71.2
5‴	-	-	-	-	-	-	-	-	-	78.0	77.9
6‴	-	-	-	-	-	-	-	-	-	62.5	62.4
Solvent	CD3OD	CD3OD	CD3OD	DMSO-d6	DMSO-d6	DMSO-d6	CD3OD	DMSO-d6	CD3OD	CD3OD	CD3OD
References	[80]	[82]	[160]	[161]	[162]	[163]	[74]	[164]	[81]	[160]	[160]

Table 32.

The ¹³C-NMR spectral data of compounds 123–129 except which has no reported ¹³C-NMR data.

C	123	124	126	127	128	129
2	167.7	168.3	171.3	170.7	167.7	169.9
3	108.0	108.5	105.6	105.5	108.3	108.4
4	182.2	182.4	184.3	183.0	182.7	182.4
5	158.8	157.8	160.2	158.1	159.5	159.6
6	110.4	111.1	112.5	112.8	107.4	105.2
7	162.3	163.1	163.8	161.0	162.9	163.1
8	93.2	90.5	94.4	93.0	92.8	92.9
9	156.1	156.6	157.8	156.1	156.7	156.4
10	103.3	104.4	106.8	105.6	103.4	103.8
11	19.9	19.9	61.6	60.0	18.8	60.0
OCH3	-	56.5	-	-	-	-
1′	20.5	20.5	22.1	20.5	26.4	26.4
2′	126.9	126.4	128.7	124.6	79.9	79.8
3′	131.8	132.3	132.9	134.1	143.7	143.7
4′	66.1	66.1	68.4	61.0	114.2	114.2
5′	21.2	21.3	21.9	20.0	15.2	15.2
1″	101.5	101.6	102.7	100.1	99.4	99.4
2″	73.6	73.6	75.3	73.2	73.6	73.6
3″	76.9	77.0	78.3	76.7	76.3	76.3
4″	70.2	70.2	71.8	67.7	70.2	70.2
5″	77.0	77.0	77.9	77.0	76.7	76.7
6″	61.1	61.1	62.9	60.1	61.2	61.2
Solvent	DMSO-d6	DMSO-d6	CD3OD	CD3OD	CD3OD	CD3OD
References	[104]	[104]	[106]	[60]	[60]	[60]

Table 33.

The ¹³C-NMR spectral data of compounds 130–139.

C	130	131	132	133	134	135	136	137	138	139
2	170.7	167.6	170.7	168.3	171.4	168.9	165.0	171.0	171.5	171.8
3	105.5	107.4	104.9	108.1	105.5	113.9	*	110.4	110.7	110.7
4	183.0	181.8	181.9	182.5	182.5	176.6	*	179.3	180.4	180.6
5	158.8	158.8	158.9	159.5	159.5	132.6	*	106.6	119.2	126.2
6	111.4	97.6	97.8	98.3	98.4	111.4	99.3	150.7	126.2	126.6
7	162.1	159.9	160.1	160.6	160.8	158.2	162.9	153.1	122.1	135.6
8	93.3	107.5	107.4	108.1	108.2	103.6	94.8	106.9	147.8	119.3
9	156.3	153.8	153.5	154.4	154.1	163.4	*	149.8	149.0	158.0
10	105.7	104.3	104.8	105.0	105.4	112.7	*	116.2	125.0	124.3
11	60.0	19.5	59.3	20.2	59.5	127.9	121.6	102.2	141.4	136.2
1′	28.2	20.3	20.3	21.0	20.9	131.9	128.5	74.3	129.5	114.0
2′	74.6	120.5	120.4	121.1	121.0	115.7	115.7	78.1	129.6	150.7
3′	147.9	134.9	134.9	135.6	135.7	157.1	161.5	71.5	127.4	146.4
4′	109.5	65.9	65.8	66.5	66.5	115.7	115.7	78.0	129.6	118.1
5′	16.6	13.1	13.1	13.8	13.7	131.9	128.5	62.8	129.5	122.0
6′	-	-	-	-	-	39.3	39.1	-	33.8	33.6
7′	-	-	-	-	-	86.3	37.5	-	37.0	37.1
8′	-	-	-	-	-	127.9	121.6	102.2	141.4	136.2
1″	101.2	100.1	100.1	100.7	100.7	101.8	100.3	131.5	103.0	102.9
2″	73.6	72.9	72.9	73.5	73.5	74.6	*	133.0	75.0	74.9
3″	76.5	76.7	76.7	76.7	76.7	78.4	*	116.3	78.2	77.8
4″	69.8	69.2	69.2	69.8	69.8	71.2	*	164.1	71.3	71.3
5″	77.1	76.1	76.1	77.3	77.3	78.2	*	116.3	78.2	78.1
6″	61.1	60.2	60.2	60.8	60.8	62.5	*	120.9	62.5	62.4
7″	-	-	-	-	-	-	-	33.9	-	-
8″	-	-	-	-	-	-	-	37.1	-	-
OCH3	-	-	-	-	-	-	-	6-OCH3 56.3 4″-OCH3 55.1	-	56.6
Solvent	CD3OD	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	CD3OD	DMSO-d6	DMSO-d6	CD3OD	CD3OD
References	[60]	[108]	[108]	[109]	[109]	[110]	[111]	[112]	[113]	[114]

* The authors missed assigning these positions.

Table 34.

The ¹³C-NMR spectral data of compounds 140–148.

C	140	141	142	143	144	145	146	147	148
2	147.2	146.9	147.3	89.9	89.0	92.9	92.1	92.3	88.2
3	106.1	105.0	104.9	24.3	28.3	28.1	27.9	28.0	30.1
4	153.7	160.5	159.2	165.5	164.5	160.3	165.3	156.3	158.5
5	177.2	185.9	184.7	176.9	176.4	184.7	176.6	176.6	182.9
6	109.7	107.8	107.2	111.9	109.8	109.5	110.9	111.4	107.2
7	163.7	169.0	168.7	163.3	164.0	169.7	162.7	162.6	166.7
9	95.8	92.0	92.0	94.8	95.2	90.4	94.0	94.2	88.8
10	157.8	156.1	154.5	159.9	160.1	168.3	159.7	165.4	166.6
11	117.0	114.3	113.4	118.7	117.2	111.3	118.1	118.5	108.7
12	152.8	106.9	106.3	112.3	111.4	106.6	112.5	112.8	102.9
13	155.6	155.7	155.2	156.4	157.7	157.9	156.1	159.9	158.6
14	65.7	67.8	66.3	21.4	20.7	20.8	66.4	66.8	66.1
4-OCH3	61.9	-	-	-	*	-	60.8	61.0	-
1′	103.0	104.4	104.4	77.3	74.3	79.7	70.8	70.8	143.7
2′	74.0	75.0	74.2	23.4	24.1	24.3	26.0	26.2	115.5
3′	77.2	77.9	77.6	22.3	23.5	23.0	25.6	25.8	15.7
4′	70.6	71.6	70.9	-	-	-	-	-	-
5′	77.1	78.0	76.7	-	-	-	-	-	-
6′	61.7	68.7	69.5	-	-	-	-	-	-
1″	-	111.1	103.3	98.9	100.1	99.5	104.0	104.4	102.8
2″	-	77.2	74.4	75.1	74.6	75.6	74.8	75.0	73.7
3″	-	80.6	77.4	78.8	78.6	78.5	78.4	78.3	76.7
4″	-	74.9	70.9	71.3	71.4	72.0	71.4	71.3	70.3
5″	-	65.5	77.7	77.1	78.2	76.8	78.1	75.7	76.9
6″	-	-	61.9	62.4	63.1	68.5	62.6	64.5	61.4
1‴	-	-	-	-	-	111.2	-	126.5	-
2‴	-	-	-	-	-	78.6	-	111.4	-
3‴	-	-	-	-	-	81.0	-	149.0	-
4‴	-	-	-	-	-	75.6	-	151.2	-
5‴	-	-	-	-	-	66.2	-	116.8	-
6‴	-	-	-	-	-	-	-	123.9	-
7‴	-	-	-	-	-	-	-	145.9	-
8‴	-	-	-	-	-	-	-	115.1	-
9‴	-	-	-	-	-	-	-	167.8	-
3‴-OCH3	-	-	-	-	-	-	-	55.9	-
Solvent	DMSO-d6, C6D6	CD3OD	DMSO-d6	CDCl3, CD3OD	CDCl3, CD3OD	CD3OD	C5D5N	C5D5N	CD3OD
References	[117]	[118]	[109]	[122]	[122]	[119]	[121]	[132]	[60]

* The authors missed assigning this position.

Table 35.

The ¹³C-NMR spectral data of compounds 149–155.

C	149	150	151	152	153	154	155
2	167.4	169.5	162.7	167.6	167.6	170.9	168.7
3	108.7	108.0	111.1	107.5	107.4	105.6	108.6
4	182.7	184.2	175.3	181.9	181.8	182.5	182.6
5	160.0	160.9	160.7 *	158.6	158.5	159.2	160.3
6	104.1	105.0	104.9	103.1	103.1	103.8	102.5
7	159.6	160.4	152.7 *	163.5	163.3	164.1	164.3
8	94.9	95.8	91.1	109.8	109.9	110.5	105.8
9	156.3	157.7	157.8	152.9	152.7	153.1	155.0
10	104.4	105.0	107.7	105.5	105.4	106.5	106.1
2′	78.4	79.3	76.6	69.6	69.6	70.2	74.2
3′	74.3	75.0	72.4	135.2	135.0	135.8	73.5
4′	22.3	22.7	22.4	124.7	124.7	125.2	132.7
5′	-	-	-	20.6	20.3	20.9	117.3
1″	102.4	102.0	100.4	101.2	100.9	101.9	103.9
2″	74.9	74.9	**	72.8	72.6	73.3	73.7
3″	78.4	78.1	76.9	76.8	76.1	76.8	76.5
4″	71.8	71.9	70.2	70.1	69.4	70.1	70.9
5″	78.4	75.0	76.9	76.6	75.2	76.6	76.0
6″	63.0	68.8	61.3	60.6	67.7	61.6	68.5
1‴	-	111.0	-	-	102.7	-	103.4
2‴	-	77.9	-	-	72.8	-	73.7
3‴	-	80.5	-	-	76.1	-	76.9
4‴	-	75.0	-	-	69.4	-	70.0
5‴	-	65.7	-	-	75.9	-	77.0
6‴	-	-	-	-	60.4	-	61.1
2a	20.1	20.4	19.0	19.4	19.2	59.7	20.1
2’a	22.3	22.4	21.2	-	-	-	-
2’b	25.7	26.1	25.2	-	-	-	-
3’a	-	-	-	69.6	69.6	70.2	73.0
7-OCH3	-	-	56.0	-	-	-	-
Solvent	CDCl3	CD3OD	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6	DMSO-d6
References	[121]	[119]	[123]	[108]	[108]	[108]	[109]

* Interchangeable data. ** The authors missed the assignment of this position.

Table 36.

The ¹³C-NMR spectral data of compounds 157–165.

C	157	158	159	160	161	162	163	164	165
Chromone moiety
2′	92.4	92.2	92.2	92.2	92.2	92.2	92.2	92.2	92.2
3′	27.9	27.8	27.8	27.8	27.8	27.8	27.8	27.8	27.8
4′	156.3	156.2	156.2	156.2	156.2	156.2	156.2	156.2	156.1
5′	176.2	176.2	176.2	176.2	176.2	176.2	176.3	176.3	176.3
6′	111.5	110.9	111.1	110.9	110.9	110.8	111.1	111.2	111.1
7′	162.1	162.5	162.4	162.4	162.7	162.5	162.6	162.6	162.5
9′	94.1	94.0	94.0	94.0	94.1	94.0	94.0	94.1	94.0
10′	165.4	165.2	165.2	165.2	165.2	165.2	165.2	165.2	165.2
11′	118.5	118.4	118.4	118.4	118.4	118.4	118.4	118.4	118.4
12′	112.9	112.8	112.8	112.5	112.8	112.8	112.8	112.8	112.7
13′	159.9	159.8	159.8	159.7	159.8	159.7	159.8	159.9	159.8
14′	66.3	66.3	66.5	66.2	66.4	66.2	66.5	66.3	66.5
4-OCH3	60.9	60.9	60.9	60.8	60.9	60.9	60.9	60.9	60.8
1″	70.6	70.6	70.6	70.6	70.6	70.6	70.6	70.7	70.6
2″	26.0	26.1	26.1	26.1	26.1	26.1	26.1	26.2	26.1
3″	25.6	25.7	25.7	25.6	25.7	25.7	25.6	25.6	25.7
Glu-1	101.7	104.1	104.2	104.1	104.1	104.0	104.2	103.9	104.3
Glu-2	74.5	74.9	74.8	74.8	74.9	74.9	74.9	74.8	74.9
Glu-3	79.1	78.3	78.1	78.4	78.4	78.4	78.4	78.2	78.1
Glu-4	69.3	71.2	71.4	71.4	71.5	71.3	71.5	72.0	71.9
Glu-5	78.4	76.9	75.4	77.1	77.1	76.7	77.0	76.8	76.7
Glu-6	62.4	63.5	64.2	62.7	62.7	62.8	62.6	62.9	62.7
Triterpene moiety
1	31.8	31.9	31.9	32.3	30.3	32.0	27.4	31.9	31.9
2	29.8	29.8	30.0	30.0	29.5	30.0	29.8	29.6	29.8
3	87.8	88.0	88.3	88.4	88.1	88.3	88.3	88.0	88.0
4	41.1	40.3	41.2	41.2	41.2	41.2	40.7	41.1	41.1
5	47.1	47.0	47.4	47.4	42.6	47.4	43.8	47.0	46.9
6	20.5	20.4	20.8	20.9	21.7	20.8	22.0	20.4	20.3
7	25.6	25.8	25.9	26.4	113.2	26.3	114.0	25.8	25.7
8	46.0	45.9	47.1	49.0	149.1	47.3	148.6	45.8	46.4
9	19.8	19.9	19.2	19.9	21.1	19.5	27.6	20.0	20.5
10	26.5	26.6	26.6	26.5	28.2	26.4	29.1	26.6	27.0
11	36.7	36.6	26.3	26.4	25.4	26.1	63.2	36.7	36.4
12	77.2	76.8	31.4	34.0	33.9	33.3	48.3	77.2	76.9
13	48.8	48.7	42.2	41.8	41.2	46.6	45.4	48.7	48.8
14	47.2	47.4	45.2	46.5	49.8	45.1	48.1	47.8	47.8
15	43.4	43.4	50.8	82.5	80.4	42.8	45.2	43.8	45.6
16	70.7	72.8	218.6	103.0	103.3	72.5	114.5	71.1	74.6
17	55.7	55.6	60.4	60.5	60.3	51.4	61.0	56.8	52.4
18	13.5	13.5	18.8	20.3	22.5	20.5	20.7	13.5	12.9
19	29.9	30.7	30.0	30.7	28.2	30.1	18.7	29.8	30.0
20	26.9	25.4	29.1	27.6	27.5	34.2	23.7	26.0	24.6
21	21.1	20.8	19.9	21.4	21.6	17.3	19.6	21.1	25.7
22	41.5	38.6	40.3	33.6	33.6	86.2	37.8	41.9	106.0
23	104.2	102.9	173.4	74.2	74.4	109.6	71.7	101.9	152.9
24	83.1	212.4	-	80.5	80.4	77.3	88.5	77.7	75.9
25	79.1	35.0	-	76.4	76.5	83.5	76.4	81.3	78.2
26	19.4	19.2	-	21.6	21.6	27.3	23.2	23.7	22.3
27	29.8	19.7	-	24.1	24.1	24.5	20.2	24.9	23.1
28	19.4	19.4	19.6	11.8	18.2	19.4	27.4	19.5	20.7
29	25.6	25.6	25.6	25.5	25.6	25.6	25.8	25.6	25.6
30	15.2	15.2	15.2	15.5	14.2	15.3	14.5	15.2	15.2
Xyl-1	107.4	107.5	107.5	107.4	107.4	107.4	107.4	107.5	107.5
Xyl-2	75.5	75.5	75.5	75.5	75.5	75.5	75.5	75.5	75.5
Xyl-3	78.5	78.6	78.5	78.5	78.5	78.5	78.5	78.5	78.5
Xyl-4	71.1	71.0	71.1	71.1	71.2	71.1	71.1	71.2	71.1
Xyl-5	67.0	67.0	67.1	67.0	67.0	67.0	67.0	67.0	67.0
COCH3	170.4 21.5	170.4 21.5	-	171.0 21.1	171.0 21.1	-	-	170.5 21.6	170.6 21.1
Solvent	C5D5N	C5D5N	C5D5N	C5D5N	C5D5N	C5D5N	C5D5N	C5D5N	C5D5N
References	[130]	[130]	[130]	[130]	[130]	[130]	[130]	[136]	[136]

Table 37.

The ¹³C-NMR spectral data of compounds 166 and 167.

C	166	167
1	98.1	98.1
3	154.5	154.5
4	105.6	105.6
5	28.7	28.6
6	30.0	29.9
7	75.1	75.0
8	133.3	133.3
9	43.9	43.8
10	121.1	121.1
11	168.6	168.5 a
1′	99.8	99.7
2′	74.8	74.7 b
3′	77.9	77.8 c
4′	71.6	71.2 d
5′	78.5	78.4 e
6′	62.7	62.4 f
2″	167.5	168.1 a
3″	118.2	118.6
4″	181.6	181.8
5″	163.5	163.1
6″	100.2	101.1
7″	166.2	164.9
8″	94.7	95.7
9″	159.2	158.7
10″	104.9	106.6
-CH3	18.9	19.0
1‴	-	101.6
2‴	-	74.8 b
3‴	-	77.9 c
4‴	-	71.6 d
5‴	-	78.5 e
6‴	-	62.7 f
NMR	CD3OD	CD3OD
References	[43]	[43]

^a−f Values with the same superscript are interchangeable.

Table 38.

The ¹³C-NMR spectral data of compounds 168–180 except those which have no reported ¹³C-NMR data.

C	168	169	170	171	172	178	179	180
2	163.7	159.3	168.0	159.6	167.5	170.2	166.3	166.3
3	108.7	108.8	109.7	109.9	110.0	110.8	110.0	110.0
4	179.2	179.5	178.9	178.8	179.0	179.0	178.7	178.8
4a	125.8	126.2	125.9 *	126.4	125.9 *	125.8 *	125.8 *	126.5
5	149.6	149.6	149.9	150.0	149.8	150.1	149.7	149.9
6	125.4	125.4	125.8	125.9	125.9 *	125.8 *	125.9	126.0
6a	137.0	137.2	137.0	137.0	137.4	137.2	137.3	136.3
7	183.0	183.3	183.2	183.5	183.3	183.1	183.1	181.5
7a	125.8	127.3	126.3 *	126.5	126.4 *	126.1 *	126.2 *	130.7
8	140.0	140.6	139.7	140.0	140.1	139.9	140.2	119.3
9	133.0	132.6	132.9	132.2	133.1	133.3	133.1	133.2
10	138.4	138.5	137.8	137.0	138.5	138.6	138.6	140.7
11	159.7	163.9	159.7	167.6	159.9	159.9	159.8	159.5
11a	116.0	115.8	116.1	116.0	116.2	116.0	116.1	116.1
12	188.1	188.0	187.9	187.7	188.1	188.3	188.0	187.7
12a	118.9	118.9	119.1	119.1	119.2	118.9	119.2	119.8
12b	155.7	155.8	156.0	156.0	156.2	155.8	156.1	156.2
13	24.0	24.1	24.3	24.2	24.1	24.2	24.1	24.1
14	127.2	125.9	57.6	60.3	59.1	75.6	57.7	57.7
15	12.1	15.0	13.8	14.9	14.5	23.5	14.5	14.4
16	134.2	134.2	62.0	61.7	61.6	71.7 *	63.9	63.9
17	14.9	12.1	14.1	123.3	123.3	127.4	55.4	55.4
18	-	-	-	134.1	134.0	130.2	51.8	51.8
19	-	-	-	14.4	13.8	13.5	17.2	17.2
2′	77.3	77.7	77.2	77.6	77.3	77.2	77.3	67.9
3′	71.9	71.8	71.3	70.6	71.9	71.7 *	71.9	71.0
4′	67.4	67.5	67.8	68.1	67.4	67.3 *	67.4	57.7
5′	28.3	41.0	28.8	38.8	28.4	28.4	28.3	35.0
6′	75.2	75.4	74.8	74.0	75.2	75.0	75.2	68.2
7′	18.9	18.9	18.8	18.5	18.9	18.9	18.9	17.5
8′	-	-	-	-	-	-	-	13.2
4′-N(CH3)2	40.4	40.5	40.3	40.4	40.4	40.3	40.4	37.1
2″	67.2	69.8	67.5	69.8	67.2	67.4 *	67.3	-
3″	70.8	76.4	70.3	74.5	70.9	70.7	70.9	-
4″	57.4	57.6	57.6	59.1	57.3	57.9	57.3	-
5″	33.6	28.6	33.3	30.4	33.6	33.3	33.7	-
6″	69.5	64.9	69.4	65.7	69.7	69.6	69.6	-
7″	17.6	15.0	17.4	15.1	17.7	17.6	17.6	-
8″	12.3	13.7	13.1	13.9	12.3	12.6	12.3	-
3″-COCH3	-	170.6 21.3	-	171.0 21.5	-	-	-	-
4″-N(CH3)2	36.8	39.3	36.9	38.8	36.8	36.8	36.8	-
Solvent	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3
References	[165]	[140]	[141]	[140]	[142]	[143]	[165]	[146]

* Interchangeable values.

Table 39.

The ¹³C-NMR spectral data of compounds 181–183.

C	181	182	183
2	168.4	176.4	176.5
3	112.0	111.1	111.3
4	180.3	181.3	178.4
4a	126.1	126.0	124.7
5	150.4	150.4	149.6
6	121.3	121.0	121.2
6a	138.3	138.1	139.0
7	182.7	182.7	182.4
7a	133.2	133.2	133.2
8	120.1	120.0	119.8
9	135.4	135.5	135.6
10	137.4	137.4	137.0
11	161.1	161.0	161.3
11a	118.1	118.0	118.0
12	189.1	189.2	189.2
12a	122.0	121.9	121.6
12b	157.7	157.4	156.9
13	70.8	70.8	175.3
14	61.2	77.7	77.7
15	63.7	72.6	72.6
16	20.2	23.9	23.9
17	13.7	17.0	17.1
1′	98.9	98.9	-
2′	37.2	37.2	-
3′	58.3	58.4	-
4′	71.2	71.1	-
5′	70.4	70.4	-
6′	17.2	17.2	-
7′	24.6	24.5	-
1″	70.2	70.1	70.3
2″	28.0	27.7	27.4
3″	65.2	65.1	64.9
4″	75.1	75.0	75.2
5″	72.6	72.6	72.3
6″	18.1	18.2	18.3
3″-N(CH3)2	43.2 41.7	43.3 41.4	42.5 42.5
1‴	101.4	101.4	101.4
2‴	33.4	33.4	33.4
3‴	66.6	66.6	66.6
4‴	72.0	72.0	72.0
5‴	69.5	69.5	69.5
6‴	17.5	17.5	17.5
Solvent	CD3OD	CD3OD	CD3OD
References	[147]	[147]	[147]

Table 40.

The ¹³C-NMR spectral data of compounds 184–192.

C	184	185	186	187	188	189	190	191	192
2	167.5	167.4	167.0	167.0	165.7	165.7	167.5	169.3	169.3
3	111.1	110.9	110.9	110.8	111.3	111.3	111.1	109.1	109.1
4	180.2	180.0	179.4	179.4	178.5	178.6	180.2	182.4	182.5
4a	126.6	126.4	126.5	126.4	126.3	126.3	126.6	113.3	113.3
5	149.2	149.1	149.4	149.2	148.2	148.2	149.3	166.7	166.7
6	122.5	122.4	122.9	122.8	124.1	124.0	122.5	110.7	110.7
6a	137.2	137.1	137.0	136.9	136.9	136.9	137.2	139.8	139.9
7	181.2	181.0	181.2	181.2	181.5	181.4	181.2	180.8	180.8
7a	130.3	130.2	130.4	130.3	130.5	130.5	130.5	130.6	130.4
8	119.8	119.7	119.7	119.7	119.5	119.5	119.8	119.4	119.5
9	133.6	133.7	133.4	133.6	133.3	133.5	133.7	132.4	132.8
10	141.3	141.1	141.0	140.9	141.0	140.9	140.7	140.2	140.9
11	159.1	159.2	159.3	158.9	159.3	159.3	159.4	159.1	159.1
11a	115.8	115.6	115.9	115.7	115.9	115.9	115.9	115.6	115.4
12	186.9	186.9	187.1	186.9	187.5	187.4	186.9	186.2	186.3
12a	121.8	121.6	121.6	121.6	120.8	120.8	121.8	112.3	112.4
12b	156.8	156.7	156.6	156.5	156.1	156.1	156.8	156.6	156.6
13	80.9	80.0	79.0	78.9	48.3	48.2	80.9	-	-
14	59.8	59.7	59.8	59.7	59.8	59.7	59.8	60.0	60.0
15	19.7	19.6	19.8	19.7	20.0	19.9	19.6	19.6	19.7
16	62.7	62.5	62.5	62.5	62.5	62.5	62.7	62.7	62.7
17	13.4	13.3	13.4	13.3	13.5	13.4	13.3	13.2	13.2
18	170.5	170.4	170.9	170.9	170.4	170.4	170.5	-	-
19	52.6	52.5	52.4	52.3	52.3	52.3	52.6	-	-
2′	73.8	73.8	74.9	74.9	74.3	74.2	73.8	-	-
3′	68.9	68.9	68.5	68.2	68.8	68.8	69.0	-	-
4′	80.2	80.1	74.8	74.9	81.5	81.4	80.2	-	-
5′	67.9	67.9	26.1	26.0	68.0	67.9	68.0	-	-
6′	73.7	73.6	70.3	70.2	73.9	74.0	73.7	-	-
7′	14.1	14.0	14.7	14.7	14.7	14.6	14.0	-	-
4′-OCH3	57.9	57.8	55.6	55.5	57.1	57.1	58.0	-	-
2″	70.3	70.7	70.2	70.8	70.3	70.8	70.0	70.0	70.7
3″	77.7	82.6	77.8	82.7	77.8	82.8	76.0	77.3	82.8
4″	54.9	58.1	55.1	58.1	54.9	58.1	51.7	56.1	58.1
5″	40.3	44.7	40.4	44.7	40.4	44.8	44.9	38.5	44.8
6″	62.1	62.2	62.3	62.2	62.2	62.3	62.3	63.6	62.3
7″	14.7	13.5	14.8	13.5	14.7	13.6	14.1	15.4	13.6
8″	24.1	14.0	23.8	13.9	24.2	14.1	32.6	22.6	14.0
4″-N(CH3)n	27.9	40.3	27.8	40.3	28.1	40.4	-	27.2	40.3
1‴	93.4	94.4	93.7	94.5	93.4	94.5	93.3	94.5	94.5
2‴	30.8	31.1	30.9	31.1	30.9	31.1	30.8	31.1	31.1
3‴	74.8	74.9	74.8	74.9	74.9	75.0	74.8	75.0	75.0
4‴	72.1	72.1	72.1	72.0	72.2	72.2	72.2	71.5	72.2
5‴	65.4	65.0	65.7	65.0	65.4	65.1	65.4	66.6	65.0
6‴	17.7	17.6	17.7	17.6	17.8	17.7	17.8	17.5	17.7
3‴-OCH3	55.9	56.1	56.1	56.1	55.9	56.2	56.0	56.4	56.1
Solvent	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3	CDCl3
References	[149]	[149]	[149]	[149]	[137]	[137]	[137]	[137]	[137]

Figure 25.

Representative guide figure for numbering of chromone glycosides attached to different substituents.

6. Conclusions

Chromone glycosides are one of the most important classes of secondary metabolites. In this review, we summarized 192 naturally occurring chromone glycosides with their sources, reported activities, and spectroscopic features. Basically, they were categorized into several classes: chromone-O-glycosides including compounds 1–59, among them, four chromanone glycosides (60–63), chromone-C-glycosides including compounds 64–122, prenyl and isoprenyl chromone glycosides including compounds 123–134, phenyl ethyl chromone glycosides including compounds 135–139, furano-chromone glycosides including compounds 140–148, pyrano-chromone glycosides including compounds 149–151, oxepino-chromone glycosides including compounds 152–155, Pyrido-chromone glycoside including compound 156, furanochromones with cycloartane triterpenes including compounds 157–165, glycoside derivatives of chromones with secoiridoids including compounds 166 and 167, and chromone alkaloids aminoglycosides including compounds 168–192. Diverse bioactivities were discovered for most of the reported chromone glycosides. Several chromone glycosides show potent biological activities as anti-viral, acetylcholinesterase inhibition, anti-tumor, anti-inflammatory, etc. This review directs the attention for further deep investigation of chromone glycosides for drug discovery.

Abbreviations

All	Allose
Api	Apiose
Ara	Arabinose
Caf	Caffeic acid
Cin	Cinnamic acid
Cou	Coumaric acid
Fer	Ferulic acid
Gall	Gallic acid
Glu	Glucose
Rha	Rhamnose
Xyl	Xylose

Author Contributions

Y.A.: conceptualization, data collection, writing, reviewing. M.E., A.O. and M.S.: data collection, writing, reviewing. K.S.: supervision, reviewing. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.