Dan Qian1,2, Yaxing Zhao3, Guang Yang4, Luqi Huang5. 1. Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China. qiandan2104@163.com. 2. The State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China. qiandan2104@163.com. 3. School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China. zhaoyaxing2013@163.com. 4. The State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China. hbykdxyg2008@163.com. 5. The State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China. huangluqi01@126.com.
Abstract
The Lycium genus is widely used as a traditional Chinese medicine and functional food. Many of the chemical constituents of the genus Lycium were reported previously. In this review, in addition to the polysaccharides, we have enumerated 355 chemical constituents and nutrients, including 22 glycerogalactolipids, 29 phenylpropanoids, 10 coumarins, 13 lignans, 32 flavonoids, 37 amides, 72 alkaloids, four anthraquinones, 32 organic acids, 39 terpenoids, 57 sterols, steroids, and their derivatives, five peptides and three other constituents. This comprehensive study could lay the foundation for further research on the Lycium genus.
The Lycium genus is widely used as a traditional Chinese medicine and functional food. Many of the chemical constituents of the genus Lycium were reported previously. In this review, in addition to the polysaccharides, we have enumerated 355 chemical constituents and nutrients, including 22 glycerogalactolipids, 29 phenylpropanoids, 10 coumarins, 13 lignans, 32 flavonoids, 37 amides, 72 alkaloids, four anthraquinones, 32 organic acids, 39 terpenoids, 57 sterols, steroids, and their derivatives, five peptides and three other constituents. This comprehensive study could lay the foundation for further research on the Lycium genus.
Entities:
Keywords:
Lycii cortex; Lycium genus; chemical constituents; goji berry
Lycium is one of the genera in the Solanaceae family, comprising 80 species, seven of which are found in China [1]. These species are all deciduous shrubbery, possessing a highly similar morphology and structure. The Lycium genus has been an important source of medicines and nutrient supplements for thousands of years in Southeast Asia, especially in China. Two species in particular, Lycium barbarum and Lycium chinense, have been widely used as traditional Chinese medicinal herbs for centuries and L. barbarum is currently widely cultivated in China.Goji berries (Chinese name Gouqizi), which are derived from the fruits of Lycium Linn, have been used as traditional herbs for a long time in China for their benefits of replenishing vital essence to improve eyesight, nourish the liver and kidneys. Lycii cortex is a “heat cleansing” drug that is derived from the root bark of L. chinense and L. barbarum [2]. Goji berries and Cortex Lycii have demonstrated good therapeutic effects in some chronic diseases such as hectic fever, night sweats, cough, hemoptysis, and diabetes. Recently, medical research has indicated that these fruits and root bark have many pharmacological functions, such as antiglaucoma, immunoregulatory, antitumor, antioxidant, antiaging, neuroprotective, and blood sugar level reducing activities [3,4,5,6,7,8,9,10].Traditionally, the berry and root bark available have been used as medicinal sources, as well as important components in some traditional Chinese patent medicines. They are not only famous medical herbs, but are also functional foods widely consumed in health-preserving cuisines, i.e., soups, congee, herbal tea, etc. People also eat the fresh leaves as vegetables. In particular, goji berries have become increasingly popular for improving overall well-being and as an anti-aging remedy. There are many goji derived-products on health food market, such as dried fruits, juice, goji wine and goji yoghurt. Many research papers were published focused on the phytochemical fingerprinting and antioxidant activity of these products [11,12,13,14].Two valuable medicinal herbs, namely L. barbarum and L. chinense, have received remarkable attention due to their effective clinical therapy, especially in the anti-aging category. In addition, there are increasing numbers of publications about several other Lycium plants, i.e., Lycium ruthenicum [15,16]. Many researchers have focused great attention on the Lycium genus in recent years, and many chemical components from this genus have been isolated. Therefore, a comprehensive and systematic review on the chemical constituents of the Lycium genus is much needed.Most of the published reviews not only covered chemical composition, but also summarized the pharmacology, clinical studies, safety, toxicology and adverse actions of L. barbarum or L. chinense [17,18,19]. The aim of this review was to focus on chemical constituents in different parts of plants from different species in Lycium genus, especially small molecular compounds with updated research reports. This paper comprehensively summarizes the reports of constituents from the genus Lycium. Up to 2016, at least 355 constituents were reported from different species in the Lycium genus and different parts (fruits, root bark, leaves, seeds, and flowers) of the plant. This review describes the advances in the phytochemistry of the genus Lycium from 1975 to 2016, based on the 142 cited references. The reported constituents can be classified as glycerogalactolipids, phenylpropanoids, coumarins, lignans, flavonoids, amides, alkaloids, anthraquinones, organic acids, terpenoids, sterols, steroids, peptides, and other constituents. The aim of this review is to illustrate the recent advances in the characterization of the Lycium genus. The results, based on these phytochemical studies, could lay a solid foundation for better understanding of pharmacological activities of Lycium and quality assessment.
2. Constituents
Until now, other than polysaccharides, more than 355 compounds have been isolated and identified from the Lycium genus. The small molecules can be assigned to various classes of glycerogalactolipids, phenylpropanoids, coumarins, lignans, flavonoids, amides, alkaloids, anthraquinones, organic acids, terpenoids, sterols, steroids and their derivatives, and peptides. Beyond that, other groups of compounds have also been reported. The proportion of different compounds of the Lycium genus is show in Figure 1. Their structures are shown below, and their names and corresponding plant sources are included in this paper.
Figure 1
Different subtype comparison of the 355 constituents reported from Lycium genus.
2.1. Macromolecules in the Lycium Genus
Polysaccharides
Polysaccharides are the most important group of substances in the goji berry, which are estimated to comprise 5–8% of the dried fruits [20], 1.02–2.48% of the raw material [21,22,23]. More than 40 polysaccharides, with a molecular weight range of 8–241 kDa, were isolated from the fruit of L. barbarum, L. chinense and L. ruthenicum. Two, LRLP4-A and LBLP5-A, were isolated from the leaves of L. ruthenicum. The polysaccharides share a glycan-O-Ser glycopeptide structure and contain galacturonic acid, 18 amino acids, and nine monosaccharides, namely, xylose (Xyl), glucose (Glc), arabinose (Ara), rhamnose (Rha), mannose (Man), galactose (Gal), fucose (Fuc), galacturonic acid (GalA), glucuronic acid (GlcA) [24]. The molar ratios of the polysaccharides are shown in Table 1. The polysaccharides can be isolated and purified by water extract alcohol precipitation, DEAE ion-exchange cellulose, gel-permeation chromatography, high performance liquid chromatography (HPLC). Sevage method and organic reagents were used to remove proteins, pigments and other impurities. The structural composition of a LBP can be studied by SDS-PAGE gel electrophoresis, high perfomance size exclusion chromatography (HPSEC), gas-chromatographic–mass-spectrometry (GC-MS), nucleic magnetic resonance (NMR), and matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-Tof-MS) [18,21,25].
At present, 17 compounds of this type, a series of glycerogalactolipids 1–17, listed in Table 2, have been isolated and identified. Compounds 1–15 have been isolated and identified from the fruits of L. barbarum [52], whereas 16 and 17 were isolated from the fruits of L. chinense [53]. Compounds 18–22, illustrated in Figure 2, were isolated from the root bark of L. chinense [54,55].
Table 2
Chemical structures of compounds 1–17.
No.
Compounds
R1
R2
R3
Source
1
Glycerogalactolipids A
Palmitoyl
Linolenoyl
Linolenoyl
L. barbarum
2
Glycerogalactolipids B
Palmitoyl
Linolenoyl
Linoleoyl
L. barbarum
3
Glycerogalactolipids C
Palmitoyl
Linolenoyl
Palmitoyl
L. barbarum
4
Glycerogalactolipids D
Palmitoyl
Linoleoyl
Palmitoyl
L. barbarum
5
Glycerogalactolipids E
Palmitoyl
Palmitoyl
Palmitoyl
L. barbarum
6
Glycerogalactolipids F
Palmitoyl
Palmitoyl
H
L. barbarum
7
Glycerogalactolipids G
Linolenoyl
Linolenoyl
H
L. barbarum
8
Glycerogalactolipids H
Linolenoyl
Linoleoyl
H
L. barbarum
9
Glycerogalactolipids I
Palmitoyl
Linolenoyl
H
L. barbarum
10
Glycerogalactolipids J
Palmitoyl
Linoleoyl
H
L. barbarum
11
Glycerogalactolipids K
Palmitoyl
Oleoyl
H
L. barbarum
12
Glycerogalactolipids L
Stearoyl
Linoleoyl
H
L. barbarum
13
Glycerogalactolipids M
Palmitoyl
Linolenoyl
–
L. barbarum
14
Glycerogalactolipids N
Palmitoyl
Linoleoyl
–
L. barbarum
15
Glycerogalactolipids O
Palmitoyl
Oleoyl
–
L. barbarum
16
Glycerogalactolipids P
Linolenoyl
Linolenoyl
–
L. chinense
17
Glycerogalactolipids Q
Linoleoyl
Linolenoyl
–
L. chinense
Figure 2
Chemical structures of compounds 18–22.
2.2.2. Phenylpropanoids 23–51
Four phenylpropanoids 23–26, namely E-cinnamic acid (23), E-ferulic acid (24), E-coniferol (25) and isoscopoletin (26) are obtained from wolfberries [56,57,58]. Four phenylpropanoids, namely scopolin (27), fabiatrin (28), lyciumin (29), and 9-O-(β-d-glucopyranosyl)lyoniresinol (30) are obtained from the root bark of L. chinense [59,60,61]. 1-O-Methyl-4-O-p-E-coumaroyl-α-l-rhamnopyranoside (31) is obtained from the fruits of L. ruthenicum [62]. The chemical structures of compounds 23–33 are listed in Table 3 and Figure 3. In 2016, 11 phenylpropanoids 32–42 were isolated for the first time by Zhou et al. from Lycium [56], including 1-O-E-feruloyl-6-O-β-d-xylopyranosyl-β-d-glucopyranoside (32), 6-O-E-feruloyl-2-O-β-d-glucopyranosyl-α-d-glucopyranoside (33), 1-O-E-feruloyl-β-d-glucopyranoside (34), ethyl-4-O-β-d-glucopyranosyl-E-ferulate (35), ethyl E-ferulate (36), E-sinapinic acid (37), syringenin (38), Z-ferulic acid (39), phloretic acid (40), dihydroferulic acid (41), and ethyl dihydroferulate (42), along with the nine new lycibarbarphenylpropanoids A–I (compounds 43–51) listed in Table 4.
Nine coumarins, namely E-p-coumaric acid (52), Z-p-coumaric acid (53), esculetin (54), fabiatrin (55), scopolin (56), and scopoletin (57), have been reported, and three new coumarins, 6-O-E-p-coumaroyl-2-O-β-d-glucopyranosyl-α-d-glucopyranoside (58), ethyl-4-O-β-d-glucopyranosyl-E-p-coumarate (59), ethyl E-p-coumarate (60) and lycibarbarcoumarin A (61), have been obtained from the fruits of L. barbarum in 2016 [56]. Compounds 55 and 56 were isolated from the root bark and fruits of L. chinense [61], while 52−54 and 57 were isolated from the fruits of L. barbarum [63]. The chemical structures of these coumarins are listed in Figure 4 and Table 5.
Eight lignans, including pinoresinol (62), arctigenin (63), arctiin (64), medioresinol (65), syringaresinol (66), 4-O-(β-d-glucopyranosyl)syringaresinol (67), threo-1,2-bis(4-hydroxy-3-methoxy-phenyl)-1,3-propanediol (68), and erythro-1,2-bis(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (69), have been isolated from the fruits of L. barbarum [56]. (β)-Lyoniresinol 3-O-β-d-glucopyranoside (70), lyciumlignan A (71), lyciumlignan B (72), lyciumlignan C (73), and (7R,8S)-4,9,9′-trihydroxy-3,3′-dimethoxy-7′-en-8,4′-oxyneolignan-7-O-β-d-glucopyranoside (74) were obtained from the root bark of L. chinense [54,60,64]. Among them, 65–70 were first isolated from the fruits of L. barbarum in 2016 [56]. The chemical structures of these lignans are listed in Figure 5 and Table 6.
Figure 5
Chemical structures of compounds 63–64 and 68–74.
Table 6
Chemical structures of compounds 62 and 65–67.
No.
Compounds
R1
R2
R3
Source
62
Pinoresinol
H
OH
H
L. barbarum
65
Medioresinol
H
OH
OCH3
L. barbarum
66
Syringaresinol
OCH3
OH
OCH3
L. barbarum
67
4-O-(β-d-glucopyranosyl)syringaresinol
OCH3
O-β-d-Glc
OCH3
L. barbarum
2.2.5. Flavonoids 75–106
Twenty-seven flavonoids 75–101 have been reported from the genus Lycium, are listed in Table 7 and Table 8 and Figure 6 and Figure 7. Compound 75 was isolated from the flowers of L. barbarum [58], while 76–83 were identified from the fruits of L. barbarum [62,65,66,67,68,69]. Compound 84 was isolated from the fruits of L. chinense [70], whereas 85–91 were isolated from the leaves of L. chinense [62,66,68,71]. Compound 92 and 93 were isolated from the leaves of L. halimifolium [72]. Compounds 94–98 were isolated from the fruits of L. ruthenicum [16,62]. Compounds 99–101 were isolated from the root bark of L. chinense [54,73,74]. Additionally, Zhou et al. isolated five isoflavonoids, namely derrone (102), alpinumisoflavone (103), auriculasin (104), maackianin (105) and maackiain (106) from the fruits of L. barbarum [56,75,76].
Table 7
Chemical structures of compounds 75–80, 82–83, 85–87 and 89–93.
Chemical structures of compounds 81, 84, 88 and 94.
Figure 7
Chemical structures of compounds 99–106.
2.2.6. Amides 107–143
Sixteen amides 107–122 have been isolated from the root bark of L. chinense [9,54,60,77,78,79,80], 19 amides (123–141) have been isolated from the fruits of L. barbarum [81,82,83,84,85,86,87,88]. Meanwhile, two cerebrosides 142 and 143 have been obtained from fruits of L. chinense [89]. The chemical structures of these amides are shown in Figure 8.
Figure 8
Chemical structures of compounds 107–143.
2.2.7. Alkaloids 144–215
To date, 72 alkaloids have been identified, which can be classified into five categories: nortropane, imidazole, piperidine, pyrrole, spermine, tropane, and other alkaloids.
Nortropane Alkaloids
Fourteen nortropane alkaloids 144–157, shiwn in Figure 9, have been isolated from the root bark of L. chinense [90].
Figure 9
Chemical structures of compounds 144–157.
Imidazole Alkaloids
Six imidazole alkaloids 158–162 were detected in the leaves of L. cestroides [91]: Meanwhile, one imidazole, Na-[(E)-cinnamoyl]histamine (163), was obtained from the leaves of L. barbarum [66], listed in Figure 10.
Figure 10
Chemical structures of compounds 158–163.
Piperidine Alkaloids
5-hydroxy-2-pyridylmethyl ketone (164), methyl 5-hydroxy-2-pyridinecarboxylate (165), fagomine (166), and 6-deoxyfagomine (167), listed in Figure 11, have been isolated and identified from the genus Lycium; among them. Compounds 164 and 165 are from the fruits of L. barbarum [92], and 166 and 167 are from the root bark of L. chinense [90].
Figure 11
Chemical structures of compounds 164–167.
Pyrrole Alkaloids
Thirteen pyrrole alkaloids 168–180 have been isolated from the fruits of L. chinense [93,94,95]. Likewise, 2-formyl-5-hydroxymethylpyrrole (181) and 2-formyl-5-methoxymethylpyrrole (182) were isolated from the fruits of L. barbarum [92]. Two pyrrolidine alkaloids, alkaloid I (183) and alkaloid II (184), are obtained from the root bark of L. chinense [96]. The chemical structures of these pyrrole alkaloids are listed in Figure 12.
Figure 12
Chemical structures of compounds 168–184.
Spermine Alkaloids
Nineteen spermine alkaloids have been found in the genus Lycium. Kukoamines A (185) and kukoamines B (186) are from the root bark of L. chinense [97,98], while N1-caffeoyl-N3-dihydrocaffeoyl spermidine (187) and lyrium spermidine A (188) are from the fruits of L. ruthenicum [62,99], listed in Figure 13. Another 15 spermine alkaloids, lycibarbarspermidine A–O (189–203), listed in Table 9 and Table 10 and Figure 13, Figure 14 and Figure 15, are from L. barbarum [100].
Figure 13
Chemical structures of compounds 185–188.
Table 9
Chemical structures of compounds 189–193.
No.
Compounds
R1
R2
R3
R4
Source
189
Lycibarbarspermidine A
H
β-d-Glc
H
H
L. barbarum
190
Lycibarbarspermidine B
H
H
β-d-Glc
H
L. barbarum
191
Lycibarbarspermidine C
β-d-Glc
H
H
H
L. barbarum
192
Lycibarbarspermidine D
H
H
H
β-d-Glc
L. barbarum
193
Lycibarbarspermidine E
H
β-d-Glc
β-d-Glc
H
L. barbarum
Table 10
Chemical structures of compounds 196–200.
No.
Compounds
R1
R2
R3
R4
Source
196
Lycibarbarspermidine H
H
H
H
β-d-Glc
L. barbarum
197
Lycibarbarspermidine I
H
β-d-Glc
H
H
L. barbarum
198
Lycibarbarspermidine J
H
H
β-d-Glc
H
L. barbarum
199
Lycibarbarspermidine K
β-d-Glc
H
β-d-Glc
H
L. barbarum
200
Lycibarbarspermidine L
H
β-d-Glc
H
β-d-Glc
L. barbarum
Figure 14
Chemical structures of compounds 194 and 195.
Figure 15
Chemical structures of compounds 201–203.
Tropane Alkaloids
As we know, the genus Lycium has been used as both a medicine and a food for a long time in Asia, particularly in China. However, the safety of Lycium has been questioned for some time, especially after the detection of the three tropane alkaloidsatropine (204), hyoscyamine (205), and scopolamine (206) [101]. Atropine and hyoscyamine were identified from the fruits of L. barbarum gathered in India, while scopolamine was identified from L. halimifolium at concentrations higher than the toxic dose. However, another scholar, seeking to verify these reports, demonstrated that the atropine content of L. barbarum from different sources was just 3.0 ppb—far below the poisoning dose [102]. It was demonstrated that none of the toxic compounds were detected in fruits, leaves, stems and roots of three L. barbarum varieties (‘No. 1’, ‘New Big’ and ‘Amber Sweet Goji’) by densitometric TLC analysis [103]. Through field investigation and model specimen inspections, the above three tropane alkaloids were determined to be from Lycium europaeum rather than the L. barbarum. Thus, the genus Lycium is likely non-toxic, and consumers can rest assured that its use is safe [104].Other than the alkaloids that have been already mentioned, there are nine others that have been obtained from this genus, including 9-formylharman (207), 1-(methoxycarbonyl)-β-carboline (208), perlolyrine (209), choline (210), 1β-amino-3β,4β,5α-trihydroxycycloheptane (211), betaine hydrochloride (212), nicotianamine (213), betaine (214), and melatonin (215). Compounds 207–209 were isolated from the fruits of L. chinense [105], while 210–212 were isolated from the root bark of L. chinense [90]. Compound 213 was isolated from the leaves and flowers of L. chinense [106], and 214 and 215 were isolated from the fruits of L. barbarum [107,108]. The chemical structures of these tropane alkaloids are listed in Figure 16.
Figure 16
Chemical structures of compounds 204–215.
2.2.8. Anthraquinones 216–219
Four anthraquinones: emodin (216), physcion (217), 6-hydroxyrubiadin (218), and 3-O-(2-O-α-l-rhamnopyranosyl-6-O-acetyl-β-d-glucopyranosyl)-6-hydroxy-rubiadin (219), listed in Figure 17, have been obtained from the root bark of L. chinense [61,109].
Figure 17
Chemical structures of compounds 216–219.
2.2.9. Organic Acids 220–251
To this point, 32 organic acids, listed in Figure 18, have been identified from the genus Lycium, which can be classified into two groups: aliphatic acids 220–238 and aromatic acids and their derivatives 239–251. Compounds 220–225 and 240–244 were isolated from the fruits of L. barbarum [56,63,65,107,110,111,112]; 239 and 245 were isolated from the leaves of L. barbarum [66]; 226 was isolated from the root of L. chinense [113]; 227, 248 and 249 were isolated from the fruits of L. chinense [70,114]; 228–233 and 248 were isolated from the leaves of L. chinense [115]; 234, 235, and 249–251 were isolated from the root bark of L. chinense [53,78,93,116,117], and 236–238 were isolated from the fruits of L. urcomanicum [118,119].
Figure 18
Chemical structures of compounds 220–251.
2.2.10. Terpenoids 252–290
Thirty-seven terpenoids, listed in Figure 19, Figure 20 and Figure 21 and Table 11 and Table 12, have been found in the genus Lycium, mainly including monoterpenes 252–256, sesquiterpenes 257–263, diterpenoids 264–274, and carotenoids 275–290. Among them, carotenoids are one of the more important constituents of the Lycium fruits. Thus compounds 256 and 275–286 were isolated from the fruits of L. barbarum [120,121,122,123]; 253, 254, 258, 259 and 287–290 were isolated from the fruits of L. chinense [120,121,124,125,126]; 252 and 264–272 were isolated from the leaves of L. chinense [127,128]; 255, 258 and 273–274 were isolated from the root bark of L. chinense [80,116]; 260 and 261 were isolated from the leaves of L. halimifolium [23]; and 262 and 265 were isolated from the leaves of L. barbarum [129].
Figure 19
Chemical structures of compounds 252–263, 266.
Figure 20
Chemical structures of compounds 271 and 274.
Figure 21
Chemical structures of compounds 283–290.
Table 11
Chemical structures of compounds 264–265, 267–270 and 272–273.
No.
Compounds
R1
R2
Source
264
Lyciumosides I
Glc
Glc
L. chinense
265
Lyciumosides II
Glc2-Glc
Glc
L. chinense
267
Lyciumosides IV
Glc
Glc4-Rha
L. chinense
268
Lyciumosides V
Glc6-Rha
Glc
L. chinense
269
Lyciumosides VI
Glc6-Rha
Glc4-Rha
L. chinense
270
Lyciumosides VII
Glc2-Rha(6-Glc)
Glc
L. chinense
272
Lyciumosides IX
Glc
6-O-malonyl-Glc
L. chinense
273
Capsianoside II
Rha3-Glc6-Rha
Glc2-Glc
L. chinense
Table 12
Chemical structures of compounds 275–282.
No.
Compounds
R1
R2
Source
275
β-Carotene
H
H
L. barbarum
276
β-Cryptoxanthin
OH
H
L. barbarum
277
Zeaxanthin
OH
OH
L. barbarum
278
Zeaxanthin monopalmitate
OCO(CH2)14CH3
OH
L. barbarum
279
Zeaxanthin dipalmitate
OCO(CH2)14CH3
OCO(CH2)14CH3
L. barbarum
280
Zeaxanthin monomyristate
OH
OCO(CH2)12CH3
L. barbarum
281
Zeaxanthin dimyristate
OCO(CH2)12CH3
OCO(CH2)12CH3
L. barbarum
282
β-Cryptoxanthin palmitate
OCO(CH2)14CH3
H
L. barbarum
2.2.11. Sterols, Steroids, and Their Derivatives 291–347
Fifty-seven sterols, steroids, and their derivatives 291–347, listed in Figure 22, have been identified from the genus Lycium, mainly from the seeds and the fruits. Compounds 293 and 343 were identified from the flowers of L. barbarum [130], 291–292; 295, 298, 319–324 and 337–339 were identified from the fruits of L. chinense [23,35,52,63,107,131]; 341 342, 346 and 347 were identified from the leaves of L. chinense [132,133]; 336 and 340 were identified from the root bark of L. chinense [80,121]; 294 was identified from the seed of L. ciliatum [66]; all others were identified from the seed of L. chinense [134,135,136,137] 344 and 345 were identified from the seeds of L. barbarum [138].
Figure 22
Chemical structures of compounds 291–347.
2.2.12. Peptides 348–352
Five peptides have been isolated from the root bark of L. chinense [80,139], including one dipeptide, lyciumamide (348), and four octapeptides, called lyciumins A–D (compounds 349–350), illustrated in Figure 23.
Figure 23
Chemical structures of compounds 348–352.
2.2.13. Other Compounds 353–355
Other than what has already been mentioned, a few other chemical constituents, listed in Figure 24, were also isolated from the genus Lycium. Digupigan A (353), 2-O-(β-d-glucopyranosyl)ascorbic acid (354) and p-hydroxybenzaldehyde (355) also have been obtained from the root bark of L. chinense, the fruits of L. chinense, and the fruits of L. barbarum [75,76,121,137,140,141], respectively. Many minerals, amino acids, and proteins have also been found in the genus Lycium, such as Ca, Mg, Zn, Fe, aminoethanesulfonic acid, γ-aminobutyric acid (GABA), Mn-SOD, etc. [121,142,143].
Figure 24
Chemical structures of compounds 353–355.
3. Discussion
Lycium species are of valuable medicinal, nutritional and functional significance, and have been studied in terms of their chemical compounds. Phytochemical investigations on eight different species, have resulted in the isolation of at least 355 constituents up to July of 2016. Research on chemical compounds has concentrated mainly on L. barbarum and L. chinense. Therefore, future phytochemistry research should be focused on the other species in Lycium genus. In addition, diverse plant parts (i.e., the flowers, leaves, seeds) have also been testified to contain new constituents, most of which possess the novel chemical structures. Polysaccharides play a particularly significant role in exerting pharmacological actions. A specific class of polysaccharides, abbreviated as LBP, is used as biomarker in the 2015 Chinese Pharmacopoeia as a measure by which wolfberry is qualified. At present, LBP in products or in pharmacological studies usually are polysaccharide mixtures with heterogeneity and polydispersity. On the other hand, development of new separation, detection techniques will greatly benefit the phytochemical isolation and structural elucidation of LBP. There is a growing recognition that not only the LBP, but also the plant secondary metabolites may have the potential active ingredients, while most of the research on goji berry was LBP rather than small molecule substances, so more intensive studies of goji berry are required to shed some light on these compounds.
Authors: Li Li; Huabo Jiang; Xuecong Wei; Dandan Geng; Ming He; Huilan Du Journal: Evid Based Complement Alternat Med Date: 2019-12-31 Impact factor: 2.629
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