Chinese Journal of Natural Medicines 2014, 12(2): 00890102
Chinese Journal of Natural Medicines
Chemistry and pharmacology of Siraitia grosvenorii: A review LI Chun1, LIN Li-Mei2, SUI Feng1*, WANG Zhi-Min1, HUO Hai-Ru1, DAI Li1, JIANG Ting-Liang1 1 2
Institute of Chinese Material Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China; Hunan University of Traditional Chinese Medicine, Changsha 410208, China Available online 20 Feb. 2014
[ABSTRACT] Siraitia grosvenorii is a perennial herb endemic to Guangxi province of China. Its fruit, commonly known as Luo hanguo, and has been used for hundreds of years as a natural sweetener and as a traditional medicine for the treatment of pharyngitis, pharyngeal pain, as well as an anti-tussive remedy in China. Based on ninety-three literary sources, this review summarized the advances in chemistry, biological effects, and toxicity research of S. grosvenorii during the past 30 years. Several different classes of compounds have been isolated or detected from various parts of S. grosvenorii, mainly triterpenoids, flavonoids, polysaccharides, amino acids, and essential oils. Various types of extracts or individual compounds derived from this species exhibited a wide array of biological effects e.g. anti-tussive, phlegm-relieving, anti-oxidant, immunomodulatory, liver-protecting, glucose-lowering, and anti-microbial. The existing research has shown that extracts and individual compounds from S. grosvenorii are basically non-toxic. Finally, some suggestions for further research on specific chemical and pharmacological properties of S. grosvenorii are proposed in this review. [KEY WORDS] Siraitiagrosvenorii; Cucurbitaceae; Chemical constituents; Pharmacological effects
[CLC Number]R284; R285
[Document code] A
[Article ID]2095-6975(2014)02-0089-14
Introduction Siraitia grosvenorii is a perennial vine of the Cucurbitaceae family, and its fruit is commonly known as Luo hanguo (LHG). A total of seven species belong to the genusSiraitia, and these plants are distributed mostly in south China, the Indo-China Peninsula, and Indonesia. There are four species in China, among which Siraitia grosvenorii (Swingle) C. Jeffreyex A. M. Lu and ZhiY. Zhang and Siraitiasiamensis(Craib) C. Jeffrey ex S. Q. Zhong & D. Fang are usually used as medicinal plants. S. grosvenoriis endemic to China, and principally grows in Guangxi province, where it has been cultivated for more than 200 years [1] (Fig. 1). S. grosvenorii fruit has been used for centuries in China as a natural sweetener and as a traditional medicine
[Received on] 15-Dec.-2012 [Research funding] This project was supported by the Beijing Joint Project Specific Funds, National Natural Science Foundation of China (Nos. 30873393, 81274112, 81373986) and the Beijing Municipal Natural Science Foundation (Nos. 7112098, 7132152). [ Corresponding author] SUI Feng: Prof., Tel.: 86-10-64041008, Fax: 86-10-64041008, E-mail: [email protected] These authors have no conflict of interest to declare. Copyright © 2014, China Pharmaceutical University. Published by Elsevier B.V. All rights reserved
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for the treatment of lung congestion, colds, and sore throat [2]. In 1987, S. grosvenorii fruit was listed as a medicinal and edible species by the China Ministry of Health [3]. To date, S. grosvenorii fruit has been shown to have the following effects: antitussive, anti-asthmatic, anti-oxidation, liver-protection, glucose-lowering, immunoregulation, and anti-cancer [4]. S. grosvenorii contains triterpenoids, flavonoids, vitamins, proteins, saccharides, and a volatile oil [5]. Mogrosides, a group of triterpenoid glycosides isolated from S. grosvenorii fruit, are regarded as the main active ingredients for the sweet taste, and responsible for the main biological effects of S. grosvenorii. LHG products have been approved as dietary supplements in Japan, the United States, New Zealand and Australia. Currently, the extracts or some compounds from LHG are used mainly for their anti-tussive, expectorant, anti-diabetic, or sweet properties in various Chinese herbal compound prescriptions or dietary supplements. In this review, the research progress of S. grosvenorii during the last 30 years is summarized.
Chemical Composition Several different classes of compounds were previously isolated from various parts of S. grosvenorii, with the main groups being triterpenoids, particularly the cucurbitane-type triterpenoid glycosides, flavonoids, polysaccharides, proteins
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
of one part in ten thousand are 425 and 563 times as sweet as that of 5% sucrose, respectively [17]. In addition, a series of cucurbitane tetracyclic triterpenoid acids, including siratic acids A-F were isolated from the root of S. grosvenorii [18-21]. So far, a total of forty-seven triterpenoids (Table 1) have been isolated, and/or detected in the fruit, roots, or leaf materials of S. grosvenorii. As shown in studies of the structure-taste relationships for the glycosides of 3-hydroxy-cucurbit-5-ene derivatives, the number of glucose units, the oxygen function at the 11-position of the aglycone moiety, the location of the glycosyl units, and the hydroxylation of the side chain, are apparently responsible for the perception of taste [17, 30-31]. The presence of at least three sugar units in the molecule is essential for the occurrence of taste. For example, compounds 6, 9 and 13 are tasteless due to their failure to meet the above-mentioned basic structural requirements. Glycosides of the 11-hydroxy compounds taste sweet, such as compounds 10, 11, 14 and 15, while glycosides in the 11-hydroxy series are tasteless, and the 11-oxo compounds, as well as the dehydro derivatives, taste bitter. The relationship between the allocation of glucosyl units and sweetness is also noteworthy. SiamenosideI (16), which has four glucosyl units, is the sweetest compound among the glycosides of this type so far isolated, and showed a similar sweetness to mogrosideV (14) which has five glucosyl units, while mogroside IV A (10) and IV E (11), with the same number of glucosyl units as 16, is less sweet than 16. Additionally, hydroxylation of the side chain also affects the taste. For example, the bitter 11-oxo glycoside became sweet on hydroxylation of the side chain double bond with osmium tetroxide.
and essential oils.
Fig. 1 Line drawing of S. grosvenorii: 1. stem; 2. leaf; 3. inflorescence; 4. fruit
Cucurbitane glycosides are the main components, and also the active ingredients of S. grosvenorii fruit. Ever since Takemoto et al. isolated mogrosides IV, V, and VI from S. grosvenorii fruit in 1983 [6-8] , more than thirty similar compounds have been obtained from the fruit [9-13]. These compounds share the mogrolaglycone structure, [10-cucurbit-5-ene-3, 11, 24(R), 25-tetraol], with two to six glucose units attached (see Fig. 2). Most of them taste sweet, so they are collectively called mogrosides, and are the main active components of S. grosvenorii fruit. Mogrosides are present at 1.19% in the fresh fruit [14], and 3.82% in the dried fruit of S. grosvenorii [15]. Mogroside 9 is the main =## # # '>?'> # dried fruit of S. grosvenorii. Siamenoside I is the sweetest among the cucurbitane glycosides so far isolated [16-17]. The sweetness values of mogroside V and siamenoside I at the concentration
R1
R2
R3
R4
R5
1
H
H
H
D-OH
H2
16
2
H
glc
H
D-OH
H2
3
glc
H
H
D-OH
4
H
H
H
5
H
R1
R3
R4
R5
H
D-OH
H2
17
H
D-OH
H2
H2
18
H
D-OH
H2
D-OH
H2
19
glc
H
D-OH
H2
D-OH
H2
20
H
H
=O
H2
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R2
glc
H
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 H
D-OH
H2
21
H
glc
H
=O
H2
H
D-OH
H2
22
glc
H
H
=O
H2
H
D-OH
H2
23
H
H
=O
H2
H
D-OH
H2
24
glc
H
=O
H2
10
H
D-OH
H2
25
glc
H
=O
H2
11
H
D-OH
H2
26
H
=O
H2
glc
D-OH
H2
27
H
=O
H2
H
D-OH
H2
28
H
D-OH
=O
14
H
D-OH
H2
29
H
D-OH
=O
15
H
D-OH
H2
30
H
H2
H2
6
glc
7
H
glc
8 9
glc
glc
12
glc
13
glc
H
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glc
glc
glc
glc
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 Fig. 2 Structures of thetriterpenoid compounds isolated from S. grosvenorii Table 1 Triterpenoid compounds isolated from S. grosvenorii No.
Compound name
Plant parts
References
1
Mogrol
Fruit
[6-9]
2
Mogroside IA (Mogroside,A 1 )
Fruit
[8-9]
3
Mogroside IE 1
Fruit
[8-9]
4
Mogroside IIA 1
Fruit
[8, 10]
5
Mogroside IIA 2
Hydrolysis product
[8]
6
Mogroside IIE
Fruit
[8-9, 11, 17-19]
7
Mogroside IIIA 1
Fruit
[8, 12]
8
Mogroside IIIA 2
Fruit
[8, 10]
9
Mogroside IIIE
Fruit
[8, 17]
10
Mogroside IV A
Fruit
[8-9, 19, 12-13]
11
Mogroside IV E
Fruit
[8-9, 12, 18]
12
Mogroside IIB
Fruit
[10]
13
Mogroside III
Fruit
[9, 17-19]
14
Mogroside V
Fruit
[8-9, 12-13, 17-18]
15
Mogroside VI
Fruit
[8]
16
Siamenoside I
Fruit
[9, 12, 17]
17
Neomogroside
Fresh Fruit
[18]
18
Isomogroside V
Fruit
[13]
19
Grosmomoside I
Fruit
[20]
20
11-Oxomogrol
Hydrolysis product
[9] [9, 19]
21
11-Oxomogroside IA 1
Fruit
22
11-Oxomogroside IE 1
Fruit
[9]
23
11-Oxomogroside IIA 1
Fruit
[10]
24
11-Oxomogroside IIE
Unripe fruit
[19]
25
11-Oxomogroside III
Unripe fruit
[21]
26
11-Oxomogroside IV A
Fruit
[10, 21] [9, 17]
27
11-Oxomogroside V
Fruit
28
7-Oxomogroside IIE
Fruit
[10]
29
7-Oxomogroside V
Fruit
[10]
30
11-DeoxymogrosideIII
Fruit
[10, 21]
31
20-Hydroxy-11-oxomogroside IA 1
Unripe fruit
[19]
32
5, 6-Epoxymogroside IE 1
Fruit
[9]
33
5-Dehydro-karounidiol dibenzoate
Fruit
[9]
34
Karounidiol dibenzoate
Fruit
[9] [9]
35
Karounidiol 3-benzoate
Fruit
36
Isomultiflorenol
Fruit
[9]
37
-Amyrin
Fruit
[9, 22]
38
10-Cucurbitadienol
Fruit
[9]
39
Siratic acid A
Root
[23-24]
40
Siratic acid B
Root
[23-24] [23-24]
41
Siratic acid C
Root
42
Siratic acid D
Root
[25]
43
Siratic acid E
Root
[18]
44
Siraitic acid F
Root
[26]
45
Mogroester
Fruit
[27-28]
46
Siraitic acid IIA
Root
[29]
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LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 47
Siraitic acid IIB
Root
Li et al studied the variation of mogrol glycosides in S. grosvenorii fruit during different growth periods. The results showed that the mogrol glycosides emerged after 5 days of pollination, with mogroside IIE (6) as the main component in the young fruits in the first 30 days. Mogroside III (13) started to appear after 30 days and reached the highest content in the 55th day, then mogroside IV A (10) and mogroside IV E (11) formed, and their contents reached the peak in the 70th day, and mogroside V(14) was generated after 70 days, and developed to be the main sweet component after 85 days of pollination, then the fruit began to be ripe [32]. Consequently, the optimum harvest time of S. grosvenorii fruit should be in the 90th day after pollination. Other studies have come to similar conclusions [33-34]. Regarding the phenolic compounds of S. grosvenorii, several authors reported the presence of various flavonoids in the fruit, leaves, stems, and flowers of the plant [35-38]. These compounds possessed the aglycone of kaempferol or quercetin. So far, a total of seven flavonoid compounds were isolated and/or detected from S. grosvenorii. With quercetin and kaempferol as reference substances, the content of the total flavones in the fresh fruits, and the mogrosides in the leaves of S. grosvenorii were determined by HPLC. The results ^ _ # # #^ ^ ` ? # fresh fruit, with 1.42% as the mogrosides, and 1.62% in the leaf of S. grosvenrii, respectively [39-40]. Furthermore, the total flavone contents in the various parts of S. grosvenorii were different, and the total flavone contents from high to low were leaf (3.718%) > stem (1.688%) > root (0.129%) [41]. For the dried fruits of different sizes, the content of kaempferol was between 1.63% to 3.49%, and the contents from high to low were peel (4.71%) > pulp (0.855%) > seed (0.197%) [42]. However, if kaempferitrin was used as reference substance, the content of total flavones determined by UV in the leaf and stem of S. grosvenrii were 5.85% and 0.29%, and the content of kaempferitrin was 1.76% and 0.167%, respectively [43-44]. Chen et al studied the variation of mogroside V and the flavonol glycosides in S. grosvenorii fruit at different growth stages, and the results showed since the date of fruiting, the content of mogroside V increased rapidly after 50 days, and became stable after 80 days, while the content of the flavonol glycosides increased rapidly from the 40th to 50th days, and reached the highest about 50 days later, and started to decrease after 60 days, and became stable when it dropped to the level of the 20th day [33]. Besides the flavonoids, three phenolic acids, two anthraquinones, three alkaloids, three sterols, three aliphatic acids, and three other compounds have been isolated from the fruit or leaf of S. grosvenorii [22, 28, 45]. The structures of flavonoids and other related compounds of S. grosvenorii are shown in Table 2 and Fig. 3. Polysaccharides are also important ingredients of S. grosvenrii. The content of polysaccharide was between
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[29]
2.88% to 5.65% in LHG of different sizes, with the highest in the pulp (7.55%) and lowest in the seeds (3.12%) [46]. In 2003, two polysaccharides, SGPS1 and SGPS2, were first isolated fromLHG and their relative molecular weights were determined by HPLC to be 430 000 and 650 000, respectively [47]. After that, Li et al reported on the monosaccharide composition and connection mode of SGPS1 and SGPS2 with the improvement of the extraction and purification technology [48-51]. Finally, SGPSl was determined as an acidicheteropolysaccharide, which was composed of Rha, Ara, Xyl, Gal, Glc, and GlcA in a molar ratio of 1.00 : 2.30 : 1.40 : 9.07 : 39.53 : 2.46. Its basic structure was made up of (1ė4) linked glucose and (1ė3) linked galactose residues in the main chain, and (1ė3) linkedglucose, (1ė6) linked glucose, (1ė4) linked galactose, and (1ė2) linked rhamnose units in the side chains. Sidechains attached the main chain to 2-O, 3-O, and 6-O of glucose, and to 6-O of galactose. On average, among the twenty main chain residues, there were five branches. By means of acid hydrolysis and TLC analysis, SGPS2 was determined to contain Rha and GlcA. However, the IR and 13C NMR analysis results showed that SGPS2 was comprised of Rha, GlcA, and amino sugars. Yan et al studied the composition of the polysaccharides from S. grosvenoriiroot,and investigated its effect on subcutaneous H22-implanted mice [52]. Asa result, the polysaccharides were shown to be composed of glucose, arabinose, and xylose, and compared with the model group, the tumor growth was not significantly suppressed (inhibition rate < 50%), but the index of thymus increased (P < 0.01), and the index of spleen decreased (P < 0.01) in the polysaccharide-treated groupsˊAs early as the 1980s, Xu et al measured the contents of various types of nutritious ingredients in S. grosvenorii fruit [53]. The content of crude protein was between 8.67% to 13.35% in the dried fruit of the wild type and three cultivars of S. grosvenorii. Furthermore, the hydrolysis products of S. grosvenorii fruit contained eighteen amino acids, including eight of the essential amino acids. Among the eighteen amino acids, the # # ^= _ ^ ^ }~~? 125 mg/100 g dried fruits), and the content of -aminobutyric acid was the ^ }?'~' ? _ _ ^ [54]. Additionally, there were a lot of sugars in the dried fruit of S. grosvenorii mainly fructose, glucose, and non-reducing sugars [53]. The content of total sugar in S. grosvenorii fruit ranged from 25.17% to 38.31%, and that of the reducing sugars in it was between 16.11% and 32.74%. S. grosvenorii fruit is rich in vitamin C. The content of vitamin C in the fresh fruit of S. grosvenorii _~? mg/100 g, bu _ ^_ '' ? g in the dried fruit [53]. With the differences in varieties, forms, producing area, growing period, and ripeness, the content of vitamin C in S. Grosvenorii fruit was remarkably different, but was
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
several times higher than that in citrus, apples, pears, grapes, and persimmons. Within a certain range, the content of
vitamin C was positively correlated with altitude, and 30 d a y s
Table 2 Flavonoids and related compounds isolated from S. grosvenorii No.
Compound name
Plant parts
References
48
Kaempferol
Fruit, Leaf, Flower
[35, 37]
49
Kaempferol 7-O--L-rhamnopyranoside
Fruit, Flower
[35, 37]
50
Kaempferol 3-O--L-rhamnopyranoside-7-O[-D-= #^}?--L-rhamnopyranoside
Fruit, Flower
[35-37]
51
Kaempferol 3, 7-di-O--L-rhamnopyranoside (kaempferitrin)
Leaf, Fresh fruit
[35-36, 38]
52
Quercetin-3-O--D-glucopyranoside-7-O--Lrhamnopyranoside
Leaf
[38]
53
7-Methoxy-kaempferol 3-O--L-rhamnopyranoside
Flower
[37]
54
7-Methoxy-kaempferol 3-O--D-glucopyranoside
Flower
[37]
55
Magnolol
Fruit
[28]
56
Vanillic acid
Fruit
[45]
57
p-Hydroxybenzylic acid
Leaf
[22]
58
1-Acetyl--carboline
Fruit
[45]
59
Cyclo-(leu-pro)
Fruit
[45]
60
Cyclo-(ala-pro)
Fruit
[45]
61
Aloe emodin
Leaf
[22]
62
Aloe-emodin acetate
Leaf
[22]
63
5, 8-Epidioxy-24(R)-methylcholesta-6, 22-dien-3-ol
Leaf
[22]
64
-Sitosterol
Fruit
[45]
65
Daucosterol
Leaf
[22]
66
Succinic acid
Fruit
[28]
67
n-Hexadecanoic acid
Leaf
[22]
68
12-Methyltetradecanoic acid
Leaf
[22]
69
5, 5'-Oxydimethylene-bis-(2-furfural)
Fruit
[28]
70
5-(Hydroxymethyl)-furoic acid
Fruit
[28]
71
5-Hydroxymaltol
Fruit
[45]
after flowering, the content of vitamin C increased gradually in the fruit of young plants [55]. S. grosvenorii seed oil contained a number and large quantity of fatty aldehydes, such as fagni aldehyde, valeraldehyde, hexanal, and nonanal, and the content of fagni aldehyde in the oil reached 52.14% [56]. The oil content of S. grosvenorii seed kernel was 48.5%, among which the first three components were squalene (51.52%), [Z, Z]-9, 12- octadecadienoic acids (23.89%) and 3-hydroxy-1, 6, 10, 14, 18, 22tetracosahexaene [57]. HPLC analysis showed the content of squalene was 12.5% in the seed kernel oil of S. grosvenorii [58]. It was reported that squalene had body-building and anti-fatigue functions, and that it can be used to treat liver diseases. Although the essential oil is sometimes mentioned among the chemical components of S. grosvenorii, there are only a few reports dealing with its detailed analysis. The volatile oil content in the dried fruit of S. grosvenorii was about 0.2%0.3%, but it was only 0.03% in the fresh fruit [59-60].
Moreover, the main components of the volatile oil from dried and fresh fruit were significantly different. n-Hexadecanoic acid (45.609%) and 9, 12-octadecadienoic acid (36.151%) were the most abundant in the essential oil from dried fruit [59], while 2-butenoic acid butyl ester (20.80%) and 2-heptanol (13.86%) were the main components of the fresh fruit. Both the ripe fruits and roots of S. grosvenorii contained sixteen essential trace elements and a wide variety of inorganic elements. Its fruit has higher contents of potassium, calcium and magnesium than its root, with a ratio of 1.229%, 0.667% and 0.55%, respectively [61]. Additionally, the content of selenium in S. grosvenorii fruit reached 0.186 1 ^ ^ # that in grains. Mo et al. measured the contents of Al, Cd, Cu, Fe, Mg, Mn, P, Pb and Zn in S. grosvenorii fruit by ICP-AESN, and the results showed that the content of these # # # ^ ^` #'? 440 ppm, and that the
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LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
concentrations in order were P highest, then Mg, Fe, Zn, Mn,
Fig. 3
Al, Cu, Pd and Cd [62].
Structures of flavonoids and related compounds from S. grosvenorii
Biological Activities Traditional Chinese medicine (TCM) believes that S. grosvenorii fruits sweet, sour, and cool, and it has many physiological functions, such as clearing away the lung-heat, eliminating phlegm, and relaxing bowels, and it can be used to treat cough, sore throat, and constipation. TCM also holds that S. grosvenorii root can be used for the treatment of carbuncle, furuncle, and swollen boils, and that the fruit hair can be used to heal cuts. As summarized below, the pharmacological and clinical investigations carried out during the last 30 years have shown that extracts and individual compounds (especially the mogrosides) isolated from different parts of the plant have specific biological effects, including relieving cough, eliminating phlegm, preventing asthma, immunostimulation, eliminating free radicals to prevent oxidizing pathology, regulating blood sugar and ing blood-fat, anti-bacterial, anticarcinogen, and anti-fatigue
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functions. Anti-tussive, phlegm-expelling, and dyspnea-relieving functions The anti-tussive, phlegm-expelling, and dyspnea relieving activities of S. grosvenorii fruit have been reported for a long time. Oral consumption of the water extract of S. grosvenorii fruit at doses of 25 or 50 gkg1 markedly reduced the mouse cough induced by ammonia water or sulfur dioxide in a dose-dependent manner [63]. Mogrosides (purity > 98%), the main active constituents of LHG, also displayed a strong inhibitory effect on the mouse cough evoked by inhalation of ammonia water dose-dependently, with the minimum inhibi ## # 1 [64]. In another in vivo mouse study, oral administration of doses ? 1 of mogroside V (purity > 94%) derived from LHG could significantly reduce the number of coughing times induced by ammonia water, and the latency to the time that the mice start to cough could also be pro#_ _^^`#_ 1 [65]. It was also
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
reported that histamine-induced mouse trachea spasm could be distinctly antagonized by oral administration of
^ _ _^^''L1 [65]. Regarding the effect of S. grosvenorii fruit on cough, the water extract showed a significant phlegm-releasing action on mice by increasing the excretion of phenol red from the mouse trachea, as well as the excretion of phlegm from the rat trachea [63]. It was reported in a mouse model study that
^ _^ _^^? 1 could significantly increase the excreted amount of phlegm dose-dependently. In addition, mogrosides could promote significantly the motility of the ciliated cells of the frog respiratory tract when locally applied [63]. Immunostimulatory actions Ever since the 1990s, the immunomodulatory effect of LHG has been reported in a number of in vivo experiments, performed mainly with rats and mice. According to the results of an earlier experiment [66], oral administration of the aqueous extract of S. grosvenorii fruit to rats at doses of 25 or 50 gkg1 showed an evident increase in the percentage of acid -naphthyl acetate acid enzyme-positive lymphocytes in the peripheral blood, as well as in the ratio of rosette-forming cells. No marked influence was found on the neutrophil phagocytosis rate in the peripheral blood. These data support the fact that LHG could significantly improve both cellular and humoral immunity processes, with no effect on the non-specific immunity of the rats. In an another study with mice, oral administration of S. grosvenorii fruit water-extraction, alcohol-precipitation extract displayed a marked inhibitory effect on the induced decrease of mononuclear phagocytic function by hydrocortisone, suggesting S. grosvenorii fruit possesses the potential to enhance the reduced immune function of the body [63]. In addition, S. grosvenorii fruit-derived mogrosides also showed a marked positive effect on the inhibited mouse macrophage phagocytic function and T cell proliferation by cyclophosphamide (CTX) in comparison with the control group. No significant influence on the immune cells of normal mice was found, indicating that mogrosides could improve the immune functions markedly [67]. Recently, it was reported that in a study in mice, S. grosvenorii polysaccharide, over a seven-day administration period, could significantly elevate the mass of immune organs, such as thymus and spleen. In addition, the level of serum hemolysin, along with boosted peritoneal macrophage phagocytic percentage, phagocytic index of chicken red blood cells, and lymphocyte transformation rate, were strongly suggestive of its immune system-strengthening actions [68]. Anti-oxidative effects The anti-oxidant effects of LHG extracts and individual compounds from various parts of S. grosvenorii, have been extensively studied. In an in vivo study performed with rats by the test methods of D-deoxyribose, superoxide anion, and spectrophotometry, it was found that both mogrosides
– 96 –
(total mogroside > 98%) and mogroside V displayed significant inhibitory effects on the oxygen free radical, hemolysis of red blood cells, and lipid peroxidation induced by Fe2+ or H 2 O 2 in vitro indicating that mogrosides has antioxidant effects, and mogroside V may be the main antioxidant component of the mogrosides [69]. In a more recent in vitro study with different extracts from the stem of S. grosvenorii, the water, ethanol, ethyl acetate, and chloroform extracts all exhibited excellent antioxidant activity, superior to the control group butylatedhydroxytoluene (BHT), but inferior to the control with rutin applied [70]. Similarly, the anti-oxidant capacities of the total flavones from the leaves of S. grosvenorii were evaluated in a recent in vitro study, and it was found that the radical scavenging abilities of the tested compounds were much higher than that of BHT, a synthetic anti-oxidant, suggesting that it might be pursued as a potential natural food anti-oxidant [71]. The anti-oxidant capacity of five flavonol glycosides isolated from the flowers of S. grosvenorii was also conducted recently by the FRAP, TEAC, and ORAC assays. At the same time, the structure-activity relationships of these compounds were investigated. The results showed that two out of the five flavonoids had significant antioxidant activity. Based on the correlation between the structure and activity, 7-hydroxyl and 3-hydroxyl groups on the aglycone were found to be positively related to the activity, and that methylation of the 7-hydroxy group, and/or glycosylation of the 3-hydroxy group decreases activity [37]. Liver protection and transaminase reduction activities Administration of S. grosvenorii fruit water-extraction alcohol-precipitation extract at a dose of 50 gkg1 by gavage could reduce the biological activities of transaminase in the serum of the tested mice with liver injury induced by carbon tetrachloride or thioacetamide [63]. Similarly, protection against mouse liver injury was also shown in another in vivo study performed recently by Yao et al. They demonstrated that oral administration of a 75% ethanol extract of S. grosvenorii fruit could promote both SOD and GSH activities in the liver tissue of the experimental mice [72]. Mogrosides were also shown to be effective in the reduction of carbon tetrachloride-induced acute liver injury, tuberculosis vaccine plus lipopolysaccharide-induced immunological liver injury, and carbon tetrachloride-induced chronic liver injury. An anti-lipid peroxidation-associated effect of mogrosides on improving pathological conditions of liver tissue was reported by Wang et al [73-74]. Anti-diabetic effects The effect of S. grosvenorii fruit extract, and individual compounds derived from S. grosvenorii fruit, on diabetes has been extensively studied, mainly in in vivo experiments. For example, 30-day administration of 0.5, 1.0 or 3.0 gkg1 S. grosvenorii fruit powder or extract was conducted by Qi et al. in mice. The results showed that all of the doses of S. grosvenorii fruit extract could significantly lower the fasting
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
and after-meal blood glucose of diabetic mice induced by alloxan (P < 0.01). Furthermore, the effect for the S. grosvenorii fruit powder was dose-dependent, with the high dose showing the best effect. On the other hand, for the S. grosvenorii fruit extract, an inverse relationship between activities and doses was displayed, with the low dose having the best effect [75]. To study the effect of mogroside extract on splenic lymphocytes subsets and expression levels of the cytokines of type 1 diabetes mellitus (TIDM) mice, an experiment with Balb/c mice was designed and conducted by Chen et al [76]. After 30-day gavage administration of
^ _ " _^ ? 1 body weight, the expression levels of IFN- and TNF- at both mRNA and protein were markedly down-regulated, as well as lowering the blood glucose levels of the tested mice. Also, both the abnormal values for the CD 4 /CD 8 ratio and the number of CD 4 -positive splenic lymphocytes in diabetic mice returned to normal levels at the end of the experiment, and the expression level of IL-4 was promoted [77]. To evaluate the action of a mogroside extract (MG) from S. grosvenorii fruit on reducing oxidative stress, hyperglycemia, and hyperlipidemia in alloxan-induced diabetic mice, as well as on the oxygen free radical scavenging activity in vitro, experimental studies by Qi et al [78] were carried out. As a result, a significant increase in the levels of serum glucose, total cholesterol (TC), triacylglycerol (TG), and hepatic malondialdehyde (MDA), as well as a reduction in the level of hepatic high-density lipoprotein cholesterol (HDL-C) associated with diminution of the corresponding antioxidant enzymes, such as glutathione peroxidase (GSH-Px) and superoxide dismutase, were observed in all diabetic mice. Moreover, treatment of the diabetic mice with MG (100, 300 #_ 1 body weight) for four weeks significantly decreased serum glucose, TC, TG, and hepatic MDA levels (P < 0.05), whereas it increased serum HDL-C level and reactivated the hepatic antioxidant enzymes (P < 0.05) in alloxan-induced diabetic mice (P < 0.05). The hypoglycemic, hypolipidemic, and anti-oxidative activities of MG (100
1 body weight) were all higher compared with all of the other diabetic groups. Furthermore, the antioxidant capacity evaluated in vitro showed that MG and mogroside V, which was the main component of MG, possessed strong, oxygen free radical scavenging activities. These results demonstrate that the extract may have the capacity to inhibit hyperglycemia induced by diabetes, and the data suggest that administration of the extract may be helpful in the prevention of diabetic complications associated with oxidative stress and hyperlipidemia [77]. To investigate the anti-diabetic effect of LHG, an experimental study of type 2 diabetic Goto-Kakizaki (GK) rats was designed and conducted. After 13-week administration of a diet supplemented with 0.4% of the S. grosvenorii fruit extract, the anti-diabetic effects were evaluated. The LHG extract had no effect on food intake or body weight. In oral glucose tolerance tests (OGTT), LHG extract supplementation improved the insulin response at 15 min (P
– 97 –
< 0.05), and reduced the plasma glucose level at 120 min after the glucose administration (P < 0.05). The total amount of insulin in the whole pancreas taken from fasting rats was higher in the S. grosvenorii fruitextract supplemented group, which may explain the greater capacity to secrete insulin during the OGTT. Thiobarbituric acid-reactive substances in both the liver and the plasma were lower in the S. grosvenorii fruitextract supplemented group than in the control, suggesting that an absorbable component in S. grosvenorii fruit extract has an anti-oxidative effect on lipid peroxidation, thereby counteracting the oxidative stress caused by a diabetic state. Excreted urine volume and urinary albumin level for 24 h were both reduced in the S. grosvenorii fruit extract supplemented group, suggesting the attenuation of kidney damage caused by diabetes. These data indicated that S. grosvenorii fruit extract supplementation may be suitable for the type 2 diabetes, along with its sweet characteristics [78]. Anticancer effects To search for cancer chemopreventive agents from natural resources, many phytochemicals and food additives have been screened. An experimental in vivo study performed by Takasaki et al showed that the two natural sweeteners mogroside V and 11-oxo-mogroside V, isolated from LHG, have a strong inhibitory effect on the primary screening test indicated by the induction of Epstein-Barr virus early antigen (EBV-EA) by a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). These sweet glycosides with a cucurbitane triterpenoida #" ` _^ # # # bitory effects in the two-stage carcinogenesis test of mouse skin tumors induced by peroxynitrite (ONOO 2 ) as an initiator and TPA as a promoter. Furthermore, 11-oxo-mogroside V also exhibited a remarkable inhibitory effect in a two-stage carcinogenesis test of mouse skin tumor induced by 7, 12-dimethylbenz[a]-anthracene (DMBA) as an initiator and TPA as a promoter [79]. To clarify the cancer chemopreventive action of the S. grosvenorii fruit waterextract, which has anti-oxidative properties, a two-stage liver carcinogenesis model in partially hepatectomized male ICR mice was employed by Matsumoto et al [81]. The mice were maintained on a diet containing dicyclanil at a concentration of 1 500 ppm for nine weeks after a single intraperitoneal injection of diethylnitrosamine (DEN) _^ 1 to experimentally induce the pathological model, and were then given water containing 2 500 ppm of LHG extract for eleven weeks after two week’s administration on dicyclanil. The LHG extract inhibited the #_ # -glutamyl transpeptidase-positive hepatocytes, lipid peroxidation, and gene expression of Cyp1a1, all of which were caused by dicyclanil. To examine whether the LHG extract indirectly inhibited Cyp1a1 expression induced by inhibition of aryl hydrocarbon receptor (Ahr)-mediated signal transduction caused by dicyclanil, mice with high (C57BL/6J mice) and low affinities (DBA/2J mice) to Ahr were given dicyclanil-containing diet and/or S. grosvenoriiextract-containing tap water for two weeks.
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
Cyp1a1 gene expression was significantly lower in C57BL/6J mice administered dicyclanil + LHG extract than in C57BL/6J mice administered dicyclanil alone. There was no significant difference in the Cyp1a1 expression between DBA/2J mice administered dicyclanil + LHG extract and dicyclanil alone. These results suggest that the S. grosvenorii extract suppressed the induction of Cyp1a1, leading to inhibition of reactive oxygen species (ROS) generation, and consequently inhibited hepatocarcinogenesis, probably due to suppression of Ahr activity. Inhibitory effect on bacteria The anti-bacterial activity of the ethanol extracts from S. grosvenoriileaf and stem on Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Micrococcus luteus and Candida albicans were performed by Ye et al [82]. The samples for test were extracted using 50% ethanol, and the bacteriostatic rate was measured. As a result, the higher the concentration of the ethanol extracts of S. grosvenorii leaf and stem was, the higher the bacteriostatic rate. The bacteriostatic rates of the ethanol extracts of leaf and stem on Pseudomonas aeruginosa reached 90.9% and 76.7%, respectively when the concentration was 50 mgmL1. It was also found that bacteriostatic rates of the ethanol extracts of leaf and stem on Staphylococcus aureus, Micrococcus luteus, and Candida albicans were all below 50%. To explore the antibacterial activity of S. grosvenorii, various extracts were prepared from S. grosvenorii fruit, leaves, vine, and roots, and the bacterial activity of these extracts were tested using a colorimetric detection method and agar plating. The results showed that different extracts from all parts of S. grosvenorii exhibited strong antibacterial activity against the oral bacteria Streptococcus mutans. To further identify the bioactive fractions, the extracts were purified with Amberlite chromatography, and the purified factions were further tested for antibacterial activity. The antibacterial activities of the positive fractions were further tested by the blood agar plating method. The experimental data demonstrated that various extracts of S. grosvenorii leaves, vines, fruits, and roots exhibited strong antibacterial activities, suggesting these parts of S. grosvenorii may have the potential to be used for pharmaceutical preparations and dietary supplements to treats infection [84]. The capacity of nine compounds isolated from the leaves of S. grosvenorii were evaluated in vitro against the growth of oral bacterial species S. mutans, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and the yeast C. albicans, and their minimum inhibition concentrations were determined. The result showed aloe emodin had the strongest activities against all the tested bacteria and yeast, with minimum inhibitory concentration values ranging from 1.22 to 12.20 μgmL1 [22]. Anti-inflammatory action A tablet made from an extract of LHG significantly inhibited mouse swelling induced by cotton, ear swelling induced by dimethylbenzene, and paw swelling induced by carrageenan, respectively. Additionally, the considerable
– 98 –
pain-relieving effect of this preparation was also demonstrated in an acetic acid writhing test [63]. The molecular basis of the anti-inflammatory effects of the mogrosides derived from LHG was further researched by Pan et al using in vitro murine RAW264.7 cells by the methods of Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses [83]. The results demonstrated that the mogrosides ^ # # ` _= # #_ "=^^ # and COX-2 in LPS-induced macrophages. Treatment with mogrosides resulted in the reduction of LPS-induced nuclear translocation of nuclear factor- }- ^`# #_ dependent transcriptional activity of NF- ` ` # phosphorylation of inhibitor jB(IjB)a and p65, and the subsequent degradation of IjBa. Transient transfection experiments using NF- = #^ ^ #_ _ mogrosides inhibited the transcriptional activity of NF- # LPS-stimulated mouse macrophages. Mogrosides also inhibited LPS-induced activation of PI3K/Akt, extracellular signal-regulated kinase1/2, and p38MAPK. Taken together, these results show that the mogrosides could down-regulate #
#_ -2 gene expression in macrophages by inhibiting the activation of NF- # rfering with the activation of PI3K/Akt/IKK and MAPK. These results have important implications for using the mogrosides towards the development of effective anti- #
# ^[83]. Improving physiological function Both the ethanol extract of S. grosvenorii fruit and the total flavonoids of S. grosvenorii leaf had effects on improving physiological function of experimental animals. Based on the incremental load swimming training experimental model, Yao et al investigated the effect of the ethanol extract of S. grosvenorii fruit on the capacity of hypoxia tolerance, heat-resistance, and exercise of swimming mice [85]. The results showed that the improvement of physiological function of mice was proportional to the dosage of the ethanol extract within a certain range, but as the dosage continues to increase, the inhibition effect decreased, and 15 gkg1d1 was the optimum dosage to exert an effect. Further study found that the exhaustion swimming time of mice was significantly prolonged after administering S. grosvenorii fruit ethanol extract. Furthermore, immediately after exhaustive exercise, and 24 h after recovery, hemoglobin and the activity of superoxide dismutase and glutathione peroxidase in the liver were higher in the treated group than that in the control group, while blood lactate, serum lactate dehydrogenase, alanine aminotransferase, and the content of malonaldehyde (MAD) in liver were lower [73]. MAD is the metabolic product of lipid peroxide, and it can indirectly reflect the level of free radicals in the body. These results established that the ethanol extract of S. grosvenorii fruit could significantly inhibit the increase of MAD content, timely eliminate excess free radicals, prevent or inhibit the body lipid peroxidation, and has a protective effect on the damage of liver tissue or its membrane structure caused by movement. Chen et al found the
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
duration of endurance training for rats swimming to exhaustion was prolonged after applying the total flavonoid preparation of S. grosvenorii leaf [86]. Furthermore, the total flavonoid fraction of S. grosvenorii leaf showed anti-oxidative effects and protection against free-radical damage in the rat experiment. Other effects In in vitro experiments, the water extract of S. grosvenorii fruit antagonized the spasm of isolated ileum of rabbit caused by acetylcholine or adrenaline, and also exhibited the same effect on the spasm of isolated ileum of mice caused by acetylcholine [63]. Hossen et al found that the water extract and glycoside fraction (a complex of sweet components) of S. grosvenorii fruit significantly inhibited histamine-induced nasal rubbing, and compound 48/80-induced skin scratching behavior in ICR mice after consecutive treatment for four weeks, but they were inactive when administered in a single dose, even at a dose of 1 000 mgkg1 [87]. Furthermore, both the extract and glycoside fraction inhibited the histamine release induced by compound 48/80 at concentrations of 300 or 1
Chinese Journal of Natural Medicines
Chemistry and pharmacology of Siraitia grosvenorii: A review LI Chun1, LIN Li-Mei2, SUI Feng1*, WANG Zhi-Min1, HUO Hai-Ru1, DAI Li1, JIANG Ting-Liang1 1 2
Institute of Chinese Material Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China; Hunan University of Traditional Chinese Medicine, Changsha 410208, China Available online 20 Feb. 2014
[ABSTRACT] Siraitia grosvenorii is a perennial herb endemic to Guangxi province of China. Its fruit, commonly known as Luo hanguo, and has been used for hundreds of years as a natural sweetener and as a traditional medicine for the treatment of pharyngitis, pharyngeal pain, as well as an anti-tussive remedy in China. Based on ninety-three literary sources, this review summarized the advances in chemistry, biological effects, and toxicity research of S. grosvenorii during the past 30 years. Several different classes of compounds have been isolated or detected from various parts of S. grosvenorii, mainly triterpenoids, flavonoids, polysaccharides, amino acids, and essential oils. Various types of extracts or individual compounds derived from this species exhibited a wide array of biological effects e.g. anti-tussive, phlegm-relieving, anti-oxidant, immunomodulatory, liver-protecting, glucose-lowering, and anti-microbial. The existing research has shown that extracts and individual compounds from S. grosvenorii are basically non-toxic. Finally, some suggestions for further research on specific chemical and pharmacological properties of S. grosvenorii are proposed in this review. [KEY WORDS] Siraitiagrosvenorii; Cucurbitaceae; Chemical constituents; Pharmacological effects
[CLC Number]R284; R285
[Document code] A
[Article ID]2095-6975(2014)02-0089-14
Introduction Siraitia grosvenorii is a perennial vine of the Cucurbitaceae family, and its fruit is commonly known as Luo hanguo (LHG). A total of seven species belong to the genusSiraitia, and these plants are distributed mostly in south China, the Indo-China Peninsula, and Indonesia. There are four species in China, among which Siraitia grosvenorii (Swingle) C. Jeffreyex A. M. Lu and ZhiY. Zhang and Siraitiasiamensis(Craib) C. Jeffrey ex S. Q. Zhong & D. Fang are usually used as medicinal plants. S. grosvenoriis endemic to China, and principally grows in Guangxi province, where it has been cultivated for more than 200 years [1] (Fig. 1). S. grosvenorii fruit has been used for centuries in China as a natural sweetener and as a traditional medicine
[Received on] 15-Dec.-2012 [Research funding] This project was supported by the Beijing Joint Project Specific Funds, National Natural Science Foundation of China (Nos. 30873393, 81274112, 81373986) and the Beijing Municipal Natural Science Foundation (Nos. 7112098, 7132152). [ Corresponding author] SUI Feng: Prof., Tel.: 86-10-64041008, Fax: 86-10-64041008, E-mail: [email protected] These authors have no conflict of interest to declare. Copyright © 2014, China Pharmaceutical University. Published by Elsevier B.V. All rights reserved
– 89 –
for the treatment of lung congestion, colds, and sore throat [2]. In 1987, S. grosvenorii fruit was listed as a medicinal and edible species by the China Ministry of Health [3]. To date, S. grosvenorii fruit has been shown to have the following effects: antitussive, anti-asthmatic, anti-oxidation, liver-protection, glucose-lowering, immunoregulation, and anti-cancer [4]. S. grosvenorii contains triterpenoids, flavonoids, vitamins, proteins, saccharides, and a volatile oil [5]. Mogrosides, a group of triterpenoid glycosides isolated from S. grosvenorii fruit, are regarded as the main active ingredients for the sweet taste, and responsible for the main biological effects of S. grosvenorii. LHG products have been approved as dietary supplements in Japan, the United States, New Zealand and Australia. Currently, the extracts or some compounds from LHG are used mainly for their anti-tussive, expectorant, anti-diabetic, or sweet properties in various Chinese herbal compound prescriptions or dietary supplements. In this review, the research progress of S. grosvenorii during the last 30 years is summarized.
Chemical Composition Several different classes of compounds were previously isolated from various parts of S. grosvenorii, with the main groups being triterpenoids, particularly the cucurbitane-type triterpenoid glycosides, flavonoids, polysaccharides, proteins
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
of one part in ten thousand are 425 and 563 times as sweet as that of 5% sucrose, respectively [17]. In addition, a series of cucurbitane tetracyclic triterpenoid acids, including siratic acids A-F were isolated from the root of S. grosvenorii [18-21]. So far, a total of forty-seven triterpenoids (Table 1) have been isolated, and/or detected in the fruit, roots, or leaf materials of S. grosvenorii. As shown in studies of the structure-taste relationships for the glycosides of 3-hydroxy-cucurbit-5-ene derivatives, the number of glucose units, the oxygen function at the 11-position of the aglycone moiety, the location of the glycosyl units, and the hydroxylation of the side chain, are apparently responsible for the perception of taste [17, 30-31]. The presence of at least three sugar units in the molecule is essential for the occurrence of taste. For example, compounds 6, 9 and 13 are tasteless due to their failure to meet the above-mentioned basic structural requirements. Glycosides of the 11-hydroxy compounds taste sweet, such as compounds 10, 11, 14 and 15, while glycosides in the 11-hydroxy series are tasteless, and the 11-oxo compounds, as well as the dehydro derivatives, taste bitter. The relationship between the allocation of glucosyl units and sweetness is also noteworthy. SiamenosideI (16), which has four glucosyl units, is the sweetest compound among the glycosides of this type so far isolated, and showed a similar sweetness to mogrosideV (14) which has five glucosyl units, while mogroside IV A (10) and IV E (11), with the same number of glucosyl units as 16, is less sweet than 16. Additionally, hydroxylation of the side chain also affects the taste. For example, the bitter 11-oxo glycoside became sweet on hydroxylation of the side chain double bond with osmium tetroxide.
and essential oils.
Fig. 1 Line drawing of S. grosvenorii: 1. stem; 2. leaf; 3. inflorescence; 4. fruit
Cucurbitane glycosides are the main components, and also the active ingredients of S. grosvenorii fruit. Ever since Takemoto et al. isolated mogrosides IV, V, and VI from S. grosvenorii fruit in 1983 [6-8] , more than thirty similar compounds have been obtained from the fruit [9-13]. These compounds share the mogrolaglycone structure, [10-cucurbit-5-ene-3, 11, 24(R), 25-tetraol], with two to six glucose units attached (see Fig. 2). Most of them taste sweet, so they are collectively called mogrosides, and are the main active components of S. grosvenorii fruit. Mogrosides are present at 1.19% in the fresh fruit [14], and 3.82% in the dried fruit of S. grosvenorii [15]. Mogroside 9 is the main =## # # '>?'> # dried fruit of S. grosvenorii. Siamenoside I is the sweetest among the cucurbitane glycosides so far isolated [16-17]. The sweetness values of mogroside V and siamenoside I at the concentration
R1
R2
R3
R4
R5
1
H
H
H
D-OH
H2
16
2
H
glc
H
D-OH
H2
3
glc
H
H
D-OH
4
H
H
H
5
H
R1
R3
R4
R5
H
D-OH
H2
17
H
D-OH
H2
H2
18
H
D-OH
H2
D-OH
H2
19
glc
H
D-OH
H2
D-OH
H2
20
H
H
=O
H2
– 90 –
R2
glc
H
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 H
D-OH
H2
21
H
glc
H
=O
H2
H
D-OH
H2
22
glc
H
H
=O
H2
H
D-OH
H2
23
H
H
=O
H2
H
D-OH
H2
24
glc
H
=O
H2
10
H
D-OH
H2
25
glc
H
=O
H2
11
H
D-OH
H2
26
H
=O
H2
glc
D-OH
H2
27
H
=O
H2
H
D-OH
H2
28
H
D-OH
=O
14
H
D-OH
H2
29
H
D-OH
=O
15
H
D-OH
H2
30
H
H2
H2
6
glc
7
H
glc
8 9
glc
glc
12
glc
13
glc
H
– 91 –
glc
glc
glc
glc
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 Fig. 2 Structures of thetriterpenoid compounds isolated from S. grosvenorii Table 1 Triterpenoid compounds isolated from S. grosvenorii No.
Compound name
Plant parts
References
1
Mogrol
Fruit
[6-9]
2
Mogroside IA (Mogroside,A 1 )
Fruit
[8-9]
3
Mogroside IE 1
Fruit
[8-9]
4
Mogroside IIA 1
Fruit
[8, 10]
5
Mogroside IIA 2
Hydrolysis product
[8]
6
Mogroside IIE
Fruit
[8-9, 11, 17-19]
7
Mogroside IIIA 1
Fruit
[8, 12]
8
Mogroside IIIA 2
Fruit
[8, 10]
9
Mogroside IIIE
Fruit
[8, 17]
10
Mogroside IV A
Fruit
[8-9, 19, 12-13]
11
Mogroside IV E
Fruit
[8-9, 12, 18]
12
Mogroside IIB
Fruit
[10]
13
Mogroside III
Fruit
[9, 17-19]
14
Mogroside V
Fruit
[8-9, 12-13, 17-18]
15
Mogroside VI
Fruit
[8]
16
Siamenoside I
Fruit
[9, 12, 17]
17
Neomogroside
Fresh Fruit
[18]
18
Isomogroside V
Fruit
[13]
19
Grosmomoside I
Fruit
[20]
20
11-Oxomogrol
Hydrolysis product
[9] [9, 19]
21
11-Oxomogroside IA 1
Fruit
22
11-Oxomogroside IE 1
Fruit
[9]
23
11-Oxomogroside IIA 1
Fruit
[10]
24
11-Oxomogroside IIE
Unripe fruit
[19]
25
11-Oxomogroside III
Unripe fruit
[21]
26
11-Oxomogroside IV A
Fruit
[10, 21] [9, 17]
27
11-Oxomogroside V
Fruit
28
7-Oxomogroside IIE
Fruit
[10]
29
7-Oxomogroside V
Fruit
[10]
30
11-DeoxymogrosideIII
Fruit
[10, 21]
31
20-Hydroxy-11-oxomogroside IA 1
Unripe fruit
[19]
32
5, 6-Epoxymogroside IE 1
Fruit
[9]
33
5-Dehydro-karounidiol dibenzoate
Fruit
[9]
34
Karounidiol dibenzoate
Fruit
[9] [9]
35
Karounidiol 3-benzoate
Fruit
36
Isomultiflorenol
Fruit
[9]
37
-Amyrin
Fruit
[9, 22]
38
10-Cucurbitadienol
Fruit
[9]
39
Siratic acid A
Root
[23-24]
40
Siratic acid B
Root
[23-24] [23-24]
41
Siratic acid C
Root
42
Siratic acid D
Root
[25]
43
Siratic acid E
Root
[18]
44
Siraitic acid F
Root
[26]
45
Mogroester
Fruit
[27-28]
46
Siraitic acid IIA
Root
[29]
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LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102 47
Siraitic acid IIB
Root
Li et al studied the variation of mogrol glycosides in S. grosvenorii fruit during different growth periods. The results showed that the mogrol glycosides emerged after 5 days of pollination, with mogroside IIE (6) as the main component in the young fruits in the first 30 days. Mogroside III (13) started to appear after 30 days and reached the highest content in the 55th day, then mogroside IV A (10) and mogroside IV E (11) formed, and their contents reached the peak in the 70th day, and mogroside V(14) was generated after 70 days, and developed to be the main sweet component after 85 days of pollination, then the fruit began to be ripe [32]. Consequently, the optimum harvest time of S. grosvenorii fruit should be in the 90th day after pollination. Other studies have come to similar conclusions [33-34]. Regarding the phenolic compounds of S. grosvenorii, several authors reported the presence of various flavonoids in the fruit, leaves, stems, and flowers of the plant [35-38]. These compounds possessed the aglycone of kaempferol or quercetin. So far, a total of seven flavonoid compounds were isolated and/or detected from S. grosvenorii. With quercetin and kaempferol as reference substances, the content of the total flavones in the fresh fruits, and the mogrosides in the leaves of S. grosvenorii were determined by HPLC. The results ^ _ # # #^ ^ ` ? # fresh fruit, with 1.42% as the mogrosides, and 1.62% in the leaf of S. grosvenrii, respectively [39-40]. Furthermore, the total flavone contents in the various parts of S. grosvenorii were different, and the total flavone contents from high to low were leaf (3.718%) > stem (1.688%) > root (0.129%) [41]. For the dried fruits of different sizes, the content of kaempferol was between 1.63% to 3.49%, and the contents from high to low were peel (4.71%) > pulp (0.855%) > seed (0.197%) [42]. However, if kaempferitrin was used as reference substance, the content of total flavones determined by UV in the leaf and stem of S. grosvenrii were 5.85% and 0.29%, and the content of kaempferitrin was 1.76% and 0.167%, respectively [43-44]. Chen et al studied the variation of mogroside V and the flavonol glycosides in S. grosvenorii fruit at different growth stages, and the results showed since the date of fruiting, the content of mogroside V increased rapidly after 50 days, and became stable after 80 days, while the content of the flavonol glycosides increased rapidly from the 40th to 50th days, and reached the highest about 50 days later, and started to decrease after 60 days, and became stable when it dropped to the level of the 20th day [33]. Besides the flavonoids, three phenolic acids, two anthraquinones, three alkaloids, three sterols, three aliphatic acids, and three other compounds have been isolated from the fruit or leaf of S. grosvenorii [22, 28, 45]. The structures of flavonoids and other related compounds of S. grosvenorii are shown in Table 2 and Fig. 3. Polysaccharides are also important ingredients of S. grosvenrii. The content of polysaccharide was between
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[29]
2.88% to 5.65% in LHG of different sizes, with the highest in the pulp (7.55%) and lowest in the seeds (3.12%) [46]. In 2003, two polysaccharides, SGPS1 and SGPS2, were first isolated fromLHG and their relative molecular weights were determined by HPLC to be 430 000 and 650 000, respectively [47]. After that, Li et al reported on the monosaccharide composition and connection mode of SGPS1 and SGPS2 with the improvement of the extraction and purification technology [48-51]. Finally, SGPSl was determined as an acidicheteropolysaccharide, which was composed of Rha, Ara, Xyl, Gal, Glc, and GlcA in a molar ratio of 1.00 : 2.30 : 1.40 : 9.07 : 39.53 : 2.46. Its basic structure was made up of (1ė4) linked glucose and (1ė3) linked galactose residues in the main chain, and (1ė3) linkedglucose, (1ė6) linked glucose, (1ė4) linked galactose, and (1ė2) linked rhamnose units in the side chains. Sidechains attached the main chain to 2-O, 3-O, and 6-O of glucose, and to 6-O of galactose. On average, among the twenty main chain residues, there were five branches. By means of acid hydrolysis and TLC analysis, SGPS2 was determined to contain Rha and GlcA. However, the IR and 13C NMR analysis results showed that SGPS2 was comprised of Rha, GlcA, and amino sugars. Yan et al studied the composition of the polysaccharides from S. grosvenoriiroot,and investigated its effect on subcutaneous H22-implanted mice [52]. Asa result, the polysaccharides were shown to be composed of glucose, arabinose, and xylose, and compared with the model group, the tumor growth was not significantly suppressed (inhibition rate < 50%), but the index of thymus increased (P < 0.01), and the index of spleen decreased (P < 0.01) in the polysaccharide-treated groupsˊAs early as the 1980s, Xu et al measured the contents of various types of nutritious ingredients in S. grosvenorii fruit [53]. The content of crude protein was between 8.67% to 13.35% in the dried fruit of the wild type and three cultivars of S. grosvenorii. Furthermore, the hydrolysis products of S. grosvenorii fruit contained eighteen amino acids, including eight of the essential amino acids. Among the eighteen amino acids, the # # ^= _ ^ ^ }~~? 125 mg/100 g dried fruits), and the content of -aminobutyric acid was the ^ }?'~' ? _ _ ^ [54]. Additionally, there were a lot of sugars in the dried fruit of S. grosvenorii mainly fructose, glucose, and non-reducing sugars [53]. The content of total sugar in S. grosvenorii fruit ranged from 25.17% to 38.31%, and that of the reducing sugars in it was between 16.11% and 32.74%. S. grosvenorii fruit is rich in vitamin C. The content of vitamin C in the fresh fruit of S. grosvenorii _~? mg/100 g, bu _ ^_ '' ? g in the dried fruit [53]. With the differences in varieties, forms, producing area, growing period, and ripeness, the content of vitamin C in S. Grosvenorii fruit was remarkably different, but was
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
several times higher than that in citrus, apples, pears, grapes, and persimmons. Within a certain range, the content of
vitamin C was positively correlated with altitude, and 30 d a y s
Table 2 Flavonoids and related compounds isolated from S. grosvenorii No.
Compound name
Plant parts
References
48
Kaempferol
Fruit, Leaf, Flower
[35, 37]
49
Kaempferol 7-O--L-rhamnopyranoside
Fruit, Flower
[35, 37]
50
Kaempferol 3-O--L-rhamnopyranoside-7-O[-D-= #^}?--L-rhamnopyranoside
Fruit, Flower
[35-37]
51
Kaempferol 3, 7-di-O--L-rhamnopyranoside (kaempferitrin)
Leaf, Fresh fruit
[35-36, 38]
52
Quercetin-3-O--D-glucopyranoside-7-O--Lrhamnopyranoside
Leaf
[38]
53
7-Methoxy-kaempferol 3-O--L-rhamnopyranoside
Flower
[37]
54
7-Methoxy-kaempferol 3-O--D-glucopyranoside
Flower
[37]
55
Magnolol
Fruit
[28]
56
Vanillic acid
Fruit
[45]
57
p-Hydroxybenzylic acid
Leaf
[22]
58
1-Acetyl--carboline
Fruit
[45]
59
Cyclo-(leu-pro)
Fruit
[45]
60
Cyclo-(ala-pro)
Fruit
[45]
61
Aloe emodin
Leaf
[22]
62
Aloe-emodin acetate
Leaf
[22]
63
5, 8-Epidioxy-24(R)-methylcholesta-6, 22-dien-3-ol
Leaf
[22]
64
-Sitosterol
Fruit
[45]
65
Daucosterol
Leaf
[22]
66
Succinic acid
Fruit
[28]
67
n-Hexadecanoic acid
Leaf
[22]
68
12-Methyltetradecanoic acid
Leaf
[22]
69
5, 5'-Oxydimethylene-bis-(2-furfural)
Fruit
[28]
70
5-(Hydroxymethyl)-furoic acid
Fruit
[28]
71
5-Hydroxymaltol
Fruit
[45]
after flowering, the content of vitamin C increased gradually in the fruit of young plants [55]. S. grosvenorii seed oil contained a number and large quantity of fatty aldehydes, such as fagni aldehyde, valeraldehyde, hexanal, and nonanal, and the content of fagni aldehyde in the oil reached 52.14% [56]. The oil content of S. grosvenorii seed kernel was 48.5%, among which the first three components were squalene (51.52%), [Z, Z]-9, 12- octadecadienoic acids (23.89%) and 3-hydroxy-1, 6, 10, 14, 18, 22tetracosahexaene [57]. HPLC analysis showed the content of squalene was 12.5% in the seed kernel oil of S. grosvenorii [58]. It was reported that squalene had body-building and anti-fatigue functions, and that it can be used to treat liver diseases. Although the essential oil is sometimes mentioned among the chemical components of S. grosvenorii, there are only a few reports dealing with its detailed analysis. The volatile oil content in the dried fruit of S. grosvenorii was about 0.2%0.3%, but it was only 0.03% in the fresh fruit [59-60].
Moreover, the main components of the volatile oil from dried and fresh fruit were significantly different. n-Hexadecanoic acid (45.609%) and 9, 12-octadecadienoic acid (36.151%) were the most abundant in the essential oil from dried fruit [59], while 2-butenoic acid butyl ester (20.80%) and 2-heptanol (13.86%) were the main components of the fresh fruit. Both the ripe fruits and roots of S. grosvenorii contained sixteen essential trace elements and a wide variety of inorganic elements. Its fruit has higher contents of potassium, calcium and magnesium than its root, with a ratio of 1.229%, 0.667% and 0.55%, respectively [61]. Additionally, the content of selenium in S. grosvenorii fruit reached 0.186 1 ^ ^ # that in grains. Mo et al. measured the contents of Al, Cd, Cu, Fe, Mg, Mn, P, Pb and Zn in S. grosvenorii fruit by ICP-AESN, and the results showed that the content of these # # # ^ ^` #'? 440 ppm, and that the
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concentrations in order were P highest, then Mg, Fe, Zn, Mn,
Fig. 3
Al, Cu, Pd and Cd [62].
Structures of flavonoids and related compounds from S. grosvenorii
Biological Activities Traditional Chinese medicine (TCM) believes that S. grosvenorii fruits sweet, sour, and cool, and it has many physiological functions, such as clearing away the lung-heat, eliminating phlegm, and relaxing bowels, and it can be used to treat cough, sore throat, and constipation. TCM also holds that S. grosvenorii root can be used for the treatment of carbuncle, furuncle, and swollen boils, and that the fruit hair can be used to heal cuts. As summarized below, the pharmacological and clinical investigations carried out during the last 30 years have shown that extracts and individual compounds (especially the mogrosides) isolated from different parts of the plant have specific biological effects, including relieving cough, eliminating phlegm, preventing asthma, immunostimulation, eliminating free radicals to prevent oxidizing pathology, regulating blood sugar and ing blood-fat, anti-bacterial, anticarcinogen, and anti-fatigue
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functions. Anti-tussive, phlegm-expelling, and dyspnea-relieving functions The anti-tussive, phlegm-expelling, and dyspnea relieving activities of S. grosvenorii fruit have been reported for a long time. Oral consumption of the water extract of S. grosvenorii fruit at doses of 25 or 50 gkg1 markedly reduced the mouse cough induced by ammonia water or sulfur dioxide in a dose-dependent manner [63]. Mogrosides (purity > 98%), the main active constituents of LHG, also displayed a strong inhibitory effect on the mouse cough evoked by inhalation of ammonia water dose-dependently, with the minimum inhibi ## # 1 [64]. In another in vivo mouse study, oral administration of doses ? 1 of mogroside V (purity > 94%) derived from LHG could significantly reduce the number of coughing times induced by ammonia water, and the latency to the time that the mice start to cough could also be pro#_ _^^`#_ 1 [65]. It was also
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reported that histamine-induced mouse trachea spasm could be distinctly antagonized by oral administration of
^ _ _^^''L1 [65]. Regarding the effect of S. grosvenorii fruit on cough, the water extract showed a significant phlegm-releasing action on mice by increasing the excretion of phenol red from the mouse trachea, as well as the excretion of phlegm from the rat trachea [63]. It was reported in a mouse model study that
^ _^ _^^? 1 could significantly increase the excreted amount of phlegm dose-dependently. In addition, mogrosides could promote significantly the motility of the ciliated cells of the frog respiratory tract when locally applied [63]. Immunostimulatory actions Ever since the 1990s, the immunomodulatory effect of LHG has been reported in a number of in vivo experiments, performed mainly with rats and mice. According to the results of an earlier experiment [66], oral administration of the aqueous extract of S. grosvenorii fruit to rats at doses of 25 or 50 gkg1 showed an evident increase in the percentage of acid -naphthyl acetate acid enzyme-positive lymphocytes in the peripheral blood, as well as in the ratio of rosette-forming cells. No marked influence was found on the neutrophil phagocytosis rate in the peripheral blood. These data support the fact that LHG could significantly improve both cellular and humoral immunity processes, with no effect on the non-specific immunity of the rats. In an another study with mice, oral administration of S. grosvenorii fruit water-extraction, alcohol-precipitation extract displayed a marked inhibitory effect on the induced decrease of mononuclear phagocytic function by hydrocortisone, suggesting S. grosvenorii fruit possesses the potential to enhance the reduced immune function of the body [63]. In addition, S. grosvenorii fruit-derived mogrosides also showed a marked positive effect on the inhibited mouse macrophage phagocytic function and T cell proliferation by cyclophosphamide (CTX) in comparison with the control group. No significant influence on the immune cells of normal mice was found, indicating that mogrosides could improve the immune functions markedly [67]. Recently, it was reported that in a study in mice, S. grosvenorii polysaccharide, over a seven-day administration period, could significantly elevate the mass of immune organs, such as thymus and spleen. In addition, the level of serum hemolysin, along with boosted peritoneal macrophage phagocytic percentage, phagocytic index of chicken red blood cells, and lymphocyte transformation rate, were strongly suggestive of its immune system-strengthening actions [68]. Anti-oxidative effects The anti-oxidant effects of LHG extracts and individual compounds from various parts of S. grosvenorii, have been extensively studied. In an in vivo study performed with rats by the test methods of D-deoxyribose, superoxide anion, and spectrophotometry, it was found that both mogrosides
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(total mogroside > 98%) and mogroside V displayed significant inhibitory effects on the oxygen free radical, hemolysis of red blood cells, and lipid peroxidation induced by Fe2+ or H 2 O 2 in vitro indicating that mogrosides has antioxidant effects, and mogroside V may be the main antioxidant component of the mogrosides [69]. In a more recent in vitro study with different extracts from the stem of S. grosvenorii, the water, ethanol, ethyl acetate, and chloroform extracts all exhibited excellent antioxidant activity, superior to the control group butylatedhydroxytoluene (BHT), but inferior to the control with rutin applied [70]. Similarly, the anti-oxidant capacities of the total flavones from the leaves of S. grosvenorii were evaluated in a recent in vitro study, and it was found that the radical scavenging abilities of the tested compounds were much higher than that of BHT, a synthetic anti-oxidant, suggesting that it might be pursued as a potential natural food anti-oxidant [71]. The anti-oxidant capacity of five flavonol glycosides isolated from the flowers of S. grosvenorii was also conducted recently by the FRAP, TEAC, and ORAC assays. At the same time, the structure-activity relationships of these compounds were investigated. The results showed that two out of the five flavonoids had significant antioxidant activity. Based on the correlation between the structure and activity, 7-hydroxyl and 3-hydroxyl groups on the aglycone were found to be positively related to the activity, and that methylation of the 7-hydroxy group, and/or glycosylation of the 3-hydroxy group decreases activity [37]. Liver protection and transaminase reduction activities Administration of S. grosvenorii fruit water-extraction alcohol-precipitation extract at a dose of 50 gkg1 by gavage could reduce the biological activities of transaminase in the serum of the tested mice with liver injury induced by carbon tetrachloride or thioacetamide [63]. Similarly, protection against mouse liver injury was also shown in another in vivo study performed recently by Yao et al. They demonstrated that oral administration of a 75% ethanol extract of S. grosvenorii fruit could promote both SOD and GSH activities in the liver tissue of the experimental mice [72]. Mogrosides were also shown to be effective in the reduction of carbon tetrachloride-induced acute liver injury, tuberculosis vaccine plus lipopolysaccharide-induced immunological liver injury, and carbon tetrachloride-induced chronic liver injury. An anti-lipid peroxidation-associated effect of mogrosides on improving pathological conditions of liver tissue was reported by Wang et al [73-74]. Anti-diabetic effects The effect of S. grosvenorii fruit extract, and individual compounds derived from S. grosvenorii fruit, on diabetes has been extensively studied, mainly in in vivo experiments. For example, 30-day administration of 0.5, 1.0 or 3.0 gkg1 S. grosvenorii fruit powder or extract was conducted by Qi et al. in mice. The results showed that all of the doses of S. grosvenorii fruit extract could significantly lower the fasting
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and after-meal blood glucose of diabetic mice induced by alloxan (P < 0.01). Furthermore, the effect for the S. grosvenorii fruit powder was dose-dependent, with the high dose showing the best effect. On the other hand, for the S. grosvenorii fruit extract, an inverse relationship between activities and doses was displayed, with the low dose having the best effect [75]. To study the effect of mogroside extract on splenic lymphocytes subsets and expression levels of the cytokines of type 1 diabetes mellitus (TIDM) mice, an experiment with Balb/c mice was designed and conducted by Chen et al [76]. After 30-day gavage administration of
^ _ " _^ ? 1 body weight, the expression levels of IFN- and TNF- at both mRNA and protein were markedly down-regulated, as well as lowering the blood glucose levels of the tested mice. Also, both the abnormal values for the CD 4 /CD 8 ratio and the number of CD 4 -positive splenic lymphocytes in diabetic mice returned to normal levels at the end of the experiment, and the expression level of IL-4 was promoted [77]. To evaluate the action of a mogroside extract (MG) from S. grosvenorii fruit on reducing oxidative stress, hyperglycemia, and hyperlipidemia in alloxan-induced diabetic mice, as well as on the oxygen free radical scavenging activity in vitro, experimental studies by Qi et al [78] were carried out. As a result, a significant increase in the levels of serum glucose, total cholesterol (TC), triacylglycerol (TG), and hepatic malondialdehyde (MDA), as well as a reduction in the level of hepatic high-density lipoprotein cholesterol (HDL-C) associated with diminution of the corresponding antioxidant enzymes, such as glutathione peroxidase (GSH-Px) and superoxide dismutase, were observed in all diabetic mice. Moreover, treatment of the diabetic mice with MG (100, 300 #_ 1 body weight) for four weeks significantly decreased serum glucose, TC, TG, and hepatic MDA levels (P < 0.05), whereas it increased serum HDL-C level and reactivated the hepatic antioxidant enzymes (P < 0.05) in alloxan-induced diabetic mice (P < 0.05). The hypoglycemic, hypolipidemic, and anti-oxidative activities of MG (100
1 body weight) were all higher compared with all of the other diabetic groups. Furthermore, the antioxidant capacity evaluated in vitro showed that MG and mogroside V, which was the main component of MG, possessed strong, oxygen free radical scavenging activities. These results demonstrate that the extract may have the capacity to inhibit hyperglycemia induced by diabetes, and the data suggest that administration of the extract may be helpful in the prevention of diabetic complications associated with oxidative stress and hyperlipidemia [77]. To investigate the anti-diabetic effect of LHG, an experimental study of type 2 diabetic Goto-Kakizaki (GK) rats was designed and conducted. After 13-week administration of a diet supplemented with 0.4% of the S. grosvenorii fruit extract, the anti-diabetic effects were evaluated. The LHG extract had no effect on food intake or body weight. In oral glucose tolerance tests (OGTT), LHG extract supplementation improved the insulin response at 15 min (P
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< 0.05), and reduced the plasma glucose level at 120 min after the glucose administration (P < 0.05). The total amount of insulin in the whole pancreas taken from fasting rats was higher in the S. grosvenorii fruitextract supplemented group, which may explain the greater capacity to secrete insulin during the OGTT. Thiobarbituric acid-reactive substances in both the liver and the plasma were lower in the S. grosvenorii fruitextract supplemented group than in the control, suggesting that an absorbable component in S. grosvenorii fruit extract has an anti-oxidative effect on lipid peroxidation, thereby counteracting the oxidative stress caused by a diabetic state. Excreted urine volume and urinary albumin level for 24 h were both reduced in the S. grosvenorii fruit extract supplemented group, suggesting the attenuation of kidney damage caused by diabetes. These data indicated that S. grosvenorii fruit extract supplementation may be suitable for the type 2 diabetes, along with its sweet characteristics [78]. Anticancer effects To search for cancer chemopreventive agents from natural resources, many phytochemicals and food additives have been screened. An experimental in vivo study performed by Takasaki et al showed that the two natural sweeteners mogroside V and 11-oxo-mogroside V, isolated from LHG, have a strong inhibitory effect on the primary screening test indicated by the induction of Epstein-Barr virus early antigen (EBV-EA) by a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). These sweet glycosides with a cucurbitane triterpenoida #" ` _^ # # # bitory effects in the two-stage carcinogenesis test of mouse skin tumors induced by peroxynitrite (ONOO 2 ) as an initiator and TPA as a promoter. Furthermore, 11-oxo-mogroside V also exhibited a remarkable inhibitory effect in a two-stage carcinogenesis test of mouse skin tumor induced by 7, 12-dimethylbenz[a]-anthracene (DMBA) as an initiator and TPA as a promoter [79]. To clarify the cancer chemopreventive action of the S. grosvenorii fruit waterextract, which has anti-oxidative properties, a two-stage liver carcinogenesis model in partially hepatectomized male ICR mice was employed by Matsumoto et al [81]. The mice were maintained on a diet containing dicyclanil at a concentration of 1 500 ppm for nine weeks after a single intraperitoneal injection of diethylnitrosamine (DEN) _^ 1 to experimentally induce the pathological model, and were then given water containing 2 500 ppm of LHG extract for eleven weeks after two week’s administration on dicyclanil. The LHG extract inhibited the #_ # -glutamyl transpeptidase-positive hepatocytes, lipid peroxidation, and gene expression of Cyp1a1, all of which were caused by dicyclanil. To examine whether the LHG extract indirectly inhibited Cyp1a1 expression induced by inhibition of aryl hydrocarbon receptor (Ahr)-mediated signal transduction caused by dicyclanil, mice with high (C57BL/6J mice) and low affinities (DBA/2J mice) to Ahr were given dicyclanil-containing diet and/or S. grosvenoriiextract-containing tap water for two weeks.
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Cyp1a1 gene expression was significantly lower in C57BL/6J mice administered dicyclanil + LHG extract than in C57BL/6J mice administered dicyclanil alone. There was no significant difference in the Cyp1a1 expression between DBA/2J mice administered dicyclanil + LHG extract and dicyclanil alone. These results suggest that the S. grosvenorii extract suppressed the induction of Cyp1a1, leading to inhibition of reactive oxygen species (ROS) generation, and consequently inhibited hepatocarcinogenesis, probably due to suppression of Ahr activity. Inhibitory effect on bacteria The anti-bacterial activity of the ethanol extracts from S. grosvenoriileaf and stem on Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Micrococcus luteus and Candida albicans were performed by Ye et al [82]. The samples for test were extracted using 50% ethanol, and the bacteriostatic rate was measured. As a result, the higher the concentration of the ethanol extracts of S. grosvenorii leaf and stem was, the higher the bacteriostatic rate. The bacteriostatic rates of the ethanol extracts of leaf and stem on Pseudomonas aeruginosa reached 90.9% and 76.7%, respectively when the concentration was 50 mgmL1. It was also found that bacteriostatic rates of the ethanol extracts of leaf and stem on Staphylococcus aureus, Micrococcus luteus, and Candida albicans were all below 50%. To explore the antibacterial activity of S. grosvenorii, various extracts were prepared from S. grosvenorii fruit, leaves, vine, and roots, and the bacterial activity of these extracts were tested using a colorimetric detection method and agar plating. The results showed that different extracts from all parts of S. grosvenorii exhibited strong antibacterial activity against the oral bacteria Streptococcus mutans. To further identify the bioactive fractions, the extracts were purified with Amberlite chromatography, and the purified factions were further tested for antibacterial activity. The antibacterial activities of the positive fractions were further tested by the blood agar plating method. The experimental data demonstrated that various extracts of S. grosvenorii leaves, vines, fruits, and roots exhibited strong antibacterial activities, suggesting these parts of S. grosvenorii may have the potential to be used for pharmaceutical preparations and dietary supplements to treats infection [84]. The capacity of nine compounds isolated from the leaves of S. grosvenorii were evaluated in vitro against the growth of oral bacterial species S. mutans, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and the yeast C. albicans, and their minimum inhibition concentrations were determined. The result showed aloe emodin had the strongest activities against all the tested bacteria and yeast, with minimum inhibitory concentration values ranging from 1.22 to 12.20 μgmL1 [22]. Anti-inflammatory action A tablet made from an extract of LHG significantly inhibited mouse swelling induced by cotton, ear swelling induced by dimethylbenzene, and paw swelling induced by carrageenan, respectively. Additionally, the considerable
– 98 –
pain-relieving effect of this preparation was also demonstrated in an acetic acid writhing test [63]. The molecular basis of the anti-inflammatory effects of the mogrosides derived from LHG was further researched by Pan et al using in vitro murine RAW264.7 cells by the methods of Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses [83]. The results demonstrated that the mogrosides ^ # # ` _= # #_ "=^^ # and COX-2 in LPS-induced macrophages. Treatment with mogrosides resulted in the reduction of LPS-induced nuclear translocation of nuclear factor- }- ^`# #_ dependent transcriptional activity of NF- ` ` # phosphorylation of inhibitor jB(IjB)a and p65, and the subsequent degradation of IjBa. Transient transfection experiments using NF- = #^ ^ #_ _ mogrosides inhibited the transcriptional activity of NF- # LPS-stimulated mouse macrophages. Mogrosides also inhibited LPS-induced activation of PI3K/Akt, extracellular signal-regulated kinase1/2, and p38MAPK. Taken together, these results show that the mogrosides could down-regulate #
#_ -2 gene expression in macrophages by inhibiting the activation of NF- # rfering with the activation of PI3K/Akt/IKK and MAPK. These results have important implications for using the mogrosides towards the development of effective anti- #
# ^[83]. Improving physiological function Both the ethanol extract of S. grosvenorii fruit and the total flavonoids of S. grosvenorii leaf had effects on improving physiological function of experimental animals. Based on the incremental load swimming training experimental model, Yao et al investigated the effect of the ethanol extract of S. grosvenorii fruit on the capacity of hypoxia tolerance, heat-resistance, and exercise of swimming mice [85]. The results showed that the improvement of physiological function of mice was proportional to the dosage of the ethanol extract within a certain range, but as the dosage continues to increase, the inhibition effect decreased, and 15 gkg1d1 was the optimum dosage to exert an effect. Further study found that the exhaustion swimming time of mice was significantly prolonged after administering S. grosvenorii fruit ethanol extract. Furthermore, immediately after exhaustive exercise, and 24 h after recovery, hemoglobin and the activity of superoxide dismutase and glutathione peroxidase in the liver were higher in the treated group than that in the control group, while blood lactate, serum lactate dehydrogenase, alanine aminotransferase, and the content of malonaldehyde (MAD) in liver were lower [73]. MAD is the metabolic product of lipid peroxide, and it can indirectly reflect the level of free radicals in the body. These results established that the ethanol extract of S. grosvenorii fruit could significantly inhibit the increase of MAD content, timely eliminate excess free radicals, prevent or inhibit the body lipid peroxidation, and has a protective effect on the damage of liver tissue or its membrane structure caused by movement. Chen et al found the
LI Chun, et al. / Chin J Nat Med, 2014, 12(2): 89102
duration of endurance training for rats swimming to exhaustion was prolonged after applying the total flavonoid preparation of S. grosvenorii leaf [86]. Furthermore, the total flavonoid fraction of S. grosvenorii leaf showed anti-oxidative effects and protection against free-radical damage in the rat experiment. Other effects In in vitro experiments, the water extract of S. grosvenorii fruit antagonized the spasm of isolated ileum of rabbit caused by acetylcholine or adrenaline, and also exhibited the same effect on the spasm of isolated ileum of mice caused by acetylcholine [63]. Hossen et al found that the water extract and glycoside fraction (a complex of sweet components) of S. grosvenorii fruit significantly inhibited histamine-induced nasal rubbing, and compound 48/80-induced skin scratching behavior in ICR mice after consecutive treatment for four weeks, but they were inactive when administered in a single dose, even at a dose of 1 000 mgkg1 [87]. Furthermore, both the extract and glycoside fraction inhibited the histamine release induced by compound 48/80 at concentrations of 300 or 1
