What Is Chinese Medicine Luo Han Guo?

The Chinese herb Siraitia grosvenori is the dried fruit of the plant Siraitia grosvenori [Siraitia grosvenori (Swing le) C∙Jeffrey] in the family Cucurbitaceae. It has the effects of clearing away heat and moistening the lungs, lubricating the intestines and promoting bowel movements, and is used to treat coughs caused by lung fire and dryness, sore throat and loss of voice, and constipation caused by dryness in the intestines [1]. In recent years, many Chinese and foreign scholars have conducted research on the saponins and other ingredients and pharmacological effects of Luo Han Guo, and have achieved many results. The author analyzes the chemical composition, pharmacological effects and clinical application of Luo Han Guo medicinal materials over the past 20 years, in order to find a scientific basis for further development and utilization of Luo Han Guo medicinal materials.

1 Chemical composition

1.1 Cucurbitane triterpenoid components

This type of compound is the main active substance in Luo Han Guo. They all have the same aglycone M og rol, and with the exception of a few, they are all sweetening components or slightly sweet substances, with a content of about 4% [2]. In 1983, Japanese scholars Takemoto and Tsunematsu [3-5] conducted a series of studies on the chemical composition of Luohanguo. First, they isolated Mogroside (mog roside) Ⅳ, Ⅴ, and Ⅵ, and used chemical and spectroscopic methods to determine their aglycone structures as the cucurbitane-type tetracyclic triterpene mogrol, and identified the structures of Mogroside Ⅴ, and the structure of mogroside Ⅵ was identified. Subsequently, Matsumoto et al. [6] isolated and identified mogroside Ⅳ (mogroside Ⅵ), mogroside Ⅴ (mogroside Ⅴ), siamenoside Ⅰ (siamenoside Ⅰ), 11-oxo-mogroside Ⅴ (11-oxo-mogroside Ⅴ), Mogroside Ⅱ E (mog roside Ⅱ E), Mogroside Ⅲ E (mog ro- side Ⅲ E), and Mogroside Ⅲ (mog roside Ⅲ ), etc. There are 7 ingredients. Among the above ingredients, Mogroside V is the main sweetening ingredient in the Luo Han Guo fruit, both in terms of content and sweetness (256-344 times the sweetness of sucrose). Siamenoside I is currently the sweetest of the cucurbitane triterpenoid glycosides discovered, with a concentration of 1/10,000 being 563 times the sweetness of 5% sucrose. In addition, Chinese scholars Wang Xuefen et al. [7,8] and Si Jianyong et al. [9] have also isolated a series of cucurbitane-type tetracyclic triterpenoid acids, siraitic acid A-E, from the liposoluble fraction of the root of Luohanguo.

1.2 Flavonoids

Si Jianyong et al. [10] also isolated several flavonoid glycosides from fresh Luohanguo, the structures of which are: kaempferol-3-O-a-L-rhamnopyranoside-7-O-[β-D-glucopyranosyl (1-2)-a-L-rhamnopyranoside], named grosvenorine Ⅰ ; kaempferol-3,7-a-L-dirhamnoside, named grosvenorine Ⅱ , and dehydrodimerized pinoresinol-4-O-β-D-glucoside. Chen Quanbin et al. [11] used Luo Han Guo leaves as a raw material to propose flavonoids, and after structural identification, it was confirmed that the aglycones were kaempferol and quercetin.

1.3 Proteins, amino acids and sugars

Xu Weikun et al. [12] determined the total nitrogen content of Luo Han Guo dried fruit, and then converted it to protein. The results showed that the protein content of the dried fruit was 8.67% to 13.35%. In addition, the types and contents of amino acids in the hydrolysate of dried fruit were also measured, which proved that there were 18 kinds of amino acids, including 8 essential amino acids for the human body. The highest content was aspartic acid and glutamic acid, and the lowest was γ-aminobutyric acid. According to Xu Weikun et al. [13], the total sugar content of dried Luohanguo fruit is 25∙17% to 38∙31%, the reducing sugar content is 16∙11% to 32∙74%, the fructose content of reducing sugars is 10∙17% to 17∙55%, and the glucose content of reducing sugars is 5∙71% to 15∙19%.

2 Pharmacological effects

2.1 Effects on organs

Wang Qin et al. [15] reported that the water extract of the fruit of Luo Han Guo has a significant inhibitory effect on cough induced by concentrated ammonia water or sulfur dioxide in mice, can increase the phenol red excretion in the trachea of mice and the sputum excretion in the trachea of rats, and significantly increase the number of defecation particles in normal mice or constipated mice, reduced the activity of carbon tetrachloride or thioacetamide in mice, which damaged serum glutamic pyruvic transaminase, suggesting that the fruit water extract has pharmacological effects of relieving cough, expectorating, laxative and protecting the liver. Zhou Xinxin et al. [16] also reported that the water extract of Luo Han Guo and Luo Han Guo saponin have the effect of relieving cough and expectorating. Jin Chunhua et al. [17] observed that Luo Han Guo extract has an antagonistic effect on the contraction of the intestinal tract caused by barium chloride or acetylcholine in rabbits, mice and dogs, and has a bidirectional regulatory effect on intestinal activity.

2.2 Effect on immunity

Wang Qin et al. [15] also reported that the water extract of the fruit of Luo Han Guo has a strengthening effect on the phagocytic function of monocytes in immunocompromised mice, suggesting that the water extract of the fruit of Luo Han Guo can enhance the non-specific immune function of immunocompromised organisms. Wang Qin et al. [18] reported that Luo Han Guo sweet saponin (purity > 80%) had no significant effect on the immune function of normal mice, but could significantly improve the macrophage phagocytic function and T cell proliferation of CTX immunosuppressed mice, thus indicating that Luo Han Guo sweet saponin has a certain positive regulatory effect on the cellular immune function of CTX immunosuppressed mice.

2.3 Effect on metabolism

Qi Xiangyang et al. [19, 20] reported that Luo Han Guo powder and its extract (with 80% Luo Han Guo saponin content) had no effect on the body weight, blood glucose, or glucose tolerance of normal mice. High-dose Luo Han Guo powder (3∙0 g/kg · bw) and low- and medium-dose (0·5–1·0 g/kg·bw) Luo Han Guo extract had the effect of lowering fasting and postprandial blood glucose in mice with diabetes induced by intraperitoneal injection of alloxan. The hypoglycemic effect of Luo Han Guo powder increased with increasing dose, and the hypoglycemic effect was better in the high-dose group, while the hypoglycemic effect of Luo Han Guo extract decreased with increasing dose, and the hypoglycemic effect was best in the low-dose group.

Zhang Liqin et al. [21] reported that Luo Han Guo saponin extract has a significant hypoglycemic effect on diabetic mice treated with alloxan, and the hypoglycemic effect of the 100 mg/kg·bw dose group is comparable to that of the traditional medicine Xiaoke pills. The experiment also showed that Luo Han Guo saponin extract has a preventive effect on the abnormal elevation of serum triglycerides and serum cholesterol, which is abnormally elevated, has a preventive effect, bringing the body's blood lipid levels closer to normal. Luo Han Guo saponin extract can reduce the production of lipid peroxides in the liver of diabetic mice, improve the activity of their antioxidant enzyme system, and help restore the liver's antioxidant capacity. Yao Jiwei et al. [22] reported that Luo Han Guo extract can effectively increase the time of mice exercising to exhaustion, effectively relieve the decrease of Hb during exercise and promote the synthesis of Hb after exercise, reduce the amount of Bla generated during exercise and accelerate the clearance of Bla, significantly promote the increase of SOD and GSH-Px activity in liver tissue of mice, significantly inhibit the increase of MDA in liver tissue, and effectively prevent or inhibit lipid peroxidation in the body.

3 Clinical application

Luohanguo fruit is cool in nature, sweet in taste, non-toxic, and has the functions of clearing away heat and detoxifying, resolving phlegm and relieving cough, cooling the blood and soothing the stomach, clearing the lungs and moistening the bowels, and generating body fluid and quenching thirst. It can be used clinically to treat hypertension, tuberculosis, asthma, gastritis, whooping cough, acute and chronic bronchitis, and acute and chronic tonsillitis. For example, if 15 g of Luo Han Guo and 9 g of Bai He are used and the mixture is brewed and then taken orally, it has a certain therapeutic effect on chronic cough in the elderly. If 15 g each of Luo Han Guo fruit, Bai Bu, Tian Dong, Xing Ren, and Sang Pi are used and the mixture is brewed and then taken orally, it has a therapeutic effect on bronchitis. If 15 g of Luo Han Guo, 12 g of Bai He, 6 g of Ci Bai Ye, 3 g each of Chen Pi and Ma Huang are used and the mixture is brewed and then taken orally, is a commonly used and effective prescription for the treatment of whooping cough in children; 2 monk fruit fruits, remove the shell, steam for 15 minutes, drink the soup with the fruit, 3 times a day, effective for treating tuberculosis cough; 2 monk fruit fruits, remove the flesh and seeds (crush), boil in water, take once a day before going to bed, effective for treating senile constipation; 2 monk fruit fruits, crush, decoct in water, let cool, then slowly drink, 1 time in the morning and 1 time in the afternoon, effective for acute and chronic pharyngitis and loss of voice. Luohanguo fruit is rich in sugar and can be used as a substitute for liquorice to improve the taste, so it is often used in many traditional Chinese medicine formulas. In addition, the fluff on the fruit is a good medicine for cuts.

4 Outlook

Luohanguo has a history of more than 300 years of medicinal use in Guangxi folk medicine. It is mainly produced in Yongfu, Lingui and Longsheng counties in Guangxi, and is now cultivated on a large scale. It is abundant in resources and has a large output. It is listed in the first batch of “species that are both food and medicine” by the Ministry of Health of the People's Republic of China. Luohanguo preparations are currently on the market for clinical use, mainly for respiratory diseases. In traditional medicine, Luo Han Guo also has a good effect on digestive system diseases, and has antibacterial, hypoglycemic, and hypotensive effects. The development prospects for these effects in health foods are very promising, and it has good medicinal and economic value.

In addition, the fruit, root and leaves of the monk fruit all contain compounds similar to the parent nucleus of monk fruit saponin (tetracyclic triterpenoid of cucurbitane). However, the current application is mainly focused on the fruit, so the comprehensive development and research potential of the monk fruit, including the root and leaves, is very high. The main component of Luo Han Guo, mogroside, has the advantages of being highly sweet, non-caloric and non-toxic. It is very suitable for the current demand in the food market for low-calorie sweeteners and can be used as a safe substitute for sweeteners. If in-depth research can be carried out on the processing of sugar-free sweeteners, the prospects are very optimistic.

At present, it has been found in research that the sweetness of mogroside is closely related to its structure, and the structure of the ingredient is closely related to the growth period. Therefore, it is necessary to conduct a comprehensive and systematic study of the active ingredients, pharmacological effects and mechanism of action of mogroside in the whole plant, in order to provide more scientific evidence and technical data for the full utilization of this advantageous resource.

References:

[1] National Pharmacopoeia Commission ∙ Pharmacopoeia of the People's Republic of China (Part 1) [S]. Beijing: Chemical Industry Press, 2005: 147.

[2] Li YQ, Wang WS, Wang C ∙ Separation and determination of saponins in Luo Han Guo [J]. Food Science, 1993, 14 (6): 66-69.

[3] Tsunematsu Takemoto, Shigenobu Zaigen, Tadashi Nakajima, et al. Research on the components of Luohanguo (I) [J]. Pharmaceutical Journal (Japanese), 1983 (103): 1151

[4] Tsunematsu Takemoto, Shigenobu Zaigen, Tadashi Nakajima, et al. Research on the components of Luohanguo (II) [J]. Pharmaceutical Journal (Japanese), 1983 (103): 1155.

[5] Tsumoto T, Shigenobu Kawahara, Nakajima M, et al. Research on the components of Luo Han Guo (Ⅱ) [J]. Pharmaceutical Journal (Japanese), 1983 (103): 1167.

[6] M a tsumoto K, K asai∙R, O h tani k, e t al∙M inor cucurbitane g lyco- sides from  fruitsof Siraitia  grosvenorii( C ucurbitaceae)  [ J] .    C hem∙Pharm∙Bull,1990,38(7):2030.

[7] Wang Xuefen, Lu Wenjie, Chen Jiayuan, et al. ∙Study on the chemical constituents of Luo Han Guo root (Ⅰ) [J]. Chinese Herbal Medicine, 1996, 27 (9): 515-517.

[8] Wang Xuefen, Lu Wenjie, Chen Jiayuan, et al. ∙Study on the chemical constituents of Luo Han Guo root (Ⅱ) [J]. Chinese Herbal Medicine, 1998, 29 (5): 293-295.

[9] Si Jianyong, Chen Dihua, Shen Liangang, et al. ∙Study on the chemical constituents of Luo Han Guo root, a specialty plant in Guangxi [J]. Journal of Pharmaceutical Sciences, 1999, 34 (12): 918-920.

[10] Si Jianyong, Chen Dihua, Chang Qi, et al. Isolation and structural determination of flavonoid glycosides in fresh Luo Han Guo [J]. Journal of Pharmaceutical Sciences, 1994, 29 (2): 158-160.

[11] Chen Quanbin, Yang Jianxiang, Yixiang Hui, et al. Research on flavonoid glycosides in Luohanguo leaves [J]. Guangxi Botany, 2006, 26 (2): 217-220.

[12] Xu Weikun, Meng Lishan. Determination of the protein content of Luohanguo [J]. Guangxi Botany, 1986, 6 (3): 295-296.

[13] Xu Weikun, Meng Lishan. Analysis of the sugar content of Luo Han Guo [J]. Guangxi Agricultural Science, 1980 (3): 29.

[14] Chen Quanbin, Chen Haiyan, Li Jun, et al. Determination of the relative molecular mass of Luo Han Guo polysaccharides by HPLC [J]. Chinese Herbal Medicine, 2003, 34 (12): 1075.

[15] Wang Q, Li A Y, Li X P, et al. Pharmacological studies on Luo Han Guo [J]. Chinese Journal of Traditional Chinese Medicine, 1999, 24(7): 425-428.

[16] Zhou X X, Song J S. Pharmacological studies on Luo Han Guo and its extracts [J]. Journal of Traditional Chinese Medicine, 2004, 22 (9): 1723.

[17] Jin Chunhua, Jiang Xiulian, Hong Tie ∙ Pharmacological study of Luo Han Guo throat tablets [J] . Traditional Chinese Medicine, 1997, 20 (11): 574-577.

[18] Wang Q, Wang K, Dai S, et al. Regulation of the immune function of mice by the sweetener of Luo Han Guo [J]. Traditional Chinese Medicine, 2001, 24 (11): 811-812.

[19] Qi Xiangyang, Chen Weijun, Song Yunfei, et al. Hypoglycemic effect of Luo Han Guo extract on diabetic mice [J]. Chinese Public Health, 2003, 19(10): 1226-1227.

[20] Qi Xiangyang, Chen Weijun, Song Yunfei, et al. Hypoglycemic effect of Luo Han Guo on diabetic mice [J]. Food Science, 2003, 24(12): 124-127.

[21] Zhang Liqin, Qi Xiangyang, Chen Weijun, et al. Effects of Luo Han Guo saponin extract on blood glucose, blood lipids and antioxidant activity in diabetic mice [J]. Chinese Journal of Pharmacology, 2006, 22(2): 237-240.

[22] Yao Jiwei, Tang Hui, Zhou Liang, et al. Effects of Luo Han Guo extract on exercise endurance and antioxidant damage in liver tissue of mice [J]. Chinese Journal of Sports Medicine, 2008, 27

(2): 221-223.

[23] Li Dianpeng, Zhang Hourui ∙Research and application of Luo Han Guo, a specialty plant in Guangxi [J] . Guangxi Botany, 2000, 20(3): 270-276.