Monk Fruit: Is It Healthy?

Monk Fruit [Siratia grosvenorii (Swingle) C. Jeffrey] is the fruit of the Monk Fruit plant in the Cucurbitaceae family. It is cool in nature, bitter in taste, non-toxic, and enters the lung and large intestine meridians. It has the effects of moistening the lungs, relieving coughs, cooling the blood, and lubricating the bowels. It is used to treat lung fire and dry coughs, sore throats and loss of voice, and dry bowels and constipation. This article provides a review of the pharmacological research progress of Luo Han Guo since 2004, as follows, to provide a reference for further research on Luo Han Guo.

1 Cough suppressant, expectorant and antispasmodic effects

Luo Han Guo and Luo Han Guo extract have expectorant effects in mice and rats [2], and have cough suppressant effects in mice and guinea pigs [2-3]. Monk Fruit saponin V has a cough suppressant and expectorant effect in mice, and inhibits the spasm of isolated guinea pig ileum and isolated trachea caused by histamine, suggesting that Monk Fruit saponin V is the main active ingredient of Monk Fruit for relieving cough [4].

2 Antioxidant effect

Monk fruit saponin extract has a strong scavenging effect on hydroxyl radicals and superoxide anion radicals, and can effectively inhibit the production of malondialdehyde during erythrocyte autoxidation hemolysis and hepatic lipid peroxidation in test rats, and shows a certain dose-effect relationship, among which monk fruit saponin V is the main active ingredient [5]. The four solvent extracts of Luo Han Guo all have antioxidant, superoxide anion scavenging, hydroxyl radical scavenging and lipid-resistant effects, with the ethyl acetate extract being the most effective [6]. Monk Fruit extract has a scavenging effect on superoxide radicals (O2-) produced by the self-oxidation of phloretin or hydroxyl radicals (-OH) produced by the Fenton reaction, and the scavenging effect on superoxide radicals is better than that on hydroxyl radicals. There is also a significant dose-effect relationship between the scavenging rate and the amount of extract [7]. The water extract, ethanol extract, ethyl acetate extract and chloroform extract of Luo Han Guo stem all have strong antioxidant properties, which are stronger than the same concentration of the synthetic antioxidant BHT, but weaker than the same concentration of rutin. The difference in antioxidant properties between the chloroform extract of Luo Han Guo stem and rutin is not significant [8].

3 Hepatoprotective effect

Mogroside has the effect of reducing ALT and AST activities in mice with acute liver injury induced by CCl4. It also has the effect of reducing serum ALT and AST activities, increasing the activity of superoxide dismutase (SOD) in liver homogenates, and reducing malondialdehyde (MDA) content in mice with immune liver injury induced by BCG plus lipopolysaccharide and in rats with chronic liver injury induced by CCl4, reducing the degree of pathological changes in liver tissue [9-10]. Luo Han Guo extract can inhibit lipid peroxidation in the body and has a significant protective effect on the damage to liver tissue and its membrane structure caused by exercise [11].

4. Immune enhancement, blood glucose and lipid lowering effects

Luo Han Guo polysaccharides have a significant immune enhancement effect on cellular immunity, humoral immunity and non-specific immunity in mice [12]. Low-dose Mogroside extract can improve immune disorders in mice treated with pyrimethamine, down-regulate the expression levels of the cytokines IFN-γ and TNF-α, restore the CD4/CD8 ratio to normal, and increase the expression level of IL-4 in the lymphocytes of the spleen in normal mice and type 1 diabetic mice [13]. A single oral dose of 30% Mogroside 200 mg/kg in normal people has no significant effect on blood glucose levels or liver enzyme activity [14]. Mogroside extract has an antagonistic effect on the abnormal increase in blood glucose, serum triglycerides, and serum cholesterol in mice with diabetes induced by alloxan, can increase the content of serum high-density lipoprotein cholesterol, and tend to normalize the body's blood lipid levels, and has a preventive effect on diabetic complications [15]. Luo Han Guo concentrate and Mogroside can reduce the total serum cholesterol and triglyceride levels and increase the high-density lipoprotein cholesterol levels in mice with hyperlipidemia [16].

5 Effect on hypoxia tolerance, high temperature tolerance and exercise capacity

The time to exhaustion in mice given Luo Han Guo extract by gavage was significantly prolonged, and it effectively promoted the synthesis of hemoglobin (Hb) in the body [11]. An experimental model of swimming training with increasing loads was established by gavage of Luo Han Guo extract in mice to measure the time to exhaustion in swimming and climbing a rope, as well as the tolerance to hypoxia and high temperatures. The results showed that within a certain range, the degree of improvement in mouse physiological function was significantly dependent on the amount of Luo Han Guo taken. The effect of different doses of Luo Han Guo on mouse physiological function showed a typical two-way effect, with the effect gradually increasing with increasing dose, but when the dose continued to increase, inhibition occurred instead. The 15.0 g/kg dose of Luo Han Guo had the most significant effect on improving mouse physiological function [17]. Monk Fruit extract can also significantly improve the exercise capacity and myocardial anti-free radical oxidation function of trained mice, and has a significant protective effect against free radical damage caused by high-intensity exercise [18].

6 Antibacterial effect

Monk Fruit fruit, leaves, stems and roots all have strong antibacterial activity against Streptococcus mutans [19]. The extract of the fruit of Luo Han Guo has a strong inhibitory effect on Streptococcus mutans. The crude extract was separated by HPLC to obtain 50 components. Two HPLC components of the fruit extract of Luo Han Guo, #18-19 and #34-35, have a strong inhibitory effect on Streptococcus mutans, while the other components have no or only weak activity. Mogroside V has no antibacterial activity [20]. The ethanol extract of the leaves and stems of Luo Han Guo has good antibacterial activity against Pseudomonas aeruginosa and Escherichia coli [21]. It has also been reported that the growth rate and adhesion of Streptococcus mutans in culture medium containing Luo Han Guo concentrated juice are significantly lower than those in sucrose (P<0.05), but the acid production is higher; in culture medium containing Luo Han Guo sweeteners, there is almost no growth and reproduction, and xylitol were not significantly different (P>0.05); Luo Han Guo concentrate is a low-caries sucrose substitute, especially Mogroside, which can be widely used as a health-care high-potency sweetener [22].

7 Other effects

Mogroside IV and its glycosides can inhibit the rubbing nose and scratching back behaviors induced by histamine and compound 48/80, indicating that they have an inhibitory effect on the mouse skin hypersensitivity model, but a single dose is ineffective [23]. Its inhibition of mouse nose rubbing and scratching behaviors may be related to a mast cell-dependent mechanism [24]. Mogroside has a protective effect on the formation of cerebral thrombosis in mice, inhibits the increase in TC and TG levels and increases HDL-C levels caused by egg yolk emulsion in mice. It also inhibits the effect of ADP on platelet aggregation in rats, indicating that mogroside has certain pharmacological effects of activating blood circulation and removing blood stasis, such as anti-thrombosis, anti-platelet aggregation and anticoagulation [25]. The results of an acute toxicity test on mice using Mogroside showed that LD50>10,000 mg/kg, which is practically non-toxic. An Ames mutagenicity test using Salmonella typhimurium was negative. Mogroside 3.0 g/kg (equivalent to 360 times the human dose) was administered by gavage for 4 weeks, and there was no significant effect on the hematological indicators, liver and kidney function, blood glucose and urinary glucose, as well as morphological changes in the heart, liver, kidney, lungs and spleen, had no significant effect. The results of the three experiments showed that Mogroside is a basically non-toxic substance [26].

8 Conclusion

In recent years, pharmacological research on Luo Han Guo has yielded many new discoveries, laying a good foundation for the development of new Luo Han Guo products. In the future, further research should be conducted on its pharmacological mechanisms and active ingredients, to accelerate the development of medicines or health foods that use Luo Han Guo as the main ingredient for cough suppression and expectorant, antioxidant, liver protection and anti-liver fibrosis, immune enhancement, blood glucose and lipid lowering, anti-fatigue, oral health care, etc.

References

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

[2] Zhou X X, Song J S. Research on the pharmacological effects of Luo Han Guo and Luo Han Guo extract [J]. Chinese Medicine Journal, 2004, 22 (9): 1723-1724.

[3] Li Jian, Li Peibo, Yuan Ganjun. Study on the antitussive effect of water extract of Luo Han Guo [J]. Journal of Hainan Medical College, 2008, 14 (1): 16-18.

[4] Liu Ting, Wang Xuhua, Li Chun, et al. Study on the antitussive, expectorant and antispasmodic effects of Luo Han Guo saponin V [J]. Chinese Journal of Pharmacy, 2007, 42 (20): 1534-1536, 1590.

[5] Qi Xiangyang, Chen Weijun, Zhang Liqin, et al. Research on the scavenging of free radicals and anti-lipid peroxidation of Luo Han Guo saponin [J]. Chinese Agricultural Science, 2006, 39 (2): 382-388.

[6] Li Haiyun, Wang Xiuli, Pan Yingming, et al. Antioxidant and free radical scavenging activities of different solvent extracts of Luo Han Guo [J]. Guangxi Botany, 2008, 28(5): 689-702.

[7] Hao Guixia. The scavenging effect of Luo Han Guo extract on free radicals [J]. Jiangxi Chemical Industry, 2005, 12(4): 89-90.

[8] Wang Kai, Zhu Zhiren, Pan Yingming, et al. Study on the antioxidant activity of different solvent extracts of Luo Han Guo stems [J]. Food Industry Science and Technology, 2008, 29(3): 57-58.

[9] Xiao Gang, Wang Qin. Research on the protective effect of mogroside on experimental liver injury in mice [J]. Chinese Pharmacy, 2008, 19(3): 163-165.

[10] Wang Qin, Xiao Gang. Experimental study on the protective effect of mogroside on chronic liver injury in rats [J]. Guangxi Traditional Chinese Medicine, 2007, 30(5): 54-56.

[11] 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.

[12] Li Jun, Huang Yan, Liao Riquan, et al. Effects of Luo Han Guo polysaccharide on immune function in mice [J]. Chinese Pharmacology Bulletin, 2008, 24(9): 1237-1240.

[13] Chen Weijun, Song Fangfang, Liu Liegang, et al. Effect of Luo Han Guo saponin extract on cellular immune function in mice with type 1 diabetes [J]. Journal of Nutrition, 2006, 28(3): 221-225.

[14] Xu Qing, Liang Ronggan, Su Xiaojian, et al. Effect of mogroside on blood glucose and liver enzyme activity in normal people [J]. Food Science, 2007, 28(6): 315-317.

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

[16] Zhao Yan, Liu Guoyan, Shi Xianming. Effects of Luo Han Guo concentrated juice and Mogroside on blood lipid metabolism in mice [J]. Chinese Journal of Food Science, 2008, 8(1): 9-12.

[17] Yao Jiwei, Xiong Juliang, Shen Weihua, et al. Effects of different doses of Luo Han Guo extract on the tolerance of hypoxic and high temperature and exercise capacity of swimming trained mice [J]. Journal of Jilin College of Physical Education, 2007, 23(2): 64-66.

[18] Yao Jiwei, Yang Yongliang, Tang Hui, et al. Effects of Luo Han Guo extract on exercise capacity and myocardial free radical metabolism in trained mice [J]. Journal of Beijing Sport University, 2009, 32 (3): 67-69.

[19] Zhou Ying, Huang Chifu. Study on the antibacterial active components of the leaves, stems and roots of Luo Han Guo [J]. Zhongguo Zhenjiu Guoyao, 2008, 19(7): 1797-1799.

[20] Zhou Ying, Guo Baisu, Zheng Yan, et al. Study on the antibacterial active components in the fruit of Monk Fruit [J]. Zhongguo Zhenjiu Guoyao, 2008, 19(6): 1544-1546.

[21] Ye Min, Zhou Ying. Bacteriostatic effect of ethanol extract from the leaves and stems of Luo Han Guo [J]. Journal of Mountain Agriculture and Biology, 2008, 27(1): 42-46.

[22] Zhao Yan. Experimental study on the cariostatic properties of Luo Han Guo concentrated juice and Luo Han Guo glycosides [J]. Food Research and Development, 2010, 31(2): 87-90.

[23] Hossen Maria. The effect of Luo Han Guo extract and its glycosides on the mouse skin allergy model [J]. Foreign Medicine: Traditional Chinese Medicine Branch, 2005, 27(6): 368.

[24] Huang Weijuan. The effect of Luo Han Guo on the rubbing and scratching behavior of ICR mice [J]. Foreign Medicine: Botanical Medicine, 2006, 21 (5): 220-221.

[25] Chen Quanbin, Shen Zhongsu, Wei Zhengbo, et al. Research on the pharmacological effect of Luo Han Guo flavonoids in activating blood circulation and resolving blood stasis [J]. Guangxi Science, 2005, 12(4): 316-319.

[26] Su Xiaojian, Xu Qing, Liang Ronggan, et al. Toxicological study of mogroside [J]. Food Science, 2005, 26(3): 221-224.