Study On The Lipid-Lowering Effect Of Ergosterol From Lentinus Edodes

The stipe of Lentinus edodes is a by-product of the processing of Lentinus edodes and is rich in various active ingredients.However,the current research mainly focuses on polysaccharides,dietary fiber,etc.Little study has been performed on the content of ergosterol in shiitake mushrooms and its lipid-lowering effect.In addition,ergosterol has the disadvantage of poor lipid solubility,which can be effectively improved by esterification to synthesize ergosterol ester.But the lipid-lowering activity of ergosterol ester is still not clear.Based on the above consideration,this study mainly carried out the following aspects of research.The cholesterol-lowering effect of the crude extract from Lentinus edodes stipe was studied.The content of ergosterol in shiitake mushroom and its stipe was analyzed by high performance liquid chromatography,and two ergosterol-rich extracts were prepared from the stipe of Lentinus edodes.The main components of these two extracts were analyzed and their effect on the lipid metabolism in SD rats fed high-cholesterol diets were further studied by oral gavage.The results showed that the content of ergosterol in dried shiitake mushrooms was 7.7 mg/g,while the content of ergosterol in shiitake mushroom cap and stipe was 7.8 mg/g and 5.2 mg/g,respectively.A higher content of protein,total sugar and polyphenols was observed in the extract using methanol/methylene chloride as solvent;while a higher content of total fat and ergosterol were found in the extract using n-hexane as solvent.Animal experiments showed that both extracts significantly reduced serum LDL-C,LDL-C/HDL-C and liver cholesterol,and the extract using methanol/dichloromethane as solvent significantly reduced serum TC and liver triglyceride levels.This chapter has made it clear that both extracts from the stipe of Lentinus edodes exhibited a cholesterol-lowering effect.Therefore,the mushroom stipe has the potential for further processing.The cholesterol-lowering effect of the the major sterol(ergosterol)in Lentinus edodes was studied.The effect of the major sterol(ergosterol)in Lentinus edodes at the dose of 0.5% and 1.5% on the cholesterol metabolism were investigated in SD rats fed a high cholesterol diet.The results showed that both 0.5% and 1.5% ergosterol could significantly reduce the serum,liver and fecal cholesterol levels in rats.And 0.5% and 1.5% ergosterol reduced serum TC levels by 19.4% and 21.6%,LDL-C by 42.1% and 42.1%,liver cholesterol by 53.2% and 46.5%,and increased fecal cholesterol by 51.0% and 59.3%,respectively.In vitro tests have shown that ergosterol can competitively inhibit cholesterol from entering the micelles,thereby affecting the absorption of cholesterol.Real-time PCR analysis showed that 0.5% and 1.5% ergosterol could up-regulate the expression of liver cholesterol metabolism-related genes,such as SREBP-2,LDL-R and CYP7A1.This chapter confirmed the cholesterol-lowering efficacy of ergosterol and provided its possible cholesterol-lowering mechanism of action.The lipid-lowering effect of ergosterol ester was studied.The effect of ergosterol linolenate on lipid metabolism was investigated using ergosterol as a positive control in C57BL/6 mice.The results showed that ergosterol and ergosterol linolenate significantly reduced body weight,fat index,liver cholesterol and total fatty acid content,and prevented liver steatosis.In addition,ergosterol linolenate significantly reduced plasma TG levels and increased total fatty acid content in feces.Real-time PCR analysis indicated that ergosterol linolenate significantly up-regulated the expression of LDL-R and HMG-CoR mRNA,down-regulated the expression of CYP7A1 and LXR-ɑ mRNA,and reduced the total bile acid level in feces.It was therefore speculated that the lipid-lowering mechanism of ergosterol linolenate is mainly through down-regulating the expression of LXR-ɑ and CYP7A1,reducing the bile acid,thereby inhibiting intestinal lipid absorption and promoting fecal lipid excretion.This chapter showed that ergosterol linolenate still retained the lipid-lowering effect of ergosterol and clarified its possible lipid-lowering mechanism.