Bioconversion of Ginsenosides in American Ginseng Extraction Residue by Fermentation with Ganoderma lucidum Improves Insulin-like Glucose Uptake in 3T3-L1 Adipocytes

Abstract

Ginseng is one of the most popular traditional Chinese medicines that have been widely used in China and other Asian countries for thousands of years. Ginsenosides are the unique bioactive saponins occurring in ginseng, and their biological activities have been extensively investigated. A large amount of ginseng residue is produced as waste product due to its applications in manufacturing functional food products, even though it may still contain bioactive components. Thus, the objective of this study was to investigate the hypoglycemic activities of American ginseng extraction residue (AmR) via fermentation with Ganoderma lucidum. Our results showed that the total phenolic contents and β-glucosidase activity of AmR profoundly increased after fermentation with G. lucidum. In 3T3-L1 adipocytes, stimulation of glucose uptake by treatment with AmR was not significant, while fermented AmR (FAmR) exhibited insulin-like glucose-uptake-stimulatory effects. Importantly, the hypoglycemic effects of FAmR were positively associated with the amount of the deglycosylated minor ginsenosides Rg1, Rg3, and compound K. Taken together, our current findings suggest that bioconversion of AmR by fermentation with G. lucidum may be a feasible and eco-friendly approach to developing a functional ingredient for the management of diabetes, while also resolving the problem of ginseng waste.