Study of antioxidant and a-glucosidase inhibitory activities of exopolysaccharide and extracts from Caterpillar fungus Ophiocordyceps sinensis cultured in olive oil-supplemented broth

Abstract

Natural remedies that can simultaneously inhibit a-glucosidase and antioxidants have been becoming effective measures to prevent type 2 diabetes and its complications. Ophiocordyceps sinensis (O. sinensis) - “Dong trung ha thao”, is a valuable medicinal mushroom containing many natural compounds such as cordycepin, d-mannitol, polysaccharides with many important biological activities. O. sinensis has been used to treat a variety of diseases such as diabetes, high blood pressure, atherosclerosis, or to restore anti-aging health. In this study, O. sinensis was cultured in 5 % olive oil-supplemented broth to collect biomass and post-culture medium. The exopolysaccharide (EPS) was then obtained from the medium and the mushroom biomass was fractionated with 96 % ethanol, 70 % ethanol, 50 % ethanol, and water. Finally, in vitro antioxidant and a-glucosidase inhibitory activities of EPS and fractions were evaluated. The results revealed that the 70 % ethanol extract presented the greatest a-glucosidase inhibitory activity (14.07±0.25 %). The supplement of olive oil helped improve the antioxidant capacity of EPS compared to the control (without supplement). The present study results have established the basis for conducting further experiments to enhance the antioxidant activity and a-glucosidase inhibition on O. sinensis and clinical applications.