New stilbenoids isolated from fungus-challenged peanut seeds and their bioactivity evaluations

Abstract

The objective of this study was to isolate and characterize new and/or known peanut stilbenoids and to evaluate their biological activities. Four new prenylated stilbene dimers of novel construction patterns and two new monomeric stilbene derivatives were isolated for the first time from wounded peanut seeds challenged by a Rhizopus oligoporus strain, a food grade starter culture for soybean fermentation in Southeast Asia. The structures of the six new stilbene compounds were elucidated on the basis of HRESIMS, UV, 1D and 2D NMR spectroscopy and the plausible mechanisms of their formations were also proposed. The antioxidant, anti-diabetic, anti-obesity and anticancer effects of six new peanut stilbenoids together with three known peanut stilbenoids and resveratrol were tested and compared in different cell based assays. The results of our study indicate that the fungus-stressed peanut seeds may become a new potential source of natural pharmaceuticals.