New arahypins isolated from fungal-challenged peanut seeds and their glucose uptake-stimulatory activity in 3T3-L1 adipocytes

Two new stilbene dimers (arahypin-8 and arahypin-9) and one monomeric stilbene derivative arahypin-10 were isolated for the first time from wounded peanut seeds challenged by a Rhizopus oligoporus strain, a starter culture for soybean fermentation in Southeast Asia. The structures of the three new compounds were elucidated on the basis of HRESIMS, UV, 1D and 2D NMR spectroscopy and the plausible mechanism of their formation was proposed. In addition, these compounds showed insulin sensitizing effect by enhancing insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes.