Two New Benzoquinone Derivatives from Vietnamese Knema globularia Stems

The chemical investigation of the stems of Knema globularia led to the isolation of two new benzoquinones derivatives, embenones A and B (1 and 2), along with three known compounds (3-5). The structures of the isolated compounds were determined using spectroscopic techniques, including HRESIMS, 1D and 2D NMR, in conjunction with comparison to existing literature data. Compounds 1 and 2 represent new carbon skeletons in nature. Furthermore, all isolated compounds were evaluated for their alpha-glucosidase inhibitory activity, with compounds 1-3 exhibiting superior potency relative to the positive control (acarbose, IC50 331 mu M). Their IC50 values ranged from 1.40 to 96.1 mu M.