In phytochemical investigation for bioactive compounds from Thai medicinal plants in the family Gnetaceae, acetone crude extract from the roots of Gnetum macrostachyum was selected for isolation, purification and structure elucidation. The chromatographic separation of acetone crude extract led to the isolation of five new stilbenoids, macrostachyol A (6), B (7), C (11), D (13), and gnetumacrosin (9) along with eight known stilbenoids, isorhapontigenin (1), trans-resveratrol (2), gnetol (3), gnetin C (4), latifolol (5), parvifolol...