Isoflavonoids from Flemingia strobilifera (L) R. Br. roots

A new isoflavone (1) isolated from the roots of Flemingia strobilifera (L) R. Br. was identified as 5,7,4'-trihydroxy 8,2',5'-tri(3-methylbut-2-enyl)isoflavone along with the known phytoconstituents: 5,7,2',4'-tetrahydroxyisoflavone (2), 5,7,4'-trihydroxyisoflavone (3) and beta-sitosterol (4). Structure assignments were performed on the basis of spectroscopic data including homo- and heteronuclear 1D and 2D NMR (COSY, HMBC and DEPT) and MS studies. The compounds were tested in vitro for antimicrobial activity and antioxidant activity and compounds (1-3) proved to be moderately active.