Two new isoflavones from Dalbergia rimosa Roxb.

Studies on chemical constituents in the rhizome of Dalbergia rimosa Roxb. The chemical constituents from the ethyl acetate part of D. rimosa were isolated and purified by silica gel, MCI gel, Sephadex LH-20 gel and semi-preparative HPLC, and the stuctures were identified by spectral method. Thirteen compounds were isolated from the ethyl acetate part of the rhizome of D. rimosa and identified as dalbergiaisoflavones A, B (1, 2), formononetin (3), 7,4′-dimethoxyisoflavone (4), 4′,6,7-trimethoxyisoflavone (5), biochanin A (6), prunetin (7), 7-O-methyltectorigenin (8), 3′-hydroxydaidzein (9), orobol 7,3′-dimethyl ether (10), 2′,7-dihydroxy-4′,5′- dimethoxyisoflavone (11), pruinosanone E (12), caviunin (13). Compounds 1 and 2 are new compounds, and compounds 3-13 were isolated from this plant for the first time. Compounds 9 and 11 had remarkable scavenging effect on DPPH free radicals.