Bioactive isoflavones from Dalbergia vacciniifolia (Fabaceae).

Three new 5-dehydroxy isoflavone compounds, 6,2'-dimethoxy-7,4'-dihydroxyisoflavone (1), 6,2',4'-trimethoxy-7-hydroxyisoflavone (2), and 6,2',4',5'-tetramethoxy-7-O-[beta-D-apiofuranosyl-(1 --> 6)-beta-D-glucopyranoside] isoflavone (3), along with a known isoflavone, 6,2',4',5'-tetramethoxy-7-hydroxyisoflavone (4), were isolated from the ethanolic extract of Dalbergia vacciniifolia Vatke. Their structures were established by spectroscopic techniques including one- and two-dimension NMR. Compound 1 showed mild cytotoxic activity against brine shrimp larvae with a LC50 value of 266 microg/mL.