A pair of new isoflavonoid enantiomers from Dalbergia benthamii Prain

Thirteen isoflavones were separated and purified from an ethanol extract of the rhizome of Dalbergia benthamii Prain by using silica gel, Sephadex LH-20, recrystallization et al. Their structures were identified by physicochemical properties and spectral analysis such as MS, 1D/2D-NMR as dalbergibenthamin (1), butesuperin A (2), xanthocercin A (3), butesuperin B (4), di-O-methylalpinum isoflavone (5), 2′-deoxgisoaunculutin (6), robustone (7), 4′-hydroxy-5, 7-dimethoxy-6-(3-methyl-2-butenyl)-isoflavone (8), formononetin (9), 6″-O-rhamnosyldaidzin (10), 3′, 4′-di-O-methylene-5-hydroxy-7-methoxy-6-isopentenyl isoflavone (11), derrubone dimethyl enter (12), and derrubone (13). Compound 1 is a pair of new isoflavonoid enantiomers, compound 12 is a new natural product and compounds 1-7 and 10-13 were obtained from D. benthamii Prain for the first time. In vitro cytotoxic activities of the compounds were explored by MTS testing with HL-60, A-549, SMMC-7721, MCF-7 and SW480 cell lines. Results show that compound 8 significantly inhibited cellular proliferation. The IC₅₀ of compound 8 in A-549 and SW480 cells was 16.68 ± 0.19 and 15.21 ± 0.60 μmol·L^-1.