New flavonoids with cytotoxicity from the roots of Flemingia latifolia.

Flemingia latifolia is a folk medicine in China, which is used for treating rheumatism, arthropathy, chronic nephritis and menopausal syndrome. The phytochemicals of the plant have seldom been studied so far. In present study, three new compounds, a flavanone quinone (flemingiquinone A) (1), a prenylated dihydroflavonoid (khonklonginol I) (2) and an isoflavonoid (flemilatifolin B) (3) were isolated from the roots of F. latifolia. Their structures were established by (1)H and (13)C NMR spectra and 2D NMR experiments, including COSY, HMQC, HMBC and ROESY. Meanwhile, the compounds were evaluated for cytotoxicity against two human cancer cell lines, SMMC-7721 and A-549. The results showed that compounds 1 and 2 possessed moderate antiproliferative effects on SMMC-7721 and A-549 cell lines.