Fissistiganoids A and B: two new flavonoids from the Fissistigma tungfangense .

Two new flavanoids fissistiganoids A and B ( 1 and 2 ), together with two known pterocarpans derivatives ( 3 and 4 ), were isolated from the stems of Fissistigma tungfangense . The structures of these compounds were elucidated using comprehensive spectroscopic methods. The absolute configurations of fissistiganoids A and B ( 1 and 2 ) were determined by comparing their ECD spectra with quantum-mechanics ECD calculations. The inhibitory activities of all compounds against three cancer cell lines HeLa, MCF-7 and A549 were evaluated. Compounds 1-4 showed moderate inhibitory effects on HeLa, MCF-7 and A549 cells with IC ₅₀ values ranging from 12.5 to 42.3  μ M.