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 IC₅₀ values ranging from 12.5 to 42.3 μM.