New cytotoxic apigenin derivatives from Selaginella doederleinii

75% aqueous ethanol extract from the whole herbs of Selaginella doederleinii was isolated, and two new apigenin derivatives, doederflavones A (1) and B (2), together with ten known compounds (3-12) were characterized. Their structures were assigned by extensive spectroscopic methods including 1D/2D NMR and HR-ESIMS. Compounds 1-6 bear an aryl substituent at the C-8 or C-6 positions in ring A of apigenin skeleton. Compounds 1 and 2 were evaluated for their in vitro cytotoxicity against four human cancer cell lines A549, MCF-7, SMMC-7721, and LoVo, both of which exhibited significant cytotoxicity against A549 with IC₅₀ values of 0.82 μmol/L and 1.32 μmol/L, respectively.