New cytotoxic apigenin derivatives from Selaginella doederleinii

Two new apigenin derivatives, doederflavones A and B (1 and 2), together with ten known compounds (3-12) were isolated from the whole herbs of Selaginella doederleinii. Compounds 1 and 2 bear an aryl substituent at C-8 of apigenin skeleton. A postulated biosynthetic pathway of 1 and 2 was also discussed. These two new compounds exhibited considerable cytotoxicity against human cancer A549 cell lines with IC50 values of 0.82 μmol/L and 1.32 μmol/L, respectively.