Antitumor activity of 2(S)-5,2',5'-trihydroxy-7,8-dimethoxyflavanone and its analogues

In an effort to increase of the antitumor activity of 2(S)-5,2',5'-trihydroxy-7,8-dimethoxyflavanone isolated fromScutellaria indica, we synthesized its analogues,II, III, andIV. They showed potent cytotoxicityin vitro against cancer cell lines, L1210, K562 and A549. On the basis of ED(50) values against the cancer cell lines,III exhibited about 2-7 times stronger activity thanI against various cell lines. We tested the antitumor activity of the analogues against Sarcoma 180 cellsin vivo and evaluated the structure-activity relationship. The antitumor activity appeared to be related to the hydrogen bond between carbonyl group at C-4 and hydroxyl group at C-5, in contrast to cytotoxic action.