Four new diterpenes from Aphanamixis polystachya.

Four novel diterpenes possessing rare five-membered peroxide ring, aphanaperoxides E-H (1-4), were isolated from stem bark of Aphanamixis polystachya. Their structures including the absolute configuration were elucidated by spectroscopic data and CD analysis. The cytotoxicities of the isolated compounds against a panel of human cancer cell lines were evaluated.