Antimalarial diterpenoid dimers of a new carbon skeleton from Aphanamixis grandifolia.

Chemical investigation into the minor constituents of Aphanamixis grandifolia yielded three new diterpenoid dimers, aphadilactones E-G (1-3) featuring a new carbon skeleton. Their structures and absolute configurations were fully established by comprehensive spectroscopic data analysis and ECD calculation. Discovery of another two new dimers (4 and 5) suggested the structure of recently reported aphanamene A to be re-investigated. Compounds 1-5 showed moderate antimalarial activities with low micromolar IC50 values.