Isolation and Stucture Elucidation of Diterpenes from Wedelia prostrata and Their Cytotoxicity Activities

In this paper, a new diterpene together with seven known diterpenes was isolated from Wedelia prostrata. The chemical structure of the new compound was elucidated via 1D and 2D nuclear magnetic resonance(NMR) techniques and mass spectrometry and identified to be 3α-phenylpropionoyloxy-ent-kaur-16-en-oic acid(1). The isolated diterpenes were tested for their cytotoxicity activities via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. The results show that compounds 1, 2, 3, 4 and 6 exhibit different levels of cytotoxic activities. Especially, compound 2 shows significant cytotoxicity toward HeLa and A549 cell lines(IC₅₀=6.14 and 8.76 μmol/L).