Zeasesquiterpene A-E, new sesquiterpenes from the roots of Zea mays

Zeasesquiterpene A-E (1-5), five new sesquiterpenes with two cyclohexanes, were isolated from the roots of Zea mays. Their structures were elucidated on the basis of 1D and 2D NMR spectral data and ECD analysis. A plausible biosynthetic pathway for the compounds (1-6) were hypothesized. All isolated compounds were screened for cytotoxicities against five human cancer cell lines (A549, MDA-MB-231, SK-Hep-1, SNU638 and HCT116) in vitro by MTT assay. Compound 4 showed potential cytotoxic activities against A549 (14.3 μΜ) and SNU638 (9.7 μΜ). By contrast, compound 1 exhibited moderate cytotoxicity to the four human cancer cell lines (A549, SK-Hep-1, SUN638 and HCT116), and the IC50 values are from 19.5 μΜ to 22.5 μΜ.