Cytotoxic ent-abietane diterpenoids from the leaves of Croton lachnocarpus Benth.

A phytochemical investigation on the 90% ethanol extract of the leaves of Croton lachnocarpus Benth. led to three new ent-abietane diterpenoids, 7β,15-dihydroxy-ent-abieta-8,11,13-trien-3-one (1), 2β,15-dihydroxy-ent-abieta-8,11,13-triene (2), and 7β,13α,15-trihydroxy-ent-abieta-8(14)-en-3-one (3). Structural elucidation of all the compounds were performed by spectral methods such as 1 D and 2 D (1H-1H COSY, HMQC, NOESY and HMBC) NMR spectroscopy, in addition to electronic circular dichroism (ECD) spectra. The isolated compounds were tested in vitro for cytotoxic activity against 6 tumor cell lines. As a result, compound 3 exhibited some cytotoxicities against all the tested tumor cell lines with IC50 value less than 30 μM.