Clerodendrumol, A New Triterpenoid from Clerodendrum yaundense Gurke (Lamiaceae)

A new lupane-type triterpene named clerodendrumol (1), i.e., (16)-lupa-12,20(29)-dien-16-ol, together with five known compounds, octacosa-(5Z,9Z)-dienoic acid (3), tetracosanoic acid (4), genkwanin (5), (12S)-hydroxyoctadeca-(9Z,13E,15E)-trienoic acid (6), and (9S)-hydroxyoctadeca-(10E,12E)-dienoic acid (7), were isolated from the twigs of Clerodendrum yaundense. O-Acetylclerodendrumol (2), a derivative of 1, was prepared by a standard acetylation procedure applied to compound 1. The structure of the new compound was elucidated using spectroscopic analysis (NMR and MS) data, and chemical conversions (acetylation and deacetylation). The human breast cancer cell line (MDA-MB-231) was sensitive to all test samples, and clerodendrumol (1) as well as its derivative 2 had good activity (IC50 values 7.5 and 13.2M). Genkwanin (5) exhibited strong activity on HeLa cell line with IC50 7.8M.