Cytotoxic constituents from Vietnamese Pterospermum truncatolobatum Gagnep.

Pterospermum truncatolobatum Gagnep. has long been used as a traditional medicine in Vietnam. Its crude extract showed cytotoxicity against human epidermal carcinoma (KB) cell lines. However, its chemical constituent and biological activity remains unknown. In the course of our investigation on the Vietnamese medicinal plants, four compounds, taraxerol (1), betulonic acid (2), beta-sitosterol (3) and eicosanoic acid (4) were purified from methanolic extract of P. truncatolobatum by silica gel column chromatography. Their structures were determined by spectral (Mass spectrometry and nuclear magnetic resonance) analysis and by comparison with the literature reports. Of which, betulonic acid (2) showed moderate cytotoxicity against all four cancer cell lines, KB, MCF7 (human breast carcinoma), LU (human lung carcinoma), and HepG2 (hepatocellular carcinoma).