In vitro cytotoxic activity of isolated compounds from Malaysian Calophyllum species

Cancer is a leading cause of death worldwide. In our continuing search for new anticancer agents, four Malaysian Calophyllum species, namely C. castaneum, C. teysmannii, C. canum, and C. sclerophyllum, had been phytochemically studied to give compounds 1-12. All the isolated compounds were evaluated for their antiproliferative activity against nasopharyngeal (SUNE1, TW01, CNE1, HK1) and breast (HCC38, MDA-MB-231, MDA-MB-468, SKBR3) cancer cell lines via methyl thiazolyl tetrazolium cell viability assay. Among the tested compounds, isodispar B (1) showed a promising dose-dependent and a broad spectrum of cytotoxic effects on all the tested cancer cell lines; in particular, potent inhibitory activities were observed on nasopharyngeal cancer cell lines (SUNE1, TW01, CNE1, HK1), with IC50 values ranging from 3.8 to 11.5 A mu M. In comparison with 5-fluorouracil as positive control, compound 1 was found to exhibit at least sixfold much higher activity than the standard drug used against the nasopharyngeal cell lines. Compound 1 was later found to induce apoptotic cell death in nasopharyngeal cancer cells, as evidenced by 'Cell Death Detection' ELISA(PLUS) kit, and exhibited good cancer-specific cytotoxicity when tested with noncancerous NP460 cells. Meanwhile, compounds 2-12 displayed moderate to weak activities against the tested cancer cell lines. The findings have highlighted the therapeutic potential of compound 1 against nasopharyngeal cancer.