Antitumor activity of ( )-a-bisabolol-based thiosemicarbazones against human tumor cell lines

Abstract

A series of thiosemicarbazones deriving from the natural sesquiterpene ( )-a-bisabolol were synthesized and tested against a panel of eight human tumor cell lines to evaluate their anti-tumor potential. Some of the compounds exhibited inhibitory effects on the growth of a wide range of cancer cell lines, but myeloid leukemia cells (K-562) were especially sensitive to all tested thiosemicarbazones (GI50 0.01e4.22 mM). Among the analogues, the ketone derivative 3l was the most active, exhibiting potent antitumoral activity (GI50 0.01 mM) and high selectivity for K-562 cells (dTGI 505). It also demonstrated high cytotoxicity, with an LC50 of 1.55 mM for the K-562 cells, but it showed only moderate selectivity dLC50 38.5 mM). Through structureeactivity relationship studies, we identified some structural requirement for the antitumoral activity exhibited by these promising compounds.