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

A series of thiosemicarbazones deriving from the natural sesquiterpene (−)-α-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 0.01–4.22 μM). Among the analogues, the ketone derivative 3l was the most active, exhibiting potent antitumoral activity (GI50 0.01 μM) and high selectivity for K-562 cells (δTGI 505). It also demonstrated high cytotoxicity, with an LC50 of 1.55 μM for the K-562 cells, but it showed only moderate selectivity (δLC50 38.5 μM). Through structure–activity relationship studies, we identified some structural requirement for the antitumoral activity exhibited by these promising compounds.

Graphical abstractA new series of thiosemicarbazone derivatives based on the natural product α-(−)-bisabolol was synthesized and the in vitro anti-cancer activity of these compounds was evaluated against eight human tumor cell lines.Figure optionsDownload full-size imageDownload as PowerPoint slide