Design, Synthesis, and Cytotoxic Bioevaluations of Some Benzylidene Cinnamoylhydrazides

Three series of benzylidene cinnamoylhydrazides (21 compounds) were synthesized and evaluated for cytotoxic activity against malignant and non-malignant cell lines. Among the compounds tested, 2d and 3c were the most active against Jurkat and CEM leukemia cells, with CC50 values in the low micromolar range. Both compounds were more potent against these leukemia cell lines than the reference compounds 5-fluorouracil, curcumin, and melphalan. However, 2d and 3c showed only modest selectivity over non-malignant Hs27 fibroblasts, with selectivity index values of 2.50 and 2.09, respectively, in CEM cells. Further studies in CEM cells showed that treatment with 2d and 3c was associated with apoptosis, caspase activation, increased ROS accumulation, mitochondrial membrane depolarization, and changes in cell-cycle distribution, with the most notable change being an increase in the sub-G0-G1 population. The compounds also showed growth-inhibitory and cytotoxic activity against several cell lines in the NCI-60 panel. Semi-empirical PM3 calculations suggested possible relationships between cytotoxic activity, electronic polarization of the α,β-unsaturated carbonyl system, and molecular dimensions. However, these relationships were not consistent across the series and should be considered preliminary. Overall, 2d and 3c represent useful hit structures for further investigation, although additional structural optimization and biological studies will be needed to improve their selectivity and better define their mechanisms of action.