Novel 3,4-dihydro-4-oxoquinazoline-based acetohydrazides: Design,synthesis and evaluation of antitumor cytotoxicity and caspase activation activity

In search for novel small molecules with antitumor cytotoxicity via activating procaspase-3, we have designed and synthesized three series of novel (E)-N′-benzylidene-4-oxoquinazolin-3(4H)-yl)acetohydrazides (5a-j, 6a-h, and 7a-h). On the phenyl ring ò the benzylidene part, three different substituents, including 2-OH-4-OCH₃, 4-OCH₃, and 4-N(CH₃)₂, were introduced, respectively. Biological evaluation showed that the acetohydrazides in series 5a-j, in which the phenyl ring of the benzylidene part was substituted by 2-OH-4-OCH₃ substituent, exhibited potent cytotoxicity against three human cancer cell lines (SW620, colon; PC-3, prostate; NCI-H23, lung). Most of the compounds, in this series, especially compounds 5c, 5b and 5h, also significantly activated caspase-3 activity. Among these, compound 5c displayed 1.61-fold more potent than PAC-1 as caspase-3 activator. Cell cycle analysis showed that compounds 5b, 5c, and 5h significantly arrested the cell cycle in G1 phase. Further apoptotic studies also demonstrated compounds 5b, 5c, and 5h as strong apoptotic cell death inducers. The docking simulation studies showed that these compounds could activate procaspase via chelating Zn²⁺ ion bound to the allosteric site of the zymogen.