Abstract
In continuation to our efforts to discover new powerful antitumor agents, a series of new carbazole-based thiazole, thiophene, and 1,3,4-thiadiazole derivatives were conveniently synthesized, spectrally characterized, and mechanistically discussed. The synthetic strategy involves the cyclization reactions of two easily attainable commencing materials,N-(9-ethylcarbazol-3-yl)-2-cyanoacetamide (1) and 2-((9-ethylcarbazol-3-yl)hydrazono)-3-oxo-N-phenylbutanethioamide (20), with alpha-chlorocarbonyl reagents, alpha-chloronitrile, and hydrazonoyl chlorides in a basic medium. They were also assessed against three human tumor cell lines (HCT-116, HepG-2, and MCF-7) and one non-tumor human cell line (REP1) for their in vitro antitumor activity. The results demonstrated that seven carbazoles4,15 a,15 b,15 d,20,22 b, and29 ahad high antitumor activity, having IC(50)values in the range 5.24-9.70 mu M. The most potent carbazoles15 b,20and22 binhibited the growth of all tested tumor cell lines and did not display human toxicity.