Thiazole and Related Heterocyclic Systems as Anticancer Agents: A Review on Synthetic Strategies, Mechanisms of Action and SAR Studies

Background: Cancer is the second leading cause of death worldwide. Many anticancer drugs are commercially available, but lack of selectivity, target specificity, cytotoxicity, and development of resistance lead to serious side effects. Several experiments have been going on to develop compounds with minor or no side effects. Objective: This review mainly emphasizes synthetic strategies, SAR studies, and mechanism of action if thiazole, benzothiazole, and imidazothiazole-containing compounds as anticancer agents. Methods: Recent literature related to thiazole and thiazole-related derivatives endowed with encouraging anticancer potential is reviewed. This review emphasizes contemporary strategies used for the synthesis of thiazole and related derivatives, mechanistic targets, and comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency thiazole-based anticancer drug candidates. Results: Exhaustive literature survey indicated that thiazole derivatives are associated with properties of inducing apoptosis and disturbing tubulin assembly. Thiazoles are also associated with the inhibition of NFkB/mTOR/PI3K/AkT and regulation of estrogenmediated activity. Furthermore, thiazole derivatives have been found to modulate critical targets, such as topoisomerase and HDAC. Conclusion: Thiazole derivatives seem to be quite competent and act through various mechanisms. Some of the thiazole derivatives, such as compounds 29, 40, 62, and 74a with IC50 values of 0.05 μM, 0.00042 μM, 0.18 μM, and 0.67 μM, respectively, not only exhibit anticancer activity, but they also have lower toxicity and better absorption. Therefore, some other similar compounds could be investigated to aid in the development of anticancer pharmacophores.