Design, Synthesis, Molecular Modeling and Biological Evaluation of Novel Benzothiazole-Based 1,3,4-Thiadiazole...

The present study aimed to design and synthesize a new series of benzothiazole analogues containing 1,3,4-thiadiazole, and assess their biological activities as potential anticancer agents.

N-(5,6-dimethylbenzo[d]thiazol-2-yl)-2-((5-(substituted amino)-1,3,4-thiadiazol-2-yl)thio)acetamide derivatives (4a-4h) were synthesized via the reaction of thiadiazole derivatives (3a-3h) with 2-chloro-N-(5,6- dimethylbenzo[d]thiazol-2-yl)acetamide (1) in the presence of potassium carbonate. All the target compounds have been characterized by spectral analysis. The anticancer activities of compounds 4a-4h were tested against two human HT-1376 bladder and HT-29 colorectal carcinoma cells using the WST-1 assay. Flow cytometry was used for the determination of apoptosis, cell cycle, and caspase 3/7 activity. Moreover, wound-healing assay was utilized to evaluate cell migration. In silico physicochemical, pharmacokinetics, and toxicological properties of compound 4g were determined by pkCSM, SwissADME, and SwissTargetPrediction online web tools.

Among all synthesized derivatives, compound 4g (N-(5,6-dimethylbenzo[d]thiazol-2-yl)-2-((5-((3- methoxyphenyl)amino)-1,3,4-thiadiazol-2-yl)thio)acetamide) recorded the highest antiproliferative activity against HT-1376 cells with an IC₅₀ as 26.51 μM at 24 h, which was less cytotoxic than cisplatin (IC₅₀=14.85 μM). The combined treatment with compound 4g and cisplatin increased the cellular apoptosis with a higher impact compared with the cisplatin group. The higher accumulation of cells in the G2 phase, a significant increase of caspase 3/7 activity, and the inhibition of migration rate were also observed in HT-1376 following a combination of compound 4g and cisplatin treatment versus cisplatin alone, which might be involved in the apoptotic effects of compound 4g.

The in vitro anticancer potential of compound 4g lays the foundation for future research to focus on its value as a novel and advanced cancer therapy.