Concise Synthesis of Some New Benzothiazole‐Based Heterocycles as Probable Anticancer and Antioxidant Agents

Abstract Benzothiazole is the basic skeleton of multi‐target drugs with remarkable anticancer and antioxidant characteristics. In this research, new sets of benzothiazole derivatives carrying different pharmacophores and heterocyclic rings (e. g. 1,2,3‐triazole, pyrazole, thiazolidinone, thiophene, benzothiazole, 1,3‐dithiane, chromene, and pyrimidine) were efficiently synthesized through different synthetic routes from the newly synthesized ethyl 3‐(benzo[ d ]thiazol‐2‐ylamino)‐3‐oxopropanoate ( 1 ). These compounds were assessed in vitro as cytotoxic agents against two human cell lines, HCT‐116 (colon carcinoma) and WI‐38 (normal lung fibroblast) employing the MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay, in which doxorubicin was used as a positive standard. Among the synthesized compounds, 1,2,3‐triazole 3 and pyrazoles 6 and 12 inhibited the growth of HCT‐116 cell line with high potency (IC 50 =7.54±0.7, 9.89±0.8, and 8.45±0.7 μM, respectively), along with low toxicity to normal cells, indicated their selectivity. Further, they were screened for their antioxidant performance using the ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid)) bioassay and the results coincided with those of the cytotoxicity test, where the most powerful anticancer candidates displayed promising antioxidant activities with % inhibition 80.98 %, 84.12 %, and 88.82 %, respectively, comparable or superior to those of ascorbic acid (88.63 %).