Synthesis of 3-heteroarylthioquinoline derivatives and their in vitro antituberculosis and cytotoxicity studies

A series of 3-heteroarylthioquinoline derivatives has been synthesized by the Friedlander annulation of 2-[(5-methyl-1,3,4-thiadiazol-2-yl)sulfanyl]-1-aryl-1-ethanone/2-(1,3-benzothiazol-2-ylsulfanyl)-1-aryl-1-ethanone/1-aryl-2-[(2-phenyl-2H-1,2,3,4-tetraazol-5-yl)sulfanyl]-1-ethanone with 2-aminobenzophenone in good yields using YbCl3 as the catalyst. These compounds have been screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and among the 21 compounds screened, 2-[2-(4-bromophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5d) and 2-[2-(4-chlorophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5c) were found to be the most active compounds with MIC of 3.2 and 3.5 μM respectively against MTB. The cytotoxic effects against mouse fibroblasts (NIH 3T3) in vitro were evaluated for 5c and 5d, which displayed no toxic effects (IC50 > 1000 μM) against the mouse fibroblast cell line NIH 3T3.

Graphical abstractA series of quinoline derivatives linked to thiadiazole, benzothiazole or tetrazole by a sulfur atom has been synthesized and screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► YbCl3 has been identified as an effective catalyst for Friedlander synthesis. ► Synthesis of novel heteroarylthioquinoline moieties has been reported. ► The synthesized compounds are tested for their antituberculosis activity. ► The cytotoxicity studies of identified active compounds have been carried out.