An Efficient Nonconventional Glycerol-Based Solid Acid Catalyzed Synthesis and Biological Evaluation of Phosphonate Conjugates of 1,2,4-triazole Thiones

A series of diethyl (3-((5-aryl-1H-1,2,4-triazol-3-yl)thio)propyl)phos-phonates (7a–t) has been synthesized in excellent yields by coupling diethyl (3-bromopropyl)phosphonate and 5-aryl-1H-1,2,4-triazol-3-thiones employing an efficient, green and nonconventional heterogeneous SO3Hcarbon catalyst derived from glycerol. In addition, a facile and green approach for the esterification of carboxylic acids by utilizing glycerol-based solid acid catalyst has been reported. Structures of the synthesized compounds were characterized by IR, NMR and HRMS studies. These triazole derivatives were screened for their in vitro cytotoxicity using the standard MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide) assay against a panel of five different human cancer cell lines (HeLa: Cervix, A549: Lung, A375: Skin, MDA-MB-231: Breast and T98G: Brain). The antimicrobial activities of the synthesized compounds were investigated against four bacterial strains: Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and three fungal strains: Aspergillus niger, Aspergillus terreus, Aspergillus fumigatus. Preliminary results indicate that the compound 7f displayed maximum anticancer activity and the compounds 7d, 7e, 7f, 7m and 7q exhibited moderate antibacterial activity. The compounds 7g, 7h, 7o and 7p showed good antifungal activity with high inhibition zone diameter compared to the standard drug.