Solvent-free synthesis of novel (E)-2-(3,5-dimethyl-4-(aryldiazenyl)-1H-pyrazol-1-yl)-4-arylthiazoles: determination of their biological activity

In search of novel biologically active azoles, some new (E)-2-(3,5-dimethyl-4-(aryldiazenyl)-1H-pyrazol-1-yl)-4-arylthiazoles 3a–p have been synthesized via Hantzsch thiazole approach under greener, mild and solvent-free conditions. Structures of all compounds were established on the basis of the rigorous elemental analysis and their IR, NMR (1H, 13C), COSY, ROSEY, HSQC and HMBC spectral data. To explore the biological potential, all the synthesized compounds were evaluated for their antimicrobial, antioxidant and UV-mediated DNA damage-protective and photocleavage activity. The results of antimicrobial study revealed that among the series, compounds 3g–l were found active selectively against C. albicans. The compound 3l exhibited twofold high antifungal potential in comparison with amphotericin-B, a standard drug against C. albicans. The compound 3k was found equipotent, and 3g–j displayed half of the potential in reference to the standard drug. In UV-induced DNA damage-protecting and photocleavage study, 3j and 3n were found as the most potent DNA damage-protecting and DNA-photocleaving agents, respectively, at 40 µg concentration. The compounds 3d, 3e, 3g, 3i, 3k, 3m and 3o also displayed a significant level of DNA damage-protective potential, whereas 3l and 3p exhibited appreciable DNA photocleavage activity. In the antioxidant study, all compounds were found inactive.