Synthesis, QSAR and anticandidal evaluation of 1,2,3-triazoles derived from naturally bioactive scaffolds

In the present study, we used eight natural precursors (1a-h) with most of them having promising antimicrobial activities and synthesised their novel 1,2,3-triazole derivatives (3a-h). In the reaction sequences, the precursor compounds (1a-h) were converted to their respective alkyne (2a-h) followed by addition of benzyl azide freshly prepared by the reaction of benzyl bromide with sodium azide using [3 + 2] azide-alkyne cycloaddition strategy. Structural elucidation of all the triazole derivatives was done using FT-IR, (1)H, (13)C NMR, mass and elemental analysis techniques. The single crystal X-ray diffraction for 3d was also recorded. The result of in vitro anticandidal activity performed against three different strains of Candida showed that compound 3e was found superior/comparable to fluconazole (FLC) with IC50 values of 0.044 μg/mL against Candida albicans (ATCC 90028), 12.022 μg/mL against Candida glabrata (ATCC 90030), and 3.60 μg/mL against Candida tropicalis (ATCC 750). Moreover, at their IC50 values, compounds 3e and 3h showed <5% hemolysis which indicates the non-toxic behaviour of these inhibitors. Cytotoxicity assay was also performed on VERO cell line and all the derivatives were found non-toxic up to the concentration of 10.0 μg/mL. The in silico technique of 3D-QSAR was applied to establish structure activity relationship of the synthesized compounds. The results reveal the molecular fragments that play an essential role in improving the anticandidal activity.