Synthesis, structure and antimicrobial evaluation of a new gossypol triazole conjugates functionalized with aliphatic chains and benzyloxy groups

Abstract

Synthetic limitations in the copper-catalyzed azide alkyne cycloaddition (CuAAC) on gossypol's skeleton functionalized with alkyne (2) or azide (3) groups have been indicated. Modified approach to the synthesis of new gossypol-triazole conjugates yielded new compounds (24-31) being potential fungicides. Spectroscopic studies of triazole conjugates 24-31 have revealed their structures in solution, i.e., the presence of enamine-enamine tautomeric forms and π-π stacking intramolecular interactions between triazole arms. Biological evaluation of the new gossypol-triazole conjugates revealed the potency of 30 and 31 derivatives, having triazole-benzyloxy moieties, comparable with that of miconazole against Fusarium oxysporum. The results of HPLC evaluation of ergosterol content in different fungi strains upon treatment of gossypol and its derivatives enabled to propose a mechanism of antifungal activity of these compounds.

Keywords: 1,2,3-Triazoles; Antifungal; Gossypol; Mechanism of action; Spectroscopy; π–π stacking.