Synthesis and antifungal activity of 8-hydroxyquinoline derivatives bearing 1,2,3-triazole moiety

Abstract

The lack of selective antifungal agents and the growth of fungal resistance to current treatments has become a worldwide concern, especially for immunocompromised patients. 8-Hydroxyquinolines and 1, 2 ,3 - triazoles have shown wide spectrum effects against several microorganisms. Thus, the purpose of this study was the synthesis of 1,4-triazole-substituted 8-hydroxyquinoline derivatives and evaluation of in vitro antifungal activity against strains of dermatophytes and Candida spp. The commercial available 8-hydroxyquinoline 1 was used to prepare triazole derivates 7a-7d in eight-step synthesis: nitrosation of 1 followed by oxidation to 5-nitro-8-hydroxyquinoline 2; reduction of 2 to 5-amino-8-hydroxyquinoline 3; diazotization of 3 followed by azide replacement to 5-azido-8-hydroxyquinoline 4; acetylation of 4 to 5-azidoquinolin-8-yl acetate 5; copper (I) catalyzed cycloaddition of 5 and deprotection of acetylated intermediates 6a-6d to triazole derivates 7a-7d. The compounds prepared were characterized by 1H and 13C NMR. The evaluation of antifungal activity was determined by broth microdilution assay. The compound 7a presented the most potent activity against dermatophytes, C. albicans and C. glabrata strains, and compounds 7c and 7d had good MIC values for the strains of Trichophyton, C. krusei and C. glabrata. These compounds have the potential to be developed as antifungal agents.