Design, synthesis and biological activity of hybrid antifungals derived from fluconazole and mebendazole

A novel series of triazole alcohol antifungals bearing a 5-benzoylbenzimidazol-2-ylthio side chain have been designed and synthesized as hybrids of fluconazole (a typical triazole antifungal) and mebendazole (an anthelmintic agent with antifungal activity). The title compounds were synthesized via the reaction of an appropriate oxirane and desired 2-mercaptobenzimidazole. Although there was possibility for formation of different N-substituted or S-substituted products, the structures of final compounds were assigned as thioether congeners by using 13C NMR spectroscopy. The SAR analysis of the primary lead compounds (series A) was conducted by simplifying the 5-benzoylbenzimidazol-2-ylthio residue to the benzimidazol-2-ylthio (series B) or benzothiazol-2-ylthio side chain (series C), and modification of halogen substituent on the phenethyl-triazole scaffold. In general, series A (compounds 4a-e) containing 5-benzoylbenzimidazole scaffold showed better antifungal activity against Candida spp. and Cryptococcus neoformans than related benzimidazole and benzothiazole derivatives. The better results were obtained with the 4-chloro derivative 4b displaying MICs