Voriconazole Inhibits Melanization in Cryptococcus neoformans

Voriconazole is a triazole antifungal drug that inhibits ergosterol synthesis and has broad activity against yeast and molds. While studying the interaction of voriconazole and Cryptococcus neoformans, we noted that cells grown in the presence of subinhibitory concentrations of voriconazole reduced melanin pigmentation. We investigated this effect systematically by assessing melanin production in the presence of voriconazole, amphotericin B, caspofungin, itraconazole, and fluconazole. Only voriconazole impeded the formation of melanin at subinhibitory concentrations. Voriconazole did not affect the autopolymerization of l-dopa, and 0.5 MIC of voriconazole did affect the gene expression of C. neoformans. However, voriconazole inhibited the capacity of laccase to catalyze the formation of melanin. Hence, voriconazole affects melanization in C. neoformans by interacting directly with laccase, which may increase the efficacy of this potent antifungal against certain pigmented fungi.