A First-in-Class Pyrazole-isoxazole Enhanced Antifungal Activity of Voriconazole: Synergy Studies in an Azole-Resistant Strain, Computational Investigation and in Vivo Validation in a Fungal Infection Model.

The widespread and irrational use of azole antifungal agents has led to an increase of azole-resistant strains with an urgent need for combination drug therapy, enhancing the treatment efficacy. Here, we report the discovery of a first-in-class pyrazole-isoxazole, namely, , that showed remarkable growth inhibition against the . ATCC 10231 strain in combination with voriconazole, acting as a downregulator of ERG 11 () gene expression with a significant reduction of the yeast-to-hypha morphological transition. Furthermore, . CYP51 enzyme assay and in-depth molecular docking studies unveiled the unique ability of the combination of and voriconazole to completely fill the CYP51 binding sites. studies using a model confirmed the previously observed synergistic effect of with voriconazole. Also considering its biocompatibility in a cellular model of human keratinocytes, these results indicate that represents a promising compound for a further optimization campaign.