Pramocaine hydrochloride potentiates fluconazole against Candida albicans biofilms by targeting Erg12 and inhibiting ubiquinone biosynthesis

Biofilms formed by Candida albicans pose significant challenges in clinical settings, particularly in medical device-related infections and recurrent candidiasis, due to their inherent resistance to azoles. Consequently, there is an urgent need to identify novel compounds that can potentiate the antifungal activity of azoles against C. albicans biofilms. In this study, we utilized a drug repositioning approach to perform high-throughput screening of a library of 2,372 Food and Drug Administration (FDA)-approved compounds, identifying pramocaine hydrochloride (pramocaine) as a potent azole potentiator with low cytotoxicity. Pramocaine significantly enhanced the antifungal activity of fluconazole (FLC) against C. albicans biofilms both in vitro (via biofilm inhibition assays) and in vivo (using a mouse subcutaneous catheter infection model), and exhibited broad-spectrum efficacy against other clinically relevant Candida and Cryptococcus species. Mechanistically, pramocaine targets Erg12, a key enzyme in the farnesyl pyrophosphate pathway, to inhibit ubiquinone biosynthesis and elevate mitochondrial reactive oxygen species (ROS) production. This leads to impaired mitochondrial function, reduced C. albicans hyphal elongation, biofilm thickness, and extracellular matrix secretion, thereby sensitizing C. albicans biofilms to FLC. As an FDA-approved compound, pramocaine offers promising translational potential for treating azole-resistant biofilm infections. This research introduces a novel strategy to potentiate the antifungal efficacy of FLC against C. albicans biofilms by targeting Erg12-mediated ubiquinone biosynthesis.