Antifungal activity of chrysin against Candida albicans biofilms In vitro and In vivo

Candida albicans (C. albicans) biofilms exhibit markedly enhanced tolerance to conventional antifungal agents, necessitating the identification of novel therapeutic alternatives. Chrysin, a naturally occurring flavonoid distributed in propolis and Passiflora species, possesses well-documented antioxidant and anti-inflammatory properties. However, its activity against C. albicans biofilms remains uncharacterized. This study comprehensively evaluated the antibiofilm efficacy of chrysin in vitro and in vivo. The sessile minimum inhibitory concentration causing 50% inhibition (SMIC₅₀) of chrysin against C. albicans SC5314 was 128 μg/mL. Chrysin suppressed biofilm metabolic activity, reduced biomass, and decreased cell viability in a concentration-dependent manner, as demonstrated by XTT reduction assay, crystal violet staining, and live/dead fluorescence staining. Scanning electron microscopy (SEM) revealed progressive dismantling of hyphal networks and disruption of biofilm architecture. Chrysin significantly elevated intracellular reactive oxygen species (ROS) levels and induced mitochondrial membrane potential (MMP) depolarization in a dose-dependent manner, indicating that oxidative stress induction is a key antifungal mechanism. In a murine oral candidiasis model, chrysin reduced fungal burden and tongue lesion scores in a concentration-dependent manner, with the 256 μg/mL group achieving outcomes comparable to fluconazole. Chrysin also attenuated pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while increasing interleukin-10 (IL-10). Biosafety assessment demonstrated cell viability above 80% in human oral keratinocytes (HOK) and above 85% in mouse fibroblasts (L929) at concentrations up to 512 μg/mL, with no observable organ toxicity in vivo. Collectively, these findings establish chrysin as a potent, mechanistically defined, and safe natural antifungal candidate with promising translational potential for the management of C. albicans biofilm-associated infections.