Antifungal activity of green propolis extract against planktonic cells and biofilms of Trichosporon asahii clinical isolates.

Trichosporon spp. have emerged as important agents of disseminated infections in immunocompromised patients, where they can express multiple virulence factors and exhibit reduced susceptibility to commonly used antifungal drugs. In this context, natural products have attracted increasing interest as alternative therapeutic agents. This study evaluated the antifungal and antibiofilm activity of a standardized green propolis ethanolic extract against ten clinical isolates of Trichosporon asahii, alone and in combination with conventional antifungals.Minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were determined using the broth microdilution method. Interactions with amphotericin B and fluconazole were assessed by the checkerboard assay. Biofilm inhibition and eradication were quantified and analyzed by scanning electron microscopy (SEM). Cytotoxicity was evaluated in murine fibroblasts.The extract exhibited significant antifungal activity against planktonic cells, with MIC and MFC values ranging from 276.25 to 1105 mg/L. Although no synergistic interactions were observed with amphotericin B or fluconazole, the combination with propolis reduced the MICs of these antifungals for some isolates. The extract also showed strong antibiofilm activity, reducing biofilm biomass by up to 100% in inhibition assays and up to 99% in eradication assays. SEM analyses confirmed a marked reduction in biofilm density and structural complexity following treatment. Cytotoxic effects were observed at concentrations ranging from 69.06 to 276.25 mg/L, whereas higher concentrations unexpectedly increased fibroblast viability. These findings demonstrate the antifungal and antibiofilm potential of standardized green propolis against T. asahii, highlighting its promise as a source of bioactive compounds for the development of alternative strategies to control difficult-to-treat trichosporonosis.