Antifungal potential of Brazilian green and brown propolis against clinically relevant yeasts

Brazilian biodiversity is rich in compounds with biological potential. Propolis is a natural product formed from bee saliva and plant exudates. Brazilian brown and green propolis exhibit antioxidant, antibacterial, antifungal, antiviral, and antiparasitic activities. These properties arise from their rich phenolic content; molecules such as artepellin-C, quercetin, and kaempferol are important phenolic biomolecules described in propolis. The objective of this study was to determine the antifungal activity and chemical parameters of brown and green propolis samples commercialized in Santa Rita do Sapucaí, southern Minas Gerais, Brazil. The total phenolic compound content was assessed using the Folin-Ciocalteu colorimetric method. Total flavonoid concentration was determined by the aluminum chloride complexation method. The pH and density were also determined. The antifungal activity of the extracts was evaluated using the disk diffusion technique against strains from the American Type Culture Collection (ATCC), following the Kirby-Bauer methodology. Both extracts showed similar densities; the green propolis extract presented a pH of 4.37, while the brown propolis extract showed a pH of 3.61. The ethanolic extract of brown propolis (706.79 mg GAE/g) exhibited a higher content of phenolic compounds compared to green propolis (697.65 mg GAE/g), whereas the green propolis extract (415.75 mg QE/g) presented a higher flavonoid content than brown propolis (378.75 mg QE/g). Clinically relevant strains, Candida albicans (EPM: 12.43 mm; EPV: 12.78 mm), Candida parapsilosis (EPM: 14.88 mm; EPV: 13.96 mm), and Cutaneotrichosporon dermatis (EPM: 11.95 mm; EPV: 12.28 mm), were the most susceptible to both extracts. It can be inferred that the extracts possess excellent antifungal activity, possibly associated with their rich phenolic and flavonoid content.