Prospecting Bioactive Potential and Phenolic Compounds in Brazilian Yeast Strains

In this study, we investigated six yeast strains isolated from different environments. Two strains (Rhodotorula mucilaginosa CHAP-208 and Aureobasidium leucospermi CHAP-221) were isolated from the nectar of Senna macranthera flowers, one strain (Meyerozyma carpophila CHAP-243) from the stingless bee Scaptotrigona postica, two strains (Papiliotrema laurentii CHAP-158 and Meyerozyma caribbica CHAP-204) from the gut of Spodoptera frugiperda larvae, and one strain (Saccharomyces cerevisiae PE-2) from Brazilian ethanol production. We produced extracts of these yeasts with different solvents and evaluated their antioxidant activity, cytotoxicity, and antimicrobial potential. Cytotoxicity assays demonstrated that aqueous extracts from the strains PE-2 and CHAP-204 were the most effective against tumor cells [with 50% inhibitory concentrations (IC₅₀) of 90.42 µg/mL and 107.5 µg/mL, respectively], while exhibiting low or no toxicity to healthy cells at the concentrations tested. Additionally, the butanol extract from CHAP-208 showed the highest antibiofilm activity on titanium (83.99% reduction of Pseudomonas aeruginosa viability), while the aqueous extract from CHAP-243 was the most effective on polypropylene (70% of biofilm reduction). Four cell extracts (from strains CHAP-158, CHAP-204, and CHAP-243 in ethyl acetate and strain CHAP-243 in butanol) demonstrated antioxidant activity in immune system cells. Among the phenolic compounds identified in the extracts, p-coumaric acid was the most abundant, followed by epicatechin, caffeic acid, kaempferol, myricetin, and quercetin. The most prevalent compound in the culture supernatants was 2-phenylethanol. These findings highlight the potential of bioactive compounds produced by wild yeasts, emphasizing the value of Brazilian microbial biodiversity.