Research background: Antioxidants are important compounds present at low concentrations that inhibit oxidation processes. Due to the side effects of synthetic antioxidants, research interest has increased considerably towards finding natural sources of antioxidants that can replace the synthetic ones. The emergence and spread of antibiotic resistance require the development of new drugs or some potential sources of novel medicine. This work aims to extract the secondary metabolites of Saccharomyces cerevisiae using ethyl acetate as a solvent and to determine the antioxidant and antimicrobial activities of these extracted metabolites.
Experimental approach: The antioxidant activity of the secondary metabolites of S. cerevisiae were determined using DPPH, ABTS and FRAP assays. Furthermore, the antimicrobial potential of the ethyl acetate extract of S. cerevisiae against Cutibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis was assessed.
Results and conclusion: Five out of 13 of the extracted secondary metabolites were identified as antioxidants. The antioxidant activity of the S. cerevisiae extract exhibited relatively high IC50 of 455.26 and 294.51 μg/mL for DPPH and ABTS respectively, while the obtained FRAP value, expressed as ascorbic acid equivalents, was 44.40 μg/mL. Moreover, the extract had a significant antibacterial activity (p<0.05) against Staphylococcus aureus and Staphylococcus epidermidis at the concentrations of 100 and 200 mg/mL, respectively. However, no inhibitory effect was observed against Cutibacterium acnes as the extract was only effective against the bacterium at the concentrations of 300 and 400 mg/mL (inhibition zones ranging from 9.0±0.0 to 9.3±0.6) respectively (p<0.05). Staphylococcus aureus was highly sensitive to the extract, with a MIC value of 18.75 mg/mL.
Novelty and scientific contribution: This report confirmed the efficacy of the secondary metabolites of S. cerevisiae as a natural source of antioxidants and antimicrobials and suggested the possibility of employing them in drugs for the treatment of infectious diseases caused by the tested microorganisms.
Keywords: Saccharomyces cerevisiae; bacterial pathogen; free radicals; secondary metabolites.