Determination of Antioxidant and Anticancer Activities and Exopolysaccharides of Metabolites Synthesized by Probiotic Levilactobacillus brevis Strains Newly Isolated from Breast Milk

In our study, the probiotic, exopolysaccharide, metabolite contents, antioxidant activities, and anticancer activities of metabolites on HT-29 and Caco-2 cell lines of four Levilactobacillus brevis (YAAS1, YAAS2, YAAS3, and YAAS4) strains isolated from breast milk in Türkiye and identified by MALDI-TOF MS were investigated. It was determined that the strains exhibited strong probiotic character by surviving in pH+pepsin, bile and pancreatin medium; although, they decreased depending on time and concentration. The strains synthesized the most acetic acid but could not synthesize tartaric, pyruvic, malic, and fumaric acids. It was determined qualitatively and quantitatively that the strains synthesized compounds similarly in terms of exopolysaccharide amount. The strains exhibited lower DPPH activity than standard antioxidants. However, ABTS activities were similar to standard antioxidants. Bacterial metabolites induced notable anticancer effects in the HT-29 cell line at low concentrations, while eliciting comparable effects in the Caco-2 cell line at high concentrations. When all the results were considered in general, it was determined that the strains showed identical properties to each other but L. brevis YAAS4 strain exhibited a better character structure. Given the scarcity of studies on Lactobacillus brevis strains newly isolated from human breast milk, this research significantly advances current understanding. Characterizing the specific properties identified in our study through future research will be crucial for determining the potential of these isolates as effective probiotics for industrial and health applications.