Effect of probiotics on antioxidant and antimutagenic activities of crude peptide extract from yogurt

Search for bioactive peptides is intensifying because of the risks associated with the use of synthetic therapeutics, thus peptide liberation by lactic acid bacteria and probiotics has received a great focus. However, proteolytic capacity of these bacteria is strain specific. The study was conducted to establish proteolytic activity of Lactobacillus acidophilus (ATCC® 4356™), Lactobacillus casei (ATCC® 393™) and Lactobacillus paracasei subsp. paracasei (ATCC® BAA52™) in yogurt. Crude peptides were separated by high-speed centrifugation and tested for antioxidant and antimutagenic activities. The degree of proteolysis highly correlated with these bioactivities, and its value (11.91%) for samples containing all the cultures was double that of the control. Liberated peptides showed high radical scavenging activities with 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), IC50 1.51 and 1.63 mg/ml, respectively and strong antimutagenicity (26.35%). These probiotics enhanced the generation of bioactive peptides and could possibly be commercially applied in new products, or production of novel anticancer peptides.