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 2,20-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