Antioxidant peptides isolated from synbiotic yoghurt exhibit antiproliferative activities against HT-29 colon cancer cells

Milk proteins are considered a reservoir of peptides possessing various bioactivities. Using ultrafiltration followed by reversed phase-high performance liquid chromatography, antioxidant peptides were purified from crude peptide extract of probiotic yoghurt supplemented with pineapple peel powder stored for 28 days at 4 °C. Two β-casein-derived peptides, 193YQEPVLGPVRGPFPIIV209 and 69SLPQNIPPLTQTPVVVPPF87 (designated P17 and P19, respectively), were identified and their antioxidant and anticancer activities assessed. P17 showed high scavenging activity against 2,2′-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) radicals, with an IC50 of 29.88 μg mL−1, compared with P19 (IC50 1.44 mg mL−1). Furthermore, the proliferation of HT-29 colon cancer cell line was inhibited (41.49% and 38.55%, respectively, by P17 and P19 at 3 mg mL−1) via inducing apoptosis and cell cycle arrest in G2/M-phase. In vitro gastrointestinal digestion of peptides resulted in increased bioactivities. These findings indicate a potential for utilising both of these peptides to manage oxidative stress mediated diseases and disorders including cancers.