Antioxidant and anticancer effects in human hepatocarcinoma (HepG2) cells of papain-hydrolyzed sorghum kafirin hydrolysates

Peptide antioxidants are becoming increasingly popular in the food industry. This study reported antioxidant and anticancer properties of papain-hydrolyzed sorghum kafirin. The optimum hydrolysis conditions were determined to be 360 kU/g enzyme-to-substrate ratio, and 4 h of reaction time. After ultrafiltration, the 1-3 kDa hydrolysate fraction demonstrating promising antioxidative activities as well as yield was selected for further analyses. In an oil-in-water emulsion system, the incorporation of the selected fraction of hydrolysates at 10 mg/mL resulted in an average inhibition of primary and secondary oxidation products by 53.7% and 43.0%, respectively, without significantly changing emulsion turbidity or stability. In a ground meat system, an average of 32.1% inhibition towards lipid peroxidation was also detected when incorporated at 1.0 mg/g. The kafirin hydrolysates also effectively reduced HepG2 cell growth via non-toxic mechanisms, indicating its anticancer potential. Further, the 1-3 kDa peptides were fractionated and 13 peptide sequences were identified using RP-HPLC analysis followed by MALDI-TOF/TOF MS from the most potent fraction.