Bovine Colostrum Whey Protein Hydrolysate Inhibits Cell DNA Damage and LDL Oxidation In Vitro

Whey protein isolated from bovine colostrums collected on the second day postpartum was two-stage hydrolyzed by alcalase and flavourzyme. The whey hydrolysates were finally fractionated by ultrafiltration (UF) with a 10 kDa molecular weight (MW) cutoff membrane and subsequently used to evaluate the effect of whey protein hydrolysis on inhibition of DNA oxidative damage and low-density lipoprotein (LDL) oxidation in vitro. Results showed that whey hydrolysis exhibited not only higher inhibitory activities of oxidative damage of deoxyribose but also an inhibitory effect on the breakdown of supercoiled DNA into open circular DNA and linear DNA. The quantities of 8-hydroxy-2′-deoxyguanosine (8-OH-2′-dG) formed with the addition of whey hydrolysate protein, the hydrolysate fraction of MW >10 kDa, and the hydrolysate fraction of MW <10 kDa were 0.25, 0.06, and 0.09 μg/mL, respectively. The lag time of conjugated diene formation of the control sample, which was only combined with cupric ions and LDL, was 90 min. The samples added with the hydrolysate fractions exhibited higher inhibitory activity on LDL oxidation. The whey hydrolysate fractions extended the lag time of conjugated diene formation to 270 min. The lag time of the whey hydrolysate fractions was 3 times that of the control.