Reduction of hexavalent chromium by digested oat bran proteins.

Hexavalent chromium (Cr(VI)) is associated with an increase in oxidative stress, such as DNA, lipid and protein oxidations. This study investigated, for the first time, the ability of digested food proteins to reduce Cr(VI) and scavenge free radicals. Protamex, an endopeptidase was used to digest oat bran protein isolates for 1, 2, 3, and 4h. The hydrolysates (1mg/ml) showed a maximum Cr(VI)-reducing activity of 5.4 ± 0.4% and 44.6% at pH 7.4 and 3.0, respectively. The difference might be due to charge or conformation changes depending on the pH. The 2h hydrolysate possessed the highest O2(-) inhibition activity (57.4 ± 5.1%), while the 1h hydrolysate had the highest HO inhibition (11.6 ± 0.6%). A correlation (R(2)=0.82) was observed between the O2(-) scavenging activities of hydrolysates and their Cr(VI)-reducing activities at pH 3.0 only. Further investigations of the digested oat bran proteins are required to determine their ability to reduce Cr(VI) oxidative stress damage in vivo.