Prolyl oligopeptidase inhibition and cellular antioxidant activities of a corn gluten meal hydrolysate

Abstract Background and Objectives Neurocognitive disorders are characterized by various symptoms caused by increased oxidative stress and nerve cell inflammation in the central nervous system. Prolyl oligopeptidase (POP) is one of the potential causes of neurocognitive disorder. To evaluate the potential of corn gluten meal, a byproduct of corn starch processing, as a nutraceutical ingredient, we developed a corn gluten meal hydrolysate (CGM‐H) with POP inhibitory activity and investigated its cellular antioxidant capacity. Finding CGM‐H was prepared using 1% pepsin; its in vitro digesta exhibited POP inhibitory, ABTS radical scavenging, ferric‐reducing antioxidant power, and hydroxyl radical scavenging activities. The activities of the former three assays decreased after in vitro gastrointestinal (GI) digestion. CGM‐H exhibited a higher protective ability against hydrogen peroxide than its digested counterparts. Additionally, CGM‐H and CGM‐H digesta reduced oxidative stress in SH‐SY5Y cells by scavenging reactive oxygen species (ROS) and upregulating CAT expression. Conclusion CGM‐H's POP inhibitory, antioxidant, and ROS scavenging activities in SH‐SY5Y cells suggest that it has potential as a raw material for manufacturing nutraceutical products. Significance and Novelty To the best of our knowledge, this study is the first to report CGM‐H's POP inhibitory and cellular antioxidant activities in SH‐SY5Y cells. Furthermore, in vitro GI digestion modifies CGM‐H bioactivity.