In vitro antioxidant and angiotensin I-converting enzyme inhibitory properties of peptides derived from corn gluten meal

Corn gluten meal (CGM) was hydrolyzed by Alcalase 2.4L and Protex 7L to obtain low-molecular-weight peptides. The antioxidant and angiotensin-I-converting enzyme (ACE) inhibitory activities of the peptides were determined by 2,2 '-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radical scavenging activity, the JHH7 cell oxidative stress model, and the ACE inhibition assay, respectively. Corn peptides (CPs) had strong antioxidant capacity to scavenge ABTS radicals (1.44 +/- 0.11 mmol/g), and significantly reduced reactive oxygen species and malondialdehyde levels in oxidized JHH7 cells, increasing superoxide dismutase, catalase, and glutathione peroxidase activities by 26.20%, 147.52%, and 43.20%, respectively, at the concentration of 800 mu g/mL. CPs had high ACE inhibitory activity, with an IC(50)value of 0.27 +/- 0.05 mg/mL. Next, the CPs were separated by reverse-phase high-performance liquid chromatography. Twelve fractions were collected, and their ABTS free radical scavenging and ACE inhibitory activities were determined. Fractions 1, 2, 3, 4, and 9 showed higher ABTS free radical scavenging and ACE inhibitory activities. Twelve peptides were identified from active fractions by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as Leu-Ser-Pro-Tyr, Leu-Asn-Ser-Pro-Ala-Tyr, Tyr-Gly-Pro-Gln, Pro-Pro-Tyr, Ala-Tyr-Pro-Glu, Thr-Tyr-Ser-Gly-Pro-Lys, Ala-Tyr-Pro-Gly-Pro-Gln, Leu-Ala-Tyr-Pro-Gln, Ala-Tyr-Leu-Gln-Gln-Gln, Ser-Ala-Pro, Asn-Ala-Pro, and Val-Asn-Ala-Pro. These peptides exhibited good ABTS free radical scavenging and ACE inhibitory activities. Therefore, CPs may have potential applications in the food industry as functional material additives.