Abstract
Corn gluten meal, a corn processing industry by-product, is a good source for the preparation of bioactive peptides due to its special amino acid composition. In the present study, the in vitro and cellular free radical scavenging activities of corn peptide fractions (CPFs) were investigated. Results indicated that CPF1 (molecular weight less than 1 kDa) and CPF2 (molecular weight between 1 and 3 kDa) exhibited good hydroxyl radical, superoxide anion radical and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) diammonium salt (ABTS) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Meanwhile, the in vitro radical scavenging activity of CPF1 was slightly higher than that of CPF2. Both CPF1 and CPF2 also exhibited significant cytoprotective effects and intracellular reactive oxygen species scavenging activity in Caco-2 cells exposed to hydrogen peroxide (H2O2). The amino acid composition analysis revealed that the CPF were rich in hydrophobic amino acids, which comprised of more than 45% of total amino acids. An antioxidant peptide sequence of Tyr-Phe-Cys-Leu-Thr (YFCLT) was identified from CPF1 using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI TOF/TOF MS). The YFCLT exhibited excellent ABTS radical scavenging activity with a 50% effective concentration (EC50) value of 37.63 µM, which was much lower than that of Trolox. In conclusion, corn gluten meal might be a good source to prepare antioxidant peptides.
Highlights
Reactive oxygen species (ROS), including free radicals such as superoxide, hydroxyl and non-radical species such as hydrogen peroxide (H2O2), are mainly generated from the respiratory chain of mitochondria and other sources under normal physiological conditions [1] and are involved in many biological systems as cell signaling molecules [2]
The antioxidant activities of corn peptide fractions (CPFs) were evaluated by the methods based on the in vitro free radical scavenging capacity, for instance, hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, azino-bis (3-ethylbenzothiazoline-6sulphonicacid) diammonium salt (ABTS) radical scavenging activity and oxygen radical absorbance capacity (ORAC) assay
These results demonstrated the positive effects of CPF1 and CPF2 fractions on the ABTS radical scavenging activities and a higher scavenging activity of CPF1
Summary
Reactive oxygen species (ROS), including free radicals such as superoxide, hydroxyl and non-radical species such as hydrogen peroxide (H2O2), are mainly generated from the respiratory chain of mitochondria and other sources under normal physiological conditions [1] and are involved in many biological systems as cell signaling molecules [2]. The accumulated intracellular ROS will attack large biomolecules and cell organs, increase lipid, protein and DNA oxidation, disturb cell membrane functions, and induce proteolysis and DNA mutations. This can promote aging and initiate several diseases, including cardiovascular disease, diabetes, cancer, rheumatoid arthritis and neurological disorders [4]. Some antioxidants such as ascorbic acid, tocopherol, flavonoids, help to clear free radicals. These molecules are often not enough to counteract the excessive ROS in living organism especially when oxidative stress occurs. Some exogenous antioxidants provided by food are critical to keep the oxidation-reduction balance [6]
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