Assessment of antioxidant properties of membrane ultrafiltration peptides from mungbean meal protein hydrolysates

Abstract

BackgroundBioactive peptides can prevent damage associated with oxidative stress in humans when consumed regularly. Recently, peptides have attracted immense interest because of their beneficial functional properties, safety and little or no side effects when used at high concentration. Most antioxidant peptides are small in size, less than 1 kDa, and contains a high proportion of hydrophobic amino acid. Particularly, tyrosine, leucine, alanine, isoleucine, valine, lysine, phenyalanine, cysteine, methionine and histidine in peptide chain exhibited high antioxidant activity. Mungbean meal protein (MMP) is highly abundant in hydrophobic amino acids. It indicated that MMP might be a good source of antioxidants. Therefore, the objectives were to optimize the conditions used to generate mungbean meal protein hydrolysate (MMPH) with antioxidant activity from bromelain and to investigate the antioxidant activities of different molecular weight (MW) peptide fraction.MethodsResponse Surface Methodology (RSM) was used for screening of the optimal conditions to produce MMPH. After that MMPH was fractionated using ultrafiltration membranes with different MW distributions. Crude-MMPH and four fractions were investigated for five antioxidant activities: 2,2,1-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, superoxide, ferric reducing antioxidant power (FRAP) and metal ion chelation activity.ResultsThe optimal condition to produce the MMPH was 15% (w/w) of bromelain and hydrolysis time for 12 h which showed the greatest DPPH and ABTS radical scavenging activity. After mungbean protein from optimal condition was separated based on different molecular weight, the DPPH radical scavenging activity was the highest for the F4 (less than 1 kDa) peptide fraction. Metal ion chelating activity was generally weak, except for the F4 that had a value of 43.94% at a protein concentration of 5 mg/mL. The F4 also exhibited high hydroxyl and superoxide activities (54 and 65.1%), but moderate activity for ferric reducing antioxidant power (0.102 mmole Fe2+/g protein) compared to other peptide fractions and crude-MMPH. Molecular weight and amino acid were the main factors that determined the antioxidant activities of these peptide fractions. Results indicated that F4 had strong antioxidant potentials.DiscussionThe lowest MW fraction (less than 1 kDa) contributed to the highest DPPH, superoxide, hydroxyl and metal chelation activity because influence of low MW and high content of hydrophobic amino acid in peptide chain. Results from this study indicated that MMPH peptides donate protons to free radicals because they had significantly high DPPH value compared to superoxide, hydroxyl and FRAP, which reactions were electron donation. Moreover, MMPH peptides had the ability to inhibit transition metal ions because of highly abundant glutamic acid and aspartic acid in peptide chain.

Purification and Identification of Antioxidant Alcalase-Derived Peptides from Sheep Plasma Proteins

“…Taking into account that the antioxidant activities of 3-5 kDa and <3 kDa fractions were not significantly different (p > 0.05) between them, the <5 kDa fraction was chosen for further isolation and purification of the antioxidative peptide. It would be in good agreement with those from other studies showing that peptides in this MW range play an important role in antioxidant activity [41,[45][46][47][48][49].…”

“…Several studies focused on determining the biological activity of protein hydrolysates, which were obtained from different raw materials and using different proteolytic enzymes, have shown that their antioxidant activity is closely related to the size of peptides, with the most relevant contribution corresponding to the <1 kDa fraction. However, some more recent studies also point out as other key factors the richness in aromatic and hydrophobic amino acids and the structure of these peptides [44,48,[50][51][52]. In order to elucidate whether F1 and F2 fractions are rich in small MW peptides, they must first be purified.…”

Comparative Investigation of Amino Acids Content in the Dry Extracts of Juno bucharica, Gladiolus Hybrid Zefir, Iris Hungarica, Iris Variegata and Crocus Sativus Raw Materials of Ukrainian Flora

“…The results show that the dry aqueous extract of Crocus leaves has the highest concentration of certain free amino acids, which possibly explains [48] the presence of a pronounced antioxidant effect in leaves [17,21,22]. The predominant amino acids Crocus leaves extract were of the hydrophobic amino acids group (alanine (2.71 mg/g), valine (3.02 mg/g), leucine (2.40 mg/g), isoleucine (2.32 mg/g), proline (4.68 mg/g)), which, according to the authors of [49], can inhibit free radicals by proton donation [50] and exhibited a high antioxidant activity in plant extracts. Among the investigated samples, the dry extract of Crocus leaves was characterized by the highest content of pyroglutamic acid (12.35 mg/g).…”

Production and Characterization of Antioxidative Hydrolysates and Peptides from Corn Gluten Meal Using Papain, Ficin, and Bromelain

“…Peptides with relatively lower and medium MW were more active as metal ion binder and chelators. Besides, the presence of some amino acid residues could generate extra electrons which improve electrostatic and ionic interaction between themselves and metal ions, such as Asp and Glu, which contributed to strong metal chelation activity especially when they are at the terminal of peptide chain [ 34 , 40 ].…”