Purification and Characterization of Novel Antioxidative Peptides From Duck Liver Protein Hydrolysate as Well as Their Cytoprotection Against Oxidative Stress in HepG2 Cells.

Jin Sun,Daodong Pan,Jinxuan Cao,Yangying Sun,Qiang Xia,Jun He,Yali Dang,Changyu Zhou

doi:10.3389/fnut.2022.848289

Abstract

This study aimed at mining antioxidant peptides derived from duck liver as a strategy for valorizing poultry byproducts utilization via the isolation and characterization of peptide molecules with great antioxidant potential and cytoprotective effects against hydrogen peroxide-induced oxidative stress. Six novel peptides, including GEHGDSSVPVWSGVN, HLDYYLGK, HLTPWIGK, DTYIRQPW, WDDMEKIWHH, and MYPGIAD were isolated and purified by Sephadex G-15 and reverse-phase high-performance liquid chromatography, followed by the identification with liquid chromatography-tandem mass spectrometry. Among the hydrolysates from different enzymes, the alcalase-originated peptides presented the strongest antioxidant capacity as revealed by DPPH and ABTS assays. The synthesized peptides were used to validate the antioxidant activities, identifying that DTYIRQPW and WDDMEKIWHH were the major antioxidative peptides capable of protecting HepG2 cells from H2O2-induced oxidative damage via stimulating antioxidant enzymes such as superoxide dismutase and catalase to eliminate free radicals and to decrease lipid peroxidation products. Molecular docking suggested that the antioxidative properties of the isolated peptides were related to the site and number of hydrogen bonds. This investigation indicated the great potential of duck liver protein hydrolysates as a base material for producing and developing dietary bioactive peptides.

Highlights

There is a growing interest in isolating and identifying antioxidant peptides from natural sources in recent years [1, 2]
trichloroacetic acid-nitrogen soluble index (TCA-NSI) value can be used as a reference indicator for the hydrolysis capacity, inferring the degree of hydrolysis of duck liver (DLv) protein
The highest TCA-NSI value (55.62 ± 0.89%) was found for alcalase-derived hydrolysates, followed by the papain (43.98 ± 0.79%) and neutrase (42.24 ± 0.21%) (Figure 1A4), suggesting that the alcalase hydrolysates attained a higher oligopeptide content than other hydrolytic enzymes. These results demonstrated that alcalase-derived DLv protein hydrolysates could be potential antioxidant peptides with great bioactivities which were further isolated and characterized

Summary

Introduction

There is a growing interest in isolating and identifying antioxidant peptides from natural sources in recent years [1, 2]. Recent researches have indicated that meat processing by-products, such as duck skin [4], porcine liver [5], porcine cerebral [6], Fish by products [7], Yak bones collagen [8] and duck plasma [9], can be a good source from which to mine antioxidant peptides with great bioactivities. Enzymolysis preparation is considered as fast, safe, highly repeatable and environmentally friendly to generate antioxidative peptides in a controllable way. This method has been the most commonly used method for industrial preparation of peptides [13]. The impact of enzymolysis on the yields and transformation efficiency of antioxidant peptides from parent proteins is highly dependent on the employed enzyme types and food matrices, and to our knowledge, no literature has examined the antioxidative capabilities of bioactive peptides prepared from DLv using different enzymes despite its great potential

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Results

Conclusion