Antioxidant Activity Of Extraction From Dry-cured Jinhua Ham

There are several traditional dry-cured ham produced in china and the three most important dry-cured hams are Jinhua ham,Xuanwei ham,and Rugao ham.Dry-cured ham has high salt level,which is about 4.5%?15%.However,many studies have shown that Jinhua dry-cured ham is nutritious and contains all the amino acids required by human body.Typically,the traditional processing technology of Jinhua dry-cured ham takes a long time for the processing.During the long ripening time,muscle proteins are hydrolyzed by endogenous enzymes to varying extents to produce many small peptides and free amino acids.Thus,Jinhua dry-cured ham may have antioxidant peptides on body functions that may influence human health.In this study,crude peptides were extracted by two solutions from Jinhua dry-cured ham,the separation and the characterization of the peptide fraction were carried out by size-exclusion chromatography(SEC),the matrix-assisted laser desorption ionization-time of flight(MALDI-TOF)and amino acid auto-analyzer.Furthermore,the protective effects of peptides against oxidative damage in PC 12 cells were further investigated.1.Effects of different extraction methods on the antioxidant activity with separation and identification of crude peptides from Jinhua hamCrude peptides were extracted by two solutions from Jinhua dry-cured ham and evaluated for antioxidant activity by radical scavenging,ferrous ion chelating,reducing power and the total antioxidant capacity(T-AOC).Results showed that the crude peptide extract from Jinhua ham using PBS as solution(crude peptide P)presented higher peptide content than crude peptide extract using HCl as solution(crude peptide H).The DPPH radical scavenging capacity and the superoxide anion radical scavenging activities of crude peptide P did not differ significantly from that of crude peptide H below 5 mg/mL(P>0.05).In addition,the crude peptide P showed higher metal ion chelating activity than crude peptide H and GSH,which presented higher reducing power than crude peptide H at 4 mg/mL(P>0.05).Total antioxidant capacity of crude peptide P reached 48%of GSH at 1 mg/mL,which was significantly higher than crude peptide H(P<0.05).In conclusion,crude peptide P had higher antioxidant activity than crude peptide H.Crude peptide was seperated into five fractions(A-E)by SEC.Each fraction was measured with the antioxidant activities.Fractions showing the strongest radical scavenging activity was gathered,and then subjected to MALDI-TOF and amino acid auto-analyzer for characterization.The results showed that CPC possessed highest DPPH radical and superoxide anion radical scavenging activities.The CPC posessed high amount of His,Phe,Glu,Ala and Pro which accounted for 59.67%of the toal amino acids and the molecular weight of major peptides in the range of 400-1000 Da.2.The establishment of cell oxidative damage modelTo further study the antioxidant activity of CPC,the oxidative damage model of PC 12 cells was established by MTT assay.Different density of PC 12 cells were treated with various concentrations of H2O2 and CPC to select the optimum concentrations.The results showed that the optimal density of PC 12 cells was 2.0×105 cells/mL,the optimal concentrations of CPC was 0?400 ?g/mL,and the optimal concentrations of H2O2 was 400?M.Under these circumstance,CPC could significantly improve the cell viability in which the cell viability was repaired from 48.19%to 52.24%,60.98%,67.44%and 80.23%at the concentrations of 50,100,200 and 400 ?g/mL,respectively.3.The protective effects of CPC against oxidative damage to PC12 cells induced by H2O2The aim was to study the cytoprotective effects of CPC against oxidative damage to PC 12 cells induced by H2O2.The activities of antioxidant enzymes including lactate dehydrogenase(LDH),catalase(CAT),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and the malondialdehyde(MDA),and reactive oxygen species(ROS)in these cells were measured.Furthermore,the protective effects of CPC attenuated H2O2-induced apoptosis in PC 12 cells were further investigated.The results suggested that CPC enhanced the antioxidant enzyme activities including CAT,SOD and GSH-Px,while reduced the leakage of LDH and cellular lipid oxidation.CPC could also inhibit apoptosis of PC 12 cells by the inhibition of intracellular ROS formation and caspase-3 activity.