Purification And Antioxidant Activities Of Moringa Oleifera Seed Peptides

This study topic is based on Moringa oleifera seeds as raw material to study the nutrient composition of M.oleifera seeds and the biological activity of M.oleifera seed peptide.The bioactive peptides were isolated by enzymatic hydrolysis,ultrafiltration,anion exchange chromatography gel chromatography and RP-HPLC,and their antioxidant activities were studied at the chemical and cellular levels.The main research contents are as follows:(1)Determination of nutrients of M.oleifera seeds:Nutritional composition analysis of M.oleifera seeds was carried out by referring to the national determination methods of crude protein,ash,crude fat,mineral elements and water content.The results of nutrient research showed that the protein content of M.oleifera seeds was as high as 40.34%,and the crude fat content was 39.12%,sodium and magnesium content was very high,and potassium content was as high as 2357.71 mg/kg.M.oleifera seeds has high protein content and abundant trace elements,so it has rich nutritional value.(2)Separation and purification of M.oleifera seed peptides:M.oleifera seed protein hydrolyzed with flavorprotease(50?,pH 6.7)for 300 min and DPPH·scavenging rate of M.oleifera seed protein hydrolysate at 10 mg/mL was 84.76%.Activity tracking showed that M.oleifera seed protein hydrolysate with molecular weight<3.5 kDa antioxidant had the strongest DPPH·,ABTS·⁺,HO·,O₂·scavenging activities with the EC₅₀ values of 4 mg/mL,6 mg/mL,4 mg/mL and 4.5 mg/mL,respectively.The F-I-I separated from<3.5 kDa peptide by Anion-exchange chromatography and Gel filtration chromatography showed significant scavenging activities on ABTS and DPPH radicals and EC₅₀ values were 1.02 mg/mL and 1.6 mg/mL respectively.Eleven peaks of F-I-I were separated by reverse phase high performance liquid chromatography(RP-HPLC).The amino acid sequences of eleven peaks were identified by ESI-MS as Gly-Tyr,Pro-Phe-Glu,Tyr-Thr-Arg,Phe-Gly,Tyr-Phe-Glu,Ile-Tyr,Gln-Tyr,Leu-Tyr,Ile-Asn,Ser-Phe and Ser-Pro.(3)Protective effect of M.oleifera seed peptides on oxidative damaged Chang liver cells:peptides SF and QY can effectively scavenge oxidative damaged Chang liver intracellular ROS by increasing the activities of intracellular SOD and CAT.When oxidative damaged hepatocytes are protected,the contents of AST and ALT of cell culture medium and the contents of intracellular MDA decreased significantly.In summary,the contents of crude protein and crude fat in the M.oleifera seeds is high,and trace elements is rich.The enzyme hydrolysate of M.oleifera seed peptides was purified by ion chromatography,gel permeation chromatography and RP-HPLC.Eleven peptides(Gly-Tyr,Pro-Phe-Glu,Tyr-Thr-Arg,Phe-Gly,Tyr-Phe-Glu,Ile-Tyr,Gln-Tyr,Leu-Tyr,Ile-Asn,Ser-Phe,and Leu-Tyr)were identified by ESI-MS.Cell experiment show that peptide SF and QY can inhibit the death of Chang liver cell induced by hydrogen peroxide and scavenge intracellular ROS by increasing the activities of intracellular SOD and CAT.