Study On Extraction, Simulated Digestion And Absorption And Anti-aging Effect Of Antioxidant Peptides From Fermented Rapeseed Meal

Rapeseed meal is the by-product during rapeseed oil producing,and it is abundant of protein.However,the existence of glucosinolate,phytic acid and tannin in rapeseed meal decreases its nutritional value,limits its utilization.Low molecule weight peptides obtained from solid-state fermentation have superior processing characters and biological activities compared with protein.The solid-state fermentation method is showing an important pathway to achieve the deep processing and utilization of rapeseed meal.In this study,high antioxidant active peptide components obtained from rapeseed meal by solid-state fermentation were separated by using ultrafiltration,ion exchange chromatography and gel filtration.The simulated external digestion characters and the absorption characteristics in in-vitro rats' everted small intestine of the separated peptides were both explored.The separated components' protection effect on memory impairment in mice with D-galactose induced sub-acute aging model and its influence on the erythrocyte lipid peroxidation injury were also investigated to explore the potential anti-aging function of rapeseed meal peptides.The major content and conclusion are presented as following:?1?Ultrafiltration,ion exchange chromatography and gel filtration were conducted for fermented rapeseed antioxidant peptides.Fermented rapeseed antioxidant peptides were filtered using ultrafiltration 5 kDa and 3 kDa molecular weight cutoff membranes sequentially.Components RP₁ with molecular weight less than 3 kDa have the highest clearance rate on DPPH·,and IC50 value descended from0.80 mg/mL to 0.27 mg/m L.Three eluting peaks were obtained in further cationic resin separation.Protein recovery rate and peptide antioxidant activity recovery rate of RP₁-E2 were both the highest in the three components,which are 53.3% and 61.1%respectively;and the IC50 on this eluting peak was the lowest,which is 0.172 mg/mL.Three eluting peaks were obtained from RP₁-E2 by further purification and separation using sephadex,the IC50 value of the third eluting peak RP₁-E2-G3 was 0.099mg/mL,decreased 42.4% than that without sephadex purification.Amino acid analysis result showed that RP₁-E2-G3 also had high nutrition value.?2?The digestion and absorption characters of fermented rapeseed peptides were studied through external digestion simulation and the in-vitro rats' everted small intestine sac experiments.Fermented rapeseed peptides were able to be digestedduring gastrointestinal digestion stage.After external digestion simulation,the degree of hydrolysis increased from 4.96% to 18.32%,while the surface hydrophobicity decreased from 61.33% to 53.48%,and the DPPH free radical clearance rate,the hydroxyl radicals clearance rate and the reducing force were significantly increased.After digested by gastro-intestine,fermented rapeseed peptides were easier for intestinal absorption.Fermented rapeseed peptides had higher absorption rate in small intestine,the highest absorption rate could reach 63.34%.The absorption of short chain peptides such as dipeptide and tripeptide were with stronger antioxidant activity,the lowest IC50 value is 0.255 mg/mL.?3?Mice memory impairment model was built using D-galactose.By using water maze test in mice and the measurements of blood serum,malondialdehyde?MDA?content in the brain tissue,glutathione peroxidase?GSH-Px?activity,Superoxide Dismutase?T-SOD?activity and ATP enzyme activity,the protection effect of RP₁ on D-galactose induced mice memory impairment model was explored.RP₁ had effective improvement of the spatial learning memory impairment in mice model,and enhanced the memory ability of mice.RP₁ also effectively improved the brain tissue and the blood serum antioxidant ability in mice model,it significantly enhanced GSH-Px,T-SOD and ATP activity and decreased MDA content in brain tissue.RP₁ also increased T-SOD and GSH-Px activity of blood serum and the spleen index and liver index of mice.?4?The rat erythrocyte lipid peroxidation injury model was built using phenazine methosulfate?PMS?.The effects of RP₁ on hemolysis,methemoglobin,malondialdehyde?MDA?content,activity of superoxide dismutase,GSH-Px and ATP enzyme,and erythrocyte membrane sulfhydryl groups content were explored.It was found that RP₁ inhibited the generation of PMS-induced rat erythrocyte hemolysis and methemoglobin.RP₁ increased the activity of superoxide dismutase,GSH-Px and ATP enzyme in PMS oxidative damaged rat erythrocyte,and decreased MDA content;and RP₁ inhibited the decrease in protein sulfhydryl groups content caused by PMS.