Isolation and purification of antioxidant peptide from tea seed by mixed fermentation and its functional properties
To promote the in-depth development and utilization of tea seed resources,tea seed peptides(TSP)from mixed fermentation were classified by ultrafiltration membranes with different molecular weight cut off.Then the corresponding relationship between antioxidant activity and molecular weight of tea seed peptides was compared.Gel filtration chromatography techniques was used to sequentially purify the TSP to obtain the characterized antioxidant peptide.The composition and content of secondary structure,thermal stability and anti-digestion stability of the antioxidant peptide were studied.The oxidative damage model was established with H2O2 induced mouse embryonic fibroblasts(MEF)to evaluate the cellular oxidative damage protection function of tea seed antioxidant peptide.The results showed that the antioxidant activity of TSP was negatively correlated with their molecular weight and TSP4 with molecular weight less than 1 kDa exhibited the highest radical scavenging capacity.The molecular weight distribution of TSP4 ranged from 90 Da to 849 Da.The average molecular weight of the TSP4-b subcomponent purified by gel filtration chromatography was 446 Da,and theβ-fold in the secondary structure increased from 16.59％of no fermented tea seed to 44.43％,the α-helix decreased from 37.61％of no fermented tea seed to 17.57％.The relative radical scavenging rate of TSP4-b remained above 90％and 80％,respectively after heat treatment at 20-60 ℃ and simulated gastrointestinal digestion,which showed the excellent thermal stability and anti-digestion ability.After the addition of TSP4-b with medium doses(0.5 mg/mL)and high doses(5.0 mg/mL),the H2O2-induced MEF survival rate reached 73.8％and 82.4％,respectively.In conclusion,the isolated antioxidant peptide from tea seed has strong antioxidant activity and protective effect against H2O2-induced cellular damage,and has good potential for development in the fields of medicine and health food.
tea seed polypeptideseparation and purificationfunctional activitycellular oxidative damage
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