Study On Preparation And Biological Activity Of Schizandrae Chinensis Protein Peptide

Schisandra chinensis（Turcz.）Baill is the dried and mature fruit of Magnolia family,which is a major medicinal material in Jilin Province.Schisandra chinensis has various biological activities and remarkable clinical efficacy.It is widely used in the clinical practice of traditional Chinese medicine and the research and development of health food and health products.The research of the project team showed that Schisandra chinensis is rich in excellent protein resources,with excellent biological activity and food processing characteristics.However,due to its large molecular weight,it is difficult for the body to quickly digest,absorb and utilize it,and it cannot give full play to its functional value and biological activity.The digestion and absorption rate will be greatly improved if the enzyme is hydrolyzed into Chinese herbal polypeptides with smaller molecular weight.In order to effectively develop and utilize the protein resources of Schisandra chinensis,it has important research significance in preparing functional health food,health food and exploring more biological activities.Objective:Taking Schisandra chinensis protein as the research object,Schisandra chinensis protein peptide was prepared by enzymatic hydrolysis,and its preparation process,physical and chemical properties,structural properties,functional properties and antioxidant activity were studied,so as to provide basic theoretical basis for the full development and utilization of Schisandra chinensis medicinal resources and the development of healthy products.Methods:1 Study on the enzymatic hydrolysis process of Schisandra chinensis protein peptide:7kinds of proteases were used for enzymatic hydrolysis,and the best proteases were selected comprehensively by multi-index evaluation.With the degree of hydrolysis and free radical scavenging activity as indexes,the optimal enzymatic parameters were obtained by single factor experiment and response surface experiment.2 Study on physical and chemical properties of Schisandra chinensis protein peptide:SDS-PAGE,Tris-Tricine-SDS-PAGE,molecular weight distribution,nutritional composition,amino acid composition analysis,surface charge distribution,surface hydrophobicity and DSC thermal stability were used to study the physicochemical properties of Schisandra chinensis protein peptide.3 Study on the structural properties of Schisandra chinensis protein peptide:The structure of Schisandra chinensis protein peptide was studied by SEM scanning electron microscopy,ultraviolet absorption spectroscopy,infrared absorption spectroscopy,circular dichroism spectroscopy,sulfhydryl and disulfide bond analysis.The relationship between its structure and physicochemical properties was revealed from the perspective of microstructure,secondary structure and chemical bond.4 Functional properties of Schisandra chinensis protein peptide:The solubility,water holding capacity,oil holding capacity,emulsification and emulsion stability,foaming and foam stability,bulk density,clarity and minimum gel concentration of Schisandra chinensis protein peptide were studied to evaluate the food processing characteristics of Schisandra chinensis protein peptide.5 Study on antioxidant activity of Schisandra chinensis protein peptide:O^2-·,OH·,DPPH·,ABTS·scavenging experiments and iron ion reduction experiments combined with H₂O₂induced oxidative stress damage model of Hep G2 cells were used to study the free radical scavenging and reducing ability of Schisandra chinensis protein peptide in vitro and its antioxidant activity at the cellular and molecular level,and to speculate its potential antioxidant activity mechanism.Results:1 Through the evaluation of SDS-PAGE,peptide content,degree of hydrolysis and free radical scavenging ability of 7 kinds of protein hydrolysates,the best enzyme was selected as alkaline protease.The optimum enzymatic hydrolysis process parameters of Schisandra chinensis protein peptide were determined.The ratio of enzyme to substrate:1%;enzymatic hydrolysis time:3 h;p H:9.0;enzymatic hydrolysis temperature:55°C.The experimental verification of the enzymatic hydrolysis process parameters showed that the preparation process parameters were accurate and feasible.2 The physicochemical properties of Schisandra chinensis protein peptide were studied.The results showed that the presence of disulfide bond was confirmed by reducing electrophoresis and non-reducing electrophoresis of Schisandra chinensis protein peptide,which made the distribution of subunit bands of Schisandra chinensis protein and Schisandra chinensis protein peptide before and after reduction different.After enzymatic hydrolysis of Schisandra chinensis protein,the molecular weight distribution in the low molecular weight region increased significantly,the weight average molecular weight decreased significantly,the amino acid content increased,the essential amino acid,hydrophilic amino acid,aromatic and branched chain amino acid increased,the nutrient composition and surface charge increased,the thermal stability increased,the fat content and hydrophobicity decreased.3 The structural properties of Schisandra chinensis protein peptide were studied.The results showed that the schisandra protein peptide was a loose multi-layer sheet microstructure.Compared with schisandra protein,the ultraviolet absorption was enhanced near 280 and 220 nm,and the content of tyrosine and phenylalanine increased.After enzymatic hydrolysis,the content ofα-helix in the secondary structure decreased,the content ofβ-sheet,β-turn and random coil increased,and the content of disulfide bond increased.4 The results of functional properties showed that compared with s Schisandra chinensis protein,Schisandra chinensis protein peptide had excellent solubility,emulsification and emulsification stability under different conditions.Qualitative,foaming and foam stability had excellent solubility,emulsification and emulsification stability,foaming and foam stability increased,and water holding capacity,oil holding capacity,turbidity and minimum gel concentration decreased.Its excellent food characteristics could become new plant resources with potential value in health food research and development and food processing.5 In vitro classical chemical antioxidant results showed that Schisandra chinensis protein peptide had excellent free radical scavenging activity and iron ion reducing activity.Hep G2 cells were induced by H₂O₂to construct oxidative stress damage model,and Schisandra chinensis protein peptide could effectively inhibit ROS and superoxide anion levels,reduce MDA and LDH levels,and maintain the stability of cell membrane system by measuring cell survival rate,cell morphology,antioxidant substances,antioxidant oxidase system,apoptosis detection and pathway protein expression content.Enhance the GSH system and the activity of antioxidant enzyme system,enhance the interaction between nucleus and organelles,enhance mitochondrial membrane potential and lysosome function,regulate intracellular"calcium overload",promote cell membrane repolarization,and affect energy metabolism.Nrf2 and HO-1 are activated and Keap1 protein expression is decreased to repair H₂O₂-induced oxidative stress in Hep G2 cells.Conclusion:In this paper,the preparation process,physical and chemical properties,structural properties,functional properties and antioxidant activity of Schisandra chinensis protein peptide were studied,the best protease was selected,and a stable and reliable enzymatic hydrolysis process was obtained,which has excellent physical and chemical properties and functional properties.The physicochemical properties and structural properties affected the functional properties and antioxidant activity of Schisandra chinensis protein peptide.Schisandra chinensis protein peptide has excellent free radical scavenging activity and reducing ability,and plays a repairing role in H₂O₂-induced oxidative stress of Hep G2 cells.