Study On The Preparation Of Sturgeon Hydrolysates And Its Anti-inflammatory Activity

Sturgeon muscles have been nutritional and health food since ancient times,which have the effect of keeping healthy.In our study,the anti-inflammatory hydrolysates were prepared from the by-product of the sturgeon muscles through enzymatic hydrolysis and ultrafiltration.The anti-inflammatory activity of the sturgeon alcalase hydrolysates was evaluated by combining the in vitro cell model and the in vivo animal model,providing the basis for the development of functional foods with sturgeon alcalase hydrolysates.The main findings are as follows:1.The composition of sturgeon muscles was analyzed and the enzymatic hydrolysis process of Alcalase was established.Sturgeon muscles had high content of protein and low content of fat,accounting for 19.92%and 3.71%,respectively,indicating that sturgeon muscles were suitable for preparing hydrolysates.The sturgeon muscles were hydrolyzed with Alcalase,and the response surface optimization experiment was performed on the basis of the single factor experiment based on the NO inhibition rate on the cells.The optimal enzymolysis conditions were:pH 9.0,enzymolysis time of 4.92 h,enzymolysis temperature of 55?,solid to liquid ratio of 1:20,and enzyme additive amount of 7674.22 U/g protein,the NO inhibition rate was 60.23%.2.The sturgeon alcalase hydrolysates?SH?were separated by ultrafiltration and identified,and their anti-inflammatory activity,antioxidant activity and physicochemical properties were studied.Results showed that SH-3 component with molecular weights less than 3 kDa had higher anti-inflammatory activity,significantly inhibited the secretion of NO and IL-6,and the inhibition rates were 66.24%and39.54%,respectively.At the same time,SH-3 had high DPPH and ABTS free radical scavenging ability,with IC₅₀0 values of 1.043±0.090 mg/mL and 1.396±0.074 mg/mL,respectively.Compared with raw fish?RF?and SH,SH-3 contained the most hydrophobic amino acids,aromatic amino acids and positively charged amino acids,which accounted for 40.76±0.45%,11.73±0.37%and 22.73±0.21%of the total amino acids,respectively.In addition,SH-3 had good emulsification,water-holding and oil-holding properties.LC/MS/MS identified the peptide sequences of SH-3.By comparing comparing peptides scores,hydrophobic amino acid,and identical sequence,we found that the peptides ALAF,ALAL,FELK,GPAGPIGPA,GPAGTRNKDCVV,LEEL,LTDY and VGPGGPNGPTGAQ may have antioxidant activity,FLDF and YALDF may have anti-inflammatory activity.3.DSS-induced ulcerative colitis in mice was used to study the effect of sturgeon alcalase hydrolysates?<3 kDa?at different doses on the improvement of colitis.The results showed that the sturgeon alcalase hydrolysates could significantly reduce DAI,improve the pathological changes such as epithelial cell defect,the disappearance of crypt structures,and inflammatory cell infiltration in mice,and reduce the inflammatory index MPO activity,the levels of IL-6,IL-1?and TNF-?.The results of western blotting showed that sturgeon alcalase hydrolysates could inhibit DSS-induced activation of NF-?B and MAPK pathways in colon tissues,thereby inhibiting excessive secretion of inflammatory cytokines and protecting the intestinal mucosa structure.In addition,the sturgeon alcalase hydrolysates could also increase the richness and diversity of the gut microbiota,increase the content of beneficial bacteria and reduce the content of harmful bacteria,thereby improving immunity and reducing the risk of intestinal diseases.The results showed that sturgeon alcalase hydrolysates have anti-inflammatory activity,which are related to the molecular weight distribution.The sturgeon alcalase hydrolysates have good anti-inflammatory activity to colitis.This study provides a novel idea and theoretical basis for the preparation of anti-inflammatory peptides from sturgeon muscles and a new way for the high value utilization of sturgeon muscles.