Effects Of Soybean Coat On Physiological Indexes And Gut Microbiota Of Mice On High-fat Diet

Objective:Obesity is a chronic metabolic disease caused by excessive accumulation of fat in the body due to the imbalance of energy intake and consumption.It is closely related to chronic diseases such as cardiovascular disease,type 2 diabetes,hypertension,and certain types of cancer.A high-fat diet represented by high calories and fat content is one of the main causes of obesity.The gut microbiota plays a key role in energy balance and metabolism and is considered to be a major factor in the development of obesity.Diet plays an important role in regulating the composition and function of the host’s gut microbiota.With the widespread application of soybean coating and oil-making technology,a large number of soybean coat by-products have been generated,but most of the soybean coat by-products have not been fully utilized or discarded.The overall utilization rate is low and there is a problem of waste of resources.Soybean coat are a rich source of dietary fiber and are also rich in phenols.However,current research on soybean coat has focused on soluble free phenols.Other major functional components,such as the combination of phenolics and dietary fiber,are barely reported.This project mainly uses ethanol extraction to remove free phenolic substances from black soybean coat and yellow soybean coat,and adds the remaining soybean coat dietary fiber,combined phenolic components and untreated whole soybean coat to high-fat feed,and explores the effects of different whole soybean coat and soybean coat dietary fiber ingredients on the physiological indexes and gut microbiota of obese mice induced by high-fat diet.In order to provide a theoretical basis for the deep processing and reuse of soybean coat byproducts.At the same time,it is expected to guide people’s diet more reasonably and scientifically to prevent the occurrence of obesity and related diseases.Methods:Forty-eight male C57BL/6J mice were randomly divided into 6 experimental groups,8 in each group: control diet group（CD group）,high-fat diet group（HFD group）,and whole black soybean coat high-fat diet group（HFD-BCW group）,black soybean coat dietary fiber component high-fat diet group（HFD-BCF group）,whole yellow soybean coat high-fat diet group（HFD-YCW group）,yellow soybean coat dietary fiber component high-fat diet group（HFD-YCF group）.The experiment lasted14 weeks,and changes in body weight were recorded.After the intervention,serum,liver,epididymal fat,subcutaneous fat,perirenal fat,scapular brown fat,cecum contents,and colon contents were measured,and obesity-related indicators and gut microbiota were measured.The composition and content of monosaccharides in soybean coat were measured by HPAEC-PAD,and the composition of phenols in soybean coat was determined by UPLC-QTOF-MS/MS system.The mice body weight,body length,and body fat were measured,and the Lee’s index was calculated to evaluate the effects of different soybean coat components on mice body weight and body fat.Hematoxylin-eosin staining was used to analyze the effects of different materials of soybean coat on the pathology of liver tissue and epididymal adipose tissue in high-fat diet mice.Oil red O staining was used to analyze the effect of high-fat diet on lipid droplet content in mice liver.Serum lipids,blood glucose,and gastrointestinal hormone-related indicators were measured by ELISA,and lipid metabolism and inflammation-related gene expression levels in the liver were measured by q PCR.The effects of different components of soybean coat on serum biochemical indexes,lipid metabolism and inflammation-related genes in liver were analyzed.16 S r DNA sequencing was used to analyze the effects of different components of soybean coat on the composition and structure of cecum and colonic microbiota,and to explore the effects of different components of soybean coat on the intestinal microecology of obese mice induced by high-fat diet.Results:（1）The glucose content is highest in BCW,BCF,YCW and YCF,followed by arabinose.Compared with BCW and BCF,the molar ratio of glucose in YCW and YCF decreases,and the molar ratio of arabinose increases.There are 19 main phenols in BCW and 8 main phenols in YCW.This may affect the fermentation process of the whole black soybean coat（BCW）and whole yellow soybean coat（YCW）components in the intestine,which in turn affects their physiological activity.（2）Compared with mice in the CD group,the body weight,weight gain,epididymal fat,perirenal fat and subcutaneous fat,and Lee’s index of the HFD group increased significantly.The intervention of BCF,YCW and YCF significantly reduced the above indexes in mice;the intake of BCW had no significant effect on the above indexes.Ingestion of BCF,YCW,and YCF significantly reduced the weight of mice and relieved obesity from weeks 8,10,and 4,respectively.BCF showed better weight loss effect than BCW,and YCF showed better weight loss effect than YCW.（3）BCW,BCF,YCW and YCF interventions significantly improved balloon-like changes of mice liver,lipid deposition,hypertrophy of epididymal adipocytes in mice induced by high-fat die.BCF and YCF interventions interventions improved obesity-related inflammation.（4）BCW,BCF,YCW and YCF interventions reduced the levels of TC,LDL-C,and GLU in the serum and improved HFD-induced blood lipid and blood glucose abnormalities;and reduced PYY levels may help reduce the amount of subcutaneous fat and serum glucose in mice.（5）16S r DNA sequencing and bioinformatics analysis found that BCW,BCF,YCW and YCF intervention increased the microbial community richness;and significant differences in the composition and structure of microbiota in HFD group compared with HFD-BCW group,HFD-BCF group,HFD-YCW group and HFD-YCF group.（6）At the phylum level,BCW,BCF,YCW and YCF interventions reduced the relative abundance of Proteobacteria and Fusobacteria,and increased the relative abundance of Tenericutes,which may help reduce inflammation.After the intervention of YCW and YCF,the relative abundance of Bacteroidetes was increased,and the relative abundance of Firmicutes was decreased,which may relieve obesity by improving energy absorption.（7）At the genus level,BCW,BCF,YCW and YCF intervention reduced the relative abundance of Anaerotruncus,Helicobacter,Mucispirillum,Oscillibacter,Bilophila,Desulfovibrio,Erysipelatoclostridium,Tyzzerella,Acinetobacter,Coriobacteriaceae_UCG₀02;increased the relative abundance of Lachnoclostridium Enterorhabdus,Bacillus,Alistipes,Prevotellaceae_UCG₀01,that may help to reduce body fat mass,inflammatory response,obesity-related metabolic disorders such as glucose metabolism and lipid metabolism.BCF and YCF interventions have increased the relative abundance of Romboutsia.Romboutsia can use carbohydrates to produce SCFA,which may be a candidate for predicting and treating obesity and related metabolic disorders.The increase in the relative abundance of Romboutsia may be one of the reasons why BCF and YCF more effectively relieve obesity,and the free phenolic substances present in BCW and YCW may affect the composition and activity of intestinal microbes and thus affect the fermentation of dietary fiber and the ability to relieve obesity.Conclusion:YCF and BCF can improve the body weight and body fat increase induced by high-fat diet,and reduce the degree of obesity;followed by YCW,while the whole BCW has no significant effect.BCW,BCF,YCW and YCF interventions alleviated HFD-induced liver damage,lipid deposition,epididymal adipocyte hypertrophy,and improved abnormal blood lipids and blood glucose.BCF and YCF interventions alleviated HFD-induced inflammation.At the same time,the HFD diet increased the relative abundance of harmful phylum and genus,and reduced the relative abundance of beneficial phylum and genus in the gut microbiota.The intervention of BCW,BCF,YCW and YCF improved the intestinal microecological disorder induced by HFD,Romboutsia may be a key genus for BCF and YCF to reduce body weight more effectively.The results of this study provide a theoretical basis for dietary intervention of simple obese people and deep processing and reuse of soybean coat by-products.