Preventive Effect Study Of Fermented Black Barley On High-fat Diet Induced NAFLD

Nonalcoholic fatty liver disease(NAFLD)is the most common chronic liver disease in high-sugar and high-fat diet,which is also the result of lipid metabolism disorder in liver.Liver is the largest metabolic organ of human body,and its lipid metabolism abnormality and oxidative stress caused by reactive oxygen radicals have become pathogenic factors of atherosclerosis,diabetes,obesity and other diseases.In addition,if NAFLD is not intervened in time,it will gradually progress to fatty hepatitis,liver fibrosis and cirrhosis.Due to the complex pathogenesis of NAFLD,there are no targeted drugs approved for NAFLD therapy.Most of the existing drugs play a role by regulating blood lipid and insulin sensitivity,but their application is limited by certain toxic and side effects.Therefore,preventing the occurrence and development of NAFLD through diet is both feasible and of great practical significance.Black barley is one of colored whole grains with high dietary fiber,low carbohydrate and low fat.Our previous studies have shown that black barley fermented by Lactobacillus plantarum can enrichγ-aminobutyric acid and polyphenol.Based on the existing research,firstly,the functional phytochemical composition changes of black barley fermented by Lactobacillus plantarum were determined by using untargeted metabolomics based on UPLC-Q-TOF-MS~E.Next,the NAFLD rat model was established by high-fat diet.Two intervention groups were orally administered fermented black barley liquid and lactic acid bacteria physiological saline(viable bacteria count:1×10~8 CFU/m L)respectively.The preventive mechanism of fermented black barley on NAFLD was studied by detecting rat liver morphology,liver total fat content,lipid level(triglyceride,total cholesterol and non-esterified fatty acids)of adipose tissue and liver tissue,antioxidant indexes(SOD,TBARS,CAT,GSH,GSH-Px)and changes of serum cytokines.Finally,the effects of fermented black barley on intestinal flora were detected by 16S r DNA sequencing;metabolomics technology based on UPLC-Q-TOF-MS~E is used to detect rat serum and liver tissues,and non-targeted analysis technology is used to find out rat differential metabolites of different treatment groups.Then,the differential metabolites identified in the online database are introduced into KEGG platform to construct metabolic pathways,and the corresponding molecular mechanisms are further studied.The results are as follows:(1)Lactobacillus plantarum fermentation treatment increased the functional components of small molecular acids(malic acid,succinic acid and phenylpropionic acid),amino acids(serine,alanine,phenylalanine,tyrosine,arginine and valine)and flavonoids(ferulic acid,catechin,proanthocyanidins and flavone)of black barley.(2)Compared with the high-fat group,fermented black barley can significantly reduce:liver TG,TC,NEFA and total fat content,and adipose tissue NEFA and TC(p<0.01).Lactic acid bacteria intervention only reduced the content of TG and TC in liver tissue(p<0.05).The weight of the rats in the fermented black barley intervention group was not significantly different from that in the normal group,and the morphology of liver tissue was also the closest to that in the normal group.(3)High-fat diet can significantly reduce the levels of serum SOD,GSH-Px,liver SOD,GSH,GSH-Px and CAT(p<0.01);The levels of lipid peroxide in liver and serum were significantly increased(p<0.05).SOD and GSH-Px in serum and liver tissue of the group intervened by fermented black barley increased significantly,while lipid peroxide decreased significantly(p<0.05).The serum cytokine TGF-β1 in fermented black barley group can be corrected to no significant difference from the normal group(p>0.05).(4)16S r DNA sequencing results of intestinal flora showed that high-fat diet significantly reduced the diversity of flora composition(p<0.05)and increased the ratio of Firmcutes/Bacteroidetes.After the intervention of fermented black barley,the diversity of flora composition can be corrected to have no statistical difference with the normal group(p>0.05),the ratio of Firmcutes/Bacteroidetes is effectively reduced,the relative abundance of intestinal probiotics Akkermensia,Blautia and Ruminococcus which are capable of synthesizing SCFAs synthesis are significantly increased(p<0.05),and the abundance of polysaccharide anabolic genes is correspondingly increased.(5)Study on rat serum metabolites has found 23 kinds of differe ntial metabolites.There are phosphatidylcholine(16:1(9Z)/20:4(8Z,11Z,14Z,17Z),15:0/18:1(11Z),18:2(9Z,12Z)/18:2(9Z,12Z),16:0/20:3(8Z,11Z,14Z)),Lyso-phosphatidylcholine(18:0,15:0,22:6(4Z,7Z,10Z,13Z,16Z,19Z))sphingosine,γ-linoleic acid and DHA.Fermented black barley reduce d the degree of hepatic steatosis by lowering the normalized abundan ce of sphingosine in sphingolipid metabolic pathway and phosphatidy lcholine in glycerophospholipid metabolic pathway.(6)Study on rat liver metabolites has found 34 kinds of different ial metabolites.There are that phosphatidylcholine(18:0/18:4(6Z,9Z,12Z,15Z),20:5(5Z,8Z,11Z,14Z,17Z)/20:3(8Z,11Z,14Z),22:6(4Z,7Z,10Z,13Z,16Z,19Z)/16:1(9Z),20:4(5Z,8Z,11Z,14Z)/16:1(9Z),20:4(5Z,8Z,11Z,14Z)/22:6(4Z,7Z,10Z,13Z,16Z,19Z),phosphatidylethanolamine(18:1(9Z)/0:0,16:0/0:0,18:0/18:1(9Z),18:1(9Z)/16:0,20:2(11Z,14Z)/18:1(11Z),16:0/18:2(9Z,12Z),glutathione,and Fermented black barley can inhibit insulin resi stance by increasing phosphatidylcholine/phosphatidylethanolamine rati o in glycerophospholipid metabolic pathway;Increasing glutathione/ox idized glutathione ratio in glutathione metabolic pathway alleviates ox idative stress in liver tissue to prevent NAFLD.In above differential metabolites,phosphatidylethanol,palmitic acid and linoleic acid are positively correlated with liver TG metabolism.Glutathione,nicotina mide and taurocholic acid were negatively correlated.Conclusion:Lactobacillus plantarum fermented black barley can si gnificantly increase free amino acids and phenolic acids and elevate antioxidant activity.Fermented black barley can reduce lipid accumul ation in liver tissue and adipose tissue of NAFLD rats induced by h igh-fat diet.The antioxidant activity of serum and liver tissue were i ncreased;Fermented black barley regulate intestinal flora disturbance in rats and correct metabolic abnormalities of serum and liver glycer ophospholipid to play the preventive role of NAFLD.