Study On The Effects Of Lipid From Phaeodactylum Tricornutum On Glucose And Lipid Metabolism And Intestinal Microbiota In High Fat Diet-Induced Obese Mice

The prevalence of obesity has risen dramatically worldwide,which is strongly associated with many chronic diseases.As a potential substitute for fish oil,Phaeodactylum tricornutum with abundant lipid is rich in functional components including polyunsaturated fatty acids and fucoxanthin.In this study,the Phaeodactylum tricornutum oil（PO）as the research object,were characterized the lipid class and fatty acid composition compared with widely studied Laminaria japonica oil（LO）,krill oil（KO）and fish oil（FO）to evaluate antioxidant activities in vitro.The C57BL/6 obese mouse model was used to evaluate the prevention and intervention effect of Phaeodactylum tricornutum oil（PO）on obesity.The effects of different Marine oils on glucose and lipid metabolism,related inflammation,oxidative stress and intestinal microbiota in obese mice induced by high fat diet were analyzed.The research contents and main conclusions are as follows:（1）The contents of fucoxanthin,total phenolic and long-chain polyunsaturated fatty acids was measured in PO by GC and LC,which were 7.48 mg/g dry weight,675.88 mg gallic acid equivalent/100 g lipids and 30.94%of total fatty acids,respectively.The scavenging capacity of PO on DPPH,ABTS and peroxyfree radicals was 76.41%,47.66%,and 0.58 mgα-Toc/mg,and the chelating rate of Fe²⁺was43.93%,respectively,indicating that PO had certain antioxidant activity in vitro.（2）PO from high-fat diet animal models was found to significantly inhibit body weight gain,inprove antioxidant content of SOD and GSH,clear excess ROS produced by HFD.The tissue inflammatory infiltration and the expression of pro-inflammatory factors IL-1β,IL-6,TNF-αof mice fed HFD supplement with PO was also effectively reduced.The results showed that PO relieved the excessive inflammatory response caused by HFD.（3）PO from high-fat diet animal models by OGTT,ITT and PTT was found to improve glucose intolerance and insulin resistance and facilitate liver glucose output to inhibit liver gluconeogenesis The total WAT index and liver lipid droplet formation were significantly reduced and adipose tissue hypertrophy was alleviated.In addition,the levels of TG,AST and ALT in liver and LDL-c in serum were significantly reduced while the levels of HDL-c in serum and polyunsaturated fatty acids in liver were improved.RT-PCR and Western blot results suggested that PO could significantly down-regulate the gene and protein expressions of PPARγand SREBP-1c,FAS and SCD-1 in liver and adipose tissue while up-regulate the protein expression of PPARαand the gene expression of CPT-1αand CPT2 The results indicated that PO played a role in regulating lipid metabolism and could alleviate liver damage caused by HFD.（4）The diversity of gut microbiota was increased and the intestinal microflora structure was regulated by PO supplement in high-fat diet mice.The abundance of Firmicutes was decreased at the phylum level.At the family level,the abundance of Erysipelotrichaceae was decreased and Bifidobacteriaceae was increased.At the genus level,compared with HFD group,the abundance of Faecalibaculum was reduced significantly,while that of Coriobacteriaceae＿UCG-002,Clostridium,Dubosiella and Christensenellaceae＿7＿group were increased significantly.In addition,correlation analysis showed that PO could alleviate HFD-induced obesity,which may be related to improving the abundance of Bifidobacterium,Coriobacterium and Dubosiella so as to regulate lipid metabolism and inhibit obesity.