Researches On Hypolipidemic And Anti-obesity Of Polymethoxyflavones And Tangerine Peel Oil

As the change of our dietary structure and lifestyle,metabolic diseases had gradually become chronic killers that threaten human health and life.Atherosclerosis,hyperlipidemia,and obesity caused by disorders of lipid metabolism have became the focus of attention in the world.Citrus polymethoxyflavones are an important dietary flavonoids and have a variety of biological activities such as antioxidant,anti-inflammatory,anti-cancer,antibacterial,lipid-lowering,and hypoglycemic.At present,it had reported in vitro and in vivo studies that polymethoxyflavones are non-toxic,with high lipid solubility and high bioavailability,and have special biological activity,which can improve human health.That was of great significance to develop it to health functional foods.In this study,lots of heptamethoxylflavone,nobiletin and tangeretin were isolated and purified from tangerine peel oils and the crude extracts of tangerine peel.To investigate the lipid-lowering and anti-obesity activities of heptamethoxyflavone,nobiletin,tangerine and tangerine peel oil by dietary interventions in sprague dawley rats induced by high-fat diet.Then the mechanism of hypolipidemic and anti-obesity effects of heptamethoxyflavonoids based on liver transcriptomics were explored.Finally the pharmacokinetic of heptamethoxylflavone and its microcapsule emulsions were studied.The main research contents and results were as follows:(1)Separation and purification of polymethoxyflavones.Tangerine oil were extracted with petroleum ether to obtain crude flavones,then crude flavones recrystallized by addition of 40% to 50% methanol and freeze-dried to obtain heptamethoxyflavone.The crude orange peel was extracted with a mixed of petroleum ether and ethyl acetate = 1:1,and the precipitate was further separated by adding ethyl acetate.Finally,30% methanol was added to recrystallize step by step to obtaine a large amount of high-purity tangeretin and nobiletin.(2)Supplementation of HMF,NOB and TAN were investigated to prevent obesity and hypolipidemic in high-fat fed male SD rats.In the present study,the body weight,total weight of fat,viscera index and the histopathological changes in the liver of rats were observed.The results showed that heptamethoxyflavone,nobiletin,tangerine and tangerine peel oil could effectively prevent obesity in high-fat diet rats in a dose-depended manner.Their high-dose group could significantly reduce body weight and body weight gain,especially the high dose of heptamethoxyflavone group,which was better for preventing obesity.Heptamethoxyflavone had an obvious hypolipidemic effect,which could significantly lower the serum total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)levels.And the effect is better than NOB,TAN and tangerine oil.Similarly,nobiletin had a hypolipidemic effect with effectively reducing serum TC,TG and LDL-C levels.Tangeretin and tangerine peel oil could significantly reduce serum TC and LDL-C levels,which had a cholesterol-lowering effect.Among them,tangeretin had the best cholesterol-lowering effect.the fatty degeneration of liver.Heptamethoxyflavone,nobiletin,tangeretin and tangerine peel oil could improve hepatic steatosis,protect liver tissue,and have a role in preventing fatty liver.Therefore,heptamethoxyflavone,nobiletin,tangeretin and tangerine peel oil had lipid-lowering and anti-obesity activities,as well as prevent fatty liver.It is found that heptamethoxyflavone has better lipid-lowering and anti-obesity activities,followed by nobiletin and tangeretin.(3)To study the effect of heptamethoxyflavone on the differential expression of liver tissue in rats,it was found that the high dose group of heptamethoxyflavone could significantly modulate the metabolic process of the liver,which heptamethoxyflavone could significantly up-regulate lipid metabolism,and down-regulate the expression of genes involved in inflammation and immune responses.Heptamethoxyflavone could promote the transmembrane transport of fatty acids by increasing the mRNA expression of intracellular fatty acid transporters Cd36,Slc27a5 and Fabp7 in the PPAR signaling pathway and reduce cholesterol levels via up-regulateing the sterol 12α-hydroxylase(Cyp8b1)mRNA levels that catalyzes the synthesis of cholesterol from bile acids.Furthermore heptamethoxyflavone could increase the expression level of carnitine palmitoyltransferase(Cpt1b)in the fatty acid degradation pathway resulting in accelerating fatty acid β-oxidation,and at the same time inhibit the activation of sterol regulatory element binding protein-1(SREBP-1),then down-regulate the expression of its downstream genes such as fatty acid synthase(Fasn)to reduce lipid synthesis,and ultimately reduce serum triglyceride level in high-fat diet fed rats.However hexamethoxyflavone could reduce gene expression of chemokine Ccl2,Cxcl10 and inflammatory factor Il-1beta in the tumor necrosis factor(TNF)signaling pathway,as well as down-regulate the recognition of receptor TLR2 and transcriptional regulatory factors AP-1 in Toll-like receptor signaling pathway,as a result it could decrease hepatic lipid accumulation,inflammatory cell infiltration and signal transduction between inflammatory factors,thereby reducing high fat diet-induced obesity in rats and improving hepatic steatosis.(4)The plasma concentrations of heptamethoxyflavone suspension and microcapsule emulsions at different time points were measured in rats.The main pharmacokinetic parameters of heptamethoxyflavone suspension were: Cmax = 1.47±0.39 mg/L;Tmax = 2.00±0.00 h;AUC0-∞ = 4.79±2.22 mg/L*h.However the absorption rate of heptamethoxyflavone microcapsules emulsion was faster than the suspension,its Tmax was 3.67±0.58 h,and the maximum plasma concentration Cmax was 2.10±0.27 mg/L,which was increased by 42.86% compared with the suspension.The clearance rate CLz/F was 15.26 L/h/kg,the area under the average drug-time curve was AUC0-t was 10.14±2.67 mg/L*h,and AUC0-∞ was 10.41±2.76 mg/L*h,which was increased by 1.21 and 1.17 fold compared with the suspension respectively.The study indicated that the emulsion can significantly increase the oral absorption and bioavailability of heptamethoxyflavone.