| Metabolic syndrome(MS),a multiplex syndrome,is a set of metabolic disorders with various nutrients.MS is closely related to cardiovascular and cerebrovascular diseases,type2 diabetes,cancer and other chronic diseases,which is the basis of high incidence of diabetes,cardiovascular and cerebrovascular diseases.The pathogenesis of MS is considered to be the long-term of chronic inflammation.Therefore,the occurrence and development mechanism of inflammation in the body and cells has been studied and prevented.The studies are positive for prevention and improvement of MS,and other cardiovascular and cerebrovascular diseases.There are a variety of nutrients in pomegranate,and many kinds of polyphenols and flavonoids are rich in it.Pomegranate contains abundant polyphenol,and the peel possesses the highest polyphenol content among various parts of the pomegranate.These particular phytochemical profiles are related to a wide range of biological properties of pomegranate peel extracts.It has been reported that pomegranate and its extracts contribute greatly to various functions,such as anti-diabetic,anti-oxidative,anti-microbial,anti-obesity,anti-cancer and hypolipidemic.Regarding its anti-inflammatory effect,several studies have demonstrated that pomegranate peel extracts can inhibit the production of several pro-inflammatory cytokines and inflammatory mediators,but the mechanism and the main bioactive compounds remains unknown.Therefore,the anti-inflammatory effect of pomegranate peel polyphenols(PPPs)and its main components as well as the signaling pathway need further studied.This paper studied from in vitro and in vivo.First,an inflammatory model was established by LPS induced in RAW264.7 mouse macrophages.The inhibitory effects of PPPs and its main components,punicalagin(PC)and ellagic acid(EA)on pro-inflammatory cytokines and inflammatory mediators in vitro were investigated.Furthermore,the molecular mechanism and target of anti-inflammatory was revealed through studying the inflammatory signaling pathway.Then,MS model of SD rats induced by high fat and sugar was established.The effects of prevention and improvement MS by PPPs on inhibiting the inflammatory response in SD rats were studied.The results of the study are as follows:(1)The major polyphenols were identified and quantified by HPLC,and we found that there were 6 compounds in presence of PPPs:gallic acid,punicalagin(including two isomers ?,?),catechin,chlorogenic acid,epicatechin and ellagic acid.Punicalagin,with the content of 464.48 mg/g,was identified to be the dominant component of PPPs,followed by ellagic acid,catechin,gallic acid,epicatechin and chlorogenic acid at the concentration of 71.50,45.14,38.24,35.28 and 8.85 mg/g,respectively.(2)In RAW264.7 macrophages,PPPs(1?100 ?g/mL),PC and EA(1?50?M)could inhibit LPS-induced intracellular ROS production in a dose-dependent manner.They also decrease pro-inflammatory cytokines(TNF-?,IL-1? and IL-6)at the mRNA and protein levels and,down-regulate iNOS and COX-2 mRNA expression,which in turn suppressed NO and PGE2.(3)PPPs(100 ?g/mL),PC and EA(50 ?M)significantly suppressed the mRNA and protein expression of TLR4.This result indicated that PPPs,PC and EA could prevent nuclear translocation of p65 by reducing the phosphorylation,ubiquitination and proteasome degradation of I?B,thus inhibiting the activation of LPS-induced NF-?B signaling pathway.In addition,PPPs,PC and EA also regulated MAPK signal pathway,which was attributed to suppressing the p38,ERK and JNK phosphorylation level in MAPK.By blocking MAPK,PPPs,PC and EA inhibited both iNOS/COX-2 protein expression and NO/PGE2 production effectively.That means the molecular mechanism by which pomegranate polyphenols reduce cellular inflammation may be through inhibiting the activation of the TLR4-MAPK/NF-?B signaling pathway.(4)The results of anti-inflammation in vitro showed that,the anti-inflammatory effect of PC was much better than EA.PC may be the main effective component that plays an anti-inflammatory role in PPPs.(5)SD rats were induced by high fat and sugar,and treated with PPPs(150mg/kg·bw·d,300mg/kg·bw·d)and simvastatin(drug control)(lmg/kg·bw·d)by intragastric administration,respectively.These treatments were followed for 12 weeks.The results showed that PPPs could significantly reduce the body weight and liver weight index of MS rats,as well as the levels of blood lipid(TC,TG,LDL),liver lipid(TC,TG)and fasting blood glucose.These inhibitory effects indicated that PPPs could prevent and improve MS.Meanwhile,PPPs could significantly inhibit the activity of serum transaminase(AST,ALT),and reduce the levels of FFA,CRP and MPO in serum.Pathological observation showed that PPPs reduced the infiltration of inflammatory cells and the accumulation of intracellular lipid droplets in liver,indicating that PPPs has protective effect on liver.Moreover,PPPs reduced the production of pro-inflammatory cytokines and inflammatory mediators in serum and liver tissues of MS rats,and reduced their mRNA expression in liver tissues,which showed the strong anti-inflammatory effects of PPPs.The molecular mechanism was associated with the inhibiting the activation of MAPK and NF-?B pathway,which was consistent with the results of cell experiments in vitro.In summary,pomegranate polyphenols can prevent and improve the MS rats.The macrophages experiment also indicated the good anti-inflammatory effect,which was consistent with the experiment in vivo.Pomegranate polyphenols could down-regulate the mRNA expression of inflammation-related factors and inhibit the production of pro-inflammatory cytokines and inflammatory mediators.The molecular mechanism of anti-inflammation might be through inhibiting the TLR4-MAPK-NF ?B signaling pathway,including the expression of TLR4,and the phosphorylation of ERK,JNK,p38,I?B.In addition,it could inhibit ubiquitination-proteasome degradation and prevent p65 nuclear translocation. |
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