Studies On Effects And Mechanisms Of Smilax China L. Against Atherosclerosis

Atherosclerosis?AS?is the common pathological basis of cardiovascular and cerebrovascular diseases.Its pathogenesis is complex,mainly involving lipid metabolism disorder,inflammatory cell infiltration,oxidative stress,vascular endothelial cell damage and smooth muscle cell activation,which seriously endangers human health.As an abnormal reaction of vascular wall to various injuries,AS has the characteristics of classical inflammation,exudation and proliferation,so inflammation theory is one of the widely recognized pathogenesis.The most commonly used drug for the treatment of atherosclerosis is statins,but long-term use of these drugs may cause liver damage.Therefore,searching for AS therapeutic drugs from traditional Chinese medicine and natural medicine is a hotspot at present.Traditional Chinese medicine Smilax China L.has the effects of dampness turbidity,heat-clearing and detoxifying,softening and resolving hard lumps,and is mostly used in the treatment of gynecological inflammation such as pelvic inflammation in clinically.Modern Pharmacolo-gical studies have found that Smilax China L.has anti-inflammatory,antioxidant,hypoglycemic,lipid-lowering and anti-tumor effects.Preliminary studies in our laboratory have also confirmed that flavonoids and saponins of Smilax China L.have strong anti-inflammatory and anti-oxidative effects.Based on the pathogenesis of atherosclerosis and the pharmacological effects of Smilax China L.,the hypothesis that Smilax China L.has anti-atherosclerosis effect was put forward.In order to verify the above hypothesis,the pharmacodynamics of Smilax China L.against atherosclerosis was studied in this thesis,its mechanism was discussed based on the NLRP3signaling pathway,and the effective parts of Smilax China L.were screened preliminarily.The results of this thesis will provide scientific basis for expanding the clinical indications of Smilax China L.and developing new anti-atherosclerosis drugs.This thesis mainly completed the following research work:1.Atherosclerosis model of rats was established by feeding high-fat diet and intraperitoneal injection of vitamin D₃.Six weeks after the establishment of the atherosclerosis model,the drugs were administered for six weeks.The aorta and liver tissues were stained with HE and oil red O to observe the pathological changes and lipid deposition in aorta and liver;TC,TG,LDL-C,HDL-C,SOD,MDA,NO,iNOS,IL-1?,IL-8,IL-10 and IL-18 in serum of rats were detected by Kit.HE staining and oil red O staining showed that the ethanol extract of Smilax china L.can improve the structure disorder and unclear texture of vascular artery wall,improve the structure of hepatic lobules and hepatocyte steatosis,and reduce the lipid deposition in rat aorta and liver tissues.The effect of Smilax china L.high dose group was better than the positive group.The results of serum indicators showed that the alcohol extract of Smilax china L.could significantly reduce the contents of IL-1?,IL-8,IL-18 and increase the contents of IL-10?P<0.01?compared with the model group,showing a strong anti-inflammatory effect;the serum levels of TG,LDL-C,NO and iNOS in AS rats could be significantly reduced in each dose group?P<0.05 or P<0.01?,the contents of HDL-C and MDA could be reduced and the activity of SOD was significantly increased?P<0.05 or P<0.01?in the high and middle dose groups;the ethanol extract of Smilax china L.had no effect on serum TC level?P>0.05?.The results showed that Smilax china L.can resist atherosclerosis through anti-inflammation,anti-oxidation,regulating blood lipid level and protecting endothelial function.2.NLRP3,IL-1?,IL-18 in aorta and liver of rats were detected by immunohistochemistry;the expression of NLRP3,ASC,pro-Casepase-1,caspase-1,IL-1?,AIM2,IKK?and I?B?in aorta and liver tissue were detected by Western blot.Immunohistochemical results showed that ethanol extract of Smilax china L.could reduce the expression of NLRP3,IL-1?and IL-18 proteins in aorta and the expression of NLRP3 and IL-1?proteins in liver,but had no significant effect on the expression of IL-18.Western blot results showed that the ethanol extract of Smilax china L.could regulate inflammation by decreasing the expression of NLRP3,ASC,pro-Casepase-1,caspase-1,IL-1?and AIM2 proteins in aorta and liver tissues and increasing the expression of I?B?protein,but had no significant effect on the expression of IKK?.The results showed that inhibiting NLRP3 signaling pathway might be one of the mechanisms of Smilax china L.in anti-atherosclerosis.3.Oxidative low density lipoprotein?ox-LDL?plays a key role in the development of atherosclerotic plaque.In this study,Cu²⁺was used to induce LDL oxidation in vitro,the oxidative modification of LDL was evaluated by the content of thiobarbituricp acid reactants?lipid oxidative degradation products?,and the effective anti-atherosclerosis parts of Smilax china L.were screened.The results showed that the IC₅₀0 values of alcohol extract,ethyl acetate fraction,n-butanol fraction,petroleum ether fraction and water fraction were 43.57,29.22,22.68,293.00 and 487.50?g/mL,respectively.The results showed that the main effective parts of anti-atherosclerosis of Smilax china L.were n-butanol fraction and ethyl acetate fraction,the anti-oxidative modification of LDL was similar to that of the positive antioxidant butylated hydroxytoluene(BHT,IC₅₀0 was 22.62?g/mL),and the latency of LDL oxidation is about twice that of BHT.The n-butanol fraction and ethyl acetate fraction can significantly prolong the latency of LDL oxidation reaction and reduce the degree of LDL oxidation modification.The results of this study have laid a foundation for further study on the anti-atherosclerosis effective substance of Smilax china L..