Studies Of Stilbenes Containing Extract-fraction From Cajanus Cajan L. And Synthetical Analog On Cholesterol Metabolism And Vascular Protection

Atherosclerosis is the basis of coronary artery disease, one of the most serious diseases in man. Hypercholesterolemia is a dominant risk factor for the development and progression of increasing atherosclerosis and related cardiovascular diseases. Thus, the therapeutic benefits of plant extracts without side effects have been the focus of many extensive studies. Plenty of studies indicate that high serum level of low density lipoprotein cholesterol (LDL-C) is associated with atherosclerosis and an increased risk of coronary heart disease.Recently, there are several investigates reveale that reverse cholesterol transport (RCT) is one key mechanism in antiatherosclerosis research. Atheroprotective effect of RCT is attributed to its ability to remove macrophage or peripheral organs redundant cholesterol into liver for degradation and eccrisis. The RCT accelerates the cholesterol cleaning in peripheral organs, decreases the serum cholesterol contents, so it is benefit to the prevention and cure of atherosclerosis.Cajanus cajan L.Millsp is the subtropical brush plant, which belongs to adjouns genus of popilionaccae family, grows in the southern part of China. There are two active components in the Cajanus cajan L, i.e. the flavonoids and the stilbenes. The stilbenes component possesses the estrogen-like property, it can been used to treat the osteoporosis, diabetes, climacteric symptom of menopause women. In our previous researches, we find the stilbenes containing extract-fraction from Cajanus cajan L (sECC) could decrease the body weight and blood sugar level. But there has been no report on the effect of sECC on cholesterol metabolism.Our research team initiately investigated the hypocholesterolemic effect of medicative extract-fraction from Cajanus cajan L. and synthetical analog (S03) on hypercholesterolemia animal models. We observed the hypocholesterolemic effects of flavonoids component and stilbenes component, respectively. Furtherly, we investigated the auxoaction of stilbenes component on reverse cholesterol transport. Based on the experimental evidences, we evaluated the potential antiatherosclerosis effectes of these compoundes. These resultes will help us to extend the drug actions of medicative extract-fraction from Cajanus cajan L in modify cholesterol metabolism and preservation atherosclerosis.1. The hypolipidemic effects of medicative extracts of Cajanus cajan L and synthetical analog on hypercholesterolemia animal modelOvariectomy induces obesity and hypercholesterolemia by removing the catabolic action of estrogen. We simulated the hypercholesterolemia in post- menopause women with the ovariectomized mice. We finded the descending tendency in the serum cholesterol and glucose content according with the dosage of the medicative extract-fraction from Cajanus cajan L.Diet-induced hypercholesterolemia mice had been used for the assessment of flavonoids extract-fraction or stilbenes extract-fraction with beneficial effects on cholesterol metabolism. The serum lipid profile, the hepatic total cholesterol and triglyceride, and the changes in the gene expressions of the key enzymes responsible for cholesterol homeostasis had been detected. After 4 weeks treatment, the increased serum and hepatic total cholesterol and triglyceride levels were markedly attenuated by sECC, the serum LDL cholesterol content also decreased accompanying with the activity of serum superoxide dismutase was increased in sECC treated mice. The mRNA expressions of HMG-CoA reductase, CYP7A1, and LDL-receptor were significantly enhanced in the mice administered with sECC. sECC's hypocholesterolemic effect may involved the enhancement of hepatic LDL-receptor and CYP7A1 mRNA expression levels. Whereas, there was no conspicuous change occurred in flavonoids component groups. In the hypercholesterolemia of the ovariectomized rats, we investigate the effects of the synthetical analog of stilbenes component (S03). The results revealed the S03 decreased the serum total cholesterol and LDL cholesterol contents. Meanwhile, there were marked reduces in the body weight and liver weight in the S03 treated rats. The S03 also decreased the abnormal contents of luteotrophic hormone and follicle-stimulating hormone induced by ovariectomized operation.2. The effect of monomer compound of sECC (C03) on the reverse cholesterol transportWe investigated the effect of monomer compound of sECC (C03) on the reverse cholesterol transport. The usage of C03 could up-regulation the protein expression of the ATP binding cassette transporter A1, following facilitate the [³H] label cholesterol effluent from the macrophage. C03 also prevented the formation of foam cell by depleted the total cholesterol and cholesterol esters in the macrophage.The investigations data indicated that C03 could enhance the protein expression of LDL-receptor in liver cell, this effect displayed the characteristic of dose dependent and time dependence. But, there was no conspicuous change occurred in the expression of scavenger receptor class B type I. So we conclude the C03 may promote the reverse cholesterol transport mainly through accelerating the initial phase.We have evaluated the binding property of C03 and the estrogen receptor with the competive receptor binding assay.3. The protective effects of C03 and S03 on cultured vascular endothelial cell and vascular smooth muscle cellOxidative damage is an important risk factor for the development and progression of vascular dysfunction. Then, vascular dysfunction is the initiating agent of atherosclerosis. We used an injury model induced by H₂O₂ in EAhy926 cells (human umbilical vein endothelial cell) and assessed the protective effect of C03. The injuries of endothelial cell induced by H₂O₂ were indicated as cell viability, release of NO and the activity of SOD. The results exhibited that C03 could significantly increase cell viability, the increased activity of SOD and secretion of NO also been observed.Proliferation of vascular smooth muscle cell (VSMC) represents an essential event in the development of atherosclerosis. The S03 represented significant inhibitory effect on VSMC proliferation. However, C03 has showed lower inhibition on it. These findings suggested that S03 and C03 may arrest the atherosclerosis via the inhibitory effect on VSMC proliferation.In a summary, we used different hyperlipoidemia animal models to evaluated the hypolipidemic effect of medicative extract-fraction from Cajanus cajan L and it's synthetical analog. Then, we investigate the accelerating effect of C03 on the reverse cholesterol transport and the effects of C03 and S03 on cultured vascular endothelial cell and vascular smooth muscle cell protection. These results indicated that sECC will be a promising drug for the hypercholesterolemia and atherosclerosis.