The effect of ethanol extract of Hypericum lysimachioides on lipid profile in hypercholesterolemic rabbits and its in vitro antioxidant activity

Hypercholesterolemia, high cholesterol diet and oxidative stress increase serum total cholesterol and LDL cholesterol levels resulting in increased risk for development of atherosclerosis. Antioxidants play an important role in inhibiting and scavenging radicals, thus providing protection to humans against infectious and degenerative diseases. Literature shows that the antioxidant activity is high in medicinal plants. Realizing the fact that, this study was carried out to determine the effect of ethanol extract of Hypericum lysimachioides Boiss var lysimachioides (Guttifera) on serum lipid levels and serum lipid peroxidation in hypercholesterolemic rabbits. The rabbits were divided into four groups and these groups were fed with diets containing standard laboratory diet (Group I), standard laboratory diet and ethanol extracts of H. lysimachioides (HL) (50mg/kg body weight) (Group II), standard laboratory diet, ethanol extracts of HL (50mg/kg body weight) and cholesterol (100mg/kg body weight) (Group III), and finally standard laboratory diet and cholesterol (100mg/kg body weight) (Group IV), for 5 weeks. Feeding cholesterol increased serum cholesterol and LDL cholesterol levels significantly in Group IV as compared to the other groups. Ethanol extract of HL with high cholesterol diet significantly lowered LDL cholesterol and total cholesterol levels in the rabbits of Group III as compared to the Group IV. The level of serum triacylglycerol was found to be similar to all comparison groups. HDL cholesterol levels were also increased significantly in Groups II and III as compared to Group IV. Statistically significant difference was found in Group IV as compared to all other groups. The ethanol extract of HL with high cholesterol diet significantly lowered the serum MDA levels in the rabbits of Group III compared to the Group IV. The histopathological findings confirmed that the ethanol extract of HL restrained the progression of the hydropic degeneration and fatty changes in the liver and some atherosclerotic lesions in the aorta. The in vitro antioxidant activities of ethanol extract of HL was also evaluated. The free radical-scavenging properties of HL (IC(50)=28 microg/ml) were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay system. Since plant phenolic compound is one of the phytochemicals possessing radical scavenging activity, the amount of total phenolic compound was also determined in ethanol extract of HL and total phenolic content of one-milligram HL ethanol extract was equivalent to 307 microg of gallic acid. Total antioxidant activity of ethanol extract of HL was tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of ethanol extract of HL was found to be comparable with Vitamin E. In conclusion, the use of this extract could be useful in the management of cardiovascular disease in which atherosclerosis is important.