Effect of garlic (Allium sativum) on lipid profiles, antioxidant activity and expression of scavenger receptor class B type I (SR-BI) in liver and intestine of hypercholesterolemic mice

Abstract

Garlic is one of the medicinal plants, which has shown many useful effects, including Antioxidant activity, hypolipidemic and hypocholesterolemic effects, anti-hypertensive and anti-diabetic effects. Scavenger receptor class B type I (SR-BI) is a cell-surface receptor which mediated selective cholesterol ester uptake from the HDL particle. SR-BI also has an important role in cholesterol absorption in the intestine.  Animals were randomly divided into three groups (n=8); group 1:  received chow + cholesterol (2%) + cholic acid (0.5%), group 2: chow + 4% (w/w) garlic extract + cholesterol (2%) + cholic acid (0.5%), and group 3: chow only. After one-month mice were sacrificed, blood was collected; lipid profile and blood glucose were determined enzymatically as well as mRNA and protein levels of SR-BI were determined by RT-PCR and westernblot respectively. Compared with hypercholesterolemic control, garlic extract significantly decreased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides, Very Low-Density Lipoprotein-Cholesterol (VLDL-C) and  atherogenic index (all of them P<0.05). The activity of  Super oxide dismutase(SOD), glutathione (GSH)  and catalase levels were markedly increased in garlic-treated animals compared with hypercholesterolemic animals (p<0.05). The plasma levels of MDA markedly reduced in garlic group compared with hypercholesterolemic group. Intestinal SR-BI mRNA and protein were significantly decreased in garlic extract mice treatment compared with hypercholesterolemic control. Levels of liver SR-BI protein significantly reduced in hypercholesterolemic group (P<0.05). In conclusion, garlic extract markedly reduced TC, LDL-C, TG, VLDL-C and atherogenic index, as compared with the hypercholesterolemic control group. On the other hand garlic extract led to down-regulation of SR-BI protein and mRNA in the intestine of mice.