Lipid-lowering effects of methanolic extract of Vernonia amygdalina leaves in rats fed on high cholesterol diet

Abstract

We investigated the lipid-lowering effects of methanolic extract of Vernonia amygdalina (VA) leaves in rats fed an high cholesterol diet, and compared with a standard hypolipidemic drug, Questran (Qu). The effects of VA on the lipid profile were assessed by measuring the levels of total cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, lipid peroxidation (LPO), phospholipid, and glutathione (GSH) in the plasma and liver of the rats. Administration of cholesterol at a dose of 30 mg/0.3 ml, five times in a week for nine consecutive weeks resulted in a significant increase (p < 0.05) in plasma and post mitochondrial fraction (PMF) cholesterol levels by 33% and 55%, respectively. However, treatment with extract of VA at doses of 100 and 200 mg/kg caused a dose dependent reduction in the plasma and PMF cholesterol by 20%, 23% and 23%, 29%, respectively. Similar reduction in cholesterol levels was obtained in Qu-treated rats. Furthermore, VA at 200 mg/kg decreased the plasma and PMF LDL-cholesterol levels by 23% and 49%, and also decreased plasma and PMF triglyceride levels by 29% and 28%, respectively. Also, VA at 100 and 200 mg/kg caused a dose-dependent increase in plasma HDL-cholesterol levels by 41% and 59%, respectively. However, there were no significant differences (p > 0.05) in the PMF HDL-cholesterol and phospholipid levels of the treated rats when compared to hypercholesterolemic rats. There were significant decreases (p < 0.05) in the LPO levels of extract-treated rats. Precisely, VA at 100 and 200 mg/kg decreased the levels of plasma and PMF LPO by 38%, 42% and 35%, 45%, respectively. In addition, VA augmented the cholesterol-induced decrease in PMF glutathione levels of the rats. Taken together, these results suggest the lipid-lowering effects of VA and, probably serve as a new potential natural product for the treatment of hyperlipidemia.

Keywords: Vernonia amygdalina; cholesterol; hypercholesterolemia; lipid-lowering effect.

Figure 1

Effect of Vernonia amygdalina on plasma and post mitochondrial fraction (PMF) cholesterol levels of hypercholesterolemic rats. Note: *Significantly different from CH group at p < 0.05. Abbreviations: CH, Cholesterol; VA, Vernonia amygdalina; QU, Questran; PMF, Post mitochondrial fraction; VA1, 100 mg/kg; VA2, 200 mg/kg.

Figure 2

Effect of Vernonia amygdalina on plasma and post mitochondrial fraction (PMF) triglyceride levels of hypercholesterolemic rats. Note: *Significantly different from CH group at p < 0.05. Abbreviations: CH, Cholesterol; VA, Vernonia amygdalina; QU, Questran; PMF, Post mitochondrial fraction; VA1, 100 mg/kg; VA2, 200 mg/kg.

Figure 3

Effect of Vernonia amygdalina on plasma and post mitochondrial fraction (PMF) lipid peroxidation levels of hypercholesterolemic rats. Note: *Significantly different from CH group at p < 0.05. Abbreviations: CH, Cholesterol; VA, Vernonia amygdalina; QU, Questran; LPO, Lipid peroxidation; VA1, 100 mg/kg; VA2, 200 mg/kg.

Figure 4

Effect of Vernonia amygdalina on plasma LDL-cholesterol and post mitochondrial fraction (PMF) reduced glutathione levels of hypercholesterolemic rats. Note: *Significantly different from CH group at p< 0.05. Abbreviations: CH, Cholesterol; VA, Vernonia amygdalina; QU, Questran; LDL, Low-density lipoprotein; PMF, Post mitochondrial fraction; GSH, Reduced glutathione; VA1, 100 mg/kg; VA2, 200 mg/kg.