Study of the hypolipidemic properties of pectin, garlic and ginseng in hypercholesterolemic rabbits

Abstract

Experimental hypercholesterolemia and its modulation by some natural dietary supplements (pectin, garlic and ginseng) and by the drug gemfibrozil were studied. Experimental hypercholesterolemia was induced by feeding rabbits a 2% cholesterol-enriched diet for 28 days. Hypercholesterolemic rabbits were classified into five groups. One group did not receive treatments and served as a control hypercholesterolemic group. The other four groups were fed the cholesterol-enriched diet in conjunction with either 10% pectin, 2% garlic, 2% ginseng or 135 mg g-1 b.w gemfibrozil in a daily oral dose. A normal group of rabbits fed a plain chow diet was also included in the study. The hypolipidemic effect of the above treatments was examined by estimating serum triglycerides (TG), total-, LDL- and HDL-cholesterol. Post-heparin total and hepatic lipase activities were estimated in post-heparin plasma obtained 10 min after an intravenous injection of heparin (200 IU kg-1 b.w). In order to evaluate the antioxidant status of the rabbits, plasma malondialdehyde (MDA) level and erythrocyte superoxide dismutase (SOD) activity were measured. After killing, aorta from all rabbits were subjected to histopathological examination. Results of the study demonstrated that feeding the cholesterol-enriched diet caused a significant increase in total-, LDL-, and HDL-cholesterol, plasma MDA and post-heparin total and hepatic lipase activities. On the other hand, serum TG and erythrocyte SOD were not changed. Histopathological examination revealed marked alteration in the aortic wall with the appearance of large multiple atheromatous plaques. Both garlic and pectin were successful in a significant reduction of the hypercholesterolemia in a way comparable to gemfibrozil. Garlic was the only treatment that has antilipid peroxidative property. Erythrocyte SOD activity was not affected by hypercholesterolemia or by any of the treatments. Also, none of the treatments were able to modify the significant elevation of post-heparin lipolytic activities associated with the hypercholesterolemia or to significantly affect the serum triglycerides level. Finally, among the hypercholesterolemic groups that received treatments, the least changes in the aortic wall were shown in the animals of the gemfibrozil group. Slight degeneration was observed in the aorta of animals treated with pectin or garlic. Ginseng administration failed to exert any significant protection from the remarkable hypercholesterolemia or atherosclerosis associated with the cholesterol- enriched diet.