Prevention of Hypercholesterolemic Atherosclerosis by Garlic, an Antioxidant
Authors: Prasad Kailash , Mantha Subrahmanyan V. , Kalra Jawahar , Lee Paul 
Published: November 2007

Background: Investigations of the effects of high cholesterol diet in the presence and absence of garlic on the genesis of atherosclerosis, the blood lipid profile, aortic tissue lipid peroxida tion product malondialdehyde, chemiluminescence, a marker for antioxidant reserve and activ ity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase were made in rabbits.

Methods and Results: Four groups of 10 rabbits each were studied: group 1 was given regu lar rabbit chow, group 2 was given rabbit chow diet supplemented with garlic powder (300 mg twice daily orally), group 3 was given 1% cholesterol diet, group 4 was given 1% cholesterol diet supplemented with garlic powder (300 mg twice daily orally). Blood concentration of triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol were measured before and after 4 and 10 weeks of experimental diets. The aorta was removed at the end of protocol (10 weeks) for assessment of atherosclerotic changes (gross and microscopic), malondialdehyde concentra tion, chemiluminescence, and activity of antioxidant enzymes. Total cholesterol, low density- lipoprotein cholesterol and ratio of low-density lipoprotein cholesterol/high-density lipopro tein cholesterol increased in group 3 and 4; the increase was smaller in group 4 than in group 3 although not significant. Scrum high-density lipoprotein cholesterol decreased to a similar extent in groups 3 and 4. Serum triglyceride and very low-density lipoprotein cholesterol remained unchanged in group 3 but increased in group 4. These values were significantly higher than those in group 1. Garlic in rabbits with control diet decreased the levels of triglyc eride and very low density lipoprotein but did not affect the levels of total cholesterol, low- density lipoprotein cholesterol, and high-density lipoprotein cholesterol and the ratio of low- density lipoprotein cholesterol/high-density lipoprotein cholesterol. There was an increase in aortic tissue malondialdehyde, chemiluminescence, and activities of catalase and glutathione peroxidase in group 3 compared with those in group 1. Levels of aortic malondialdehyde, chemiluminescence, catalase, and glutathione peroxidase were lower in group 4 compared with group 3; however, values for malondialdehyde and chemiluminescence were lower and that of catalase and glutathione peroxidase were higher in group 4 compared with group 1. Superoxide dismutase activity was similar in all the four groups. Malondialdehyde, chemilu minescence, and activity of catalase of aortic tissue decreased while activity of glutathione peroxidase increased in group 2. Atherosclerotic changes were lower in group 4 compared with group 3. Histologic changes were practically similar in groups 3 and 4.

Conclusions: Increased levels of malondialdehyde, chemiluminescence, and antioxidant enzymes associated with development of atherosclerosis suggests a role for oxygen free radi cals in the pathogenesis of hypercholesterolemic atherosclerosis. The protection afforded by garlic was associated with decrease in aortic malondialdehyde and chemiluminescence inspite of no change in serum cholesterol. These findings suggest that oxygen free radicals are involved in the genesis and maintenance of hypercholesterolemic atherosclerosis and that use of garlic can be useful in preventing the development of hypercholesterolemic atherosclerosis.