Antiatherogenic effect of naringin independent of lipid-lowering action in hypercholesterolemic rabbits = 고콜레스테롤혈증 토끼에서의 지질강하효과와 독립적인 Naringin의 항동맥경화 효과

Abstract

Background：Naringin, one of the flavonoids in citrus fruit peels, is known to have antioxidant and hepatotonic effects in animal studies. We evaluated the effect of naringin on 1) blood lipid profiles, 2) regression of fatty streak of aorta, and 3) liver toxicity in diet-induced hypercholesterolemic rabbits. Methods：New Zealand White Rabbits (2.0-2.5 Kg) were divided to three groups；group without treatment, group treated with 100 mg/kg/d or 500 mg/kg/d naringin, and group treated with 1 mg/kg/d or 20 mg/kg/d lovastatin. They were fed on 0.25% or 1.0% cholesterol-containing diet for 8 weeks and then sacrificed. Blood samples were collected for measurement of total cholesterol, HDL-cholesterol, triglyceride, serum GOT and GPT. Aortas and livers were harvested for evaluation of fatty streak and pathologic examination. Results：1) Feeding of 1% cholesterol diet for eight weeks significantly increased the cholesterol level upto 20 folds. Neither lovastatin nor naringin did lower these marked hypercholesterolemia. But both naringin (500 mg/kg/d) and lovastatin (1 mg/kg/d) significantly reduced the area of fatty streak by 75% and 58%, respectively. Naringin was more effective in inhibition of fat infiltration into liver than lovastatin which showed hepatotoxicity as increase of serum GPT level (p<0.01). 2) Feeding of 0.25% cholesterol diet for eight weeks significantly increased the cholesterol level upto 17 folds. Total cholesterol and triglyceride levels tended to decrease by treatment with naringin (500 mg/kg/d) and lovastatin (20 mg/kg/d), but this decreases were not statistically significant. However, areas of fatty streak significantly decreased by treatment with naringin and lovastatin by 64 and 82%, respectively (p<0.05). Microscopic analysis revealed that foam cell infiltration into intima was significantly reduced by naringin and lovastatin. In contrast to lovastatin, naringin significantly reduced the level of serum GPT (p<0.05). Conclusion：Like lovastatin, naringin has strong antiatherogenic action which may not be associated with its very mild lipid lowering action. In contrast to lovastatin, naringin does have hepatoprotective effect.