Abstract: The inhibitory effect of soybean isoflavones (ISF) on lipid peroxidation of serum lipoproteins in rabbits with atherosclerosis was studied. An atherosclerotic model was established by feeding rabbits high-fat diet. ISF at dosages of 100 and 50 mg/(kg ·d) and was added to the high-fat diet to create high dosage and low dosage treatment groups, and simvastatin at 2 mg/(kg ·d) added as a control. After 8 weeks of feeding, all rabbits were killed and aorta was collected, then HE staining was used to examine the pathological change during the formation of atherosclerosis. Serum lipoproteins were isolated to investigate the cholesterol (CH) level, lipid peroxidation (LPO) and the oxidation susceptibility of low-density lipoprotein (LDL). The results showed that ISF administration suppressed the formation of atherosclerotic plaques, reduced the levels of plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-CH) in atherosclerotic rabbits, decreased the LPO level of serum lipoproteins, and prolonged the lag phage of LDL oxidation in vitro. These results suggested that ISF could reduce cholesterol level, decrease the lipid peroxidation of LDL, and promote resistance to LDL oxidation, which may be useful in the prevention and treatment of atherosclerosis.

Key words: soybean, isoflavones, atherosclerosis, hypercholesterolemia, lipoproteins, lipid peroxidation, oxidation susceptibility