Evaluation of the effect of flavangenol on serum lipid peroxide levels and development of atherosclerosis in spontaneously hyperlipidemic B6.KOR-Apoe shl mice

Abstract

Antioxidative flavonoids are used to reduce the risk of cardiovascular diseases in humans. However, the precise mechanism for the anti-atherosclerotic actions of flavonoids remains to be elucidated. In the present study, to assess the mechanism for the action of antioxidative flavonoids on atherosclerosis, we investigated the effect of flavangenol, one of the most potent antioxidants currently known, on spontaneously hyperlipidemic B6.KOR-Apoeshl mice. Flavangenol was orally administered to B6.KOR-Apoeshl mice ad libitum (6 mg flavangenol/mouse/day). After 6 months, serum levels of lipids (total cholesterol, triglyceride, HDL-cholesterol and LDL-cholesterol) and lipid peroxide were measured, and histopathological changes (lipid accumulation and inflammatory cell infiltration) in the aortic root were evaluated. Serum levels of total cholesterol and LDL-cholesterol were markedly increased, and HDL-cholesterol levels were decreased in B6.KOR-Apoeshl mice compared to C57BL/6 mice used as a control (p<0.001). Among these serum lipids, only HDL-cholesterol levels were significantly increased by flavangenol administration (p<0.05). Moreover, Oil Red O staining (lipid accumulation) was significantly increased in B6.KOR-Apoeshl mice compared to C57BL/6 mice (p<0.001). Notably, flavangenol administration significantly suppressed the increase in Oil Red O staining (p<0.01). Similarly, inflammatory cell infiltration into the intima was significantly increased in B6.KOR-Apoeshl mice compared to C57BL/6 mice (p<0.01), and flavangenol administration significantly suppressed the inflammatory cell infiltration (p<0.01). Importantly, flavangenol administration significantly reduced the increase of serum lipid peroxide levels in B6.KOR-Apoeshl mice (p<0.05). Together, these observations indicate that flavangenol, one of the most potent antioxidants, exerts its anti-atherosclerotic action on spontaneously hyperlipidemic and atherosclerotic B6.KOR-Apoeshl mice, possibly by increasing HDL-cholesterol levels and reducing lipid peroxide levels, thereby suppressing the lipid accumulation (formation of atherosclerotic lesions) and inflammatory cell infiltration (chronic inflammation) in the intima of the aortic root.