Chinese Yam Extracts Containing β‐Sitosterol and Ethyl Linoleate Protect against Atherosclerosis in Apolipoprotein E‐Deficient Mice and Inhibit Muscular Expression of VCAM‐1 In Vitro

Abstract Atherosclerosis is a chronic inflammatory disease, which is associated with increased expression of adhesion molecules and monocyte recruitment into the arterial wall. This study evaluated whether hexane extracts from the edible part (DB‐H1) or bark region (DB‐H2) of Dioscorea. batatas Decne have anti‐atherosclerotic properties in vivo and in vitro experiments. We also identified bioactive components in the hexane extracts. Thirty‐six apolipoprotein E (ApoE −/− ) mice and 12 control (C57BL/6J) mice were given a Western‐type diet for 11 or 21 wk. To examine the effects of yam extracts on lesion development, ApoE −/− mice were orally administered DB‐H1 or DB‐H2 for the duration of the study (200 mg/kg b.w./day, 3 times per wk). Both DB‐H1 and DB‐H2 significantly reduced the total atherosclerotic lesion area in the aortic root. In addition, plasma concentrations of total cholesterol, oxidized‐low‐density lipoprotein, and c‐reactive protein were decreased by administration of DB‐H1 and DB‐H2. Consistent with the in vivo observations, DB‐H1 and DB‐H2 inhibited tumor necrosis factor (TNF)‐α–induced vascular cell adhesion molecule‐1 expression and adhesion of THP‐1 monocytes to TNF‐α–activated vascular smooth muscle cells. It was also found that treatment with DB‐H1 or DB‐H2 resulted in the inhibition nitric oxide (NO) and reactive oxygen species production and iNOS expression in macrophages. Thus, DB‐H1 and DB‐H2 seem to influence atherosclerosis by affecting the production of inflammatory mediators in vivo . Our results suggest that yam extracts have the potential to be used in the prevention of atherosclerosis.