Oryzanol decreases cholesterol absorption and aortic fatty streaks in hamsters.
Oryzanol is a class of nonsaponifiable lipids of rice bran oil (RBO). More specifically, oryzanol is a group of ferulic acid esters of triterpene alcohol and plant sterols. In experiment 1, the mechanisms of the cholesterol-lowering action of oryzanol were investigated in 32 hamsters made hypercholesterolemic by feeding chow-based diets containing 5% coconut oil and 0.1% cholesterol with or without 1% oryzanol for 7 wk. Relative to the control animals, oryzanol treatment resulted in a significant reduction in plasma total cholesterol (TC) (28%, P < 0.01) and the sum of IDL-C, LDL-C, and VLDL-C (NON-HDL-C) (34%, P < 0.01). In addition, the oryzanol-treated animals also exhibited a 25% reduction in percent cholesterol absorption vs. control animals. Endogenous cholesterol synthesis, as measured by the liver and intestinal HMG-CoA reductase activities, showed no difference between the two groups. To determine whether a lower dose of oryzanol was also efficacious and to measure aortic fatty streaks, 19 hamsters in experiment 2 were divided into two groups and fed for 10 wk chow-based diets containing 0.05% cholesterol and 10% coconut oil (w/w) (control) and the control diet plus 0.5% oryzanol (oryzanol). Relative to the control, oryzanol-treated hamsters had reduced plasma TC (44%, P < 0.001), NON-HDL-C (57%, P < 0.01), and triglyceride (TG) (46%, P < 0.05) concentrations. Despite a 12% decrease in high density lipoprotein cholesterol (HDL-C) (P < 0.01), the oryzanol-treated animals maintained a more optimum NON-HDL-C/HDL-C profile (1.1 +/- 0.4) than the control (2.5 +/- 1.4; P < 0.0075). Aortic fatty streak formation, so defined by the degree of accumulation of Oil Red O-stained macrophage-derived foam cells, was reduced 67% (P < 0.01) in the oryzanol-treated animals. From these studies, it is concluded that a constituent of the non-saponifiable lipids of RBO, oryzanol, is at least partially responsible for the cholesterol-lowering action of RBO. In addition, the cholesterol-lowering action of oryzanol was associated with significant reductions in aortic fatty streak formation.
Rong
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Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111, USA.
Ausman
L M
LM
Nicolosi
R J
RJ
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D001161:Arteriosclerosis / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism* / Q000493:pharmacokinetics; D008078:Cholesterol, LDL / Q000097:blood; D015243:Cholesterol, VLDL / Q000097:blood; D006224:Cricetinae; D000960:Hypolipidemic Agents / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010666:Phenylpropionates / Q000494:pharmacology*; D010938:Plant Oils / Q000737:chemistry; D000073879:Rice Bran Oil
D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D000960:Hypolipidemic Agents; D008055:Lipids; D008074:Lipoproteins; D010666:Phenylpropionates; D010938:Plant Oils; D002784:Cholesterol; D000073879:Rice Bran Oil; C013172:gamma-oryzanol