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Oryzanol decreases cholesterol absorption and aortic fatty streaks in hamsters
Author(s) -
Rong Ni,
Ausman Lynne M.,
Nicolosi Robert J.
Publication year - 1997
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-997-0037-9
Subject(s) - cholesterol , chemistry , triglyceride , coconut oil , very low density lipoprotein , food science , high cholesterol , endocrinology , biochemistry , medicine , biology , lipoprotein
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 contorl (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 nonsaponifiable 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.