Evaluation of palm antioxidants : vitamin E, phenolic-flavonoids and combinations thereof, for the prevention of atherosclerosis in an atherogenic rabbit model

The protective effects of vitamin E and palm phenolics, either singly or in combination, against atherosclerosis was studied in an atherogenic rabbit model. Thirty-two New Zealand White rabbits were divided into four groups of 8 and fed an atherogenic diet for100 days. The diet contained 35% energy from fat, with added cholesterol 0.15% (w/w). The fat comprised 67.1% saturated fatty acids, primarily as C12:0+C14:0. Group 1; the Control group (CTR) was fed the atherogenic diet, and Group 2; the Vitamin E group(VIT E) was fed the atherogenic diet with added vitamin E (500mg vitamin E/kg diet). Animals in Groups 1 and 2 were provided distilled water as their drinking water. Group 3; the palm phenolics group (AO) was fed the atherogenic diet and palm phenolics (at a concentration of 1500 mg gallic acid equivalent/L (mg GAE/L)) was provided as drinking fluid, while Group 4; the combination of vitamin E and palm phenolics group (AOE), were fed the atherogenic diet with added vitamin E and palm phenolics (l500mg GAE/L) was provided as their drinking fluids. Animals were fed diets ad libitum and had free access to drinking fluids. Fasting blood was obtained prior to sacrifice and plasma total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) and triglycerides (TG) were analyzed. The plasma antioxidant capacity was measured by the 2,2' - azinobis (3-ethylbenzothiazoline) 6-sulfonic acid radical cation (ABTS+) decolorization assay and ferric reducing ability of plasma (FRAP). The entire aorta was traced, dissected and stained with Oil Red-O for delineation of atheromatous deposits in the intima and lesions were quantified using a digital image analysis system. Results fromthe lipid profile analysis and both the FRAP and ABTS assays in all the experimental groups did not show any significant differences. Fibrous plaques were detected in the CTR group (8.90±5.41) but were significantly reduced in the VIT E (2.88±2.01) and AO (1.48±4.45) groups. On the other hand, no fibrous plaques were detected in the AOE group. Similar outcomes were observed for fatty plaques. Our findings suggest that despite the high-fat atherogenic diet, palm vitamin E showed an inhibitory effect against atherosclerotic lesion development. The palm phenolics on its own or in combination with palm vitamin E provided the highest protective effect against development of atherosclerotic lesions in this animal model.