Journal of APPLIED BIOMEDICINE J Appl Biomed. 10: 91–101, 2012 DOI 10.2478/v10136-011-0014-3 ISSN 1214-0287 ORIGINAL ARTICLE Modulation of antioxidant enzymes activities and lipid peroxidation products in diet-induced hypercholesterolemic rats fed ortanique peel polymethoxylated flavones extract Curtis Omar Green 1, 2 , Andrew O’Brien Wheatley 2, 3 , Donovan Anthony McGrowder 4 , Lowell Lloyd Dilworth 2 , Helen Nosakhare Asemota 2, 3 1 Tropical Medicine Research Institute, 2 Department of Basic Medical Sciences (Biochemistry Section), 3 Biotechnology Centre, 4 Department of Pathology, University of the West Indies, Kingston , Jamaica Received 3 rd August 2011. Revised 7 th September 2011. Published online 22 nd September 2011. Summary The primary aim of this study was to investigate the effects of ortanique peel polymethoxylated flavones extract (PMF ort ) on antioxidant enzymes activities and lipid peroxide levels in organs of hypercholesterolemic and normal rats. Thirty Sprague-Dawley rats were fed high cholesterol diets supplemented with 1.5% PMF ort and niacin respectively for 49 days. Hypercholesterolemic rats fed PMF ort had significant reductions in malondialdehyde levels in the liver and brain compared to untreated hypercholesterolemic control rats. This reduction also occurred in the brain of the rats fed niacin. The activities of catalase, glutathione reductase, transferase and peroxidase were significantly reduced in the spleen, brain and liver of hypercholesterolemic rats fed PMF ort compared to control. The activities of these enzymes were only reduced in the brain and liver of rats fed niacin. The results would suggest that PMF ort modulates hypercholesterolemia-associated organ injury and oxidative stress in rat organs. PMF ort could therefore be a suitable candidate of natural origin for prophylactic and therapeutic treatment of hypercholesterolemia-associated oxidative stress and organ injury. Key words: hypercholesterolemia; ortanique; antioxidant enzymes; polymethoxylated flavones INTRODUCTION We have demonstrated in previous publications that Ortanique peel PMF extract (PMF ort ) is a very potent hypolipidemic supplement that significantly reduced serum total, LDL, VLDL and triglycerides levels and increased HDL cholesterol levels (Green et al. 2011a). We also derived the mechanism of action which included reductions in the hepatic activity of the rate-limiting cholesterol synthesizing enzyme 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA HMG-CoA) reductase as well as absorption of cholesterol in the small intestines due to reductions in villi length and goblet cell proliferation. Our histopathological findings also demonstrated that PMF ort ameliorated hypercholesterolemic-associated organ injury (Green et al. 2011b). Therefore another objective that warrants further exploration is to investigate the effects of PMF ort on antioxidant enzymes activity and organ injury. This is important as several studies have shown that hyper- cholesterolemia usually results in oxidative stress and since flavonoids are potent antioxidants they could be explored as possible supplements for treating hypercholesterolemia-induced oxidative stress.  Curtis Omar Green, Tropical Medicine Research Institute, University of the West Indies (Mona), Kingston 7, Jamaica W.I.  curtis.green@uwimona.edu.jm  876-9271884  876-9770632 © Journal of Applied Biomedicine