The effect of lutein (100, 200, 300 mu g/ml), sesamol (500,1000, 2000 mu g/ml), ellagic acid (300, 600, 900 mu g/ml) and olive leaf extract (100, 200, 300 mu g/ml) on oxymyoglobin oxidation and lipid oxidation in bovine and porcine muscle model systems (25% M. longissimus thoracis et lumborum homogenates) was examined. Radical scavenging activity, using the DPPH assay, and iron-chelating activities of lutein, sesamol, ellagic acid and olive leaf extract were assessed at concentrations ranging from 200 to 1000 ppm. The radical scavenging activity was of the order: ellagic acid > sesamol > olive leaf extract > lutein. None of the natural antioxidants examined exhibited iron chelating activity. Following induced lipid oxidation (FeCl3/sodium ascorbate addition), lipid oxidation and oxymyoglobin oxidation were measured after 24 h at 4 degrees C. In bovine and porcine muscle model systems, lipid oxidation decreased (P < 0.001) following addition of each of the natural antioxidants relative to the control and antioxidant potency followed the order: sesamol > ellagic acid > olive leaf extract > lutein. Ellagic acid and olive leaf extract decreased oxymyoglobin oxidation (P < 0.001) while sesamol increased oxymyoglobin oxidation in both systems. The natural antioxidants examined may have applications in the development of nutritional enhanced meat products with enhanced shelf-life characteristics. (C) 2009 Elsevier Ltd. All rights reserved..