The antioxidative effect of plant extracts rich in polyphenols differs between liver and muscle tissues in rats fed n-3 PUFA rich diets

The susceptibility of lipids to lipoperoxidation in tissues can be enhanced by increasing the content in polyunsaturated fatty acids (PUFA) in lipids or by inducing an overproduction of reactive oxygen species (ROS) as it is the case under oxidative stress conditions. In contrast, the intake of dietary antioxidants limits lipoperoxidation by preventing the attack of PUFA by ROS. Domestic animals are particularly exposed to lipoperoxidation since the use of PUFA rich diets has been developed to improve the nutritional value of animal's products. Vitamin E is the antioxidant most commonly used in animal nutrition but it presents some drawbacks which have lead to research new natural and powerful antioxidants. In this context, it was assumed that plant extracts rich in polyphenols (PERP) could be good candidates and the aim of this experiment was to investigate the bioefficiency of PERP to prevent lipoperoxidation in animals fed a n-3 PUFA rich diet. Four PERP (rosemary, RO; grape, GP; citrus, CI and marigold, MA) were selected and orally administrated (0.5 g/kg diet) to rats given a diet enriched with 15% of linseed oil (rich in 18:3n-3). The present experiment was specifically designed to investigate the ability of the PERP to limit lipoperoxidation in different tissues (liver, Longissimus thoracis muscle and heart) and therefore to support results already reported in plasma. In liver, malondialdehyde (MDA) production was decreased by 30% in PERP supplemented rats, especially with RO and CI (-34%, P<0.05). This effect was associated with an increase in vitamin E for RO and GP (+24 and +11% respectively, P<0.05) and an enhancement of catalase activity for GP and MA (+13% and +11%, P<0.05). In muscle tissues, lipoperoxidation intensity was not significantly modified by PERP and it was assumed that a longer supplementation period would have been necessary to improve the oxidative stability of extra-hepatic tissues. It was concluded that the bioefficiency of the 4 PERP depended on the type of tissue and their protective effects were probably achieved by different mechanisms. Further work is now necessary to confirm these biological properties in domestic animals of agronomical interest.