Plant extracts rich in polyphenols (PERP) could represent interesting alternative antioxidants but their use in ruminants needs further investigation since the antioxidant capacity of PERP could be altered by digestive processes. The aim of the study was to investigate the bioavailability and the antioxidant capacity of four PERP (rosemary; grape; citrus; marigold) in ruminants made highly susceptible to lipoperoxidation by a continuous linseed oil infusion (4 % DM) in the duodenum. The PERP were given, as a single acute dose (10 % DM), directly into the rumen of sheep (n 5) and blood was then collected every 3 h over a period of 30 h. Grape was particularly efficient to enhance the plasma total antioxidant status (P < 0·05). Moreover, many new polyphenols were detected in the plasma and the identification of epicatechin in the grape group suggested that, contrary to monogastrics, ruminants can benefit from the antioxidant effect of polymeric proanthocyanidins. Finally, the four PERP tested, and more especially marigold, significantly reduced plasma susceptibility to liperoxidation (mean increase of lag phase: +5·9 min, P < 0·02; mean reduction of oxidation rate: − 1·7 A₂₃₄/min, P < 0·01). In conclusion, the digestive processes in ruminants do not inhibit the antioxidant properties of PERP in vivo and are beneficial by improving the biological effect of polymeric proanthocyanidins. Further experiments are now necessary to determine the optimum dose of administration and to characterize the bioactive molecules.

The anti-atherogenic effects of omega 3 fatty acids, namely eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) are well recognized but the impact of dietary intake on bioactive lipid mediator profiles remains unclear. Such a profiling effort may offer novel targets for future studies into the mechanism of action of omega 3 fatty acids. The present study aimed to determine the impact of DHA supplementation on the profiles of polyunsaturated fatty acids (PUFA) oxygenated metabolites and to investigate their contribution to atherosclerosis prevention. A special emphasis was given to the non-enzymatic metabolites knowing the high susceptibility of DHA to free radical-mediated peroxidation and the increased oxidative stress associated with plaque formation. Atherosclerosis prone mice (LDLR^−/−) received increasing doses of DHA (0, 0.1, 1 or 2% of energy) during 20 weeks leading to a dose-dependent reduction of atherosclerosis (R² = 0.97, p = 0.02), triglyceridemia (R² = 0.97, p = 0.01) and cholesterolemia (R² = 0.96, p<0.01). Targeted lipidomic analyses revealed that both the profiles of EPA and DHA and their corresponding oxygenated metabolites were substantially modulated in plasma and liver. Notably, the hepatic level of F₄-neuroprostanes, a specific class of DHA peroxidized metabolites, was strongly correlated with the hepatic DHA level. Moreover, unbiased statistical analysis including correlation analyses, hierarchical cluster and projection to latent structure discriminate analysis revealed that the hepatic level of F₄-neuroprostanes was the variable most negatively correlated with the plaque extent (p<0.001) and along with plasma EPA-derived diols was an important mathematical positive predictor of atherosclerosis prevention. Thus, oxygenated n-3 PUFAs, and F₄-neuroprostanes in particular, are potential biomarkers of DHA-associated atherosclerosis prevention. While these may contribute to the anti-atherogenic effects of DHA, further in vitro investigations are needed to confirm such a contention and to decipher the molecular mechanisms of action.