No abstract

Specific antioxidant activity (SAA) (i.e., activity related to the molar or gallic acid equivalent amount of antioxidant) of natural polyphenolic mixtures or pure phenolic compounds was studied using their capacity to delay the conjugated diene production brought about by in vitro LDL copper-mediated or AAPH-mediated oxidation. The cinnamic acid series (caffeic, sinapic, ferulic acids) displayed a constant SAA over a large range of concentrations, whereas the benzoic acid series (gallic and protocatechuic acids) showed much higher SAA at low concentrations. The natural phenolic mixtures had a constant SAA. The highest SAA was obtained with caffeoyl esters (caffeoylquinic, rosmarinic, and caffeoyltartaric acids) and catechin for the copper-oxidation and the AAPH-oxidation system, respectively. Phenolic mixtures and acids delayed vitamin E depletion and decreased proinflammatory lysophosphatidylcholine production. As with polyphenols, probucol delayed lysophosphatidylcholine and conjugated dienes production, at higher concentrations, but was not effective at preventing vitamin E depletion. Polyphenols prevent the oxidation of LDL and its constituents (vitamin E, phosphatidylcholine), which is compatible with an antiinflammatory and antiatherosclerotic role in pathophysiological conditions.

Dietary lipids are known to affect the composition of the biological membrane and functions that are involved in cell death and survival. The mitochondrial respiratory chain enzymes are membrane protein complexes whose function depends on the composition and fluidity of the mitochondrial membrane lipid. The present study aimed at investigating the impact of different nutritional patterns of dietary lipids on liver mitochondrial functions. A total of forty-eight Wistar male rats were divided into six groups and fed for 12 weeks with a basal diet, lard diet or fish oil diet, containing either 50 or 300 g lipid/kg. The 30 % lipid intake increased liver NEFA, TAG and cholesterol levels, increased mitochondrial NEFA and TAG, and decreased phospholipid (PL) levels. SFA, PUFA and unsaturation index (UI) increased, whereas MUFA and trans-fatty acids (FA) decreased in the mitochondrial membrane PL in 30 % fat diet-fed rats compared with 5 % lipid diet-fed rats. PL UI increased with fish oil diet v. basal and lard-rich diets, and PL trans-FA increased with lard diet v. basal and fish oil diets. The 30 % lipid diet intake increased mitochondrial membrane potential, membrane fluidity, mitochondrial respiration and complex V activity, and decreased complex III and IV activities. With regard to lipid quality effects, b-oxidation decreased with the intake of basal or fish oil diets compared with that of the lard diet. The intake of a fish oil diet decreased complex III and IV activities compared with both the basal and lard diets. In conclusion, the characteristics and mitochondrial functions of the rat liver mitochondrial membrane are more profoundly altered by the quantity of dietary lipid than by its quality, which may have profound impacts on the pathogenesis and development of non-alcoholic fatty liver disease. Key words: High-fat diet: Lipid metabolism: Mitochondrial functions: Mitochondrial membrane: Respiratory complexes: RatsIncreasing consumption of fat-rich diets and reduced physical activity are the major contributors to the observed increase in body weight, diabetes and fatty liver diseases in many developed and developing countries, and have become a major public health concern (1 -4) . Lipids play varied and critical roles in cellular metabolism, with functions dramatically modulated by the individual fatty acid (FA) moieties in complex lipid entities. Moreover, biological membranes are composed of more than 50 % of lipids, and the quantity and quality of dietary lipids are known to have an impact on the composition, characteristics and functions of the biological membrane (5 -7) . FA as components of biological membranes strongly influence membrane fluidity, which, in turn, may influence many physiological processes involved in cell death and survival such as signal transduction, protein import, membrane receptor function and metabolite transport (8) . Moreover, the quality of administered lipid seems to play a crucial role in the occurrence (or not) of these alterations and their severity (9) . The...

Objectives: To evaluate the effect of the red wine phenolic compound (RWPC) dietary supplementation without alcohol interference on: (1) some of the biochemical characteristics of LDL, (2) the oxidative susceptibility of LDL and (3) the antioxidant capacity of total plasma (Pl-AOC). In order to account for discrepancies between the three series of data, the in vitro stability of the association of phenolic compounds and LDL was tested. Design: An intervention study with 20 volunteers. Each served as his own control. Cu 2 -oxidizability of LDL and Pl-AOC were tested on blood samples before and after dietary supplementation. Cu 2 -oxidizability of LDL was also tested by co-incubation in the presence of RWPC or phenolic acids with or without extensive dialysis. Setting: The Laboratory of Lipid Biochemistry and Biology, School of Medicine, and the Laboratory of Metabolic Diseases, Lapeyronie Hospital, University of Montpellier, France. Subjects: Healthy males, nonsmokers and moderate drinkers, submitted to a dietary regimen deprived of vitamin E and C for a period of 10 d before supplementation. They also abstained from alcohol, wine, fruit juices, coffee, tea and cola beverages during this period. Intervention: Six 0.33 g capsulesad (namely two capsules at each meal) of a preparation of red wine phenolic compounds in a dry powder form were given to the volunteers over a period of two weeks. Blood samples were drawn in fasting conditions at day 0 and day 14 of the supplementation period. Results: Supplementation led to: (1) in LDL, a signi®cant increase in vitamin E content (n 20, P 0.01) or vitamin Eatotal fatty acid bis-allylic carbon number ratio (n 20, P 0.006) without modi®cation in the other biochemical characteristics or Cu 2 -oxidizability; (2) in plasma, a signi®cant increase in the antioxidant capacity (n 11, P 0.01). In vitro studies showed that RWPC or sinapic, caffeic or ferulic acids incubated in the presence of LDL increased the protection of the lipoparticle against oxidation (caffeic b sinapic b ferulic). This effect, however, was totally lost after extensive dialysis. Conclusions: The enhancing effect of the RWPC supplementation on Pl-AOC may be due to a phenoliccompound action both in the aqueous phase of plasma and at the surface of lipoprotein particles. Surface location possibly explains the enhancing-sparing effect of supplementation on LDL vitamin E and the absence of effect on dialysed-LDL oxidizability.