Assessment of physiological interaction between vitamin E and vitamin C

Cardiovascular risk and benefits from antioxidant dietary intervention with red wine in asymptomatic hypercholesterolemics

BACKGROUND & AIMS

The role of red wine in cardiovascular risk prevention has been documented by several epidemiological studies in patients and normocholesterolemic healthy individuals. However, it is unclear whether hypercholesterolemic individuals free of cardiovascular disease would equally benefit from moderate red wine consumption to prevent atherosclerosis and the development of cardiovascular disease.

METHODS

Forty (40) healthy male and female volunteers were recruited, divided into 2 age-adjusted groups according to their total cholesterol levels; in asymptomatic hypercholesterolemics (AHC), and normocholesterolemics (NC). Total Antioxidant Capacity (TAC), Lipid profile, Vitamin E, and cardiovascular risk indexes (Low Density Lipoproteins (LDL)/High Density Lipoproteins (HDL) and Vitamin E/Total Cholesterol (TC) were evaluated in the blood serum of all subjects prior to and 1 month after once daily red wine consumption as well as prior to and after being given a placebo drink following a 1 month wash out period.

RESULTS

TAC significantly increased after the intervention in all subjects in AHC and NC group with a mean difference (post-pre) 1.78 mmol/l and 0.87 mmol/l, respectively. Vitamin E significantly increased especially in AHC group (13.1% increase) compared to NC group (5.41%) after red wine consumption, with higher increase in the AHC group. There was marginal significant treatment effect (decrease) on fasting LDL/HDL ratio (p = 0.05) and a statistically significant increase on Vitamin E/TC ratio relative to drinking placebo for NC (p < 0.005) and AHC group (p < 0.002).

CONCLUSIONS

Asymptomatic hypercholesterolemic (AHC) individuals are more likely to develop cardiovascular disease as presented by high cholesterol levels in addition to the presence of low baseline serum α-tocopherol (vitamin E) concentrations, leading to atherosclerosis. AHC individuals following an early dietary intervention, seem likely to reduce the risk factors for cardiovascular disease by increasing circulating concentrations of TAC and α-tocopherol (vitamin E) so as vitamin E/TC ratio increases.

Vitamin E in early stages of sea bass (Dicentrarchus labrax) development

This study reports titration of vitamin E levels in the sea bass (Dicentrarchus labrax) using high-pressure liquid chromatography. The first part of the work is devoted to vitamin E detection in: (1) plasma of maturing females and males characterized by different body sizes; (2) seminal fluid and eggs; and (3) developing embryos of sea bass fed with vitamin E. In the second part of the study, variations of vitamin E levels during larval development are analyzed. The results show a direct correlation between plasma vitamin E content and body size for both adult male and female sea bass. High vitamin E levels were found in seminal fluid, in eggs before and after fertilization, and in embryos during development and at hatching, whereas vitamin E level was low in dead embryos and in embryos with limited survival. During larval development, the vitamin E content decreased slowly but steadily during the first four days of larval growth; subsequently, it progressively increased from day 9 to day 40. In teratogenic larvae, vitamin E content was significantly higher than in normal larvae. This study provides evidence on how vitamin E exerts an antioxidant defense in sea bass reproduction.

Antioxidants in grasshoppers: higher levels defend the midgut tissues of a polyphagous species than a graminivorous species

Polyphagous grasshoppers consume plants that contain markedly greater amounts of potentially prooxidant allelochemicals than the grasses eaten by graminivorous grasshoppers. Therefore, levels of antioxidant defenses maintained by these herbivores might be expected to differ in accordance with host plant ranges. Antioxidant levels were compared in midgut tissues and gut fluids of a polyphagous grasshopper. Melanoplus sanguinipes, and a graminivorous grasshopper, Aulocara ellioti. Glutathione concentrations in midgut tissues of M. sanguinipes (10.6 mM) are among the highest measured in animal tissues and are twice as high as those in A. ellioti. Alpha-tocopherol levels are 126% higher in midgut tissues of M. sanguinipes than in those of A. ellioti, and remain at high levels when M. sanguinipes is reared on plants containing a wide range of alpha-tocopherol concentrations. Ascorbate levels in M. sanguinipes midgut tissues are 27% higher than in those of A. ellioti, but vary depending on the host plant on which they are reared. Midgut fluids of both species contain elevated levels of glutathione, as well as large (millimolar) amounts of undetermined antioxidants that are produced in the insects. The consumption of tannic acid decreases ascorbate concentrations in midgut tisssues and gut fluids of A. ellioti but has no effect on ascorbate levels in M. sanguinipes. The results of this study provide the first measurements of antioxidants in grasshoppers and suggest that the maintenance of high levels of antioxidants in the midgut tissues of polyphagous grasshoppers might effectively protect them from oxidative stress.

Is pharmacological prevention of Alzheimer's a realistic goal?

A growing body of evidence suggests that several classes of drugs marketed for other indications may be effective in the prevention of Alzheimer's disease. Among the most promising of these are nonsteroidal anti-inflammatory agents, oestrogens (oestrogen replacement therapy) and antioxidant vitamins. Other less well-established candidates include histamine H(2) receptor antagonists (H(2) blockers) and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). For each of these, we discuss possible mechanisms for their postulated neuroprotective effects and review the studies suggesting their benefits in Alzheimer's disease. We conclude that nonsteroidal anti-inflammatory drugs and oestrogen replacement therapies may be effective in preventing Alzheimer's disease only if taken during the latent phase of the disease several years prior to the appearance of disturbances. Antioxidants may also prevent Alzheimer's disease, but unlike nonsteroidal anti-inflammatory drugs and oestrogen replacement therapies, they may continue to have beneficial effects even after the clinical onset of the disease. The only way to demonstrate the efficacy of these agents will be through randomised, controlled prevention trials. Such trials are currently underway but conclusive results may not be available for several years. Although intriguing, more studies on the neuroprotective effects of statins and H(2) blockers are needed before trials of these agents are initiated. Finally, there are other classes of pharmacological compounds emerging on the horizon, including folic acid, anti-beta-sheet conformational agents, secretase inhibitors and vaccines, that may soon prove to be effective for the prevention of Alzheimer's disease.

Flavonoids can replace alpha-tocopherol as an antioxidant

Endogenous antioxidants such as the lipid-soluble vitamin E protect the cell membranes from oxidative damage. Glutathione seems to be able to regenerate alpha-tocopherol via a so-called free radical reductase. The transient protection by reduced glutathione (GSH) against lipid peroxidation in control liver microsomes is not observed in microsomes deficient in alpha-tocopherol. Introduction of antioxidant flavonoids, such as 7-monohydroxyethylrutoside, fisetin or naringenin, into the deficient microsomes restored the GSH-dependent protection, suggesting that flavonoids can take over the role of alpha-tocopherol as a chain-breaking antioxidant in liver microsomal membranes.

Constitutive hsp70 attenuates hydrogen peroxide-induced membrane lipid peroxidation

Thermal pretreatment improves cardiac recovery from subsequent ischemia/reperfusion. Induction of heat shock proteins (hsps) may contribute to this protection. We have demonstrated that augmentation of the constitutive hsp70 (hsc70) in H9c2 heart myoblasts promotes oxidative resistance. We employed a model oxidant to explore potential target(s) of protection by hsc70. Upon exposure to 54 microM of hydrogen peroxide (H(2)O(2)), hsc70-overexpressing cells exhibited a lower lipid peroxidation than the sham-transfected control. Constitutive hsc70 overexpression, however, did not protect against H(2)O(2)-induced depletion of ATP and glutathione (GSH). Lipid protection also occurred in cells preconditioned at 39 degrees C (selectively induces hsc70) during H(2)O(2) exposure. Interestingly, the protection conferred by hsc70 was comparable in magnitude to that provided by alpha-tocopherol, and was followed with a reduced release of lactate dehydrogenase and a unaltered calcium uptake during H(2)O(2) challenge. Collectively, our observations suggest that hsc70 may preserve membrane function via attenuation of lipid peroxidation during oxidative insult.