Ocular tissues and fluids oxidative stress in hares fed on verbascoside supplement.

The influence of a prolonged diet supplemented with the powerful antioxidant verbascoside on the oxidative state of 20 healthy hares eye fluids and tissues has been studied. Verbascoside was dosed at 2, 3, 4 mg/die and the impact on the oxidative state of ocular tissues and fluids was tested by TBARS (thio barbituric acid reactive substances) and TEAC (trolox equivalent antioxidant capacity) assays. The percentage of change in antioxidant activity increased largely in retina and lenses at a daily verbascoside dose of 3 mg, whereas for optic nerve and vitreous humor the higher antioxidant capacity was measured at 4 mg/die verbascoside dose. The present findings demonstrate that verbascoside supplementation is able to protect ocular tissue and fluids from naturally occurring oxidation and that its protective effect depends on the daily dose, being maximum up to 3 mg/die.

Effects of verbascoside-based diet on blood and plasma constituents of rabbits.

OBJECTIVE: Oxidative stress brought on by free radicals can lead to an increased risk of some chronic pathologies. Antioxidants can scavenge free radicals by turning them into nonradical and nontoxic metabolites. The purpose of this study is to investigate the effect of a phenylpropanoid glycosides-based prolonged diet on blood constituents in animals. METHODS: Tests were carried out on healthy New Zealand white rabbits and the following parameters were evaluated at baseline and after 90 days' follow-up: plasma triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, aspartate transaminase, alanine aminotransferase, bilirubin, the reactive oxygen metabolites, thiobarbituric acid-reactive substances, vitamin A, and vitamin E. The same parameters were analyzed in an age- and sex-matched animal control group. RESULTS: We first defined the concept of average rate and then used it to calculate, by experimental data fitting, the formation or destruction rate of some blood or plasma constituents as a function of the daily dose. The results indicate that the effects can be categorized into 2 classes. The first includes the effects that produce monotonously continuous changes with daily dose, and the second includes those that exhibit a saturating trend. CONCLUSIONS: The experimental results suggest that high doses of verbascoside can potentially cause adverse effects through prooxidative effects. Risk is increased by the use of pharmacological doses of polyphenols in prevention, treatment, and as dietary supplements.

Lipid oxidation in water-in-olive oil emulsions initiated by a lipophilic radical source.

The lipophilic 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) was used to study thoroughly the oxidation reaction in a model water-in-olive oil emulsion system. This radical species decomposes thermally generating a constant flux of radicals in the oil phase. The dissociation constant k(d) in olive oil at 40 degrees C for AMVN was calculated as 2.5 x 10(-4) min(-1) and the rate of initiation of the oxidation reaction, R(i) was calculated by using vitamin E as antioxidant. The olive oil oxidation in emulsion was monitored by measuring the hydroperoxide concentration by a sensitive fluorimetric method. The DPPP (diphenyl-1-pyrenylphosphine) was used as a probe because it reacts stoichiometrically with hydroperoxides to yield a fluorescent product, the diphenyl-1-pyrenylphosphine oxide (DPPP-O). Oxidation data together with emulsion droplet size data showed that in the presence of radical initiator and a large interface, the oxidation reaction is accelerated in W/Olive oil emulsion with respect to whole oil. The mediation of the surface area of water droplets is surely involved in this process because the addition of saturated solutions of ascorbic acid (AA) dispersed in the oil brings about the strong reduction of the oxidation rate even in the presence of the highest AMVN quantity.