Antioxidants in vivo

The lag-phase measurement at 234 nm of the development of conjugated dienes on copper-stimulated LDL oxidation is used to define the oxidation resistance of different LDL samples (Esterbauer et al., 1992). During the lag phase, the antioxidants in LDL (vitamin E, carotenoids, ubiquinol-10) are consumed in a distinct sequence with a-tocopherol as the first followed by 7-tocopherol, thereafter the carotenoids cryptoxanthin, lycopene and finally /3-carotene. a-Tocopherol is the most prominent antioxidant of LDL (6.4 1.8 mol/mol LDL), whereas the concentration of the others 7-tocopherol, /3-carotene, lycopene, cryptoxanthin, zea-xanthin, lutein and phytofluene is only 1/10 to 1/300 of a-tocopherol. Since the tocopherols reside in the outer layer of the LDL molecule, protecting the monolayer of phospholipids and the carotenoids are in the inner core protecting the cholesterylesters, and the progression of oxidation is likely to occur from the aqueous interface inwards, it seems reasonable to assign to a-tocopherol the rank of the front-line antioxidant. In vivo, the LDL will also interact with the plasma water-soluble antioxidants in the circulation, not in the artery wall, as mentioned above. 

Carew, T.E., Schwenke, D.C. and Steinberg, D. (1987). Antiatherogenic effect of probucol unrelated to its hypocholesterolaemic effect evidence that antioxidants in vivo can selectively inhibit low density lipoprotein degradation in macrophage-rich fatty streaks and slow the progression of atherosclerosis in the Watanabe heritable hyperlipidaemic rabbit. Proc. Natl Acad. Sci. USA 84, 7725-7729. 

Gharbi N, Pressac M, Hadchouel M, Szwarc H, Wilson SR, Moussa F (2005) [60]Fullerene is a powerful antioxidant in vivo with no acute or subacute toxicity. Nano Lett. 5 2578-2585. 

In its reduced form, a-lipoic acid (Fig. 9.5) is a powerful antioxidant. It can reduce GSSG to GSH, dehydroascorbate to ascorbate, and regenerate a-tocopherol from the cy-tocopheryl radical either directly or via ascorbate. Supplementation with a-lipoic acid decreases oxidative stress and restores reduced levels of other antioxidants in vivo. However, a-lipoic acid and dihydrolipoic acid may exert pro-oxidant properties in vitro. a-Lipoic acid and dihydrolipoic acid promote the permeability... 

Although many in vitro studies on the antioxidative property of food constituents have been reported, little is known about the biological functions of dietary antioxidants in vivo, except for several well-known antioxidants such as tocopherols, (i-carotene, and ascorbic acid. Because the bioavailability of food constituents is limited by their digestibility and metabolic fate, an oral administration trial of a dietary antioxidant is favored to evaluate its biological function. 

Asai et al. (1999) determined that phospholipid hydroperoxides (PLOOH) are key products for oxidative injury in membranous phospholipid layers in the plasma, red blood cells (RBC), and liver of mice. The formation and accumulation of PLOOH have been confirmed in several cellular disorders, various diseases, and in aging. A lower PLOOH level was found in RBC of the spice-extract-fed mice (65 to 74% of the nonsupplemented control mice). The liver lipid peroxidizability induced with Fe2+/ascorbic acid was effectively suppressed in mice by dietary supplementation with the turmeric and capsicum extracts. Although no difference in the plasma lipids was observed, the liver triacylglycerol concentration of the turmeric-extract-fed mice was markedly reduced to half of the level in the control mice. These findings suggest that these spice extracts could act antioxidatively in vivo by food supplementation, and that the turmeric extract has the ability to prevent the deposition of triacylglycerols in the liver. 

Antioxidant in vivo (diabetic rat) scavenges DPPH (weak) [>L Dehydroascorbate, T lysosomal stability]... 

At present there are can be no doubt that investigations into the enzymatic regulation of free radical reactions in the body is of high priority. A number of enzymes called as antioxidative enzymes may act as effective antioxidants in vivo. It is known that... 

Hove, E. L. (1944). Gossypol as a carotene-protecting antioxidant, in vivo and in vitro.J. Biol. Chem. 156, 633-642. 

The concentration of ascorbate in the human plasma is 25 pM and above. Cells take up ascorbate by a Na -coupled uptake mechanism against a concentration gradient. A marked stereo-selectivity for L-ascorbic acid relative to D-isoascorbic acid in their cellular transport has been shown by Franceschi et al. [12]. The same transport is also important in the intestine. The nutritional supply of ascorbic acid is the only source for this vitamin in humans, primates, and guinea pigs. Other mammals are able to produce ascorbic acid. There exists sufficient evidence for an active role of ascorbate as an antioxidant in vivo. Decreased ascorbic acid will increase lipid peroxidation and decrease vitamin E and is connected with oxidative DNA damage. The supply of ascorbate in some cases will reduce the amount of oxidative damage in diseases that... 

Without doubt vitamin E is the most important lipid-soluble chain-breaking antioxidant in the human body. It is able to interact with lipid peroxyl radicals and is also able to react with singlet oxygen. The role of vitamin E as an antioxidant in vivo has been established several times by measuring tissue lipid peroxidation in vitamin E-deficient or in vitamin E-supplemented animals. 

Antioxidant and prooxidant properties of carotenoids have recently been reviewed [50,51]. Carotenoids serve as efficient quenchers of single oxygen. Their assumed function as antioxidants in vivo is largely based on model experiments. 

Together, such studies demonstrate that lycopene can function as an antioxidant In vivo and In vitro and can reduce genetic damage In humans, animal models, and cell systems. 

Stuefy of Synthetic and Natural Antioxidant in vivo and in vitro. E. B. Burlakova (Ed.), Nauka, Moscow (1992). 

Tsepalov, V. F. Research of synthetic and connatural antioxidants in vivo and in vitro. Moscow, Nauka, 1992,16 (in Russian). 

Ozten-Kanda N, Bosland MC (2011) Chemoprevention of prostate cancer natural compounds, antiandrogens, and antioxidants - in vivo evidence. J Carcinog 10 27... 

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