Depletion of antioxidants

Only one study to date has been conducted on the treatment of acute pancreatitis with antioxidants. Clemens et al. (1991) were unable to show any difference in the incidence or severity of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis in a prospective, randomized, double-blind, placebo-controlled trial of allopurinol. However, Salim (1991) performed a similar trial of the effect of allopurinol and DMSO in patients with pain from recurrent pancreatitis, and found significant benefit. On the basis that depletion of antioxidants is important in the pathogenesis of chronic pancreatitis, the administration of a cocktail of antioxidants was assessed for its effect on pain in this disease. Treatment with a combination of organic selenium, d-carotene, vitamins C and E, and methionine was of benefit in the initial pilot study, and in a placebo-controlled trial (San-dilands etal., 1990 Uden et al., 1990). 

A number of studies have demonstrated the depletion of antioxidants during ischaemia. SOD and hepatic GSH are decreased after periods of ischaemia or haemorrhagic shock (Shi et al., 1986 Younes and Strubelt, 1988 Marubayashi et al., 1989 Stein et al.,... 

Minimal processing steps could be expected to induce a rapid enzymatic depletion of several natural antioxidants. Depletion of antioxidant capacity in cubed and sliced papaya fruit could be associated with depletion of both ascorbic acid and (3-carotenes, but in general, the highest loss of these important nutrients was reached before the product was unacceptable or spoiled (Rivera-Lopez and others 2005). 

Overproduction of free radicals by erythrocytes and leukocytes and iron overload result in a sharp increase in free radical damage in T1 patients. Thus, Livrea et al. [385] found a twofold increase in the levels of conjugated dienes, MDA, and protein carbonyls with respect to control in serum from 42 (3-thalassemic patients. Simultaneously, there was a decrease in the content of antioxidant vitamins C (44%) and E (42%). It was suggested that the iron-induced liver damage in thalassemia may play a major role in the depletion of antioxidant vitamins. Plasma thiobarbituric acid-reactive substances (TBARS) and conjugated dienes were elevated in (3-thalassemic children compared to controls together with compensatory increase in SOD activity [386]. The development of lipid peroxidation in thalassemic erythrocytes probably depends on a decrease in reduced glutathione level and decreased catalase activity [387]. 

Sharma, J. N., K. C. Srivastava, and E. K. Gan. Suppressive effects of eugenol and ginger oil on arthritic rats. Pharmacology 1994 49(5) 314-318. Shanmugasundaram, K. R., S. Rama-nujam, and E. R. Shanmugasundaram. Amrita Bindu—a salt-spice herbal health food supplement for the prevention of nitrosamine induced depletion of antioxidants. J Ethnopharmacol 1994 42(2) 83-93. 

In animal studies, NAC has been shown to prevent hemorrhagic cystitis that results from administration of cyclophosphamide or its position isomer ifosfamide. Hemorrhagic cystitis results from the toxic effect of acrolein, a metabolic product of cyclophosphamide or its position isomer ifosfamide. The mechanism whereby NAC prevents this toxicity may be prevention of the intracellular depletion of antioxidants, such as GSH, by acrolein. Concomitant administration of NAC with cyclophosphamide or ifosfamide does not impair antineoplastic activity, because both anticancer drugs are inactive until they are metabolized by the liver to their phosphoramide mustard metabolites. 

An equilibrium between 0- and N-centered radical is suggested. Complication in this simple mechanism is caused by the participation of the respective radicals in coupling, disproportionation, oxidation and recombination reactions. It is connected with the formation of products different from those in the original mixture and not involved in the regeneration cycle. A stepwise depletion of antioxidant active species depedent on both the amine and phenol structures should therefore be considered. 

Glyoxals, a class of organic molecules containing a dialdehyde, have antiviral activity (De Bock et al. 1957). They have been shown to be lipid peroxidation products from lipid and glucose metabolism. Increased levels of glyoxals, specifically methyl glyoxal, have been associated in rheumatoid arthritis (Mukhopadhyay et al. 2007) and diabetes (Kilhovd et al. 2003) via depletion of antioxidant... 

Probe 32 can report the depletion of antioxidant by monitoring emission enhancement. It shows weak fluoreseenee due to reduetive PET quenching by the chromanol moiety. In contrast, a marked fluoreseenee increment was observed upon oxidation of chromanol by peroxyl radical (Scheme 7.28), demonstrating that probe 32 is a hydrophobie fluoreseent antioxidant indicator with desirable off/on ratio properties. 

Although the radicals formed by reaction of reducing compounds with hypervalent myoglobin may be harmless, the pseudoperoxidase activity contributes to the depletion of antioxidants in the system and thereby affects the oxidative status of the meat system. 

The process of LDL oxidation is unlikely to occur in plasma because plasma contains high concentrations of antioxidants and of metal ion chelators. It is more likely to occur within the artery wall, an environment, that is depleted of antioxidants and therefore where the LDL is exposed to oxidative stress. The identity of the cells responsible for the oxidation of LDL along athero-genesis in the arterial wall is uncertain. Monocyte-derived macrophages are... 

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