Glutathione antioxidant

Asparagus is a super source of the antioxidant glutathione, which lowers cancer risk (see Chapter 13). 

Rhodopsin, visual cycle, night vision Blood clotting factors II, VII, IX, and X Calcium and phosphorus homeostasis Antioxidant, glutathione oxidase... 

Petzold H, Sadler PJ (2008) Oxidation induced by the antioxidant glutathione (GSH). Chem Commun 4413 1415... 

Selenium is an essential trace element, being important in at least two critical enzymes, the antioxidant glutathione peroxidase (GPx), and type 1 iodothyronine deiodinase. GPx converts hydrogen peroxide to water, in the presence of reduced glutathione, while iodothyronine deiodinase catalyzes the conversion of thyroxine to triiodothyronine, the physiologically active hormone species. 

An observational study, part of a population-based case-control study of dietary antioxidants and asthma, has shown an association between the regular use of paracetamol and the incidence of asthma and rhinitis in adults (10). After controlling for potential confounding factors the OR for asthma in daily users, compared with never users, was 2.38 (Cl = 1.22,4.64). Not unexpectedly, there was also an association in users and non-users of aspirin, strongest when cases with more severe disease were compared with controls. This adverse effect of paracetamol may be due to depletion of the antioxidant glutathione in the lungs. However, further studies are needed before paracetamol can be blamed for an increase in the prevalence and severity of asthma. 

The effect of reduction in antioxidant activity has been explored in another way, by exposure to paracetamol, which depletes the antioxidant glutathione. In adults in Britain there was a positive relationship between paracetamol use and asthma [89(111)]. Paracetamol sales per capita have been examined in relationship to ISAAC data in 36 countries, and European Community Respiratory Health Survey data in 18 countries. There were positive correlations between paracetamol sales and symptoms of wheeze, rhinoconjunctivitis and eczema. An increase in paracetamol sales of lOg/capita was associated with an increase of 5.2% in asthma symptoms in 13- to 14-year-olds and 2.6% in adults [90(111)1. 

When co-treating rats with the PPARa activator ciprofibrate and the antioxidant vitamin E, the levels of the antioxidant glutathione were paradoxically... 

A wide variety of interactions of selenium with essential and nonessential elements, vitamins, xenobiotics, and sulfur-containing amino acids have been demonstrated in numerous studies. Selenium has been reported to reduce the toxicity of many metals including mercury, cadmium, lead, silver, and to some extent, copper (Frost 1972). Most forms of selenium and arsenic interact to reduce the toxicity of both elements (Levander 1977). Because of selenium s role in the antioxidant glutathione peroxidase enzymes, selenium also reduces the toxicity of metals in vitamin E-deficient animals (Diplock et al. 1967). 

Selenium substitutes for sulfur in amino acids to form seleno-cysteine, cystine, and methionine. The selenium-containing antioxidant glutathione peroxidase is biologically important, and selenium is a necessary trace nutrient in warm-blooded animals. Grazing animals develop a form of muscular dystrophy and other disorders when grazing in areas in which the selenium has been depleted with selenium-depleted diets, people develop... 

Note that NADPH is also a substrate for glutathione reductase, regenerating the powerful antioxidant glutathione in conditions of oxidative stress. 

Mugesh, G and HB Singh (2000). Synthetic organoselenium compounds as antioxidants Glutathione peroxidase activity. Chemical Society Reviews, 29,347-357. 

Recently there has been a widespread interest in thiol antioxidants, glutathione, and related enzymes, hydrogen sulfide, sesame oil components, L-arginine (L-Arg) and other nitric oxide modulators [129]. While the former compounds may have direct antioxidant actions, L-Arg is both a direct precursor of nitric oxide as well as an antioxidant [110]. These compounds may assist in lowering high blood pressure. 

With the possible exception of acyl glucuronides and cyclic iminium ions, most reactive metabolites are short-lived and are not detectable in circulation. Their formation can be inferred from the characterization of stable conjugates formed via reaction with the endogenous antioxidant glutathione (GSH). The presence... 

---