Glutathione antioxidant properties

It is possible that dietary flavonoids participate in the regulation of cellular function independent of their antioxidant properties. Other non-antioxidant direct effects reported include inhibition of prooxidant enzymes (xanthine oxidase, NAD(P)H oxidase, lipoxygenases), induction of antioxidant enzymes (superoxide dismutase, gluthathione peroxidase, glutathione S-transferase), and inhibition of redox-sensitive transcription factors. 

The antioxidant system in humans is a complex network composed by several enzymatic and nonenzymatic antioxidants. In addition to being an antioxidant, lycopene also exerts indirect antioxidant properties by inducing the production of cellular enzymes such as superoxide dismutase, glutathione S-transferase, and quinone reductase that also protect cells from reactive oxygen species and other electrophilic molecules (Goo and others 2007). 

Although inorganic selenium does not have antioxidant properties, selenium has an important role in cellular antioxidant defenses as a necessary component of selenoproteins. Selenium is incorporated into selenoproteins as selenocysteine. The glutathione (GSH) peroxidases are the best-characterized selenoproteins, although other circulating selenoproteins also have antioxidant functions. 

Other enzymes that have antioxidant properties include paraoxonase [32], glutathione-S transferases [33], aldehyde dehydrogenases [34], peroxiredox-ins [35] and the recently discovered sulfiredoxin [36]. The existence of antioxidant enzymes in biological systems proves the importance of oxidative damage as a real threat to cellular and organismal survival. 

Glutathione is a peptide of non-proteic origin, present in grapes and wines that merits a special mention. It was described for the first time in grapes by Cheynier et al. (1989). Because of its strong antioxidant properties, it has been recommended as an additive to prevent the enzymatic browning of white wines (Vaimakis and Roussis 1996). Nevertheless, neither its evolution during wine manufacture nor its precise role in wine manufacture are fully understood. 

Selenium deficiency in experimental animal studies is exacerbated by vitamin E depletion. The antioxidant properties of tocopherol and glutathione peroxidase are similar and can to some extent overlap, although this is highly species dependent. °... 

Aside from general caveats that apply to many in vitro models, there is one concern specific to research on AGs and cisplatin. Their mechanisms of toxicity involve the formation of ROS and are therefore sensitive to the antioxidant capacity of the incubation medium. This parameter is rarely controlled and different standard media contain varying amounts of redox-active amino acids, glutathione, or other compounds. Even the common pH indicator phenol red is an important contributor to the total antioxidant capacity of cell and tissue culture media [97]. Thus, the antioxidative capacity of the incubation media may differ from the endolymph and comparable media need to be used to compare therapeutic efficiencies. The concern applies not only to studies of ototoxic mechanisms of these drugs but perhaps even more also to attempts to identify protective treatments which most frequently include therapeutics with antioxidant properties. 

In transgenic tomato, resveratrol synthesis was able to increase the overall antioxidant properties of the fruit, as well as the ascorbate/glutathione content with... 

It is worth mentioning that reductions in plasma carotenoids up to 10-20% of plasma carotenoids could not be associated with negative physiological effects [145, 146]. However, it has been hypothesized that a reduction on carotenoid plasma levels could induce some disturbance in the antioxidative pathways associated with the prevention of cancer development [81]. Glutathione-S-transferases (GST) are enzymes with antioxidant properties which can be partly involved in the prevention of some cancers [147]. In prostate cancer, a reduction of GSTl expression may promote the susceptibility to the carcinogenic effect of chemicals, while induction of GST (i.e., by carotenoid supplementation) in early-stage prostate... 

Hyperglycemia-induced oxidative stress has an important role in the pathogenesis of diabetic complications. Human monocytes exposed to 2-deoxy-D-ribose exhibited loss of cell viability, overproduction of ROS, depletion of glutathione, and apoptosis. Treatment with PLP inhibited these as well as lipid peroxidation and protein oxidation (4). Pyridoxine has a very high level of quenching of hydroxyl radicals (5). Mono- and bicyclic amino pyridinols have been synthesized from pyridoxine hydrochloride and have been shown to have antioxidant properties (6). 

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