Antioxidative defense

In biological systems molecular oxygen can be reduced by any of the three possible mechanisms  

Reduction to H2O takes place when electron transfer in the respiratory chain is completed by terminal oxidases. Reduction to H2O2 is associated with flavoproteins in flavin respiration, and superoxide radicals (O2 ) arise constantly in the respiratory chain and some other biological systems. Hydroperoxide is toxic to the cell and is degraded by catalase and/or peroxidase. Superoxide radicals are highly toxic to the cell, in addition, they promote the formation of more toxic products, namely, singlet oxygen and hydroxyl radicals  

This is why almost all aerobic and aerotolerant organisms are equipped with the enzyme superoxide dismutase (SOD) that captures and, in conjunction with catalase, destroys these radicals  

The enzymes SOD, catalase and peroxidase are components of the antioxidative defense of the cell. As follows from the above, the CN-resistant respiration of propionic acid bacteria is responsible for most of the oxygen consumed by the cell with the attendant production of H2O2. The same type of respiration is the main source of superoxide radicals. It was shown (Vorobjeva and Kraeva, 1982) that NADH oxidation by membrane fractions of three strains, representing three different species, is accompanied by the formation of superoxide radicals (Table 3.11). Succinate oxidation, however, was not accompanied by a noticeable production of radicals. The highest rate of superoxide production was found in P, globosum, followed by P. coccoides and P. shermanii. Antimycin inhibited NADH oxidase activity in all the strains and simultaneously increased superoxide production by 32, 36 and 15%, respectively, in P. shermanii, P. globosum and P. coccoides. This showed that superoxide radical formation by propionic acid bacteria occurs in that part of the respiration chain that precedes the site of antimycin action. 

coccoides P. shermanii P. globosum P. pentosaceum P. petersonii P. rqfflnosaceum 

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Biological Antioxidant Models. Tea extracts, tea polyphenol fractions, and purified catechins have all been shown to be effective antioxidants in biologically-based model systems. A balance between oxidants and antioxidants is critical for maintenance of homeostasis. Imbalances between free radicals and antioxidants may be caused by an increased production of free radicals or decreased effectiveness of the antioxidants within the reaction system. These imbalances can be caused by the radicals overwhelming the antioxidants within the system, or by an excess of antioxidants leading to a prooxidant functionaHty (105—118). When antioxidant defense systems are consistently overwhelmed by oxidative reactions, significant damage can... 

BRUCE B, SPILLER G A, KLEVAY L M, GALLAGHER s K (2000) A diet high in whole and unrefined foods favorably alters lipids, antioxidant defenses, and colon function. . 1 Am Coll Nutr. 19 61-7. 

PACKER L (1995) Antioxidant defenses in biological systems an overview. In Proceedings of The International Symposium on Natural Antioxidants - Molecular Mechanisms and Health Effects. Eds Packer, L, Traber, M G, Xin, W, Champaign, IL, USA AOCS Press 9-23. 

Hiraishi, H., Razandi, M., Terano, A. and Ivey, K.J. (1990). Antioxidant defenses of culture gastric mucosal cells against toxic oxygen metabolites. Role of glutathione redox cycle and endogenous catalase. Gastroenterology 98, A544. 

Singh, S., Shackelton, G., Ah-Sing, E., Chakraborty, J. and Bailey, M.E. (1992). Antioxidant defenses in the bile duct-ligated rat. Gastroenterology 103, 1625-1629. 

Kawase, T., Kato, S. and Lieber, C.S. (1989). Lipid peroxidation and antioxidant defense systems in rat liver after chronic ethanol feeding. Hepatology 10, 815-821. 

Ames, B.N., Cathcan, B, Schwiers, E. and Hochstein, P. (1981). Uric acid provides an antioxidant defense in humans against oxidant- and radical-caused aging and cancer a hypothesis. Proc. Natl Acad. Sci. USA 78, 6858-6862. 

Grosser N et al (2004) The antioxidant defense protein heme oxygenase 1 is a novel target for statins in endothelial cells. Free Radic Biol Med 37(12) 2064-2071... 

Carotenoids have been found to exert numerous other effects of potential importance for the RPE. Carotenoids can activate transcription pathways (Ben-Dor et al., 2005 Kalariya et al., 2008 Palozza et al., 2006 Sharoni et al., 2004) for example, by activation of the antioxidant response element (ARE) (Ben-Dor et al., 2005 Sharoni et al., 2004). The ARE is an enhancer sequence responsible for the expression of many phase-II detoxification and antioxidant genes. Thus carotenoids may upregulate cellular antioxidant defenses. 

Mascio, P.D., Murphy, M.E., Sies, H., 1991. Antioxidant defense systems The role of carotenoids, tocopherols, and thiols. Am J Clin Nutr. 53, 194S-200S. 

Grinder-Pedersen L, Rasmussen S E, Bugel S, Jorgensen L V, Dragsted L O, Gundersen V and Sandstrom B (2003), Effect of diets based on foods from conventional versus organic production on intake and excretion of flavonoids and markers of antioxidative defense in humans , J Agric. Food Chem, 51, 5671-5676. 

Overproduction of ROS can be harmful. Thus, cells have developed a complex antioxidant defense system to counteract the biological potential of ROS formation [213],... 

Ramarathnam N, Ochi H, Takeuchi M. 1997. Antioxidative defense system in vegetable extracts. In Shahidi F, editor. Natural Antioxidants. Chemistry, Health Effects, and Applications. Champaign, IL AOCS Press, pp. 76-87. 

Svendsen M, Blomhoff R, Holme I, Tonstad S. 2007. The effect of an increased intake of vegetables and fruit on weight loss, blood pressure and antioxidant defense in subjects with sleep related breathing disorders. Eur JOin Nutr 61(11) 1301—1311. 

Dragsted LO, Pedersen A, Hermetter A, Basu S, Hansen M, Haren GR, Kail M, Breinholt V, Castenmiller JJM, Stagsted J, Jakobsen J, Skibsted L, Rasmussen SE, Loft S and Sandstrom B. 2004. The 6-a-day study effects of fruit and vegetables on markers of oxidative stress and antioxidative defense in healthy nonsmokers. Am J Clin Nutr 79(6) 1060-1072. 

Figure 15 presents a qualitative comparison of different oxidation types on histidine ACW. Hence, the ACP cannot be seen to be characteristic for antioxidant defense, but more likely it is a feature of prehistory connected with the free-radical processes, reflecting the degree of oxidative stress. 

Kakkar et al. (1992) exposed six male Wistar rats to a single nominal concentration of 15,302 ppm for 10 min the animals were sacrificed 24 h later. Earlier studies (not presented) had shown this to be the highest concentration tolerated without any mortality or acute toxicity. Biochemical changes in the brains of these rats suggested impairment of antioxidant defenses. No other signs of toxicity were reported. The exposure was performed under static conditions, and the measurement method was not described. 

Nitric oxide and peroxynitrite contribute to oxidative damage 569 Production of eicosanoids from polyunsaturated fatty acids such as arachidonic acid may generate reactive oxygen species 570 Brain antioxidant defenses modify ischemia-reperfusion injury 570 Reactive oxygen species may modify both the excitotoxic and the apoptotic components of ischemic brain damage 570... 

Oxidative stress generally describes a condition in which cellular antioxidant defenses are inadequate to completely detoxify the free radicals being generated, because of excessive production of ROS, loss of antioxidant defenses or, typically, both [23]. This condition may occur locally, as antioxidant defenses may become overwhelmed at certain subcellular locations while remaining intact overall, and selectively with regard to radical species, as antioxidant defenses are radical-specific - for example SOD for superoxide and catalase or glutathione peroxidase for H202. 

Brain antioxidant defenses modify ischemia-reperfusion injury. The high metabolic rate ofbrain cells implies a high baseline ROS production, and brain cells possess high concentrations of both enzymatic and small-molecule antioxidant defenses. SOD1 may represent as much as 1% of total protein in brain it converts 02 to H202, which is then further metabolized to water and oxygen by... 

Redox reactions involving nitric oxide have important implications beyond their fundamental chemistry as demonstrated by the controversy in the biomedical literature regarding conditions under which generation of NO leads to the amelioration or the exacerbation of oxidative stress in mammalian systems (95). Oxidative stress is defined as a disturbance in the balance between production of reactive oxygen species (pro-oxidants) and antioxidant defenses (96). Reactive oxygen species include free radicals and peroxides as well as other reactants such as oxidative enzymes with metal ion sites in high oxidation states. The... 

Aherne GW, Hardcastle A, Valenti M, Bryant A, Rogers P, Pettit GR, Srirangam JK, Kelland LR (1996) Antitumour evaluation of dolastatins 10 and 15 and their measurement in plasma by radioimmunoassay. Cancer Chemother Pharmacol 38 225-232 Ahmad S, Pardini S (1990) Antioxidant defense of the cabbage looper, Trichoplusia ni enzymatic responses to the superoxide-generating flavonoid, quercetin and photodynamic furanocou-marin, xantotoxin. Photochem Photobiol 51 305-312 Amsler CD, Fairhead VA (2006) Defensive and sensory chemical ecology of brown algae. Adv BotRes 43 1-91... 

Gort AS, Imlay JA. 1998. Balance between endogenons snperoxide stress and antioxidant defenses. J Bacteriol 180 1402-10. 

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