Copper free radical scavenger

As mentioned above, in contrast to classic antioxidant vitamins E and C, flavonoids are able to inhibit free radical formation as free radical scavengers and the chelators of transition metals. As far as chelators are concerned their inhibitory activity is a consequence of the formation of transition metal complexes incapable of catalyzing the formation of hydroxyl radicals by the Fenton reaction. In addition, as shown below, some of these complexes, for example, iron- and copper-rutin complexes, may acquire additional antioxidant activity. 

Flavonoids have the ability to act as antioxidants by a free radical scavenging mechanism with the formation of less reactive flavonoid phenoxyl radicals [Eq. (1) and (2)]. On the other hand, through then-known chelating ability these compounds may inactivate transition metals ions (iron, copper), thereby suppressing the superoxide-driven Fenton Reaction, Eqs. (3) and (4), which is currently believed to be the most important route to activate oxygen species [51]. 

Many free-radical scavengers (including dithiols and dithiocarbamates) have potential therapeutic usefulness as radioprotective agents. Copper complexes are known to be scavenging agents for the superoxide radical, which is believed to play a role in the induction of radiation damage. The toxic effects of superoxide are believed to lie in its ability to reduce metal ions, for example Cu(II) to Cu(I),... 

CIDNP studies have proven to be a valuable tool in investigating the mechanisms of decarbonylation and disproportionation reactions in micelles27 29). Since the mechamisms involve the formation of triplet radical pairs, nuclear polarization of the protons near the radical centers occurs and results in the observation of emission or enhanced absorption in the NMR spectra of products of the radical pairs. For example, the photolysis of di-t-butyl ketone (11) in HDTCI yields both decarbonylation and disproportionation products (Scheme VII)27,29). The CIDNP spectra (Fig. 12) taken at various concentrations of copper chloride (free radical scavenger) illustrates that the intramicellar product is isobutylene (72), while 2,2,4,4-tetramethylbutane (13) and 2-methyl-propane (14) are the extramicellar products. 

H2 ANTAGONISTS COPPER AND IRON 1 plasma and body concentrations of copper, iron, zinc and calcium As a class, H2 antagonists act as free radical scavengers and cause depletion of calcium, iron and zinc. Cimetidine in particular binds to copper and iron, and these minerals are not made available for free radical production Be aware and separate oral intake by 2 hours... 

The superoxide dismutase activity and the malodialdehyde level in blood platelets were higher in SM exposed cells in vitro (Buczynski et al, 1999). SM skin bums in guinea pigs were pretreated with oxygen free radical scavengers, like copper-zinc, and manganese superoxide dismutase. 

The decomposition of alkyl and aryl copper compounds has been the subject of much debate. Initially free radical mechanisms were advanced, such theories being supported by the reduced yields of hydrocarbons in the presence of benzoquinone or other free-radical scavengers (24, 150). However, under all conditions very poor yields of dimeric alkanes are obtained. These would be the likely products of a free-radical decomposition. 

There is no antidote for benzidine poisoning. Since it produces reactive metabolites, administration of free radical scavengers would alleviate the toxicity. A complex of benzidine metabolites with copper and hydrochloride is known to decrease its mutagenic effects. 

While the primary physiological role of MT involves the homeostasis of zinc and copper, it remains that MT also has a role in the cellular defense against cadmium and mercury. In addition, being a thiol containing protein MT has the potential to be an effective free radical scavenger, therefore, important in regulating the cellular redox-state. 

The ability of the constituents of tea, particularly (+)-catechin, to inhibit LDL oxidation has been investigated [46] as expected, LDL modified by cells or copper-induced oxidation was endocytosed and degraded by macrophages more quickly than native LDL. However, in the presence of (-i-)-catechin, the rates of endocytosis and degradation were similar to those of native LDL [46]. In addition to the inhibition of LDL oxidation, flavonoids such as catechin, rutin, and quercetin, at levels of 10-20 mmol/L, minimize the cytotoxicity of oxidized LDL [47]. Moreover, cells preincubated with these flavonoids were observed to be resistant to the cytotoxic effects of previously oxidized LDL (47, 48). The postulated mechanisms by which flavonoids protect against the cytotoxicity of oxidized LDL are consistent with their antioxidant and free radical-scavenging properties [4]. 

Alcoholic extracts of the roots and leaves of E. angustifolia, E. pallida, and E. purpurea exhibited comparable in vitro antioxidant activities in ABTS free radical scavenging assay, and the root extracts were also active in the lipid peroxidation inhibition assay.Methanolic extracts of freeze-dried roots of the three species act as in vitro antioxidants through the scavenging of DPPH and ABTS radicals, as well as by chelation of the copper ion (Cu Copper-catalyzed oxidation of human LDL was further demonstrated in vitro by different preparations from E. purpurea root containing alkamides, caffeoyl derivatives, and polysaccharides, as well as by pure caffeoyl derivatives. The antioxidant effect was synergistic and dose dependent. ... 

The additional protection given to nylon by antioxidants has already been mentioned. Since the need is to protect against oxidation by free radicals, antioxidants are essentially of two types peroxide decomposers and radical scavengers. Reviews of these products are available [409,410,413] these should be consulted for details of the mechanisms involved. Peroxide decomposer types include compounds of manganese (II) or copper(I) and copper(II) complexes, such as azomethine bridge derivatives of the type represented by 10.160, of which numerous water-soluble or water-insoluble variants are possible [409]. These products have a catalytic action and are therefore used in very small amounts. 

In 1998, Schlotte et al. [259] showed that uric acid inhibited LDL oxidation. However, subsequent studies showed that in the case of copper-initiated LDL oxidation uric acid behaves itself as prooxidant [260,261]. It has been suggested that in this case uric acid enhances LDL oxidation by the reduction of cupric into cuprous ions and that the prooxidant effect of uric acid may be prevented by ascorbate. On the other hand, urate radicals formed during the interaction of uric acid with peroxyl radicals are able to react with other compounds, for example, flavonoids [262], and by that participate in the propagation of free radical damaging reactions. In addition to the inhibition of oxygen radical-mediated processes, uric acid is an effective scavenger of peroxynitrite [263]. 

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