Copper-induced oxidation

Tea extracts and tea polyphenols inhibit copper- and peroxide-induced oxidation of LDL in vitro (116,123,124). The inhibitory concentration for 50% reduction (IC q) values for inhibition of copper-induced oxidation of LDL by some phenoHc antioxidants are Hsted in Table 7. The IC q for epigaHocatechin gaHate was found to be 0.075 p.mM, which was the most potent of all the phenoHc antioxidants tested (123,124). Similar results have been reported elsewhere (115,116,125,126). 

Dairy phospholipids are important structurally, because they are able to stabilise emulsions and foams, and to form micelles and membranes (Jensen and Newburg, 1995). Phospholipids also have the potential to be pro-oxidants, because they contain mono-unsaturated and poly-unsaturated fatty acids and have the ability to attract metal ions. Phosphatidyl ethanolamine binds copper strongly and is believed to be important in copper-induced oxidation in milk (O Connor and O Brien 1995 Deeth, 1997). The polyunsaturated fatty acids and metal ions accelerate lipid oxidation, especially when heat is applied hence, phospholipids can be degraded during the processing of milk. However, in dairy products, the situation is complex and it appears that phospholipids are able to act as either pro-oxidants or antioxidants, depending on the pH, ratio of water and phospholipid species (Chen and Nawar, 1991). 

The feasibility of increasing the a-tocopherol concentration of milk by supplementation of the feed has been investigated in many studies (Dunkley et al., 1966, 1967 King et al., 1966 St. Laurent et al., 1990 Barrefors et al., 1995 Focant et al., 1998 Granelli et al., 1998). These studies showed that when feed was supplemented with varying levels of a-tocopheryl acetate, the a-tocopherol content of the milk was increased with consequent increased resistance to spontaneous and copper-induced oxidation. King et al. (1967) reported that when feed was supplemented to achieve an intake of 1 g a-tocopherol per day per cow, oxidation was effectively controlled in milk... 

Spray-dried elderberry juice with high amounts of anthocyanin glucosides caused prolongation of the lag phase of copper induced oxidation of human LDL, while the maximum oxidation rate remained unchanged (Abuja et al., 1998). For peroxyl-radical-driven LDL oxidation, however, both prolongation of lag time and reduction of maximum oxidation rate occurred. When the extract was added after LDL oxidation was initiated, the elderberry extract demonstrated a pro-oxidative action. The pro-oxidative effect was more pronounced the longer the LDL oxidation was allowed to proceed before the extract was added. 

Ide, N., Nelson, A.B. and Lau, B.H. (1996) Aged garlic extract and its consituents inhibit copper-induced oxidative modification of low density lipoprotein. Planta Med. 63 263. 

Symptoms in patients with Wilson s disease usually begin in the second or third decade of life, but may be earlier or later. However, mutations that completely destroy gene function may be associated with onset of liver disease as early as 3 years of age. The initial clinical presentation may be hepatic, with presentation similar to acute hepatitis or to chronic active hepatitis neurological (e.g., clumsiness, dysarthria, ataxia, and tremors) renal (renal tubular acidosis with aminoaciduria) or, less commonly, hematological, with hemolysis secondary to acute release of free copper from tissue and subsequent oxidation of erythrocyte membranes. The hepatic, and possibly CNS, damage may also be secondary to copper-induced oxidative damage to mitochondrial membranes. Hepatic levels of Cp messenger ribonucleic acid (mRNA) are reduced in patients with Wilson s disease, probably secondary to inhibition of transcription by increased intracellular levels of apoCp. ... 

In conclusion, a regular dietary intake of co-3 PUFA didn t have any influence on the susceptibility of LDL to copper-induced oxidation, including foods rich in co-3 PUFA reduced in vivo lipid peroxidation and hence urinary F2 isoprostane excretion [86],... 

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]. 

M9. Mukhopadhyay, C. K., and Fox, P. L., Ceruloplasmin copper induces oxidant damage by a redox process utilizing cell-derived superoxide as reductant. Biochem. 37, 14222-14229 (1998). 

Effect of ascorbic acid on copper-induced oxidative changes in erythrocytes of individuals with a glucose-6-phosphate dehydrogenase deficiency. 

There has been an increased interest in natural antioxidants from plant-derived foods and then-by-products for their role in preventing oxidation of human LDL cholesterol. Table 13.8 shows the inhibition of copper-induced human LDL oxidation by hazelnut extracts. Hazelnut skin and hazelnut green leafy cover extracts at 50 ppm concentration effectively inhibited copper-induced oxidation of... 

Oxidative induction time (OIT) provides an index useful in comparing the relative resistance to oxidation of a variety of hydrocarbon materials. The OIT procedure was first developed in 1975 by Gilroy and coworkers at Bell Laboratory as a test procedure to screen polyethylene insulation used in telephone wire and cable for its oxidation resistance. The method first became available as a Western Electric Specification and later as ASTM Test Method for Copper-Induced Oxidative Induction Time of Polyolefins. Polyolefin manufacturers quickly embraced the procedure and began to apply it to other applications including raw resins, finished pipes, wire and cable insulation, and, most recently, geosynthetic waste pit liners (ASTM D3895 2009). 

Several lines of evidence support the in vivo oxidation of LDL, but how and where LDL is oxidized in vivo is not yet clear. The LDL extracted from atherosclerotic lesions manifest the same physicochemical and biological properties as LDL oxidized under in vitro conditions. The susceptibility of plasma LDL to copper-induced oxidation in vitro correlates with the extent of coronary atherosoclerosis in patients with previous experience of myocardial infraction. However, the many cellular biological effects established for oxidized LDL in vitro could not be assumed to cause atherosclerosis in vivo. 

Both phosphohpid-containing dehpidated human low-density hpoprotein ghosts and trihnolein-reconstituted low-density hpoprotein were devoid of antioxidants and were extremely susceptible to 2,2 -azobis-(2-amidino propane) hydrochloride-induced oxidation but, paradoxically, were rather resistant to copper-mediated oxidation (Visioli et al. 2000). The dynamic reduction of Cu(II) to Cu(I) was quantitatively decreased in low-density hpoprotein ghosts and in trihnolein-reconstituted low-density Hpoprotein, also lacking the initial rapid reduction and the subsequent inhibition phases, due to the absence of endogenous antioxidants. Conversely, the rate of copper reduction was hnear and hkely due to hpid peroxides, either already present of formed during copper-induced oxidation. 

DeLuca, A.P., Teichman, R., Rousseau, J.E., Morgan, M.E., Eaton, H.D., MacLeod, P., Dicks, M.W. and Johnson, R.E. (1957) Relative effectiveness of various antioxidants fed to lactating dairy cows, on incidence of copper-induced oxidized milk flavor and on apparent carotene and tocopherol utilization. J. Dairy Sci. 40, 877-886. 

D 3713 MEASURING RESPONSE TO SMALL FLAME IGNITION D 3748 EVALUATING HD RIGID CELLULAR PLASTICS D 3810 EXTINGUISHING CHARACTERISTICS-VERT POSITION D 3835 RHEOLOGICAL PROPERTIES/CAPILLARY RHEOMTR D 3846 IN PLANE SHEAR OF REINFORCED PLASTICS D 3895 COPPER INDUCED OXIDATIVE INDUCTION BY DSC D 3914 IN PLANE SHEAR OF RODS D 3916 TENSILE OF PLASTIC ROD... 

Ahuja KDK, Kunde DA, Ball MJ, Geraghty DP (2006) Effects of capseiicin, dihydrocapsaicin, and curcumin on copper-induced oxidation of human serum lipids. J Agric Food Chem 54 6436-6439... 

Oxidation of LDL plays an important role in the development of atherosclerosis. Turmeric extract decreased the susceptibility of LDL to lipid peroxidation, thus suggesting its value in the management of cardiovascular disease (Ramirez-Tortosa et al. 1999). In healthy hiunans, the daily intake of 200 mg of turmeric extract resulted in a decrease in total blood lipid peroxides as well as in HDL- and LDL-lipid peroxidation (Miquel et al. 2002). The beneficial influence of dietary curciunin on the susceptibility of LDL to oxidation was examined in an animal study. Dietary curcumin significantly inhibited the in vivo iron-induced LDL oxidation as well as copper-induced oxidation of LDL in vitro (Manjunatha and Srinivasan 2006). 

The antioxidant activity has been demonstrated in several models of oxidative stress, such as H202-induced stress in human kera-tinocytes and mouse fibroblasts (silymarin and flavanolignans) superoxide radical and lipid peroxidation in PMNs and hepatocytes (silymarin and flavanolignans) high-sucrose diet in hypertriglyceridemic rats (si-lymarin) UV-induced stress in rats (sily-marin) and copper-induced oxidation of human LDL (silymarin). ... 

In a study to evaluate the antioxidant activity of a number of gums, resins, and pigments, storax was among those that protected human LDL against copper-induced oxidation in vitro. ... 

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