Lipid hydroperoxides measurements

Jiang, T.Y., Wollard, C.S. and Wolff, S.P. (1991) Lipid hydroperoxide measurement by Fe in the presence of xylenol orange. Comparison with TBA assay and an iodometric method. Lipids 26, 853-856. 

K-Assay LPO-CC Oxidation by lipid hydroperoxides of a derivative of the leuco form of Methylene Blue (90) to the colored form (91), catalyzed by hemoglobin, according to equation 29 measurement is at 675 nm . e... 

A correlation may be established between the concentration of oxidized lipids and the TEARS value, expressed as MDA equivalents, in uM units. Correction is due in some cases for the interference by dyes or other factors. For example, the presence of anthocyanins in red cabbage leaves or turbiditjf causes overestimation of lipid hydroperoxides in plant tissue by the TEARS method. TEARS was used to assert the level of endogenous peroxides in hypo- and hyperthyroidism, both conditions being characterized by low lipid and lipoprotein plasma levels and enhanced oxidative metabolism . In a procedure for determination of TEARS in edible oils, the sample is placed in a centrifuge at 12000 g before measuring at 532 nm (e = 1.56 x 10 M cm ) . A usual procedure for determination of TEARS in certain complex matrices involves steam distillation of the aldehydes responsible for the value, instead of extraction. In nitrite-cured meats, excess nitrite may cause nitrosation of MDA, thus interfering with distillation. To avoid this interference sulfanilamide is added, which is converted to a diazonium salt and... 

The following spectrophotometric methods are conceptually related to the POV however, they are intended for other purposes. HPLC-UVD at 234 nm was applied to detect lipid hydroperoxides, obtained in a set of experiments for assessing the effectiveness of lipoxygenase enzymes extracted from various microorganisms. The absorbance. A, measured at three different wavelengths is linearly correlated to the concentrations in xM units of lipid hydroperoxides, Clh, 7-oxocholesterol, Cqc and dienals, Cde according to the set of simultaneous equations 60. This method was used to track the Cu(II)-induced oxidation of LDL" °. 

Hydroperoxides may be determined by measuring at 290 nm (e = 44100 M cm ) or 360 nm (e = 28000 cm ) the concentration of 13 formed in the presence of a large excess of ions. The reaction may be too slow for practical purposes, unless a catalyst is present. For example, an assay for lipid hydroperoxides conducted without a catalyst may require several measurements every 6 min until the absorbance reaches a maximum. Exclusion of air from the sample cuvette is important. The method is about 1000-fold more sensitive than thiosulfate titration The iodometric method with UVD at 360 was adopted for detecting the presence of hydroperoxides derived from protein, peptide or amino acid substrates subjected to y-radiation, after destroying the generated H2O2 with catalase. ... 

The dry residue is dissolved in EtOH containing AICI3 and 1,10-phenanthroUne (182), an aliquot of fresh solution of KI in EtOH is added, all is incubated in the dark for 15 min at 37 °C and the absorbance is measured at 357 nm (e =4.5 0.2 x 10 M cm ). The LOD is 1.4 (xM, with linearity up to 20 (xM. It is important to avoid contact with air during the incubation, that may oxidize ions, and the presence of water in the system, which reduces the analytical result . HPLC with UVD at 234 nm can be applied in the analysis of lipid hydroperoxides in LDL, using a conjugated diene as internal standard . ... 

A kit in Table 2 is used to determine lipid hydroperoxides by producing Methylene Blue (91) according to equation 29 and measuring the absorbance at 675 run. The assay was applied to determine the concentration of lipid hydroperoxides in serum of patients infected with HIV . 

A procedure for determination of lipid hydroperoxides in human plasma is based on kinetic measurement of the CL of luminol (124) with hemin (75a) catalysis . CLD of microperoxidase-catalyzed oxidation of luminol (124) or isoluminol (190) was applied to detection and determination of amino acid hydroperoxides after exposure to UV and y-irradiation A method for determination of hydroperoxides in the phospholipids of cultured cells uses isoluminol (190) and microperoxidase as catalyst " . Simultaneous determination of phosphatidylcholine hydroperoxides and cholesteryl ester hydroperoxides in human serum is carried out by quantitative extraction of the lipids, HPLC separation by column switching and CLD using isoluminol (190) with microperoxidase catalysis . ... 

A sensitive assay for lipid hydroperoxides is afforded by prostaglandin endoperoxide synthase, that in the presence of hydroperoxides is activated to liberate O2, which is measured with an oxygen electrode . Although it may be of advantage in certain cases, the procedure seems too complex to become of widespread application in practical analysis. 

Lipid peroxidation activity. Solubilized green tea, administered orally to rats for 5 weeks, reduced lipid peroxidation products. The treatment produced increased activity of glutathione (GSFf) peroxidase and GSH reductase, increased content of reduced GSH, a marked decrease in lipid hydroperoxides and malondialdehyde in the liver, an increase in the concentration of vitamin A by about 40%. A minor change in the measured parameters was observed in the blood... 

In the second experiment, mice were irradiated with the highest dose from the dose-response experiment. Concentrations of lipid hydroperoxides and lipophilic antioxidants were measured simultaneously on single skin samples from irradiated and non-irradiated sides of each mouse. The lipid hydroperoxide assay directly measured lipid peroxidation and thus was superior to the TBARS assay, which is indirect. Lipid-peroxyl radicals have been linked to chemically induced cutaneous carcinogenesis [31] as well as to UV-light-induced cutaneous carcinogenesis [32],... 

The measurement of lipid hydroperoxides in biological samples is frequently used as an index of lipid peroxidation. In practice such measurements are complicated by the lability of these compounds in the presence of metal ions, and thiols and by the metabolism of hydroperoxides by peroxidases such as glutathione peroxidase and the glutathione 5-transferases. 

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