Hydroperoxides phosphatidylcholine

Detection of cholesteryl linoleate hydroperoxides and phosphatidylcholine hydroperoxides 63... 

It follows from the above that the neutrophil-mediated LDL oxidation may occur by both NADPH oxidase- and MPO-dependent mechanisms. It was recently demonstrated [162] that the rates of formation of phosphatidylcholine and cholesteryl ester hydroperoxides during LDL oxidation by PMA-stimulated neutrophils of MPO-knockout mice were about 66% and 44% of those by wild-type neutrophils. In both cases LDL oxidation was inhibited by SOD. These findings suggest that superoxide mediates both NADPH oxidase- and MPO-dependent pathways of oxidation by stimulated neutrophils. 

LOX-catalyzed oxidation of LDL has been studied in subsequent studies [26,27]. Belkner et al. [27] showed that LOX-catalyzed LDL oxidation was not restricted to the oxidation of lipids but also resulted in the cooxidative modification of apoproteins. It is known that LOX-catalyzed LDL oxidation is regio- and enantio-specific as opposed to free radical-mediated lipid peroxidation. In accord with this proposal Yamashita et al. [28] showed that LDL oxidation by 15-LOX from rabbit reticulocytes formed hydroperoxides of phosphatidylcholine and cholesteryl esters regio-, stereo-, and enantio-specifically. Sigari et al. [29] demonstrated that fibroblasts with overexpressed 15-LOX produced bioactive minimally modified LDL, which is probably responsible for LDL atherogenic effect in vivo. Ezaki et al. [30] found that the incubation of LDL with 15-LOX-overexpressed fibroblasts resulted in a sharp increase in the cholesteryl ester hydroperoxide level and a lesser increase in free fatty acid hydroperoxides. 

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 . ... 

The hydroperoxides of various phospholipids, such as phosphatidylcholine (PC— OOH, 155), phosphatidylserine (PS—OOH), phosphatidylethanolamine (PE—OOH), phos-phatidylinositol (PI—OOH) and cardiolipin (CL—OOH), can be determined by HPLC-ELD on a polar LC—NH2 column, using as mobile phase a MeOH//-PrOH/40 mM aqueous NaH2P04 mixture (61 30 9 by volume). ELD is by the hanging Hg drop electrode method set at —150 mV vs. SCSE. The relative mobility for the given chromatographic system is shown in equation 68, which is almost a reversal of the order shown in equation 63 for HPTLC. The LOD varies from about 0.5 to 1.0 pmol, depending on the class of phospholipid hydroperoxide . ... 

The quenching mechanism of Vitamin E (21) toward hydroperoxides is depicted in equation 11 (Section II.A.2.d). The structure of products 38 obtained when quenching hydroperoxides from phosphatidylcholines (155) was elucidated by the usual MS and NMR techniques. ... 

P Therond, M Couturier, JF Demelier, F Lemonnier. Simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides obtained by lipoxygenase treatment. Lipids 28 245-249, 1993. 

Singh SK, Suurkuusk M, Eklsater C. Kinetics of decomposition of hydroperoxides formed during the oxidation of soya phosphatidylcholine by analysis of chemiluminescence generated. Int J Pharm 1996 142 215-225. 

Chemiluminescence has been used to assess phosphatidylcholine oxidation, and to measure the kinetics of decomposition of hydroperoxides formed during the oxidation of soya phosphatidylcholine. The direct chemiluminescence method correlated well with other methods of determining oxidation status (chemical, UV, HPLC, and microcalorimetry), and it was concluded that chemiluminescence was an ideal method for estimating the oxidation of phosphatidylcholine (and phospholipids in general). Kinetics measurements revealed that... 

Many references to kinetic measurements may have already been covered earlier with other physical methods. These include studies on pseudorotation of stereoisomers of a 10-P-5 spirophosphorane, on the formation rate of acylpho-sphonate hemiketals, on the rate of decomposition of hydroperoxides formed by the oxidation of soya phosphatidylcholine, on the kinetics of the reaction of trimethyl phosphite with benzylidene acetophenones, calorimetric studies on the reaction kinetics of dithiophosphoric acid 0,0 -dialkyl esters with zinc oxide, " and the kinetics of selective dephosphorylation of 2 -phosphorylated and 2 -thiophosphorylated dinucleotides. 

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