Fatty acids peroxides

With the above procedure, dienoic fatty acid peroxidation products yield a conjugated triene chromophore with second-derivative absorption minima iocated at 258, 269.5 and 281 nm, whilst trienoic fatty-acid peroxidation products give rise to a conjugated tetraene chromophore with minima at 278, 289, 303 and 318 nm. The arrows in (c) denote second-derivative absorption minima corresponding to the conjugated triene adduct arising from linoleate-derived peroxidation products (conjugated hydroperoxydienes, hydroxydienes and oxodienes). 

Pentane and ethane (end products of n-6 and n-3 polyunsaturated fatty acid peroxidation, respectively) in expired air are useful markers of in vivo lipid peroxidation. Nevertheless, when gas chromatography is used to measure hydrocarbons, some technical difficulties may be experienced because chromatographic resolution of pentane from isoprene and isopentane is extremely difficult to achieve. Another possible problem could be the presence of these gases as contaminants in atmosphere. Furthermore, the production of hydrocarbon gases depends on the presence of metal ions to decompose lipid peroxides. If such ions are only available in limited amounts, this index may be inaccurate. 

As already indicated when protein structure is damaged, hsps may repair it. As well as reduction by vitamin E as described, lipids damaged by oxidation to peroxides can be broken down by phospholipase A2 and the fatty acid peroxide replaced. 

Oxidation is also the main cause of perfume instability in poor-quality toilet soaps here it is caused by the fatty acid peroxides formed at the stage of incipient rancidity. Perfumes may to some extent be protected against oxidation by the incorporation of 1% to 2% of an antioxidant such as BHT (butylated hydroxy toluene) into the perfume oil. 

Aside from free fatty acid, peroxide, aldehydes (by para-anisidine, pAV test), and conjugated dienes, the oil must also be low in trace components as listed in Table 3. 

Quality control systems usually used for judging the quality of oils and fats or oil blends used in margarine production could evaluate color, color stabihty, flavor, flavor stabihty, free fatty acid, peroxide value, active oxygen method (AOM) stabihty, iodine value, shp melting point, fatty acid composition, refractive index, crystallization rate, and sohd fat/temperature relationship (solid fat index) (5, 91, 112, 113). 

Oil Sample Chlorophylls (ppm) Free Fatty acid %) Peroxide Value (meg/kg) Tocopherol (ppm)... 

Peroxides can play a physiological role in the cell but also mediate processes leading to heart disease and carcinogenesis. Fatty acid peroxidation may also be related to free radical-mediated metabolic activation of carcinogens or drugs, which lead to the initiation of carcinogenesis or cytotoxicity. Modification of membrane function as a consequence of lipid peroxidation includes imcoupling of oxidative phosphorylation... 

Steinbrecher UP, Lougheed M, Kwan WC, et al. (1989) Recognition of oxidized low density lipoprotein by the scavenger receptor of macrophages results from derivatization of apolipoprotein B by products of fatty acid peroxidation. J Biol Chem 264 15216-15223... 

The odoriferous substances in oils are free fatty acids, peroxides, aldehydes, alcohols and other organic compounds. Experience has shown that the flavor and odor removal correlates well with the reduction of free fatty acids. Therefore, all commercial deodorization consists of steam stripping the oil for free fatty acid removal. Currently, batch, semi-continuous, and continuous systems of various designs are utilized to produce deodorized oils. All of the systems utilize steam stripping with four interrelated operation variables vacuum, temperature, stripping steam rate, and holding time. 

In conjunction with glutathione S-transferases, glutathione participates in detoxification of many substances, such as organic halides, fatty acid peroxides derived from lipid oxidation, and products derived from radiation-damaged DNA. Glutathione reacts with compounds as shown here. 

P450 catalyzes the isomerization of a variety of fatty acid hydroperoxides, including 15-hydro-peroxyeicosatetraenoic acid (15-HPETE) and of the prostaglandin H2 (PGHj) endoperox-ide. A distinctive feature of some P450 fatty acid peroxide isomerases is their inability to accept electrons from NADPH and to activate molecular... 

TPU, PS, PO, EVAc, EVAl, EAA, EMAc, PVAl, EBAc, PMMA and PEG Polysaccharide, fatty acid peroxide, benzophenone, ferric hydroxy stearate, copper stearate, and hindered phenol Chapman and Downie, 1994... 

During the last steps of lipid oxidation, the fatty acid chains breakdown to give aldehydes (hexanal, propanal, malondialdehyde), depending on the lipid structure. These compounds react with thiobarbituric acid to give coloured compounds the measurement of which at 535 nm can be used to follow the oxidation process in its terminal phase [91]. In addition, hexanal, which is an important decomposition product of n-6 polyunsaturated fatty acid peroxidation in rat liver samples, human red blood cell membranes, and human LDL (low density lipoproteins), can be measured by headspace gas chromatography [92]. Malondialdehyde, another important decomposition product, can also be analysed by GC (Gas Chromatography) [93], and, after reaction with urea to give 2-hydroxypyrimidine, by HPLC [94]. 

Budowski, P. (1996) The Omega-3 Fatty Acid Peroxidation Paradox, Redox Report 2,75 77. 

On the basis of presented data, it may be supposed that a prevention of unsaturated fatty acids peroxidation, in particular C and C acids in membranes of plant tissnes leads to enhancement of plant resistance to IW. In fact, a close correlation was observed between the unsaturation coefCbient of C fatty acids in mitochondrial membranes (Xnnsatnrated C fatty acids/ C ) and maximum rates of NAD-dependent snbstrate oxidation (the correlation coefCbient r = 0.765) (Figure 2). 

Principal Reaction Pathways for Fatty Acid Peroxides.26... 

PRINCIPAL REACTION PATHWAYS FOR FATTY ACID PEROXIDES... 

Another mechanism postulates the formation of fatty acid peroxide dimers and oligomers that give rise to vicinal peroxides [64]. 

---