Methyl linoleate , oxidation

In a study of 92 Finnish edible and nonedible plant materials, a total of 15 berry samples were screened for antioxidant activity (Kahkonen et al., 1999). The activity was compared with the total phenolic content of the samples. Inhibition of methyl linoleate oxidation was used as a measure of antioxidant activity of berry acetone extracts and total phenolics determined by the Folin-Ciocalteau method as GAE/g dry matter of extracts. Berry extracts were high in antioxidant activity among the... 

Figure 4.24. Volatile decomposition products from hydroperoxy epidioxides of methyl linoleate oxidized with singlet oxygen (Frankel etal, 1982).

Table 6.4. NMR and preparative HPLC analyses (rel %) of dienol isomers from hydroperoxides of methyl linoleate oxidized at different temperatures ...

Methyl linoleate Oxidized at 40°C in bulk or oU-in-water emulsions, monitor conjugated diene (234 nm), 72 hr oxidation Inappropriate substrate, one time point oxidation Kahkonen etcd. (1999, 2001, 2003)... 

NIKI E, SAITO T, KAWAKAMI A and KAMIYA Y (1984) Inhibition of oxidation of methyl linoleate by vitamin E and vitamin C, J Biol Chem, 259, 4177-82. 

Yoshida, Y. and Niki, E. (1992). Oxidation of methyl linoleate in aqueous dispersions induced by copper and iron. Arch. Biochem. Biophys. 295, 107-114. 

Probucol, another di-r-butyl phenol, is an anti-atherosclerotic agent that can suppress the oxidation of low-density lipoprotein (LDL) in addition to lowering cholesterol levels. The antioxidant activity of probucol was measured, using EPR, with oxidation of methyl linoleate that was encapsulated in liposomal membranes or dissolved in hexane. Probucol suppressed ffee-radical-mediated oxidation. Its antioxidant activity was 17-fold less than that of tocopherol. This difference was less in liposomes than in hexane solution. Probucol suppressed the oxidation of LDL as efficiently as tocopherol. This work implies that physical factors as well as chemical reactivity are important in determining overall lipid peroxidation inhibition activity (Gotoh et al., 1992). 

Yamauchi, R. and K. Kato (1998). Products formed by peroxyl radical-mediated oxidation of canthaxanthin in benzene and in methyl linoleate. J. Agric. Food Chem. 46(12) 5066-5071. 

Yamauchi, R. et al. (1998). Oxidation products of beta-carotene during the peroxidation of methyl linoleate in the bulk phase. Biosci. Biotechnol. Biochem. 62(7) 1301-1306. 

Yellow and red onions (Allium cepa) were reported to be poor antioxidants toward oxidation of methyl linoleate (Kahkonen and others 1999) in contrast to their high antioxidant activity toward oxidation of LDL (Vinson and others 1998). Garlic (Allium sativum L) was reported to have four times more antioxidant activity than onions when using the ORAC assay (Cao and others 1996). 

In 1977, Kellogg and Fridovich [28] showed that superoxide produced by the XO-acetaldehyde system initiated the oxidation of liposomes and hemolysis of erythrocytes. Lipid peroxidation was inhibited by SOD and catalase but not the hydroxyl radical scavenger mannitol. Gutteridge et al. [29] showed that the superoxide-generating system (aldehyde-XO) oxidized lipid micelles and decomposed deoxyribose. Superoxide and iron ions are apparently involved in the NADPH-dependent lipid peroxidation in human placental mitochondria [30], Ohyashiki and Nunomura [31] have found that the ferric ion-dependent lipid peroxidation of phospholipid liposomes was enhanced under acidic conditions (from pH 7.4 to 5.5). This reaction was inhibited by SOD, catalase, and hydroxyl radical scavengers. Ohyashiki and Nunomura suggested that superoxide, hydrogen peroxide, and hydroxyl radicals participate in the initiation of liposome oxidation. It has also been shown [32] that SOD inhibited the chain oxidation of methyl linoleate (but not methyl oleate) in phosphate buffer. 

Quantitative information on the antioxidant actions of allicin (by radical scavenging through one-step allylic hydrogen transfer) against the oxidation of cumene and methyl linoleate (ML) initiated with 2,2/-azobis(isobutyronitrile) in chlorobenzene has been obtained.283... 

For vapor phase measurement of dry oil oxidation, the plate assembly shown in Figure 5 is used. The lower glass or terephtha-late plastic plate holds a disk of polyamide (1.2 x 0.1 cm) on which 1 pi of a suitable oil (linoleic acid, methyl linoleate, cottonseed oil) is deposited from a micropipette. A Buna "0" ring of 1.5-mm thickness is placed surrounding the spot and a similar plate with a polyamide disk is inverted over the ring forming a tight seal when clamped with "C" clamps. The plate assembly is placed in a 65°C draft oven with the receiver plate bottommost. 

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