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E N Frankel

Publications and source records attributed to E N Frankel.

45 records · Page 3Linked to original sources
PubMed1980

Lipid oxidation.

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Antioxidants↗
PubMed1979

Lipid oxidation products and chick nutritional encephalopathy.

Safflower oil and its distilled methyl esters were thermally oxidized and fed to young chicks in a vitamin E deficient diet. At a dietary level of 10%, the oxidized lipids caused more severe nutritional encephalopathy (NE) than the unoxidized methyl esters, indicating that factors other than dietary linoleic acid and vitamin E affect the development of NE. A polar lipid extract from oxidized methyl esters accelerated the induction of NE, as did the synthetic methyl esters of keto-octadecenoic and keto-octadecadienoic acids. Dicumarol exerted a protective action against NE. The possibility is discussed that conjugated keto-polyenoic fatty acids, provided by oxidized oils or formed endogenously in vitamin E deficiency, may play a role in causing NE.

Aging↗
PubMed1977

Analysis of autoxidized fats by gas chromatography-mass spectrometry: I. Methyl oleate.

A structural investigation of autoxidation products of methyl oleate was carried out by gas chromatography-mass spectrometry (GC-MS) of trimethylsilyl (TMS) ether derivatives. GC-MS using computer plots of selected masses afforded structural assignments of GC peaks due to incompletely resolved mixtures. This method provided evidence of epoxy and keto esters which are not completely separated from the main components consisting of the TMS derivatives of the allylic hydroxy esters. Use of an MS-computer system also showed that the hydroxyoctadecanoate TMS ethers were partially separated by GC. The use of synthetic hydroxyoctadecanoates for the first time enabled us to demonstrate the quantitative reliability of a GC-MS computer summation approach to analyze the isomeric composition of oleate hydroperoxides (as the saturated TMS ether derivatives). Consistently higher concentrations were found of the 8- and 11-hydroperoxides than of the 9- and 10-hydroperoxides. Minor products of autoxidation identified by GC-MS include allylic enones, isomeric epoxyoctadecanoates, dihydroxyoctadecenoates, and dihydroxyoctadecanoates.

Chromatography, Gas↗
PubMed1977

Analysis of autoxidized fats by gas chromatography-mass spectrometry: II. Methyl linoleate.

The gas chromatography-mass spectrometry (GC-MS) approach developed in the preceding paper was applied for qualitative and quantitative investigations of autoxidation products of methyl linoleate. A GC-MS computer summation method was standardized with synthetic 9- and 13-hydroxyoctadecanoate. Equal amounts of 9- and 13-hydroperoxides were found in all samples of linoleate autoxidized at different temperatures and peroxide levels. The results are consistent with the classical free radical mechanism of autoxidation involving a pentadiene intermediate having equivalent sites for oxygen attack at carbon-9 and carbon-13. Minor oxygenated products of autoxidation indicated by GC-MS include keto dienes, epoxyhydroxymonoenes, di- and tri-hydroxy monoenes. These hydroxy compounds are presumed to be present in the form of hydroperoxides. The quantitative GC-MS method was found suitable for the analysis of autoxidized mixtures of oleate and linoleate. By this method, it is possible to determine the origin of the hydroperoxides formed in mixtures of these fatty esters.

Chromatography, Gas↗
PubMedDate not supplied

Secondary products of lipid oxidation.

In the last decade, a multitude of secondary products have been identified from the radical and photosensitized oxidations of polyunsaturated lipids. These secondary products consist of oxygenated monomeric materials including epoxy-hydroperoxides, oxo-hydroperoxides, hydroperoxy epidioxides, dihydroperoxides, hydroperoxy bis-epidioxides, and hydroperoxy bicycloendoperoxides. More recently, higher molecular weight dimeric compounds have been identified from autoxidized methyl linoleate and linolenate. Decomposition of these oxidation products form a wide range of carbonyl compounds, hydrocarbons, furans, and other materials that contribute to the flavor deterioration of foods and that are implicated in biological oxidation. The interaction of some of these degradation products with DNA may be involved in cell-damaging reactions.

Carcinogens↗