Thesis (M.D.)--University of Adelaide, 1988. / Includes bibliographical references (leaves 171-211).

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 279-310.

Thesis (M.S.)---University of North Carolina Wilmington, 2008. / Title from PDF title page (viewed September 22, 2008) Includes bibliographical references (p. 45-50)

Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Call number: LD2668 .T4 1965 D12 / Master of Science

Malonaldehyde, a very reactive member of the homologous series of dialdehydes, is associated with the autoxidative deterioration of lipids. Its measurement, in autoxidized lipid systems is an expression of the extent of oxidation, in lipids. Malonaldehyde lends itself well to such determinations because of the sensitivity and specificity of its quantification in complex lipid systems. Complete knowledge of the formation of malonaldehyde in autoxidized lipids. is lacking. Such knowledge would undoubtedly promote a better understanding of lipid autoxidation mechanisms. In this investigation, a method for detecting malonaldehyde through the use of its reaction with p-aminobenzoic acid was developed. This was adapted for use in measuring malonaldehyde in lipids and in tissue samples. The reaction between p-aminobenzoic acid and malonaldehyde was partially characterized, and a mechanism for the formation of the reaction product was postulated. The quantification of malonaldehyde in lipid systems by the use of p-aminobenzoic acid involves the use of a mild reducing agent such as stannous chloride to prevent interference from hyd roperoxides present in the system. The p-aminobenzoic acid reaction is highly specific for malonaldehyde and proceeds smoothly and rapidly at room temperature in a non-aqueous chloroform-methanol solvent system to yield a highly colored compound having a maximum absorbance at 406 mμ. and with a molar absorptivity of 73,500. The absorbance value may be converted directly to parts-per-million malonaldehyde through the use of a conversion factor in a simple equation. The limits of detectability of themethod are on the order of one ppm malonaldehyde. The measurement of malonaldehyde in the lipid fraction of tissue samples involves the prior extraction of the lipid with a non-aqueous chloroform-methanol solvent, by an extraction method which was developed for this purpose. The reaction of malonaldehyde with p-aminobenzoic acid involves the condensation of two molecules of p-aminobenzoic acid with one molecule of malonaldehyde. The reaction exhibits a rate maximum at a hydrogen ion concentrations of about 0.1 molar, and also exhibits rate dependencies upon the concentrations of both malonaldehyde and p-aminobenzoic acid. This strongly suggests that the reaction proceeds according to an S [subscript N] 2 mechanism. A postulated mechanism involves nucleophilic 1,4-addition of the amino nitrogen of p-aminobenzoic acid to the enol of malonaldehyde followed by-loss of water to form the enamine. The reaction with a second molecule of p-aminobenzoic acid involves nucleophilic substitution of the amino nitrogen at the carbonyl function of malonaldehyde followed by loss of water to form an imine linkage. / Graduation date: 1968

The lipid composition of swine is characteristic of the species and is also a reflection of their dietary history. Other investigators have established that the physical properties and composition of swine depot fat may be altered by variation of the dietary lipid. Dietary regimens employing vegetable oil-bearing materials and their effect on meat quality has received the attention of animal nutritionists for a considerable period. Less is known about the nutritive value of the more highly unsaturated lipids, such as fish oils, and their effect on the lipid composition of swine tissues. Even less is known about the fate of oxidized fish oil lipids in swine rations. This research had for its purpose the investigation of the fate in swine of the dietary marine lipid, menhaden oil, and its effect on composition of depot lipids. The state of autoxidation of the oil and the effect of certain antioxidants on the fatty acid composition of swine was determined. Growth studies on swine were made using menhaden oil of various oxidation states as the dietary lipid. The effect of antioxidants, ∝-tocopherol acetate and ethoxyquin, was also investigated. At the conclusion of the diet trials, tissue samples, representing the five dietary regimens, were removed for analysis. The fatty tissues examined were outer back fat, inner back fat, and kidney fat. Samples of liver tissue for lipid analysis were also taken. The lipids from the respective tissues were extracted and interesterified with methanol to yield the methyl esters of the fatty acids. Hydrogenation of the unsaturated methyl esters for chain length confirmation was carried out. Qualitative and quantitative gas-liquid chromatographic analysis of the unhydrogenated and hydrogenated methyl esters of the fatty acids were performed on diethylene glycol succinate column. The results of these investigations showed that a particular dietary fatty acid can be selectively deposited in animal tissues. Long chain polyunsaturated fatty acids of menhaden oil, such as 20:5, 22:5, 22:6 were sparsely deposited in adipose tissues. The depot fat composition showed a mixture of characteristic menhaden oil fatty acids with the typical fat synthesized by swine. Fatty acid composition of tissue from swine fed oxidized menhaden oil with and without antioxidants showed very similar fatty acid composition as those fed fresh menhaden oil. The results of this investigation supported the beneficial effect of vitamin E (∝-tocopherol acetate) and ethoxyquin as in vivo antioxidants. / Graduation date: 1964

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