Demetrios S. Sgoutas

Hydrolysis of synthetic cholesterol esters containing trans fatty acids

Abstract The aim of this work was to test the specificity of rat liver cholesterol esterase (sterol-ester hydrolase, EC 3.1.1.13) with regard to the hydrolysis of cis and trans unsaturated cholesterol esters. Several synthetic cholesterol esters were employed as model substrates for the soluble fraction and microsomes from rat liver homogenates. In all cases, trans fatty acid cholesterol esters were hydrolyzed to a lesser degree than cis unsaturated esters. Furthermore, a preference for the 9-cis-unsaturated octadecanoates was indicated. The ability of cholesterol esterase to recognize the shape of the acyl moiety of cholesterol esters is discussed.

Phospholipid changes during hepatic injury caused by carbon tetrachloride.

Abstract Male rats were fed carbon tetrachloride by stomach tube. Four hours later the animals were sacrificed, their livers removed and total lipid extracted. Phospholipids were chromatographed on silicic acid columns. The fraction which eluted with 9 per cent methanol in cholorform was hydrolyzed with alkali and the hydrolysis products were subjected to ion exchange chromatography on Nalcite SAR. Phosphatidyl glycerol was increased 4 times over the control value to become a significant component. Phosphatidic acid increased slightly, cardiolipin and phosphatidyl choline remained almost unchanged, phosphatidyl serine and phosphatidyl ethanolamine declined, the latter considerably, whereas phosphatidyl inositol and the combined sphingomyelin and lysophosphatidyl choline fraction increased slightly in treated rats. Fatty acid analysis indicated a considerable reduction in the polyunsaturated fatty acid content of phospholipids in carbon tetrachloride-treated rats.

Thin-layer chromatographic separation of some bromo-and hydroxyderivatives of stearic acid

Addition of polar substituents to unsaturated fatty acids or their methyl esters enhanced the adsorption affinity contributed by each unsaturation site to such an extent that the resulting derivatives could be easily separated by differential adsorption on a silica gel coating. Saturated and unsaturated fatty acids could be separated by thin layer chromatography after either bromination of their methyl esters or oxidation of their mixture into unsaturated esters, monoenoates, dienoates, and trienoates. Furthermore, it was possible to separate the configurational isomers of the hydroxystearic acids derived fromcis andtrans hydroxylation of oleic and linoleic acids.

Synthesis of six lower homologs of methyl sterculate

Abstract In three synthetic steps, methyl sterculate and six lower homologs were synthesized from their corresponding alkynoic esters. In addition, methods for the synthesis of alkynoic fatty acids have been evaluated according to their reliability and efficiency, and the best combinations of these procedures were summarized. The homologous series of alkynoic esters and cyclopropenoic diesters were described and characterized.

Assignment of the anomalous lines in the proton nuclear magnetic resonance spectra of alkynoic fatty acids and esters

Abstract The proton nuclear magnetic resonance spectra (NMR) of a homologous series of alkynoic fatty esters having the terminal portion of methyl 9-octadecynoate and proximal methylenes varying from one to seven were studied. The previously designated anomalous lines in the NMR spectra of alkynoic acids have been assigned to the proximal internal protons. The change of shape of the lines is attributable to virtual coupling of the proximal internal protons. The chemical shift of the lines is shown to arise as a result of the deshielding of the proximal internal protons by the lateral deshielding zones of the carboxyl group acting in concert with the deshielding effect of the triple bond. The direct change in peak intensity of lines results from the change in the number of proximal internal protons.

Effect of carbon tetrachloride on incorporation of linoleic-1-C14 acid into liver lipids in rats in vivo.

Summary Linoleic-1-C14 acid was rapidly incorporated into the liver lipids of both control and carbon tetrachloride treated rats. Twenty minutes after the injection, a pronounced fall in incorporation into phospha-tidyl ethanolamine with a concurrent rise in incorporation into cardiolipin and phospha-tidyl choline fractions was observed in the degenerating liver. The increased incorporation of radioactivity into cardiolipin and phos-phatidyl choline was reflected in an increased content of linoleic acid in these phospho-lipids but not in phosphatidyl ethanolamine. These results sugested the existence of separate pools of linoleic acid for incorporation into individual phospholipids.