stearates and ethyl-linoleate

A kinetic study of the prooxidant effect of alpha-tocopherol was performed. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl stearate 1, ethyl oleate 2, ethyl linoleate 3, ethyl linolenate 4, and ethyl arachidonate 5) by alpha-tocopheroxyl radical in toluene were determined, using a double-mixing stopped-flow spectrophotometer. The second-order rate constants (k (p)) obtained are <1 x 10(-2) M(-1 )s(-1) for 1, 1.90 x 10(-2) M(-1 )s(-1) for 2, 8.33 x 10(-2 )M(-1 )s(-1) for 3, 1.92 x 10(-1) M(-1 )s(-1) for 4, and 2.43 x 10(-1 )M(-1 )s(-1) for 5 at 25.0 degrees C. Fatty acid esters 3, 4, and 5 contain two, four, and six -CH(2)- hydrogen atoms activated by two pi-electron systems (-C=C-CH(2)-C=C-). On the other hand, fatty acid ester 2 has four -CH(2)- hydrogen atoms activated by a single pi-electron system (-CH(2)-C=C-CH(2)-). Thus, the rate constants, k (abstr)/H, given on an available hydrogen basis are k (p)/4 = 4.75 x 10(-3 )M(-1 )s(-1) for 2, k (p)/2 = 4.16 x 10(-2) M(-1 )s(-1) for 3, k (p)/4 = 4.79 x 10(-2 )M(-1 )s(-1) for 4, and k (p)/6 = 4.05 x 10(-2 )M(-1 )s(-1) for 5. The k (abstr)/H values obtained for 3, 4, and 5 are similar to each other, and are by about one order of magnitude higher than that for 2. From these results, it is suggested that the prooxidant effect of alpha-tocopherol in edible oils, fats, and low-density lipoproteins may be induced by the above hydrogen abstraction reaction.

Topics: alpha-Tocopherol; Arachidonic Acids; Free Radicals; Hydrogen; Linoleic Acids; Linolenic Acids; Lipids; Oleic Acids; Oxidants; Stearates; Vitamin E

Fatty acid ethyl esters (FAEE) are nonoxidative ethanol metabolites that have been shown to be long term markers of ethanol intake and have been implicated as mediators of ethanol-induced cell injury. Previous studies have indicated that the fatty acid composition of the FAEE found in the plasma of human subjects after ethanol ingestion is predominantly ethyl palmitate and ethyl oleate. This raised the possibility that there is some selectivity toward the fatty acid used for FAEE to be exported from the liver into the blood.. To address the hypothesis that the fatty acid composition of FAEE secreted from organs, such as the liver and pancreas, differs from the fatty acid composition of FAEE in the organs, this study was performed using rats that received ethanol by intra-arterial infusion.. It was found that the fatty acids in FAEE differed significantly in plasma versus liver, bile versus liver, and pancreatic secretions versus pancreas.. These results indicate that organs selectively export certain FAEE species.

Topics: Animals; Bile; Esters; Fatty Acids; Linoleic Acids; Liver; Male; Oleic Acids; Pancreas; Pancreatic Juice; Rats; Rats, Sprague-Dawley; Rats, Wistar; Stearates

Fatty acid ethyl esters (FAEE) are the end products of a non-oxidative pathway for ethanol metabolism in a variety of human, rabbit, rat and murine tissues. Our objective was to determine the significance of this pathway in the metabolism of ethanol by the rat lung. In vitro, 14C-labeled ethyl oleate formation was assayed in the lung and compared with the pancreas, liver, heart and brain. Lipids were extracted with acetone, and 14C-labeled ethyl oleate was isolated and quantified by thin layer chromatography (TLC) and scintillation spectrometry. FAEE synthetic activity in the lungs (in vitro) was found to be intermediate among the organs examined. In vivo, male rats received 10% ethanol in their drinking water with or without daily i.p. injections of 4-methylpyrazole (1 mmol/kg body wt) for 15 days. Another group of male rats received 4 g/kg body wt ethanol as a 50% (v/v) solution by gavage every 12 h for 2 days. FAEE from the three organs with the highest in vitro activity for FAEE synthesis (pancreas, liver and lung) were extracted with acetone, isolated from normal lipids by TLC and separated by gas chromatography. The lung had lower FAEE-forming activity than the pancreas or the liver in the 15-day studies. However, in the 2-day study, the lung had higher activity than the liver but lower activity than the pancreas. Ethyl oleate, ethyl stearate and ethyl palmitate were the predominant FAEE formed in the intact organism. Ethanol-induced FAEE may play a role in the development of alcohol-related injuries to the lung.

Topics: Animals; Esterification; Ethanol; Fomepizole; Gas Chromatography-Mass Spectrometry; In Vitro Techniques; Linoleic Acids; Liver; Lung; Male; Oleic Acids; Palmitates; Pancreas; Pyrazoles; Rats; Rats, Inbred Strains; Stearates