Analysis of Fatty Acid Composition in Adrenal Cholesterol Esters from Human and Rats
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Fatty acids in adrenal cholesterol ester (CE) from humans and rats were analyzed by AgN0<SUB>3</SUB>-impregnated silica gel thin-layer chromatography (AgNO<SUB>3</SUB>-TLC) and gas-liquid-chromatography (GLC). Methylated fatty acids were partitioned on AgNO<SUB>3</SUB>-TLC according to their number of double bonds and the location of double bonds was assumed by the retention time in GLC. Some of them were identified by the method of potassium permanganate oxidation. Double bonds were oxidized to form two carboxyl groups; mono- and di-carboxylic acids were methylated and could be analyzed by GLC.<BR>Great difference was shown between the fatty acid composition of adrenal CE and that of plasma lipids in human. Most of the fatty acids having more than 20 carbon atoms of chain length were supposed to be synthesized in adrenal glands. Twenty-six kinds of fatty acids were found in adrenal CE from two men. Percentage of 18: 1 was most high, and 20: 3ω6 and 22: 4ω6 were found much among polyunsaturated fatty acids. 20: 3, 20: 4 and 22: 4 were demonstrated to be linoleic family by the method of KMnO<SUB>4</SUB>-oxidation. The results matched with past reports. Docosatrienoic acid took 1.5% and 2.8% in the two men and was demonstrated to be 22: 3Δ <SUP>10, 13, 16</SUP> by the same method. Existence of 22: 3ω6 suggests a new pathway of fatty acid conversion in linoleic family; 20: 3→22: 3→22: 4. 24: 1 took more than 1% and proved to be 24: 1Δ<SUP>15</SUP> by KMnO<SUB>4</SUB>-oxydation. The fatty acid conversion in monenes of oleic family in adrenal glands seemed to be as follows; 18: 1→20: 1→22: 1→ 24: 1. Two kinds of 20: 2, that is ω6 and ω9, and 22: 2ω9 were also found and took a minor percentage. Fatty acid composition in CE from adenoma of primary aldosteronism was studied in the similar way. It resembled in most part the fatty acid pattern in adrenal CE from the adjacent normal tissue, but percentages of 20: 4, 22: 4 and 22: 5 in linoleic family, especially of 22: 4ω6, were lower in adenoma.<BR>In adrenal CE from rats fed on fat free diet for 10 weeks, 18: 2 and 20: 4 in linoleic family and 20: 5, 22: 5 and 22: 6 in linoleic family markedly decreased in comparison with rats fed on control diet, but 20: 3 and 22: 3 appeared and took 6.0% and 8.8%, respectively. Eicosatrienoic and docosatrienoic acids in fat deficient rats were identified to be 20: 3Δ <SUP>5, 8, 11</SUP>and 22: 3Δ <SUP>7, 10, 13</SUP> by the method of KMnO<SUB>4</SUB>-oxidation. This result agreed with pastreports in adrenal CE from fat deficient rats. 22: 3ω6 found in human adrenal CE did notexist in rats and its retention time in GLC was clearly different from 22: 3 in fat deficient rats. One of the interesting phenomena in fat deficient rats was that the percentage of22: 4ω6 and 22: 5ω6 were maintaind to the same level as those in control rats, in spite of marked decrease of arachidonate in fat deficient rats. Difference in metabolic speed in each fatty acid should be considered but furthermore, characteristic mode of fatty acid conversion, of selective esterification or of demand of essential fatty acid in adrenal glands was necessary to be studied.