Isoprenoid Fatty Acids Research Articles

Selection of internal standards for determining quantitative recovery of isoprenoid acids after urea complexing

AbstractVarious types of esters are considered as internal standards for the quantitative gas liquid Chro‐matographic determination of isoprenoid fatty acids after urea complex treatment of esters of total or saturated fatty acids. It is shown that aromatic esters are potentially unsuitable because of on‐column losses with polyester columns. Two classes of ali‐phatic esters, either of 2‐ethyl‐l‐hexanol, or of 3‐cyclohexylpropionic acid, have been evaluated as satisfactory and certain gas liquid Chromatographic retention data is given to show which ester might be selected for a particular application.

Isoprenoid Fatty Acids in the Human Diet: Distinctive Geographical Features in Butterfats and Importance in Margarines Based on Marine Oils

Comparison of the three principal isoprenoid fatty acids in eight butterfats from six different continents shows that proportions among these acids are surprisingly constant. However examination of the phytanic acids showed a higher proportion of the 3D, 7D, 11D diastereoisomer in samples from cattle introduced into the southern hemisphere. Margarines based on marine oils showed a distinctly different proportion for the two phytanic acid diastereoisomers. These dietary factors are discussed in terms of deposition of phytanic acid in patients with Refsum's syndrome

C18-Isoprenoid Ketone in Recent Marine Sediment

ISOPRENOID hydrocarbons, fatty acids and alcohols occur in ancient rocks, oil shales, young sediments and living organisms1,2. During thermal alteration experiments on a recent marine sediment from Tanner Basin, Southern California continental shelf, we isolated a C18-isoprenoid ketone, namely 6,10,14-trimethylpentadecan-2-one. Samples of sediment from the Tanner Basin were sealed in glass bombs and exposed to temperatures from 60° to 150° C for 7 d, 30 d and 60 d. The sediment was then extracted with benzene-methanol and the extract chromatographed on a silicic acid column. The ketone was found in both the heat-treated and untreated sediment. It was extracted with the fatty acid fraction which had been converted to methyl esters, and was separated with the other branched components by the urea adduction method. For comparative purposes, the C18-isoprenoid ketone was also synthesized3. Analytical comparisons by gas-liquid chromatography, using two 5 foot × inch columns (3% OV 101 on 100/120 mesh ‘Gas Chrom’ Q and 3% DEGS on 100/120 mesh ‘Gas Chrom’ Z), showed the synthetic product to be identical to the sedimental ketone.

Fatty acids of the female horseshoe crab Xiphosura (Limulus) polyphemus

The fatty acid composition of 9 different tissues and organs of the female horseshoe crab Xiphosura (Limulus) polyphemus — one of the very few recent representatives of the ancient arthropod class Merostomata — was investigated in reference to the distribution of fatty acids through the marine food web. Fatty acid spectra, in which polyunsaturated fatty acids are predominant, especially eicosapentaenoic acid (20:5 ω3), revealed features characteristic of marine lipids. However, rather large quantities of monoenoic fatty acids also occur in all organs. In the saturated fatty acid fractions, the high content of branched-chain components is worth noticing, particularly in the gills and the carapace (35%); in all probability, the high amount of the branched-chain fatty acids is associated with their protective function in surface lipids. Isoprenoid fatty acids such as pristanic and phytanic acid were absent.

The distribution of saturated and isoprenoid fatty acids in the lipids of three species of molluscs, Littorina littorea, Crassostrea virginica and Venus mercenaria

1.1. Marine molluscs (periwinkle, oyster, quahaug) were found to contain isoprenoid, iso, anteiso and normal odd-numbered fatty acids qualitatively similar to those in higher aquatic life forms.2.2. In all three species the branched-chain and normal odd-numbered fatty acids tended to be quantitatively associated with trends in the neighbouring normal even-numbered fatty acids, specifically with myristic, palmitic and stearic acids.3.3. Periwinkle lipids had very little phytanic or pristanic acids, suggesting an adaptation to rapidly degrade ingested phytol. The obvious degradation product was 4,8,12-trimethyltridecanoic acid.

Isoprenoid fatty acids in antarctic krill (Euphausia superba)

AbstractIn an attempt to elucidate the origin of phytanic (3,7,11,15‐tetramethylhexadecanoic), pristanic (2,6,10,14‐tetramethylpentadecanoic) and 4,8,12‐trimethyltridecanoic acids found in small quantities in whales, the fatty acid composition of the lipids from Antarctic krill (Euphausia superba Dana) was determined by gas‐liquid chromatography. Phytanic acid was found to be present to the extent of 1·4% of the total fatty acids, and was isolated and identified by mass and infra‐red spectrometry. Two other isoprenoid fatty acids, pristanic acid (0·04%) and 4,8,12‐trimethyltridecanoic acid (0·05%) were detected by gas‐liquid chromatography. E. superba constitute almost exclusively the diet of whales inhabiting Antarctic waters, and the phytanic acid in whale oils is probably derived from ingested krill which presumably biosynthesise this acid from the phytol moiety of chlorophyll present in the diatoms on which these planktonic crustaceans live.

Branched-chain fatty acids of four fresh-water fish oils

1. 1. The methyl esters of the total fatty acids from four frest-water fish oils have been hydrogenated and examined in detail by open-tubular gas-liquid chromatography for minor saturated fatty acid components. 2. 2. Iso and anteiso, and normal branched-chain fatty acids with odd carbon numbers are present in number and proportions similar to those observed in marine oils and lipids. 3. 3. Three isoprenoid fatty acids, respectively 4,8,12-trimethyltridecanoic, pristanic and phytanic, also occur in proportions and diastereoisomer ratios similar to those occurring in marine oils.

The isolation and identification of 4,8,12-trimethyltridecanoic acid from butterfat

SummaryThe isoprenoid fatty acid 4,8,12-trimethyltridecanoic acid has been isolated from butterfat and identified. This acid was found to be a DD diastereoisomer, and was thought to have been derived from the phytol moiety of chlorophyll. It was estimated that in the sample of butterfat investigated, 4,8,12-trimethyltridecanoic acid constituted about 0·005% of the total weight of fatty acids.

Phytanic acid l-menthyl esters : Gas-Liquid chromatographic separation of diastereoisomers

l-Menthyl esters of a naturally occurring (marine) phytanic acid, of an all-synthetic phytanic acid, and of a phytanic acid known to be of 3 d, 7 d, 11 d configuration were compared by GLC. As in the pristanates, the ldd and ddd diastereoisomers were the farthest apart, but in the marine phytanate only two diastereoisomers, presumably ldd and ddd, could be detected. A general guideline is proposed that in the GLC of l-menthyl esters of isoprenoid fatty acids with 2-methyl and 3-methyl substituents the ldd and ddd diastereoisomers will be, respectively, the first and last to elute.

Correlation of stereoisomerism in present day and geologically ancient isoprenoid fatty acids.

High resolution gas chromatography of the methyl esters of individual isoprenoid fatty acids isolated from a geological source of the Eocene period has shown a diastereoisomer composition compatible with a chlorophyll derivation for the acids. The L-menthyl esters give enhanced separation of isoprenoid acid diastereoisomers on an optically inactive GC substrate and could be employed on samples with more complex stereochemistry.

Isoprenoid Fatty Acids Isolated from the Kerogen Matrix of the Green River Formation (Eocene)

Demineralized oil shale was oxidized with chromic acid, and C(14) to C(22) isoprenoid fatty acids were isolated and identified. The major components of the branched-chain acid fraction after successive 3-, 6-, and 15-hour oxidations are C(15) and C(16) branched-chain acids; C(17), C(19) (norphytanic acid), and C(20) (phytanic acid) were obtained in lower concentration; no C(18) product was obtained. Separations were effected by column and gas-liquid chromatography, and the structures of individual components were determined by high- and low-resolution mass spectrometry.

Examination of isoprenoid fatty acids as distinguishing characteristics of specific marine oils with particular reference to whale oils

1. 1. The proportions of three isoprenoid fatty acids were compared in samples of twelve fish oils and fourteen oils from marine mammals. 2. 2. Antarctic and North Atlantic fin whale oils could be distinguished, the former having very low levels of 4,8,12-trimethyltridecanoic acid relative to 3,7,11,15-tetramethylhexadecanoic (phytanic) acid. 3. 3. The gradation in proportions of the three acids from Antarctic whale oil through North Atlantic whale oils to seal oils suggests a correlation with a change in food intake for marine mammals from a primarily zooplankton diet through a partial fish diet to an exclusive fish diet. 4. 4. In both fish and marine mammals a decrease in the ratio of L,D,D to D,D,D diastereomers for 2,6,10,14-tetramethylpentadecanoic (pristanic) and phytanic acids correlated with a high level of 4,8,12,-trimethyltridecanoic acid and suggested a relation to fat catabolism.

Occurrence of Isoprenoid Fatty Acids in the Green River Shale

The most abundant free fatty acids present in a sample of shale from the Green River Formation (Eocene, about 60 x 10(6) years) from Sulfur Creek are the acylic C(19) and C(20) isoprenoid acids. The dominance of these acids parallels the abundance of the corresponding hydrocarbons pristane and phytane.