Eicosatrienoic acid

Synthetic chemical approaches to the preparation of carbon-14 labeled materials iavolve a number of basic building blocks prepared from barium [ CJ-carbonate (2). These are carbon [ C]-dioxide [ CJ-acetjlene [U— C]-ben2ene, where U = uniformly labeled [1- and 2- C]-sodium acetate, [ C]-methyl iodide, [ C]-methanol, sodium [ C]-cyanide, and [ CJ-urea. Many compHcated radiotracers are synthesized from these materials. Some examples are [l- C]-8,ll,14-eicosatrienoic acid [3435-80-1] inoxn. [ CJ-carbon dioxide, [ting-U— C]-phenyhsothiocyanate [77590-93-3] ftom [ " CJ-acetjlene, [7- " C]-norepinephrine [18155-53-8] from [l- " C]-acetic acid, [4- " C]-cholesterol [1976-77-8] from [ " CJ-methyl iodide, [l- " C]-glucose [4005-41-8] from sodium [ " C]-cyanide, and [2- " C]-uracil [626-07-3] [27017-27-2] from [ " C]-urea. All syntheses of the basic radioactive building blocks have been described (4). 

Considering their heat sensitivity, the separation of fatty acids and rosin with minimal degradation by fractional distillation under vacuum and/or in the presence of steam is surprisingly good (3). Tad od rosin (TOR) contains about 2% fatty acid and smad amounts of neutrals. Tad od fatty acid (TOFA) contains as Htde as 1.2% rosin and 1.7% neutrals. In typical U.S. TOFA, 49% of the fatty acids is oleic, 45% linoleic, and 3% palmitic, stearic, and eicosatrienoic acid. TOR and TOFA are upgraded to resins and chemicals for the manufacture of inks (qv), adhesives (qv), coatings (qv), and lubricants (see Lubrication AND lubricants). 

Essential fatty acid deficiency Deficiency of linoleic acid, linolenic acid, and/or arachidonic acid, characterized by hair loss, thinning of skin, and skin desquamation. Long-chain fatty acids include trienes (containing three double-bonds [e.g., 5,8,11-eicosatrienoic acid, or Mead acid trienoic acids) and tetraenes (containing four doublebonds [e.g., arachidonic acid]). Biochemical evidence of essential fatty acid deficiency includes a trieneitetraene ratio greater than 0.4 and low linoleic or arachidonic acid plasma concentrations. 

Tissue accumulation of exogenously added tritiated PGs was shown for the spider crab Libinia emarginata [107]. The earliest report of possible oxylipin production in marine arthropods was from gill and stomach tissues of the lobster Homarus sp. [15]. These were tested for their ability to produce prostaglandins in incubations with all-cis-[8,9,ll,12,14,15-3H6]eicosatrienoic acid. Carrier PGEj was added and the PGErtype compounds from the extract were purified by TLC. Quantitation was done by UV absorption at 278 nm after... 

Linoleic (A 2 octadecadienoic) acid Dihomo-y-linolenic (A8.ii.i4-eicosatrienoic) acid... 

Mutant Mut49 was considered to be defective in A6 desaturase because of a high 18 2co6 level and low levels of 18 3o>6, DHGA and A A in its mycelia. In addition to the accumulation of 18 2 6, two nonmethylene-interrupted PUFAs, i.e., 5,11,14-cis-eicosatrienoic acid (20 3A5) and 5,11,14,17-cis-eicosatetraenoic acid (20 4A5), were found [158], These PUFAs are considered to be converted from 18 2co6 or 18 3ca3, respectively, by three subsequent reactions, i.e., A6 desaturation, elongation and A5 desaturation (Fig. 15). 

For the study of the physical and chemical properties of triply unsaturated fatty acids and for the comparison with y-linolenoic acid [6Z,9Z.12Z)-6,9,l2-octadeca-trienoic acid] coworkers of the Unilever Research Centre in Vlaardingen (Netherlands) synthesized some methyl esters of ( ,Z,Z)-trisunsaturated fatty acids 73). For the preparation of the esters of (2E,9Z, 12Z)-2,9,12-octadecatrienoic acid and of (2 ,11Z,14Z)-2,11,14-eicosatrienoic acid (68 a and b) they used the Wittig reaction to introduce the ( )-2-double bond into the starting diunsaturated aldehyde. Reduction of the acid chlorides of (7Z,10Z)-7,10-hexadecadienoie acid and of linolenoic acid (65a and b) with lithium tri-tert-butoxyaluminium hydride affords the corresponding aldehydes 66 a and b which can be olefinated with the stable ylide 67 to methyl ( ,Z,Z)-alkatrienoates 68a, b with a (Z)-2-isomer content of 4.6%73) (Scheme 13). 

Strain ALA2 converted y-linolenic acid (18 3 all ds-6,9,12) to several products including 12,17 13,17-diepoxy-6,9-octadecadienoic acid 12,13,17-trihydroxy-6(Z),9(Z)-octadecadienoic acid and 12-hydroxy-13,16-epoxy-6(Z),9(Z)-octadecadienoic acid as depicted in the top half of Figure 16.2 (Hosokawa et al, 2003a). Strain ALA2 also converted the substrate arachidonic acid (20 4 all civ-5,8,11,13) to cyclic and trihydroxyl fatty acids as reported previously (Hosokawa et al., 2003a). These reactions resulted in compounds 14,19 15,19-diepoxy-5(Z),8(Z),ll(Z)-eicosatrienoic acid 14-hydroxy-15,18-epoxy-5(Z),... 

Z),ll(Z)-eicosatrienoic acid and 12,15,19-trihydroxy-5(Z),8(Z),ll(Z)-eico-satrienoic acid, which were isolated as shown in the lower portion of Figure 16.2 (Hosokawa et al., 2003a). Both of these sets of compounds are analogous to metabolites derived from linoleic acid as detailed in Figure 16.1. 

Samuelsson, B. (1965) On the incorporation of oxygen in the conversion of 8,11,14-eicosatrienoic acid to prostaglandin Ei. Journal of the American Chemical Society, 87, 3011-3013. 

A strong isotope eflFect was observed when the methylene H was removed, indicating that this may be the rate-controlling step in the reaction sequence. These results confirm the earlier findings of Hamberg and Samuelsson 111) with stereospecifically-labeled H at C-15 of 8,11,14-eicosatrienoic acid. 

Figure 1. Metabolic pathway for linoleic acid. COX, Cycloozygenase, LOX, Lipoxygenase, PGEi, Prostaglandin Ej, PGE2, Prostaglandin E2, PGI2, Prostaglandin l2,TXA2, Thromboxane A2, 15-HETrE, 15-hydroxy eicosatrienoic acid, LTB4, Leukotriene B4.

Eicosatrienoic acid (ETA 20 3, n-9 Mead acid) (here a double mutant of the parent fungus was produced that lacked both delta-12 and delta-15 desaturase activities so that oleic acid, 18 1,n-9, could only be desaturated between its existing double bond and the carboxylate head group). 

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