A pathway for biosynthesis of divinyl ether fatty acids in green leaves

[1-¹⁴C]α-Linolenic acid was incubated with a particulate fraction of homogenate of leaves of the meadow buttercup (Ranunculus acris L.). The main product was a divinyl ether fatty acid, which was identified as 12-[1′(Z),3′(Z)-hexadienyloxy]-9(Z), 11(E)-dodecadienoic acid. Addition of glutathione peroxidase and reduced glutathione to incubations of α-linolenic acid almost completely suppressed formation of the divinyl ether acid and resulted in the appearance of 13(S)-hydroxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid as the main product. This result, together with the finding that 13(S)-hydroperoxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid served as an efficient precursor of the divinyl ether fatty acid, indicated that divinyl ether biosynthesis in leaves of R. acris occurred by a two-step pathway involving an ω6-lipoxygenase and a divinyl ether synthase. Incubations of isomeric hydroperoxides derived from α-linolenic and linoleic acids with the enzyme preparation from R. acris showed that 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid was transformed into the divinyl ether 12-[1′(Z)-hexenyloxy]-9(Z), 11(E)-dodecadienoic acid. In contrast, neither the 9(S)-hydroperoxides of linoleic or α-linolenic acids nor the 13(R)-hydroperoxide of α-linolenic acid served as precursors of divinyl ethers.     

Hydrogenation of conjugated fatty acids with hydrazine

The reduction of α- and β-eleostearic acids with hydrazine has been studied. GLC analysis of the products coupled with oxidative degradation using permanganate-periodate reagent showed an initial attack mainly at the 9,10 and 13,14 bonds in the triene without change in configuration. The method should be useful in structural studies on conjugated fatty acids. Issued as NRC No. 7987.     

New phospholipid fatty acids from the marine spongeCinachyrella alloclada uliczka

The fatty acid composition of phospholipids from the Senegalese spongeCinachyrella alloclada was examined. Two new fatty acids not hitherto found in nature, namely 10,13-octadecadienoic acid and 16-tricosenoic acid, were identified. 8-Hexadecenoic, 13-nonadecenoic and 5,9,13-trimethyltretradecanoic fatty acids were also found for the first time in sponges. The latter compound (1.4% of the total fatty acid mixture), an isoprenoid fatty acid, accompanies the major fatty acid 4,8,12-trimethyltridecanoic acid (19.7%). The monomethyl branched fatty acids (22%) identified include 23-methylpentacosanoic acid (anteiso-26∶0), not previously observed in sponged. The major long-chain fatty acids encountered were the known 17-tetracosenoic 19-heptacosadienoic and 5,9,23-tricontatrienoic acid. Some sixty fatty acids were identified as methyl esters andN-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry.     

Composition and biosynthesis of fatty acids inPyramimonas grossii

The green algaPyramimonas grossii orginating in the coastal waters of the Atlantic Ocean Argentina was subcultured until a monoalgal culture was obtained. The fatty acid composition of the alga grown in a mineral medium at 12 C was determined by gas liquid chromatography (GLC) on 2 columns. The major fatty acids were oleic, linoleic, palmitic and α-linolenic acids, but the 20-carbon polyunsaturated acids, 20∶4ω6 and 20∶5ω3, respectively, belonging to the linoleic and α-linolenic series, were also found. Incubation with [¹⁴C] oleate, [¹⁴C] acetate, [¹⁴C] linoleate and [¹⁴C] α-linolenate suggests that linoleate is not directly converted to α-linolenate. [¹⁴C] Acetate was easily converted to palmitic, palmitoleic and oleic acids. However, after 48 hr of incubation, only traces of radioactivity were detected in linoleic acid and no label was found in α-linolenic acid.     

A survey of the conjugated fatty acids of seed oils

Fatty acids with conjugated unsaturation occur in many seed oils. Thirty of these acids are reviewed with emphasis on their detection, isolation, and structure determination. Their distribution among plant families is shown, and a botanical source of each acid is given. Some reactions, derivatives, and methods of determining configuration are described. Current theories of their biosynthesis in the seed, involving oxygenated precursors, are summarized.     

Two novel phospholipid fatty acids from the caribbean spongeGeodia gibberosa

The novel fatty acids (Z)-6-nonadecenoic acid (1) and (Z)-17-pentacosenoic acid (2) were characterized in the spongeGeodia gibberosa. These fatty acids were mainly found in phosphatidylethanolamine and phosphatidylcholine.     

Esterification of glycerol with conjugated linoleic acid and long-chain fatty acids from fish oil

Free fatty acids from fish oil were prepared by saponification of menhaden oil. The resulting mixture of fatty acids contained ca. 15% eicosapentaenoic acid (EPA) and 10% docosahexaenoic acid (DHA), together with other saturated and monounsaturated fatty acids. Four commercial lipases (PS from Pseudomonas cepacia, G from Penicillium camemberti, L2 from Candida antarctica fraction B, and L9 from Mucor miehei) were tested for their ability to catalyze the esterification of glycerol with a mixture of free fatty acids derived from saponified menhaden oil, to which 20% (w/w) conjugated linoleic acid had been added. The mixtures were incubated at 40°C for 48h. The ultimate extent of the esterification reaction (60%) was similar for three of the four lipases studied. Lipase PS produced triacylglycerols at the fastest rate. Lipase G differed from the other three lipases in terms of effecting a much slower reaction rate. In addition, the rate of incorporation of omega-3 fatty acids when mediated by lipase G was slower than the rates of incorporation of other fatty acids present in the reaction mixture. With respect to fatty acid specificities, lipases PS and L9 showed appreciable discrimination against esterification of EPA and DHA, respectively, while lipase L2 exhibited similar activity for all fatty acids present in the reaction mixture. The positional distribution of the various fatty acids between the sn-1,3 and sn-2 positions on the glycerol backbone was also determined.     

2-Hydroxy fatty acids from marine sponges 2. The phospholipid fatty acids of the caribbean spongesVerongula gigantea andAplysina archeri

The α-hydroxy fatty acids 2-hydroxy-eicosanoic (1) acid, 2-hydroxyheneicosanoic (2) acid, 2-hydroxydocosanoic (3) acid, 2-hydroxytetracosanoic (4) acid, 2-hydroxy-23-methyl-tetracosanoic acid and 2-hydroxypentacosanoic (5) acid were isolated from the Caribbean spongesVerongula gigantea andAplysina archeri. The very long chain fatty acids 5,9-nonacosadienoic acid (29∶2) and 5,9,23-tricontatrienoic acid (30∶3) were also identified together with theiso-prenoid fatty acid 3,7,11,15-tetramethylhexadecanoic (phytanic) acid that seems to be common in the Aplysinidae.A. archeri contained an extremely long chain fatty acid tentatively characterized as dotricontaenoic (32∶1) acid. These acids were found to occur in phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine and traces of phosphatidylglycerol.     

Oxidative stability of conjugated linoleic acids relative to other polyunsaturated fatty acids

Contrary to current opinion, conjugated linoleic acids (CLA) as a mixture of several isomers have been previously shown to function as prooxidants in the form of free fatty acids and methyl esters in heated canola oil. Furthermore, CLA oxidizes considerably faster than linoleic acid. However, stability of CLA relative to other polyunsaturated fatty acids remains undetermined. The present study was therefore undertaken to examine the relative oxidation rate of CLA compared with that of linolenic acid (LNA), arachidonic acid (AA), and docosahexaenoic acid (DHA) in air at 90°C. CLA, both in the form of free fatty acids and triacylglycerols, were extremely unstable to the same extent as DHA, but they oxidized considerably faster than LNA and AA. The mechanism by which CLA were readily decomposed was probably due to formation of the unstable free-radical intermediate.     

15,18,21,24-triacontatetraenoic and 15,18,21,24,27-triacontapentaenoic acids: New C30 fatty acids from the marine spongeCliona celata

The marine sponseCliona celata contains 3.5% 30∶4ω6 and 7.0% 30∶5w3 in its total fatty acids. These C₃₀ polyunsaturated structures are unknown in other living organisms. Both acids occur mainly as phosphatidylserine esters.     

The biosynthesis of polyunsaturated fatty acids in plants

This paper is a review of some of the work being done at the author's laboratory. The phospholipids and glycolipids of the alga,Chlorella vulgaris, have been implicated in fatty acid transformations such as chain elongation and desaturation. Labeling studies with [¹⁴C] acetate have shown that newly synthesized galactosyl glycerides have mainly saturated fatty acids. Subsequent to de novo synthesis, a series of alterations of fatty acid structure takes place within the same glycolipid molecules. The specific incorporation of [¹⁴C] oleic acid intoChlorella phosphatidyl choline provides a convenient model system for studying the lipid dependent desaturation of oleic to linoleic acid. The inhibitor of fatty acid desaturation, sterculic acid, only inhibits the conversion of oleate into linoleate if added before the precursor fatty acid has been incorporated into a complex lipid. Studies with isomeric monoenoic fatty acids have suggested that there are two enzymes which catalyze the formation of linoleic from oleic acid. One measures the position of the second double bond from the carboxyl group, the other, from the methyl end of the chain. The latter enzyme probably requires the complex lipid substrate.     

The phospholipid fatty acids of the marine spongeXestospongia muta

The rare phospholipid fatty acids 3,7,11-trimethyldodecanoic (1), 5,9-hexadecadienoic (2) and 12-methyl-hexadecanoic (3) were identified in the marine spongeXestospongia muta. Branched fatty acids inX. muta accounted for 35% of the total fatty acid mixture. It was observed that the occurrence of the 5,9-hexadecadienoic acid (2) coincides with the complete absence of the very long chain fatty acid 5,9-hexacosadienoic. The acid 5,9,19-octacosatrienoic seems to be found in mostXestospongia species.     

In vitro biosynthesis of fatty acids inDrosophila melanogaster

A new in vitro technique, utilizing ruptured larvae ofDrosophila melanogaster, was employed to study the incorporation of³H-acetate into long-chain fatty acids. Preparative gas-liquid chromatography and scintillation spectroscopy were used to determine the relative activity of each fatty acid from total lipid extracts. Quantitative changes were observed in the distribution of label during the course of the incubation times, which ranged from five minutes to nine hours. All fatty acids which were observed to incorporate acetate in previous in vivo studies also showed incorporation of label under these in vitro conditions. It is concluded that this system may be useful for studying aspects on insect metabolism for short intervals of time.     

Isoprenoid fatty acids from marine sponges. Are sponges selective?

The burrowing spongesAnthosigmella varians andSpheciospongia vesparium were found to be rich in the isoprenoid phospholipid fatty acid 4,8,12-trimethyltridecanoic (5.2% and 23%, respectively, of the total fatty acid composition), while the burrowing spongeChondrilla nucula and the demospongeAgelas dispar contained the acid 3,7,11,15-tetramethylhexadecanoic (13.8% and 8.6%, respectively, of the total phospholipid fatty acid composition). No other isoprenoid fatty acid was found, and the two acids described in this work did not occur concomitantly in the same sponge.     

Identity and configuration of conjugated fatty acids in certain seed oils

Punicic acid was found in the seed oils ofCayaponia grandifolia, Trichosanthes cordata andT. cucumerina. α-Eleostearic acid was found inMomordica cochinchinensis, M. cochinchinesis varietymixta andM. cymbalaria. The identity of the conjugated triene acid ofAleurites trisperma, Garcia nutans andCyclandrophora laurina was confirmed as α-eleostearic acid (cis, trans, trans configuration). The configuration of kamlolenic acid was proved to becis-9,trans-11,trans-13. The oils ofAleurites remyi andLicania platypus did not contain any conjugated acid. Issued as N.R.C. No. 10589.     

Seasonal fat and fatty acids variations of seven marine fish species from the Mediterranean Sea

Seasonal variations of proximate compositions, muscle lipids and fatty acids (FA) of seven seawater species (Silllago sihoma, Upeneus pori, Sparus aurata, Saurida undosquamis, Epinephelus auneus, Mullus barbatus, Solea solea) from the Mediterranean Sea, were determined in all seasons. The results showed that the fatty acid compositions of each species ranged from 26.41 to 38.70% saturated (SFA), 13.78 to 26.52% monounsaturated (MUFAs) and 25.02 to 50.83% PUFAs. The highest proportions of EPA were obtained from M. barbatus (8.34%) in spring, S. sihoma (7.54%), U. pori (6.75%), S. aurata (6.31%), S. undosquamis (5.12%), E. auneus (5.10%) in summer, and also S. solea (6.19%) in spring. The highest proportions of DHA were found in spring, ranging from 25.14% for M. barbatus to 34.87% for S. aurata, except for S. solea (30.44%) in winter and S. sihoma (15.83%) in summer. The results showed that from a quality point of view, all species were suitable for human nutrition, since muscle lipids are rich in EPA + DHA in all seasons. Practical application : The American and Canadian Dietetic Associations recommend two servings of fatty fish per week and a daily combined intake of EPA and DHA of 500 mg. This follows a trend of numerous publications and other guidelines recognizing the health benefits of long‐chain n‐3 PUFA from fish or marine microbial sources with respect to cardiovascular health, neurological diseases, infant health and development, inflammation and cancer and other health effects. The seven species analyzed here provide muscle lipids that are rich in EPA and DHA. Only minor season‐to‐season changes in the total content of n‐3 and n‐6 PUFA were observed for the same species. The results provide valuable information for preparing diet tables.     

GC-MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

The FA composition of 12 strains of marine aerobic anoxygenic phototrophic bacteria belonging to the genera Erythrobacter, Roseobacter, and Citromicrobium was investigated. GC-MS analyses of different types of derivatives were performed to determine the structures of the main FA present in these organisms. All the analyzed strains contained the relatively rare 11-methyloctadec-12-enoic acid, and three contained 12-methyl-octadec-11-enoic acid, which has apparently never been reported before. High amounts of the very unusual octadeca-5,11-dienoic acid were present in 9 of the 12 strains analyzed. A FA containing a furan ring was detected in three strains. Analytical data indicated that this FA was 10,13-epoxy-11-methyloctadeca-10,12-dienoic acid. A very interesting enzymatic peroxidation of the allylic carbon 10 of cis-vaccenic acid was observed in three strains. Deuterium labeling and GC-MS analyses enabled us to demonstrate that this enzymatic process involves the initial dioxygenase-mediated formation of 10-hydroperoxyoctadec-11(cis)-enoic acid, which is then isomerized to 10-hydroperoxyoctadec-11(trans)-enoic acid and converted to the corresponding hydroxy-acids and oxoacids. Different biosynthetic pathways were proposed for these different compounds.     

Component fatty acids of marine fish liver oils

Summary 1. Two liver oils (Elasmobranch) fromCarcharias melanopterus andPristis cuspidatus, caught off the Madras coast are studied, and their component fatty acids are reported. 2. The mixed acids were separated into three groups (varying unsaturation) of acids, and their methylesters were fractionated. 3. The liver oils are found to belong to the fourth group of Tsujimoto’s classification of Elasmobranch fish liver oils.Carcharias melanopterus liver oil contains 31.1% unsaturated acids (myristic 3.1, palmitic 18.4, stearic 9.5, and 0.1% arachidic) and 68.9% unsaturated acids (C₁₆ 10.8, C₁₈ 19.7, C₂₀ 15.2, C₂₂ 17.1, C₂₄ 5.3%, and traces of C₁₄ monoethenoid).Pristis cuspidatus liver oil contains 36.9% saturated acids (myristic 1.2, palmitic 22.9, stearic 12.7, and arachidic 0.1%) and 67.1% unsaturated acids (C₁₆ 8.2, C₁₈ 28.5, C₂₀ 16.4, C₂₂ 5.2, C₂₄ 4.6%, and traces of C₁₄ monoethenoid). The unsaturations of the different groups of acids are almost of the same order. 4. The abnormal content of saturated acids can be explained by the process of bio-hydrogenation. The relatively less amount of saturated acids inCarcharias melanopterus liver oil along with its higher content of polyethylenic acids (C₂₀ and above) points strongly to the possible presence of intermediate types of fats among the four groups of Elasmobranch oils.     

Reactions of conjugated fatty acids. VIII. Dibasic acids by hydrogenation and oxidative cleavage

Summary Conjugated linoleic acid can be hydrogenated as sodium soap in an aqueous or ethylene glycol solution with commercial nickel catalysts. Under suitable conditions the acid is reduced predominantly to monounsaturated acids with only a slight increase in saturated acids. An alkali-conjugation reaction mixture may be hydrogenated without isolating the conjugated acids. One set of conditions found suitable for hydrogenation is as follows: 10 g. of conjugated linoleic acid, 7 g. of sodium hydroxide, 250 ml. of water, and 0.05 g. of nickel placed under 40 p.s.i. hydrogen pressure and heated at 140°C. for 1 hour. Acids prepared from this reaction mixture have an iodine value of about 90. Oxidation and chromatographic analyses of the resultant dibasic acids indicate that with alkali-conjugated linoleic acid, 1,2, 1,4, and 3,4 addition of hydrogen take place with equal ease. The reduced acids contain 66%trans acids. Withtrans,trans conjugated linoleic acid, 1,4 addition takes place to a greater extent that 1,2 and 3,4 addition, and the reduced acids are allrans. Presented at the fall meeting, American Oil Chemists' Society, Cincinnati, O., September 30–October 2, 1957. Part VII is in press, Journal of Organic Chemistry.