Fatty acids,part 38: Neighbouring group participation in the oxymercuration-demercuration reaction. Another route to 1,4- and 1,5-epoxides

Oxymercuration-demercuration of hydroxy alkenes follows an intramolecular pathway to furnish 1,4-epoxides (tetrahydrofurans) when the hydroxyl group is β (trans only) or γ to a double bond and 1,5-epoxides (tetrahydropyrans) when the hydroxyl group is δ to the double bond. The cis and trans isomers of methyl ricinoleate and methyl 9-hydroxyoctadec-12-enoate, and a series of cis and trans octadecenols (Δ2–Δ6) are used to establish these relationships.1,4- and 1,5-Epoxides are also formed during the oxymercuration of methyl densipolate and methyl 12,13-dihydroxyoleate and during the hydroxymercuration of methyl octadeca-9,12 and 8,12-dienoates.     

Fatty acids,Part 35 the preparation and properties of the complete series of methyl epoxyoctadecanoates

The complete series of methyl epoxyoctadecanoates (31 isomers) has been made by epoxidation of the octadecenoates. The melting points of the acids are reported along with the chromatographic (TLC and GLC) and spectroscopic (NMR and MS) behaviour of the methyl esters.     

Fatty acids,Part 44 The preparation of some long-chain hydroperoxides and t-butyl peroxides

A number of long-chain hydroperoxides and t-butyl peroxides have been prepared — some of them for the first time — by the application of known procedures.     

Fatty acids. Part 13. The synthesis of all the cis n-octadecenoic acids

All the cis n-octadecenoic acids (Δ²–Δ¹⁷) have been synthesised along with several dodecenoic (Δ⁷–Δ¹¹), dodecynoic (Δ⁷–Δ¹¹), and octadecynoic (Δ², Δ⁴–Δ¹²) acids required as intermediat es.     

Fatty acids,Part 47 The mass spectra of bis(trimethylsilyloxy) and methoxy trimethylsilyloxy ethers derived from a series of methyl epoxyoctadecenoates and methyl epoxyoctadecynoates

Twenty-two methyl epoxyoctadecenoates and four methyl epoxyoctadecynoates were converted to bis(trimethylsilyloxy) and methoxy trimethylsilyloxy derivatives for mass spectroscopic examination at 17 eV. From the results the position of the ether groups (and hence of the epoxide functions) can be determined. Additionally it is possible to discover whether the unsaturated group lies between the ether groups and the ester function or between the ether groups and the terminal methyl and to differentiate those esters of the type -CH(OR)CH(OR)(CH₂)_nCH=CH- where n = 1 from those in which n > 1. The major fragmentation pathways are outlined.     

Fatty acids synthesized from hexadecane by Pseudomonas aeruginosa

Romero, Ethel M. (Universidad Nacional de la Plata, La Plata, Argentina), and Rodolfo M. Brenner. Fatty acids synthesized from hexadecane by Pseudomonas aeruginosa. J. Bacteriol. 91:183-188. 1966.-The lipids extracted from Pseudomonas aeruginosa incubated with hexadecane in a mineral medium were separated into a nonpolar and three polar fractions by thin-layer chromatography. The fatty acid composition of the four cellular fractions and that of the lipids excreted into the medium was studied by gas-liquid chromatography. Saturated fatty acids with 14 to 22 carbons were recognized, together with monoenoic, dienoic, and hydroxylated acids. Hydroxylated fatty acids were principally found in two polar fractions containing rhamnose and glucose; the other polar fraction, containing serine, alanine, ethanolamine, and leucine, was richer in monoenoic fatty acids. Octadecadienoic acid was found in the neutral fraction.     

Fatty acids,Part 46 PMR spectra of several epoxyoctadecenoic,epoxyoctadecynoic, and diepoxyoctadecanoic esters

The PMR spectra (220 MHz) of methyl epoxyoctadecenoates (22 isomers), methyl epoxyoctadecynoates (4 isomers), and methyl diepoxyoctadecanoates (11 isomers) are reported. Observed chemical shifts compare favourably with those calculated from deshielding effects along an alkyl chain which have recently been reported.     

Effect of bile acids on formation of the mutagen, quercetin, from two flavonol glycoside precursors by human gut bacterial preparations

Human fecal cultures, induced with either of the flavonols, quercitrin or rutin, were grown in the presence of various concentrations of chenodeoxycholic acid, deoxycholic acid or cholic acid. Cell-free preparations (fecal preparations) from these cultures were then incubated with rutin or quercitrin. The formation of the aglycone, quercetin, was monitored by the Ames assay using tester strain TA98. The presence of chenodeoxycholic or deoxycholic acids in the quercitrin-induced culture resulted in a fecal preparation which enhanced the mutagenesis of quercitrin approximately two-fold at optimal concentrations of 0.6 mM and 0.8 mM respectively. Higher concentrations of these bile acids decreased the activity of the fecal preparations. Cholic acid gave similar results except a much higher concentration (3.0 mM) was required to achieve this effect. Analogous results with rutin-induced cultures were less clear cut: considerable variation in bile acid effect was noted among volunteers. The authors propose that bile acid in the medium may enhance the ability of rutin- and quercitrin-glycosidase elaborating organisms to successfully compete with other microbial populations. Additionally, the greater variation in results using rutin as inducer may reflect more heterogeneous populations of organisms active against this substrate. The possible role of bile acids and flavonols in bowel cancer is discussed.     

Lipid biosynthesis in developing mustard seed: formation of triacylglycerols from endogenous and exogenous Fatty acids

Cotyledons of developing mustard (Sinapis alba L.) seed have been found to synthesize lipids containing the common plant fatty acids and very long-chain monounsaturated (icosenoic, erucic, and tetracosenic) and saturated (icosanoic, docosanoic, and tetracosanoic) fatty acids from various radioactive precursors. The in vivo pattern of labeling of acyl lipids, either from fatty acids synthesized `endogenously' from radioactive acetate or malonate, or from radioactive fatty acids added `exogenously', indicates the involvement of the following pathways in the biosynthesis of triacylglycerols. Palmitic, stearic, and oleic acid, synthesized in the acyl carrier protein-track, are channeled to the Coenzyme A (CoA)-track and converted to triacylglycerols via the glycerol-3-phosphate pathway. Pools of stearoyl-CoA and oleoyl-CoA are elongated to very long-chain saturated and monounsaturated acyl-CoA, respectively. Most of the very long-chain saturated acyl-CoAs acylate preformed diacylglycerols. Very long-chain monounsaturated acyl-CoAs are converted to triacylglycerols, partly via phosphatidic acids and diacylglycerols, and partly by acylation of preformed diacylglycerols.     

Biosynthesis of Fatty acids by a soluble extract from developing soybean cotyledons

Fractionation of developing soybean cotyledons into cellular components demonstrates that most of the activity necessary to incorporate acetate-1-¹⁴C into lipid remains in the supernatant from a 198,000g spin for 1 hr. The system studied is dependent upon ATP, CoA, and CO₂. Concentrations of ATP greater than 4 × 10⁻³m are inhibitory, while 1 × 10⁻⁴m CoA is needed for optimal activity. Avidin inhibition of acetate incorporation into lipid could be reversed by biotin. Studies indicated that NADPH is a better source of reducing power than NADH. The system studied is inhibited by p-chloromercuribenzoic acid and this inhibition can be reversed by an excess of GSH. The system studied shows maximum activity in tris buffer at pH 8.6 or in glycine buffer, pH 9.4.     

Fatty acid synthesis by spinach chloroplasts II. The path from PGA to fatty acids

By incorporation of ³H₂O into the fatty acid chain in the presenceof unlabeled precursor, we showed that fatty acids are synthesizedfrom PGA, PEP and pyruvate by intact spinach chloroplasts inthe light. ¹³C-tracer experiments confirmed that 1-C of pyruvateis decarboxylated and 2-C is incorporated into fatty acids bythe chloroplasts. The patterns of fatty acids synthesized fromPGA and pyruvate were the same as that from acetate. The highestrate of fatty acid synthesis was reached at the physiologicalconcentration of PGA (3 mM) and pyruvate (1 mM). These resultsindicate the operation of the following path in the chloroplastsin light: PGA-PEPPyruvateacetylCoAfatty acids. Since citrateand OAA were much less active and malate and glyoxylate wereinert as precursors for fatty acid synthesis, PEP or pyruvatecarboxylation, citrate lyase reaction and malate synthetasereaction are not involved in the formation of acetylCoA andfatty acids. Since pyruvate was much more effective as a substratefor fatty acid synthesis than lactate, acetaldehyde or acetate,direct, decarboxylation path is considered to be the primarypath from pyruvate to acetylCoA. The insignificant effect ofchloroplast-washing on fatty acid synthesis from PGA and pyruvateindicates that the glycolytic path from PGA to pyruvate is associatedwith the chloroplasts. Since pyruvate was more effectively incorporatedinto fatty acids than acetylCoA, it is unlikely that pyruvatedecarboxylation to acetylCoA is due to mitochondria contaminatingthe chloroplast preparation. On the basis of measurements of ³H₂O incorporation in the lightand dark, the activity of fatty acid synthesis in spinach leavesappears to be shared by the activities in chloroplasts (87%)and other organelles (13%). ¹ Present address: Radioisotope Centre, University of Tokyo,Yayoi, Bunkyo 113, Japan. (Received August 26, 1974; )     

Fatty acids of sponges from the Sea of Okhotsk

The fatty acid (FA) composition of Demospongiae species from the Sea of Okhotsk was studied. Fifteen sponge species were investigated for the first time, and the previously studied species Desmacella rosea and Myxilla incrustans were reexamined for their FA composition. Gas chromatography-mass spectrometry revealed 150 different fatty acids, of which 15 have not been identified in sponge lipids previously. The relative content of saturated FAs varied from 7.6 in Melonachora kobjakovae to 29.6% in Amphilectus digitata, with an average of 14.6% of total FAs. The relative content of monoenic FAs ranged from 12.8 in T. dirhaphis to 27.0% in Polymastia sp., with an average of 20.6% of total FAs. Non-methylen-interrupted, primarily unsaturated Δ5,9-FAs contributed a significantly to the amount of polyunsaturated fatty acids of sponges; this being a distinguishing feature of the FA composition of the investigated group of organisms.     

Fatty acids of lichen species from Tian Shan Mountains

Eight lichen species growing in the Tian Shan Moutains were investigated for their fatty acid composition using capillary GC-MS. Seventy-three fatty acids were identified: 24 saturated, 28 monoenoic, 5 dienoic, 11 trienoic and eight tetra-, penta- and hexaenoic. Very long-chain fatty acids,viz. 26:0, 26:1(11), 26:3(3), 27:1, 28:1 and 30:1 were also identified. For the first time 36 fatty acids were identified in these lichens.     

Fatty acids ofStreptomyces cinnamonensis,producer of monensin

Using the gas chromatography-mass spectrometry (GC-MS) method we found inStreptomyces cinnamonensis saturated fatty acids of iso-and anteiso-types, cyclopropyl acids, and unsaturated fatty acids where the double bond position was determined by MS of their pyrrolidine derivatives.     

Fatty acids,part XVI: The synthesis of all isomeric C18 furan-containing fatty acids

The synthesis of all isomeric C₁₈ furan-containing fatty acids from furan, furfural or methyl octadecadiynoate is described.