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1.
13-[18O] Hydroperoxylinolenic acid was permitted to react with an extract of flaxseed acetone powder containing hydroperoxide cyclase
activity. The resulting product, 12-oxo-cis-10,cis-15-phytodienoic acid (12-oxo-PDA), contained18O in the carbonyl oxygen at carbon 12, suggesting that an epoxide was an intermediate in the hyderoperoxide cyclase reaction.
A substrate specificity study showed that acis double bond β,γ to the conjugated hydroperoxide group was essential for the substrate to be converted to a cyclic product
by hydroperoxide cyclase. 相似文献
2.
Characterization of a prostaglandin-like metabolite of linolenic acid produced by a flaxseed extract
One of the products formed upon incubation of linolenic acid (cis9,12,15-octadecatrienoic acid) with an extract of flaxseed acetone powder has been characterized as 8-[2-(cis-pent-2′-enyl)-3-oxo-cis-cyclopent-4-enyl]octanoic acid. The cyclopentenone ring structure of this acid is analogous to that of the A-type prostaglandins
produced in mammalian systems. 相似文献
3.
The seed oil ofCuspidaria pterocarpa contains three keto fatty acids with unusually long carbon chains: 15-oxo-cis-18-tetracosenoic (5.4%), 17-oxo-cis-20-hexacosenoic (13.4%), and 19-oxo-cis-22-octacosenoic (3.3%) acids. These acids were isolated by countercurrent distribution of the corresponding methyl esters.
Their structures were established by oxidative degradation, by reduction to known compounds, and by nuclear magnetic resonance
and infrared spectra.
Presented at the AOCS Meeting, Los Angeles, April 1966.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
4.
Magdi M. Mossoba Martin P. Yurawecz John A. G. Roach Hubert S. Lin Richard E. McDonald Brent D. Flickinger Edward G. Perkins 《Journal of the American Oil Chemists' Society》1995,72(6):721-727
Gas chromatography (GC)-electron ionization mass spectrometry of 2-alkenyl-4,4-dimethyl-oxazoline derivatives was used to
confirm the identities of a complex mixture of C18 diunsaturated cyclic fatty acid monomers (CFAMs) that were isolated from heated flaxseed (linseed) oil. The positions of
double bonds and 1,2-disubstituted unsaturated 5- and 6-membered rings along the fatty acid hydrocarbon chains were established
by this method. The oxazoline spectra exhibited a homologous ion series with a pattern of peaks that were 14 u (u=atomic mass
unit) apart but interrupted when a double bond (12-u mass interval) or a ring was present along the fatty acid chain. The
identity and location of a ring were indicated by a large interval of 68, 82, 66, 80, 78, or 120 u for a saturated 5- or 6-membered
ring, monounsaturated 5- or 6-membered ring, diunsaturated 6-membered ring, or monounsaturated bicyclic ring system (fused
5- and 6-membered rings), respectively. The double bond configuration for the methyl ester derivatives of these CFAMs was
established by GC-matrix isolation-Fourier transform infrared spectroscopy. The elucidated alkenyl structures at C2 in diunsaturated 2-[alkenyl]-4,4-dimethyloxazolines were 8-(2-but-trans-1-enyl-cyclopentenyl)octyl, 9-(2-propyl-cyclopentenyl)non-rans-8-enyl, 9-(2-propyl-cyclopentenyl)non-cis-7-enyl, 8-(2-but-cis-1-enyl-cyclopentenyl)ocytl, 9-(2-propylcyclopentenyl)non-cis-8-enyl, 8-(2-propyl-cyclohex-cis-4-enyl)oct-trans-7-enyl, 8-(prop-trans-1-enyl-cyclohex-cis-4-enyl)ocytl, and 8-(2-propylcyclohexa-cis,cis-3,5-dienyl)octyl.
Physical science aide, 1991–1992; currently a medical student at the University of Maryland, Baltimore, MD. 相似文献
5.
Kenji Fukuzawa Katsuya Kishikawa Akira Tokumura Hiroaki Tsukatani Masayuki Shibuya 《Lipids》1985,20(12):854-861
The fluorescent products formed on reaction of 12-oxo-cis-9-octadecenoic acid (12-keto-oleic acid) with about 20 different amino acids, polylysine and bovine serum albumin (BSA) were
studied. Besides glycine, only the basic amino acids histidine, lysine and arginine gave products with strong fluorescence.
N-Acetylation of amino acids greatly reduced the fluorescence of their reaction products. The formation of fluorescent products
was inhibited strongly by SH-amino acids such as N-acetyl-cysteine and glutathione. Polyacrylamide gel electrophoresis showed
that BSA treated with 12-keto-oleic acid was more acidic than untreated or ricinoleic acid-treated BSA, indicating that basic
amino acid residues in BSA were modified by reaction with the keto fatty acid. None of the structural analogs of 12-keto-oleic
acid tested–12-oxo-trans-10-octadecenoic acid, 12-oxo-octadecanoic acid, 12-hydroxy-cis-9-octadecenoic acid (ricinoleic acid),cis-9-octadecenoic acid (oleic acid) and linoleic acid—reacted with glycine to give a fluorescent product. The fluorescent products
formed on reaction of 12-keto-oleic acid methyl ester with benzyl amine and glycine methyl ester were shown to be 8-(N-substituted-4,5-dihydro-4-oxo-5-hexyl-5-hydroxy-2-pyrrolyl)
octanoic acid methyl esters. The fluorescence properties of these compounds were attributed to the chromophobic system NC=CC=O
which contains 6π electrons. This investigation contributes to insight of the mechanism of formation of fluorescent pigments,
probably by a similar reaction of other compounds of the β,γ-unsaturated carbonyl type. 相似文献
6.
Dr. Shala Afaque Dr. M. H. Ansari Dr. M. S. Siddiqui 《European Journal of Lipid Science and Technology》1988,90(12):470-475
9-Oxo-cis-octadecenoic acid (I) when treated with an excess of hydrazoic acid in the presence of BF3-etherate as catalyst gave an isomeric mixture of amide derivative (III). On the other hand, 12-oxo-cis-9-octadecenoic acid (II) on the similar treatment afforded urea (IV) and isomeric amide (V) derivatives. 相似文献
7.
An isomeric mixture of linoleic acid hydroperoxides, 13-hydroperoxy-cis-9,trans-11-octadecadienoic acid (79%) and 9-hydroperoxy-cis-12,trans-10-octadecadienoic acid (21%), was decomposed homolytically by Fe(II) in an ethanol-water solution. In one series of experiments,
the hydroperoxides were decomposed by catalytic concentrations of Fe(II). The 10−5 M Fe(III) used to initiate the decomposition was kept reduced as Fe(II) by a high concentration of cysteine added to the
reaction in molar excess of the hydroperoxides. Nine different monomeric (no detectable dimeric) fatty acids were identified
from the reaction. Analyses of these fatty acids revealed that they were mixtures of positional isomers identified as follows:
(I) 13-oxo-trans,trans-(andcis,trans-) 9,11-octadecadienoic and 9-oxo-trans,trans- (andcis,trans-) 10,12-octadecadienoic acids; (II) 13-oxo-trans-9,10-epoxy-trans-11-octadecenoic and 9-oxo-trans-12, 13-epoxy-trans-10-octadecenoic acids; (III) 13-oxo-cis-9,10-epoxy-trans-11-octadecenoic and 9-oxo-cis-12, 13-epoxy-trans-10-octadecenoic acids; (IV) 13-hydroxy-9,11-octadecadienoic and 9-hydroxy-10,12-octadecadienoic acids; (V) 11-hydroxy-trans-12, 13-epoxy-cis-9-octadecenoic and 11-hydroxy-trans-9, 10-epoxy-cis-12-octadecenoic acids; (VI) 11-hydroxy-trans-12, 13-epoxy-trans-9-octadecenoic and 11-hydroxy-trans-9,10-epoxy-trans-12-octadecenoic acids; (VII) 13-oxo-9-hydroxy-trans-10-octadecenoic acids; (VIII) isomeric mixtures of 9, 12, 13-dihydroxyethoxy-trans-10-octadecenoic and 9, 10, 13-dihydroxyethoxy-trans-11-octadecenoic acids; and (IX) 9, 12, 13-trihydroxy-trans-10-octadecenoic and 9, 10, 13-trihydroxy-trans-11-octadecenoic acids. In another experiment, equimolar amounts of Fe(II) and hydroperoxide were reacted in the absence of
cysteine. A large proportion of dimeric fatty acids and a smaller amount of monomeric fatty acids resulted. The monomeric
fatty acids were examined by gas liquid chromatography-mass spectroscopy. Spectra indicated that the monomers were largely
similar to those produced by the Fe(III)-cysteine reaction.
Presented in part at the American Chemical Society Meeting, Los Angeles, March 1974.
ARS, USDA. 相似文献
8.
A reexamination of the flaxseed hydroperoxide isomerase reaction showed that a minor enzymic product (ca. 5%), identified
as a γ-ketol, was present. The substrates were the 13- or 9-hydroperoxides of linolenic acid, which were converted to 9-hydroxy-12-oxo-cis-15-trans-11-octadecadienoic acid, respectively. These compounds were formed in addition to the major products reported earlier: a
12,13-α-ketol and 12-oxo-cis-10,15-phytodienoic acid from the 13-isomer, and a 9,10-α-ketol from the 9-isomer. 相似文献
9.
12-Oxo-10,15(Z)-phytodienoic acid biosynthesized from 13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid using a preparation of corn (Zea mays L) hydroperoxide dehydrase recently was found to be a mixture of enantiomers in a ratio of 82∶18 (Hamberg, M., and Hughes,
M.A. (1988)Lipids 23, 469–475). In this work, 12-oxophytodienoic acid and (+)-7-iso-jasmonic acid were converted into a common derivative, methyl
3-hydroxy-2-pentyl-cyclopentane-1-octanoate. From gas liquid chromatographic analysis of the (−)-menthoxycarbonyl derivative
of methyl 3-hydroxy-2-pentyl-cyclopentane-1-octanoates prepared from 12-oxophytodienoic acid and (+)-7-iso-jasmonic acid,
it could be deduced that the major enantiomer of 12-oxophytodienoic acid had the 9(S),13(S) configuration. Therefore, in the major enantiomer of 12-oxophytodienoic acid, the configurations of the side chainbearing
carbons are identical to the configurations of the corresponding carbons of (+)-7-iso-jasmonic acid, thus giving support to
previous studies indicating that 12-oxophytodienoic acid serves as the precursor of (+)-7-iso-jasmonic acid in plant tissue.
When absolute configurations of C-9 and C-13 are not specifically indicated, phytonoic acid is used to denote 2-pentyl-cyclopentane-1-octanoic
acid in which the two side chains have thecis relationship, whereas phytonoic acid (trans isomer) denotes 2-pentyl-cyclopentane-1-octanoic acid in which the two side chains have thetrans relationship. 相似文献
10.
Henry Rakoff 《Lipids》1988,23(4):280-285
Methylcis-9,cis-12,cis-15-octadecatrienoate-15,16-d
2 was obtained from Wittig coupling of methyl 12-oxo-cis-9-dodecenoate,18, and 3,4-dideutero-cis-3-hexenyltriphenylphosphonium bromide,16. Compound18 was obtained by periodic acid oxidation of methyl 12,13-dihydroxy-cis-9-octadecenoate,17, obtained fromVernonia oil. Compound18 also was synthesized from methyl oleate as the starting material. The deuterated fragment,16, was prepared from 3-hexynol and using Lindlar's catalyst and deuterium gas to introduce the deuterium atoms.
Methylcis-9,cis-12,cis-15-octadecatrienoate-6,6,7,7-d
4 was prepared by Wittig coupling of 3,6-nonadienyltriphenylphosphonium iodide,5, with methyl 9-oxononanoate-6,6,7,7-d
4,11. Deuterium atoms were introduced during the synthesis of11 from 3-butynol and 5-bromopentanoic acid with deuterium gas in the presence of [Ph3P]3-RhCl. For the preparation of5, the 3,6-nonadiynol intermediate was reduced to 3,6-nonadienol with P-2 Nickel and hydrogen.
The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography. 相似文献
11.
Incubations of the 13- and 9-hydroperoxides of linolenic acid with a flax acetone powder extract containing hydroperoxide
isomerase resulted in the formation of 13-hydroxy-12-oxo-cis-9,15-octadecadienoic acid and 9-hydroxy-10-oxo-cis-12,15-octadecadienoic acid, respectively. The rate of formation of product from 13-hydroperoxy linolenic acid was 36 times
that from 9-hydroperoxy linolenic acid. Analogous results were obtained with the 13- and 9-hydroperoxides of linoleic acid.
The results demonstrated the substrate specificity of flax hydroperoxide isomerase. 相似文献
12.
Robert L. Wolff Mohamed Nour Corinne C. Bayard 《Journal of the American Oil Chemists' Society》1996,73(3):327-332
To understand thecis-trans isomerization reaction of ethylenic bonds in heated octadecatrienoic acids (occurring during industrial deodorization of
oils), we have prepared a mixture ofcis-9,cis-12,cis-15, andcis-9,cis-15 18:2 acids by partial hydrazine reduction ofcis-9,cis-12,cis-15 18:3 acid present in linseed oil. This mixture (as fatty acid methyl esters) was heated under vacuum at 270°C for 2.25
h. The two methylene-interrupted acids isomerize at a similar rate under such conditions, but the nonmethylene-interruptedcis-9,cis-15 18:2 acid remains unchanged. This means that the mechanism of isomerization does not involve a direct interaction between
the two external ethylenic bonds as previously hypothesized. The centralcis-12 ethylenic bond is apparently necessary for the isomerization of the two externalcis-9 andcis-15 ethylenic bonds. However, this bond is itself rather protected against isomerization in the originalcis-9,cis-12,cis-15 18:3 acid which is mainly isomerized totrans-9,cis-12,trans-15,cis-9,cis-12,trans-15, andtrans-9,cis-12,cis-15 18:3 acids. Thecis-9,trans-12,cis-15 18:3 isomer is less than 10% of totaltrans isomers of α-linolenic acid. As a general rule, only one of the two double bonds in a methylene-interrupted diethylenic system
can undergocis-trans isomerization when submitted to heat treatment, at least for temperatures equal to or less than 270°C. 相似文献
13.
Tsung Min Kuo Terry A. Isbell Alejandro Rooney William E. Levinson Hans Frykman 《Journal of the American Oil Chemists' Society》2007,84(7):639-643
The objective of this study was to explore the extent of microbial conversion of lesquerolic acid (14-hydroxy-cis-11-eicosenoic acid; LQA) by whole cell catalysis and to identify the newly converted products. Among compost isolates including
NRRL strains B-23212 (Sphingobacterium multivorum), B-23213 (Acinetobacter sp.), B-23257 (Enterobacter cloacae B), B-23259 (Escherichia sp.) and B-23260 (Pseudomonas aeruginosa) the S.
multivorum strain was the only microorganism that converted LQA to produce a new product identified as 14-oxo-cis-11-eicosenoic acid by GC-MS and NMR analyses. The conversion yield was 47.4% in 48 h at 200 rpm and 28°C in small shake flask
experiments. In comparison, both Acinetobacter and Pseudomonas strains failed to convert LQA to major new products but used LQA apparently as an energy source during fermentation. For
structural analysis, 6.88 g of 14-oxo-cis-11-eicosenoic acid was produced from converting 11 g LQA (a 62% yield) in 72 h at 200 rpm and 28 °C in Fernbach flasks using
18-h-old NRRL B-23212 cultures and an improved medium that also contained EDTA and glycerol in lieu of glucose as carbon source.
NRRL B-23212 was further identified by 16S rRNA gene sequence analysis as a unique strain of S. multivorum. Therefore, S. multivorum NRRL B-23212 possesses an enzymatic activity presumably a secondary alcohol dehydrogenase for converting LQA to produce 14-oxo-cis-11-eicosenoic acid, a first report that demonstrates the functional modification of LQA by whole cell catalysis. 相似文献
14.
J. L. Sebedio J. L. LeQuere O. Morin J. M. Vatele A Grandgirard 《Journal of the American Oil Chemists' Society》1989,66(5):704-709
Fractions of cyclic fatty acid monomers (CFAM) were isolated from linseed oil heated at 275°C for 12 hr under nitrogen, at
240°C for 10 hr under nitrogen and at 240°C for 10 hr under air. Cyclic fatty acid monomers fractions were also isolated from
a sunflower oil heated at 275°C for 12 hr under nitrogen and at 200°C for 48 hr in a commercial fryer. The CFAM fractions
were hydrogenated and their composition studied by gas liquid chromatography coupled with mass spectrometry (GC-MS). The CFAM
in the fraction isolated from heated linseed oil samples were a mixture (1:1) ofcis andtrans cyclopentyl and cyclohexyl isomers, while the CFAM in the fractions isolated from heated sunflower oils were mostly cyclopentyl
isomers. The major cyclopentyl isomers weretrans andcis methyl 7-(2′-hexylcyclopentyl) -heptanoate, methyl 9-(2′-butyl-cyclopentyl)-nonanoate and methyl 10-(2′-propylcyclo-pentyl)-decanoate.
The major cyclohexyl isomers were thetrans andcis methyl 9-(2′-propylcyclohexyl)-nonanoate which represented about 50% of the CFAM isomers isolated from heated linseed oil
samples.
For part II in this series see Ref. 1. 相似文献
15.
Robert L. Wolff Jean-Louis Sébédio 《Journal of the American Oil Chemists' Society》1994,71(2):117-126
Heating of borage oil, either under vacuum as a model or during steam-vacuum deodorization, produces artifacts that are geometrical
isomers of γ-linolenic acid (cis-6,cis-9,cis-12 18∶3 acid). In a first approach, we have studied the behavior of these fatty acids in the form of either methyl or isopropyl
esters on two capillary columns (CP-Sil 88 and DB-Wax). From this study, it appears that the DB-Wax capillary column is the
best suited analytical tool to study in some detail γ-linolenic acid geometrical isomers. In a second approach, the structure
of these isomers was formally established by combining several analytical techniques: Argentation thin-layer chromatography,
comparison of the equivalent chainlengths with those of isomers present in NO2-isomerized borage oil on two different capillary columns, partial hydrazine reduction, oxidative ozonolysis, gas chromatography
coupled with mass spectrometry and gas chromatography coupled with Fourier transform infrared spectroscopy. The two main isomers
that accumulate upon heat treatments are thetrans-6,cis-9,cis-12 andcis-6,cis-9,trans-12 18∶3 acids with minor amounts ofcis-6,trans-9,cis-12 18∶3 acid. One di-trans isomer, supposed to be thetrans-6,cis-9,trans-12 18∶3 acid, is present in low although noticeable amounts in some of the heated oils. The content of these artificial fatty
acids increases with increasing temperatures and duration of heating. The degree of isomerization (DI) of γ-linolenic acid
is less than 1% when the oil is deodorized at 200°C for 2 h. Heating at 260°C for 5 h increases the DI up to 74%. Isomerization
of γ-linolenic acid resembles that of α-linolenic (cis-9,cis-12,cis-15 18∶3) acid in several aspects: The same kinds and numbers of isomers are formed, and similar degrees of isomerization
are reached when the octadecatrienoic acids are heated under identical conditions. It seems that the reactivity of a double-bondvis-à-vis cis-trans isomerization is linked to its relative position, central or external, and not to its absolute position (Δ6, 9, 12 or 15). 相似文献
16.
Positional isomers ofcis-methyleneoctadecanoic acid differed greatly in their efficiency for growth of an unsaturated fatty acid auxotroph ofEscherichia coli upon glucose as a carbon source. The 8, 9, and 11 isomers were more efficient in producing cells (60–70 cells/fmole) than
the others (0–7 cells/fmole), although all isomers were found esterified to a similar extent into cellular lipid. WithSaccharomyces cerevisiae mutants, all isomers between 6 and 12 supported some growth of the eukaryotic cells, and the 7 and 9 isomers were slightly
more efficient than the 8-isomer. WhenE. coli were grown with glycerol, all isomers from 5 to 14 supported growth, and those with the substituent near the center of the
acyl chain had the greatest efficiency (70 cells/fmole). With the glycerol medium, the pattern of efficiencies for the variouscis-methylene acyl chains resembled the broad selectivity reported earlier for thecis-ethylenic isomers in glucose medium, which agreed closely with predictions based upon the physical property of their phospholipid
derivatives. Thus, metabolism of glycerol appeared to allow the cyclopropane acyl chains to support cell functions to the
limits expected for bulk phase chain-chain fluidity considerations. This broad specificity was also obtained when cells were
grown on glucose with cyclic AMP added to the culture. Therefore, the selective inadequacies of the 5, 6, 7, 10, 12 and 13
isomers in supporting cell growth on glucose may occur through an interaction modified by cAMP and dependent upon reduced
cellular levels of cyclic AMP. The highly selective pattern of efficiency of thecis-methylene acids forE. coli growth on glucose resembles that with the acetylenic acids, but was shifted one carbon atom toward the methyl terminus. This
observed selectivity pattern seems due to interactions of the individual acyl chains with cellular protein(s) rather than
to chain-chain interactions in a bulk phase. The ability of certain positional isomers to support cell function equally well
in both nutrient conditions suggests that the role of those acyl chain isomers may be independent of metabolite flux or cyclic
nucleotide contents of the cell, whereas the actions of other isomeric fatty acids seem closely related to the metabolic status
of the cell. A highly selective role for different fatty acids in modulating cellular function seems possible on the basis
of the current evidence. 相似文献
17.
A novel 1-pyrroline fatty acid ester isomer [viz. 8-(5-hexyl-1-pyrrolin-2-yl)octanoate] has been synthesized from methyl ricinoleate by two routes with an overall yield of
42 and 30%, respectively. Most of the reactions are carried out under concomitant ultrasonic irradiation (20 KHz,ca. 53 watts/cm2). Under such a reaction condition, the reaction time is considerably shortened, and product yields are high. Dehydrobromination
under concomitant ultrasonic irradiation of methyl 9,10-dibromo-12-hydroxyoctadecanoate with KOH in EtOH furnishes methyl
12-hydroxy-9-octadecynoate (66%) within 15 min. Hydration of the latter under ultrasound with mercury(II)acetate in aqueous
tetrahydrofuran yields exclusively methyl 12-hydroxy-9-oxo-octadecanoate (95%) in 30 min. The hydroxy group in the latter
compound is transformed to the azido functionvia the mesylate, and treatment of the azido-oxo intermediate (methyl 12-azido-9-oxooctadecanoate) with Ph3P under ultrasonic irradiation furnishes the requisite 1-pyrroline fatty acid ester (77%). The same azido-oxo intermediate
has also been obtained by the oxidation of methyl 12-azido-9-cis-octadecenoate using benzoquinone and a catalytic amount of Pd(II)chloride in aqueous tetrahydrofuran under concomitant ultrasonic
irradiation (90 min) to give the product in 45% yield. The latter reaction does not take place even under prolonged silent
stirring of the reaction mixture. 相似文献
18.
Jamal Mustafa M. S. Ahmad A. Rauf S. M. Osman 《Journal of the American Oil Chemists' Society》1984,61(3):555-558
Methyl 4-oxo-trans-2-octadecenoate (II), when treated with excess hydrazoic acid in the presence of BF3-etherate, produced 66% methyl 5-aza-nonadec-trans-2-enoate (4,5-d)-tetrazole (III), 10% methyl 5-aza-nonadec-4-oxo-trans-2-enoate (IV) and 7% pentadecamide (V). Individual products were characterized by spectral and elemental methods. 相似文献
19.
Linoleic acid was heated at 200°C under helium. Analysis of degradation products by GC on a long polar open tubular capillary
column showed the presence of CLA isomers. The identified mono trans CLA isomers were cis-9, trans-11, trans-9, cis-11, trans-10, cis-12, cis-10, trans-12, trans-8, cis-10, and cis-11, trans-13 18:2 acids. Oils containing different levels of linoleic acid (peanut, sesame seed, and safflower seed oils) were also
heat treated, resulting in similar CLA distributions. Elution order was confirmed using cis-9, trans-11 and trans-10, cis-12 acid methyl esters standards and their respective configuration isomers (trans-9, cis-11, cis-10, trans-12), obtained after mild selenium-catalyzed isomerization. These results indicated that two conjugated mono trans isomers of 18:2 acid, cis-8, trans-10 and trans-11, cis-13 18:2 were absent from the series, thus strongly suggesting that some constraints were preventing their formation. By heating
pure methyl rumenate (cis-9, trans-11 18:2) under similar conditions, isomerization resulted principally in a nearly equimolar mixture of methyl rumenate and
trans-8, cis-10 18:2. Similarly, the methyl ester of trans-10, cis-12 18:2 acid was partially transformed into cis-11, trans-13 18:2 acid. Respective geometrical isomers were also formed in trace amounts. A concerted pericyclic isomerization mechanism,
a [1,5] sigmatropic rearrangement, is proposed that limits the conjugated system to isomerization from a cis-trans acid to a trans-cis acid, and vice versa. This mechanism is consistent with undetected cis-8, trans-10 and trans-11, cis-13 18:2 isomers in heated oils containing linoleic acid. 相似文献
20.
Nstor M. Carballeira Aikomari Guzmn Jordan T. Nechev Kantcho Lahtchev Albena Ivanova Kamen Stefanov 《Lipids》2000,35(12):1371-1376
The lipid composition of a Bacillus sp., isolated from Lake Pomorie in Bulgaria, was unusual and consisted of 26 different fatty acids between C12 and C26, with anteiso C15−C17 saturated fatty acids predominating. The furan fatty acid, 10,13-epoxy-11-methyloctadeca-10,12-dienoic acid, was also identified,
a new finding for this genus. The hydrocarbons consisted of 30 different monounsaturated hydrocarbons, between C25 and C30, with the iso-iso, iso-anteiso, anteiso-anteiso, iso-normal, and anteiso-normal methyl branching for odd-numbered chains,
and the iso-iso, iso-anteiso, iso-normal, and anteiso-normal methyl branching for even-numbered chains. The double bond positions
in these hydrocarbons were determined by dimethyl disulfide derivatization followed by GC-MS, and the double-bond cis configuration was confirmed by infrared spectroscopy. Some previously unknown hydrocarbons in bacteria, such as (Z)-3,21-dimethyl-9-tricosene,
(Z)-3,21-dimethyl-10-tricosene, (Z)-2,24-dimethyl-11-pentacosene, and (Z)-2,25-dimethyl-13-hexacosene were identified. Sterols
were detected and were based on the sitosterol nucleus. 相似文献