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1.
The mixture of diene hydroperoxides from methylene blue-sensitized oxidation of methyl linoleate was reduced with NaBH4 and the resulting alcohols were separated by high pressure liquid chromatography (HPLC). Four diene alcohols were isolated
in approximately equal yields from adsorption and reversed phase HPLC; the isomers were identified as methyl esters of 9-hydroxy-10,12-,
10-hydroxy-8,12-, 12-hydroxy-9,13- and 13-hydroxy-9,11-octadecadienoate. Formation of equal yields of both conjugated and
nonconjugated diene alcohols from methyl linoleate is characteristic of singlet oxygen oxidations. The detection of the easily
separated nonconjugated isomer methyl 10-hydroxy-trans-8,cis-12-octadecadienoate from methyl linoleate is proposed as a test to probe the involvement of singlet oxygen in biological
oxidations.
A preliminary report of these results was presented at the 177th meeting of the American Chemical Society, Honolulu, HI, April
1–6, 1979; see abstracts of papers, paper No. ORGN-375. 相似文献
2.
Bernard Freedman 《Journal of the American Oil Chemists' Society》1967,44(2):113-116
Transformations of hydroxy to keto fatty esters have been monitored successfully by converting the hydroxy compounds to their
trifluoroacetyl (TFA) or trimethylsilyl (TMS) derivatives followed by gas-liquid chromatography (GLC). The TFA derivatives
have shorter retention times, are better separated from the keto esters, and permit more complete resolution of saturated
and unsaturated hydroxy fatty esters than the TMS derivatives. Improved methods for derivative preparation which are rapid
and convenient are described. Methyl dimorphecolate (methyl 9-hydroxy-trans,trans,10,12-octadecadienoate), which is thermally unstable and cannot be chromatographed as the trifluoroacetate or free hydroxy
compound, was chromatographed satisfactorily as the trimethylsilyl ether.
Presented at the AOCS Meeting in Philadelphia, October 1966.
W. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
3.
E. Fehling S. Schönwiese E. Klein K. D. Mukherjee N. Weber 《Journal of the American Oil Chemists' Society》1998,75(12):1757-1760
A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling
(6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in
the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation.
Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in
particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C18 reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97
and 95–98%, respectively. 相似文献
4.
A simple method of preparation of methyl trans-10,cis-12- and cis-9,trans-11-octadecadienoates from methyl linoleate 总被引:2,自引:0,他引:2
O. Berdeaux L. Voinot E. Angioni P. Juanéda J. L. Sébédio 《Journal of the American Oil Chemists' Society》1998,75(12):1749-1755
Pure conjugated isomers of linoleic acid were prepared on a large scale by alkali-isomerization of purified methyl linoleate.
The methyl esters of alkali-isomerized linoleic acid contained mainly the methyl cis-9,trans-11- and trans-10,cis-12-octadecadienoates (44 and 47%, respectively). These two isomers were then separated and purified by a series of low-temperature
crystallizations from acetone. The isomeric purity obtained for the cis-9,trans-11-octadecadienoate isomer was >90% and that of the trans-10,cis-12-octadecadienoate isomer was 89 to 97%. The isolated yield of the two isomers corresponded to 18 and 25.7%, respectively,
of the starting material. The structure of the two isomers was confirmed using partial hydrazine reduction, silver nitrate-thin-layer
chromatography of the resulting monoenes and gas chromatography coupled with mass spectrometry of the 4,4-dimethyloxazoline
derivatives. Fourier transform infrared spectroscopy of the monoenes gave the confirmation of the geometry of each double
bond. 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.
The NMR spectra of olefinic protons in the four representative conjugated fatty acid methyl esters, methylcis-9,trans-11-octadecadienoate, methyltrans-9,trans-11-octadecadienoate, methyl α eleostearate, and methyl β eleostearate, were studied. The chemical shift of each olefinic
proton in these compounds was determined by considering their intramolecular environment. Coupling constants were also obtained
as the results of spectral analysis. 相似文献
7.
O. Berdeaux W. W. Christie F. D. Gunstone J. -L. Sebedio 《Journal of the American Oil Chemists' Society》1997,74(8):1011-1015
The conjugated linoleic acid methyl cis-9,trans-11-octadecadienoate has been prepared on a large scale from methyl ricinoleate. Methyl ricinoleate was purified from castor
esters by a partition method. It was converted to the mesylate, which was reacted with a base (1,8-diazabicyclo[5,4,0]-undec-7-ene)
to give a product that contained 66% of the desired ester. Two urea crystallizations produced a product containing 83% methyl
cis-9,trans-11-octadecadienoate, the identity of which was confirmed by gas chromatography linked to mass spectrometry and by Fourier
transform infrared spectroscopy. The remaining impurities were methyl cis-9,cis-11- and cis-9-,trans-12-octadecadienoate. 相似文献
8.
Kenneth D. Carlson Robert Kleiman Marvin O. Bagby 《Journal of the American Oil Chemists' Society》1994,71(2):175-182
Lesquerella gordonii (Gray) Wats andLimnanthes alba Benth. (Meadowfoam) are species being studied as new and alternative crops. Triglyceride oil from lesquerella contains 55–60%
of the uncommon 14-hydroxy-cis-11-eicosenoic acid. Meadowfoam oil has 95% uncommon acids, includingca. 60%cis-5-eicosenoic acid. Both oils are predominantly unsaturated (3% saturated acids), and have similar iodine values (90–91),
from which oxirane values of 5.7% are possible for the fully epoxidized oils. Each oil was epoxidized withm-chloro-peroxybenzoic acid, and oxirane values were 5.0% (lesquerella) and 5.2% (meadowfoam). The epoxy acid composition of
each product was examined by gas chromatography of the methyl esters, which showed that epoxidizedL. gordonii oil contained 55% 11,12-epoxy-14-hydroxyeicosanoic acid, and epoxidized meadowfoam oil contained 63% 5,6-epoxyeicosanoic
acid, as expected for normal complete epoxidation. Mass spectrometry of trimethylsilyloxy derivatives of polyols, prepared
from the epoxidized esters, confirmed the identity of the epoxidation products and the straightforward nature of the epoxidation
process. Synthesis and characterization of these interesting epoxy oils and derivatives are discussed. 相似文献
9.
E. A. Emken J. C. Hartman C. R. Turner 《Journal of the American Oil Chemists' Society》1978,55(7):561-563
A column packed with silver-saturated ion exchange resin (Amberlyst XN 1010) was found to have lipid separation capabilities
superior to Amberlyst XN 1005 and similar to Amberlite XE 284. The separation of unsaturated fatty methyl ester isomers by
silver resin chromatography using methanol as the eluting solvent has been extended to mixtures containing polyunsaturate
and acetylenic fatty esters. Separations are possible on the basis of both total number of double bonds and the geometric
configuration. Mixtures containing saturates, elaidate, oleate, linoleate, and linolenate can be separated, but 10% 1-hexene
must be added to the methanol to elute the linolenate. Mixtures containingtrans,trans-;trans,cis-; andcis,cis-octadecadienoate isomers have also been separated, and partial resolution ofcis-9,cis-12- andcis-2,cis-15-octadecadienoate isomers was obtained. Sterolate, a monounsaturated acetylenic fatty ester was eluted at the same time
as oleate. Crepenynate (cis-9-octadecen-12-ynoate) can be separated from linoleate but not fromcis,trans-octadecadienoate.
Employed at the Northern Regional Research Center under a USDA cooperative education program with Purdue University. 相似文献
10.
K. D. Carlson A. Chaudhry R. E. Peterson M. O. Bagby 《Journal of the American Oil Chemists' Society》1990,67(8):495-498
To conduct product development research onLesquerella seed oils, we explored methods to obtain >100 g quantities of lesquerolic (14-hydroxy-cis-11-eicosenoic) acid. Preliminary experiments with open-column silica gel chromatography showed thatL. fendleri oil could be separated into 3 triglyceride (TG) fractions. The first (10%) contained nonhydroxy 16-(13%) and 18-carbon acids
(65% 18∶1,2,3). The second fraction (15%) contained monolesquerolins (39% lesquerolic acid). The major TG fraction (73%) was
mainly dilesquerolins (66% lesquerolic acid) showing that a hydroxy acid-enriched TG oil was obtainable by this procedure.
Silica gel chromatography easily separatedL. fendleri fatty acid methyl esters (FAME) into a hydroxy-free ester fraction (40–44%) consisting largely of 18∶1 (39%), 18∶2 (19%)
and 18∶3 (31%), and a hydroxy ester fraction (56–60%) that was largely methyl lesquerolate (94%) with small amounts of auricolate
(5%) (14-hydroxy-cis-11,cis-17-eicosadienoate) and traces of 18-carbon hydroxy esters. This process for isolating the hydroxy FAME ofLesquerella oil was scaled up 15-to 100-fold with a preparative high performance liquid chromatograph. Thirty-gram samples ofL. gordonii FAME were dissolved in eluting solvent, pumped onto the high performance liquid chromatography (HPLC) silica column and eluted
with 97∶3 hexane/ethyl acetate. In an 8-hr period, up to 200 g of methyl lesquerolate could be obtained with a purity >98%,
the only contaminants being methyl auricolate and methyl ricinoleate.
Presented at the AOCS meeting in Phoenix, AZ, May 1988.
The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of
Agriculture over other firms or similar products not mentioned. 相似文献
11.
L. J. Morris R. T. Holman K. Fontell 《Journal of the American Oil Chemists' Society》1960,37(7):323-327
Summary The interference of certain unsaturated hydroxy acids in the Durbetaki method of epoxide determination has been demonstrated.
The concentrations of these constituents were determined concurrently with those of epoxy components by measurement of the
near infrared spectra of samples before and after treatment with anhydrous ethereal hydrogen chloride. The individual hydroxy
esters were separated and isolated from samples of mixed esters by thinlayer chromatography. GLC of these esters resulted
in their alteration to conjugated trienoates and gave proof of their conjugated diene hydroxyl structure. Thin-layer chromatographic
and infrared studies verified theTrans-trans diene unsaturation of the acid fromDimorphotheca aurantiaca oil and showed that the other hydroxy compounds examined have acistrans diene system. These data suggest that the seed oils ofArtemisia absinthium, Calliandra eriophylla, Balanites aegyptica, Cosmos bipinnatus, and Helianthus annuus contain 9-hydroxy-trans-10-cis-12- and 13-hydroxy-cis-9-trans-11-octadecadienoic acids.
Supported by grants from The Hormel Foundation and the National Institutes of Health (Research Grant No. H-3559), and presented
in part at the 33rd fall meeting, American Oil Chemists’ Society, Los Angeles, Calif., September 28–30, 1959.
Fulbright Scholar to the Hormel Institute, 1958–1960. 相似文献
12.
Methyl esters from seed oils of four Chenopodiaceae species are unusual in that they contain methylcis-5-hexadecenoate (4.6–12%) and methyl 5-octadecenoate (1.1–1.2%). There are indications of small amounts of 18∶25,9 and 18∶35, 9, 12 along with unsaturated acids commonly found in seed oils-oleic (14–21%), linoleic (53–57%) and linolenic (3.5–7.8%). Fatty
acid composition of the oils was determined by gas chromatography, and positions of the double bonds were established by application
of gas chromatography-mass spectrometry to the methoxylated methyl esters.
N. Market. Nutr. Res. Div., ARS, USDA. 相似文献
13.
Many studies have been published on the effect of antioxidants on unsaturated fatty acid esters but the differences of the
effects of antioxidants on geometric isomers have never been investigated. In this study, methylcis-9,cis-12-octadecadienoate and itstrans isomer methyltrans-9,trans-12-octadecadienoate were used as methyl nonconjugated dienoates, and BHA, BHT, PG, NDGA, 4,4′-dihydroxy-3,5,3′,5′-tetratert-butyl
diphenyl methane, L-thyroxine sodium salt,a-tocopherol and sesamol were used, as antioxidants. The differences of the effects of antioxidants on both geometric isomers
were investigated by determining the induction period using the weighing method. Also determined were the infrared and ultraviolet
spectra, peroxide values, conjugated diene contents, isolatedtrans double bond contents and molecular weights for the controls and the samples containing antioxidants. Thecis,cis isomer was more easily autoxidized and had a shorter induction period than thetrans,trans form. By the end of the induction period, no isolatedtrans double bond forms in thecis,cis isomer, but a considerable amount of isolatedtrans double bond decreased in thetrans,trans isomer. In general, the effects of antioxidants, except NDGA, on thecis,cis isomer were larger than thetrans,trans form. 相似文献
14.
The gas chromatography-mass spectrometry (GC-MS) method developed in preceding papers was extended to the structural analysis
of autoxidation products of methylcis-9,cis-15-octadecadienoate and of an 87% concentrate ofcis-12,cis-15-octadecadienoate. Eight isomeric hydroxydienes with one allylic and one isolated double bond were identified from oxidized
9,15-diene and 2 conjugated hydroxydienes from oxidized 12,15-diene, after reduction of the hydroperoxides. The proportions
of 16-(15%) and 17-hydroperoxides (22%) from 9,15-diene were significantly higher than that of the other isomers (8–12% each:
8-, 9-, 10-, 11-, 14- and 15-OOH). Similarly, the amount of 16-hydroperoxide from 12,15-diene was larger (42%) than the 12-hydroperoxide
(31%). Substantial amounts of dihydroxy esters with one OH substituent on carbons-8,-9,-10 or-11 and the other OH on carbons-14,-16
or-17, were identified after hydrogenation in highly oxidized 9,15-diene. The implications of these hydroperoxide analyses
are discussed in relationship to the precursors of flavor deterioration of oils and partially hydrogenated oils containing
an ω-3 double bond. 相似文献
15.
Theerythro andthreo isomers of methyl 9,10-dihydroxyoctadecanoate and thethreo isomer of methyl 12,13-dihydroxy-cis-9-octadecenoate were converted into methylcis- andtrans-9-octadecenoate and methylcis-9,rans-12-octadecadienoate, respectively, by reaction of the dihydroxy ester with triethyl orthoformate to give the 2-ethoxy-1,3-dioxolane
which was thermally decomposed to the unsaturated ester. 相似文献
16.
Column chromatography on silver ion-saturated Amberlyst XN 1010 cation exchange resin gave very good separation of a mixture
of methyl 12-hydroxy-cis-andtrans-9-octadecenoates and of methylthreo-12, 13-dihydroxy-cis- andtrans-9-octadecenoates. Comparison of the retention volumes of nonhydroxy, monohydroxy, and dihydroxy saturated and monoenoic methyl
esters and of dienoic methyl esters shows that the hydroxy group interacts with the column packing to slow passage of the
compound through the column, although the effect of a hydroxy group is less than that of atrans double bond. The effects of the hydroxy groups are additive; the ratio of retention volumes of dihydroxy ester to monohydroxy
ester is slightly larger that that of monohydroxy ester to nonhydroxy ester. The retention volume of a cis monoenoic ester
is equal to that of a hydroxytrans monoenoic ester and that of a hydroxycis monoenoic ester is equal to that of a dihydroxytrans monoenoic ester. 相似文献
17.
The proportion of geometrical hydroperoxide isomers generated by aerobic oxidation of methyl linoleate (18∶2 Me) in either
aqueous emulsion consisting of Tris-HCl buffer (pH 7.4) or in a homogeneous dichloromethane solution was determined to understand
the mechanism of lipid oxidation in different reaction systems. Four geometrical isomers were generated after oxidation of
18∶2 Me in dichloromethane: methyl 13-hydroperoxy-cis-9,trans-11-octadecadienoate, methyl 13-hydroperoxy-trans-9,trans-11-octadecadienoate, methyl 9-hydroperoxy-trans-10,cis-12-octadecadienoate, and methyl 9-hydroperoxy-trans-10,trans-12-octadecadienoate in the ratios of 1∶4∶1∶4, respectively. The ratios between each isomer did not change until the peroxide
value (PV) increased to 58 meq/kg. Oxidation of 18∶2 Me in aqueous emulsion yielded the same geometrical isomers of hydroperoxide.
However, the ratios were different: 3∶2∶3∶2 until the PV increased to 110 meq/kg. Predominant (60%) formation of trans,trans hydroperoxide isomers was obtained in the oxidation of a mixture of 18∶2 Me and methyl laurate (12∶0 Me). These results are
interpreted to reflect the importance of the concentration of hydrogen atom-donating equivalents to the kinetic preference
for different products. The high effective concentration of hydrogen donors in the oxidation of 18∶2 Me in emulsions favored
the formation of the less stable cis,trans isomers. The lower concentration of hydrogen donor in the dichloromethane solution effectively slowed hydrogen donation and
led to the strong preference for the more stable trans,trans isomers. This interpretation was further tested by preparing emulsions of 18∶2 Me and 12∶0 Me to dilute concentration of
hydrogen-donating species using the nonhydrogen-donating 12∶0 Me. Consistent with the proposed hypothesis, the proportion
of trans,trans isomers increased as a result of 12∶0 Me addition. 相似文献
18.
Methyl 9,12-epoxy-10-phenyl-9,11-octadecadienoate was prepared by acid catalyzed cyclization of methyl 9,12-dioxo-10-phenyloctadecanoate,
which was derived from the oxidation of methyl 9-hydroxy-12-oxo-10-phenyloctadecanoate. The latter was exclusively obtained
from methylcis-9,10-epoxy-12-oxooctadecanoate with phenyllithium in the presence of copper (I) bromide. A mixture of positional isomers,
methyl 9,12-epoxy-10(11)-phenyl-9,11-octadecadienoates, was also prepared by another route. The spectroscopic properties of
the various intermediates and products were studied. The positional isomers of the phenyl substituted furanoid fatty esters
were characterized by13C nuclear magnetic resonance spectrometry. 相似文献
19.
Lipase-catalyzed fractionation of conjugated linoleic acid isomers 总被引:14,自引:0,他引:14
Haas MJ Kramer JK McNeill G Scott K Foglia TA Sehat N Fritsche J Mossoba MM Yurawecz MP 《Lipids》1999,34(9):979-987
The abilities of lipases produced by the fungus Geotrichum candidum to selectively fractionate mixtures of conjugated linoleic acid (CLA) isomers during esterification of mixed CLA free fatty
acids and during hydrolysis of mixed CLA methyl esters were examined. The enzymes were highly selective for cis-9,trans-11–18∶2. A commercial CLA methyl ester preparation, containing at least 12 species representing four positional CLA isomers,
was incubated in aqueous solution with either a commercial G. candidum lipase preparation (Amano GC-4) or lipase produced from a cloned high-selectivity G. candidum lipase B gene. In both instances selective hydrolysis of the cis-9,trans-11–18∶2 methyl ester occurred, with negligible hydrolysis of other CLA isomers. The content of cis-9,trans-11–18∶2 in the resulting free fatty acid fraction was between 94 (lipase B reaction) and 77% (GC-4 reaction). The commercial
CLA mixture contained only trace amounts of trans-9,cis-11–18∶2, and there was no evidence that this isomer was hydrolyzed by the enzyme. Analogous results were obtained with these
enzymes in the esterification in organic solvent of a commercial preparation of CLA free fatty acids containing at least 12
CLA isomers. In this case, G. candidum lipase B generated a methyl ester fraction that contained >98% cis-9,trans-11–18∶2. Geotrichum candidum lipases B and GC-4 also demonstrated high selectivity in the esterification of CLA with ethanol, generating ethyl ester fractions
containing 96 and 80%, respectively, of the cis-9,trans-11 isomer. In a second set of experiments, CLA synthesized from pure linoleic acid, composed essentially of two isomers,
cis-9,trans-11 and trans-10,cis-12, was utilized. This was subjected to esterification with octanol in an aqueous reaction system using Amano GC-4 lipase
as catalyst. The resulting ester fraction contained up to 97% of the cis-9,trans-11 isomer. After adjustment of the reaction conditions, a concentration of 85% trans-10,cis-12–18∶2 could be obtained in the unreacted free fatty acid fraction. These lipase-catalyzed reactions provide a means for
the preparative-scale production of high-purity cis-9,trans-11–18∶2, and a corresponding CLA fraction depleted of this isomer. 相似文献
20.
The rate of addition of hydrogen sulfide to high purity methyl oleate, methyl linoleate, methyl linolenate, methyl 9,11-trans,trans-octade-cadienoate and methyl β-eleostearate was investigated at 25 C with UV irradiation. A similar study was carried out
with soybean, linseed and tung oils in the absence and presence of 2,2′-azo-bis(isobutyronitrile) with UV photolysis. Initially
the reaction of hydrogen sulfide with methyl esters appears to follow pseudo-zero-order kinetics although as the reaction
proceeds the kinetics of the polyunsaturated ester reactions become more complex. For nonconjugated systems the overall rate
is determined by the initiation step, whereas the overall rate of addition to conjugated systems is a function of the stability
of the resonance-stabilized addition radical in the chain transfer step. For methyl esters the following order of reactivity
appears to hold:
Methyl oleate ≅ methyl linoleate ≅ methyl linolenate >> methyl 9,11-trans,trans-octadecadienoate > methyl β-eleostearate. Using 2,2′-azo-bis(isobutyronitrile) with UV photolysis markedly increases the
rate of addition of hydrogen sulfide to nonconjugated vegetable oils.
Presented at the AOCS Meeting, New York, October 1968.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献