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1.
A procedure for the preparation of specific molecular species ofd-erythro-lactosylceramide involving deacylation and reacylation of lactosylceramide prepared from bovine brain gangliosides is described.
Lactosylceramide wasN-deacylated by alkaline hydrolysis and the resulting four lysolactosylceramides, which contained d18∶1, d20∶1, d18∶0 and d20∶0
long-chain bases, were simultaneously re-N-acylated with theN-succinimidyl ester of either 16∶0, 18∶0, 20∶0, 24∶0, 20∶1, 22∶1 or 24∶1 fatty acid. The resulting lactosylceramide contained
four molecular species of lactosylceramides, i.e., d18∶1, d20∶1, d18∶0 and d20∶0 long-chain bases coupled with the fatty acid
that was introduced. Lactosylceramides prepared in this manner were separated into four individual molecular species by high-performance
liquid chromatography (HPLC). Each of the purified molecular species of lactosylceramide was quantitated by HPLC after derivatization
with benzoylchloride and was characterized by mass spectrometry. The yields of reacylated lactosylceramide were 38–58% relative
to the starting lactosylceramide; the purity of each of the molecular species of lactosylceramide was greater than 95%.
The glycosphingolipid nomenclature is as recommended by the IUPAC-IUB Commission on Biochemical Nomenclature (1). GalCer,
galactosylceramide, Gal(β1-1)Cer; GlcCer, glucosylceramide, Glc(β1-1)Cer; LacCer, lactosylceramide, Gal(β1-4)GlcCer; GbOse3Cer, globotriaosylceramide, Gal(α1-4)Gal(β1-4)GlcCer; GbOse4Cer, globotetraosylceramide, GalNAc(β1-3)Gal(α1-4)-Gal(β1-4)GlcCer; GgOse3Cer, gangliotriaosylceramide, GalNAc-(β1-4)Gal(β1-4)GlcCer; GgOse4Cer, gangliotetraosylceramide, Gal(β1-3)GalNAc(β1-4)Gal(β1-4)GlcCer; GM3, (NeuAcα2-3)-Galβ1-4GlcCer; GM1, Galβ1-3GalNAcβ1-4(NeuAcα2-3)Galβ1-4-GlcCer.
The molecular species abbreviations suggested by Breimeret al. (2) are used. For example, in the notation d18∶1−18∶0, the d18∶1 represents the long-chain base sphingosine (d-erythro-1,3-dihydroxy-2-amino-trans-4-octadecene) and 18∶0 represents the fatty acid (octadecanoic acid). 相似文献
2.
K. Kuhajda J. Kandrac S. Dobanović-Slavica J. Hranisavljević D. Miljković 《Lipids》1993,28(9):863-865
Conjugated bile acids, namely glyco- and tauro-3α,6α-dihydroxy-5β-cholanoic acid (hyodeoxycholic acid), 3α,7α-dihydroxy-5β-cholanoic
acid (chenodeoxycholic acid), 3α,6α,7α-trihydroxy-5β-cholanoic acid (hyocholic acid) and 3α-hydroxy-6-oxo-5β-cholanoic acid
(6-keto-litocholic acid) were isolated from pig bile, and subsequently transformed into the corresponding methyl esters. Separation
of the methyl esters of the isolated bile acids by high-performance liquid chromatography (HPLC) was accomplished on a ZORBAX-CN
column (Dupont, Boston, MA) withn-hexane/2-propanol/methylene chloride (89∶6∶5, by vol) as the mobile phase containing traces (≈1%) of amyl alcohol and water
as moderators. HPLC analysis of the methyl esters also showed the presence of methyl 3α-hydroxy-6-oxo-5α-cholanoate, which
was probably produced in the course of alkaline hydrolysis of the conjugated bile acids. 相似文献
3.
The acceptance of Solanum surattenses as a host plant for the larvae of Manduca sexta was explained by the presence of feeding stimulants in foliage. Bioassay-guided fractionation of plant extracts resulted in the isolation of a highly active compound (1), which was identified as a furostan derivative {26-O-β-d-glucopyranosyl-(25R)-furosta-5-ene-3-β-yl-O-α-l-rhamnopyranosyl-(1″-2′)-O-α-l-rhamnopyranosyl-(1′″-3″)-O-β-d-glucopyranoside}. This compound has the same steroidal core substructure as that in a stimulant (indioside D) previously identified from potato foliage. However, the sugar substituents attached to the core are different. 相似文献
4.
Members of the Daphne genus have been of interest owing to their excellent medicinal value. In this work, we describe the results of phytochemical
analysis and the antioxidant activity of the methanol extracts from leaves and stems of D. gnidium L. grown wild in Sardinia, Italy. Four coumarins (daphnetin, daphnin, acetylumbelliferon, and daphnoretin), nine flavonoids
(apigenin, luteolin, quercetin, orientin, isoorientin, luteolin 7-O-glucoside, apigenin 7-O-glucoside, genkwanin, and 5-O-β-d-primeverosyl genkwanine), and α-tocopherol were isolated. We investigated the ability of the two extracts and five pure compounds
(daphnetin, daphnoretin, apigenin, luteolin, and α-tocopherol) to protect linoleic acid against free radical attack in simple
in vitro systems by autoxidation and iron- or EDTA-mediated oxidation. Pure compounds were the most active antioxidants. During autoxidation,
daphnetin, luteolin, and α-tocopherol were effective at a molar ratio of 1∶1600, 1∶2500, and 1∶2000, respectively. Daphnoretin
was active only at high concentrations. During the iron-catalyzed oxidation of linoleic acid, all the materials tested showed
activity in the following order: luteolin>daphnetin>α-tocopherol >leaf extract>stem extract>daphnoretin. Apigenin was not
active in any of the experimental systems used. 相似文献
5.
Chemo-enzymatic synthesis of amino acid-based surfactants 总被引:5,自引:0,他引:5
Rao Valivety Paula Jauregi Iqbal Gill Evgeny Vulfson 《Journal of the American Oil Chemists' Society》1997,74(7):879-886
The application of lipases to the synthesis of amino acid-based surfactants was investigated. Low yields (2–9%) were obtained
in the acylation of free amino acids, such as l-serine and l-lysine, as well as their ethyl esters and amides with fatty acids, owing in part to low miscibility of the reactants. When
the N-carbobenzyloxy (Cbz)-l-amino acids were used in an effort to improve miscibility of the amino acid derivatives with the acyl donor, a dramatic improvement
was observed for N-Cbz-l-serine (92% yield) but not for N
α-Cbz- or N
ζ-Cbz-l-lysine (7 and 2% yield, respectively). As an alternative, and efficient synthesis of N
ζ-acyl-l-lysines was developed, based on the regiospecific chemical acylation of copper(II) lysinate. In pursuit of a general route
to amino acid-fatty acid surfactants, the utility of a polyol linker was investigated. Thus, the glycerol ester of N
α′
N
ζ-di-Cbz-l-lysine was prepared and evaluated as a substrate for acylation. As expected, this and other glycer-1-yl esters of N-protected amino acids were excellent substrates for lipase-catalyzed acylation. Their reaction with myristic acid in the
presence of Novozyme resulted in the regioselective acylation of the primary hydroxyl group of the glycerol moiety to afford
the corresponding 1-O-(N-Cbz-l-aminoacyl)-3-O-myris-toylglycerols with conversions of 50–90%. These were readily deprotected to give a range of 1-O-(aminoacyl)-3-O-myristoyl-glycerols with overall yields of 27–71%. 相似文献
6.
The prerequisites for a commercial fermentation process of biosurfactants include the use of low- or negative-cost substrates
and maximum conversion yields. Under competitive market conditions, the price of canola oil is expected to decrease in response
to its increased supply. Lactose, obtained from cheese whey, is a by-product of the dairy industry. In this work, canola oil
with glucose or lactose as carbon sources was used as substrates to produce sophorose lipids (SLs) by means of the yeastCandida bombicola. Fermentations were conducted in either shaker flasks or 1-L Bellco (Vineland, NJ) stirred reactors for 5–7 d at 450 rpm
and 30°C. The production of SLs reached 150–160 g/L in a medium consisting of 10% glucose, 10.5% canola oil, 0.1% urea and
0.4% yeast extract. When lactose was substituted for glucose, 90–110 g/L SL was obtained. The apolar SL 17-l-([2′-O-β-d-glucopyranosyl-β-d-glucopyransoyl]oxy)-octadecanoic acid 1′-4″-lactone 6′,6″-diacetate (SL-1) was the major one (73%) when canola oil was used
instead of safflower oil (SL-1, 50%). Use of canola oil generally resulted in increased yields of SLs comparable to the yields
obtained when safflower oil was used in the medium. Other literature reports present yields of 70 g/L and 120 g/L SLs, respectively,
with these substrates. 相似文献
7.
Recently, we have reported that anthocyanins show strong antioxidative activity, but no attention has been paid to anthocyanins
from the viewpoint of the reaction mechanism of alkylperoxyl radicals; therefore, we investigated the reaction products of
antioxidative anthocyanins (cyanidin 3-O-β-d-glucoside). Cyanidin 3-O-β-d-glucoside was reacted with 2,2′-azobis(2,4-dimet hylvaleronitrile) to generate the alkylperoxyl radicals, and the reaction
products were isolated by high-performance liquid chromatography. The products were identified as 4,6-dihydroxy-2-O-β-d-glucosyl-3-oxo-2,3-dihydrobenzofuran and protocatechuic acid. Based on reaction products, the antioxidative mechanism of
cyanidin 3-O-β-d-glucoside may be different from that of α-tocopherol; cyanidin 3-O-β-d-glucoside would produce another radical scavenger, as it would break down the structure and scavenge the radicals. 相似文献
8.
Five cerebrosides (1–5), including three new ones named cortenuamide A (1), cortenuamide B (2), and cortenuamide C (3), were isolated from the fruiting bodies of the basid-iomycete Cortinarius tenuipes. The structures of those compounds were elucidated as (4E,8E)-N-d-2′-hydroxytetracosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (1), (4E,8E)-N-d-2′-hydroxytricosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8 sphingadienine (2), (4E, 8E)-N-d-2′-hydroxydocosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (3), (4E, 8E)-N-d-2′-hydroxyoctadecanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (4), and (4E, 8E)-N-d-2′-hydroxypalmitoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (5) by spectral and chemical methods. 相似文献
9.
New glyceroglycolipid and ceramide from <Emphasis Type="Italic">Premna microphylla</Emphasis> 总被引:1,自引:0,他引:1
Iwo new compounds (1,2) were isolated from the ethanolic extract of the leaves of Premna microphylla, together with five known compounds. The structures of compounds 1 and 2 were elucidated as (2S,3S,4R,11E)-2-[(2R)-2-hydroxytetracosanoylamino]-11-octadecene-1,3,4-triol (1) and 1-O(9Z,12Z, 15Z-octadecatrienoyl)-3-O-[β-d-galactopyranosyl-(1→6)-O-β-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl] glycerol (2) by means of spectroscopic and chemical methods. 相似文献
10.
Significant correlations have been reported by epidemiologists between the mortality from colorectal cancer in various populations
and the consumption of meat or lipids by these populations. These have directed considerable attention to possible relationships
between diet and the occurrence of this neoplasm. We have carried out studies of the composition of bile from rats as influenced
by diets of varying lipid content. Two cannulas were surgically implanted to form an externalized bile duct through which
bile was drained from the common duct and returned to the duodenum. Small aliquots were analyzed for total bile acids by enzymatic
assay and for individual bile acids by high-pressure liquid chromatography, gas chromatography and gas chromatography-mass
spectrometry. Animals consuming diets highest in lipid content provided bile with the greatest amounts of bile acids. The
primary bile acids, taurocholic, taurochenodeoxycholic, and tauro α- and β-muricholic acids made up more than 99% of the 3α-hydroxy
bile acids and were found in approximate molar ratio of 2∶1∶1. Either complete drainage of bile without return to the duodenum,
or biliary tract obstruction had pronounced influence on the rate of secretion of bile and its composition. 相似文献
11.
Sequestration of Furostanol Saponins by <Emphasis Type="Italic">Monophadnus</Emphasis> Sawfly Larvae
Prieto JM Schaffner U Barker A Braca A Siciliano T Boevé JL 《Journal of chemical ecology》2007,33(3):513-524
Sawfly larvae of the tribe Phymatocerini (Hymenoptera: Tenthredinidae), which are specialized on toxic plants in the orders
Liliales and Ranunculales, exude a droplet of deterrent hemolymph upon attack by a predator. We investigated whether secondary
plant metabolites from Ranunculaceae leaves are sequestered by phymatocerine Monophadnus species, i.e., Monophadnus alpicola feeding upon Pulsatilla alpina and Monophadnus monticola feeding upon Ranunculus lanuginosus. Moreover, two undescribed Monophadnus species were studied: species A collected from Helleborus foetidus and species B collected from Helleborus viridis. Comparative high-performance liquid chromatographic–photodiode array detection–electrospray ionization–mass spectrometric
analyses of plant leaf and insect hemolymph extracts revealed the presence of furostanol saponins in all samples. Larvae of
species A and B actively sequestered (25R)-26-[(α-l-rhamnopyranosyl)oxy]-22α-methoxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→3)-O-[6-acetyl-β-d-glucopyranosyl-(1→3)]-O-β-d-glucopyranoside (compound 1). This compound occurred at a 65- to 200-fold higher concentration in the hemolymph of the two species (1.6 and 17.5 μmol/g
FW, respectively) than in their host plant (0.008 and 0.268 μmol/g FW, respectively). In M. monticola, compound 1 was found at a concentration (1.2 μmol/g FW) similar to that in the host plant (1.36 μmol/g FW). The compound could not be
detected consistently in M. alpicola larvae where, however, a related saponin may be present. Additional furostanol saponins were found in H. foetidus and H. viridis, but not in the two Monophadnus species feeding on them, indicating that sequestration of compound 1 is a highly specific process. In laboratory bioassays, crude hemolymph of three Monophadnus species showed a significant feeding deterrent activity against a potential predator, Myrmica rubra ant workers. Isolated furostanol saponins were also active against the ants, at a concentration range similar to that found
in the hemolymph. Thus, these compounds seem to play a major role for chemical defense of Monophadnus larvae, although other plant secondary metabolites (glycosylated ecdysteroids) were also detected in their hemolymph. Physiological
and ecological implications of the sequestered furostanol saponins are discussed.
Dedicated to the memory of Professor Ivano Morelli (1940–2005) 相似文献
12.
The facile acid-catalyzed conversion of cholest-5-ene-3β,7α-diol (but not of cholest-5-ene-3β, 7β-diol) in methanol or ethanol
solution to the corresponding 7α-methyl or 7α-ethyl ethers and epimerization of the 7α-alkyl ethers to the corresponding 7β-alkyl
ethers were established. The epimeric cholest-5-ene-3β, 7-diols, their 7-methyl ethers, and their 7-ethyl ethers are readily
interconverted in acidified solvents, the quasiequatorial 7β-epimer predominating in each case. Both 7α- and 7β-alkyl ethers
may be encountered as artifacts in analyses of sterol mixtures from mammalian tissues. 相似文献
13.
In recent years, defects of bile acid synthesis caused by disorders of peroxisome biogenesis have led to increased interest
in C27 bile acids. In humans, while the majority of bile acids are C24 carboxylic acids, the presence of increased concentrations of C27 bile acids and their metabolites in hereditary diseases associated with peroxisomal dysfunction can serve as a useful marker
for the intensity of the metabolic disorder. Our present studies describe an efficient method for the rapid hydrolysis of
C27 and C24 bile acid conjugates using a commercial microwave oven. The advantages of this method include freedom from racemization,
minimal activation, mild reaction conditions, and the highly stereocontrolled nature of the reaction, thus allowing for free
bile acid recovery in high yield. For example, when (25R) 3α,7α,12α-trihydroxy-5β-cholestan-26-oyl taurine, a major compound present in the bile of Alligator mississippiensis, was deconjugated with 4% NaOH/diethylene glycol or 1 M LiOH/propylene glycol in the microwave oven for 4–6 min, 3α,7α,12α-trihydroxy-5β-cholestan-26-oic
acid (THCA) was obtained in 81% yield with retention of configuration at C-25. It is suggested that present studies will be
helpful in delineating the absolute stereochemistry of 3α,7α,12α-trihydroxy-5β-cholestanoyl-CoA oxidase, the peroxisomal enzyme
that catalyzes the first step in the oxidation of THCA. 相似文献
14.
Acylated glycoglycerolipids were identified in the total lipid extract from cyanobacerium Synechocystis sp. PCC 6803. These compounds have a palmitoyl group esterified to the hydroxyl group at the C-6 position of the terminal
glycosyl moiety of digalactosyl monoacylglycerol and digalactosyl diacylglycerol. Their structural elucidation was accomplished
by tandem mass spectrometry coupled with fast atom bombardment ionization. Acylated digalactosyl monoacylglycerol has a structure
of 1-hydroxy-2-palmitoyl-3-O-[(6-O-palmitoyl)-α-d-galactopyranosyl-(1→6)-β-d-galactopyranosyl]-sn-glycerol. This compound has not been reported previously. 相似文献
15.
Reaction selectivities were determined in multicompetitive reactions mediated by Rhizomucor miehei (RM) lipase at water activity of 0.19 in hexane. Saturated FA (C4–C18 even chain) and oleic acid (C18∶1) were reacted with
a single alcohol, glycerol, or α-or β-MAG containing C4, C10, C16, or C18∶1 individually as alcohol cosubstrate. Similar patterns
of broad FA selectivity toward C8–C18 FA were generally observed for esterification into specific acylglycerol (AG) pools
with the different α/β-CX-MAG cosubstrates. Exceptions were enrichment of C18 in the MAG pool with α-C16-MAG substrate, and
a general suppression of C4/C6 FA reactivity and a specific discrimination toward >C8 FA incorporation into the TAG pool,
both for reactions with α-C10- and α-C16-MAG. RM lipase selectivity toward MAG was in descending order: β-C18∶1-MAG>α/β-C4-MAG∼β-C10-MAG∼β-C16-MAG>α-C18∶1-MAG
>α-C10-MAG∼α-C16-MAG. Selectivity in channeling CX of the original CX-MAG substrates into higher AG species was in descending
order: α-C10-MAG∼α-C16-MAG>β-C10-MAGβ-C16-MAG>α-C18∶1-MAG>β-C18∶1-MAG∼ α/β-C4-MAG. Aside from their characteristic FA selectivity,
Burkholderia cepacia (PS-30) and RM lipases behaved similarly in terms of MAG selectivity as well as a general conservation of FA selectivity
throughout the sequential steps of TAG assembly from FA and glycerol for processes designed to yield specifically structured
TAG. 相似文献
16.
Seeds of oat (Avena sativa L.) were recently shown to contain significant quantities of a new hydroxy acid, (15R)-hydroxy-(9Z)-(12Z)-octadecadienoic acid (trivial name, avenoleic acid). In the present work, avenoleate was found to be mainly (63%) localized
in the glycolipid fraction of oat seed lipids. Fractionation of the glycolipids by thin-layer chromatography and reversed-phase
high-performance liquid chromatography revealed the presence of a main molecular species which accounted for 20% of the total
avenoleate content of oat seeds. Structural studies by chemical methods and mass spectrometry demonstrated that the avenoleate-containing
glycolipid was a galactolipid assembled of one molecule of avenoleic acid, two molecules of linoleic acid, two molecules of
D-galactose, and one molecule of glycerol. Degradation of the new galactolipid by chemical and enzymatic methods demonstrated
the localization of acyl chains, i.e., linoleate at sn-1 and linoleoylavenoleate at sn-2. Nuclear magnetic resonance spectroscopy gave independent support for this structure and also demonstrated that the two
galactoses formed an α-d-galactopyranosyl-1-6-β-d-galactopyranosyl moiety which was bound to the sn-3 position. Based on these experiments, the new galactolipid could be formulated as 1-[(9′Z),(12′Z)-octadecadienoyl]-2-[(15″R)-{9″'Z), (12″'Z)-octadecadienoyloxy}-(9″Z),(12″Z)-octadecadienoyl]-3-(α-d-galactopyranosyl-1-6-β-d-galactopyranosyl)-glycerol. Quantitatively, the amount of the avenoleate-containing galactolipid was of the same order of
magnitude as those of individual molecular species of digalactosyldiacylglycerol containing nonoxygenated acyl chains. The
content of the new galactolipid in oat seeds was 0.5–0.6 mg per g of seed. 相似文献
17.
A method is described for the preparation of ganglioside Glac2 [(II3(NeuAc)2-LacCer, GD3] from cream of bovine milk using liquid-phase extraction with methanol or ethanol followed by anion exchange
chromatography. The method is rapid and inexpensive; 1 kg cream, centrifuged from 14–15 L of bovine milk, yields approximately
70 mg of pure ganglioside Glac2. The sialic acid constituent of ganglioside Glac2 isolated from bovine milk cream consists solely of theN-acetylneuraminic acid derivative. The major components of its ceramide consist of octadecasphing-4-enine and the 22∶0 (behenic
acid) and 23∶0 fatty acids.
Short hand notations for gangliosides are according to Wiegandt (Ref. 1). Glac2, (II3(NeuAc)2-LacCer) is NeuAcα,8NeuAcα,-3Galβ,4Glcβ,1Cer; Gtet1, (II3NeuAc-Gg4Cer) is Gal\,3GalNAcβ,-4(NeuAcα,3)Galβ,4Glcβ,1Cer. 相似文献
18.
A new phytosphingosine-type ceramide (1) was isolated along with nine other compounds—5α,8α-epidioxy-(22E,24R)-ergosta-6,22-dien-3β-ol, 5α,8α-epidioxy-(24S)-ergosta-6-en-3β-ol, (24S)-ergosta-7-ene-3β,5α,6β-triol,(22E,24R)-ergosta-7, 22-dien-3β,5α,6β-triol, inosine, adenine, l-pyroglutamic acid, fumaric acid, and d-allitol from the ethanol and chloroform/methanol extract of the fruiting bodies of the basidiomycete Russula cyanoxanotha (Schaeff.) Fr. The structure of (1) was established as (2S,3S,4R,2′R)-2-(2′-hydroxytetracosanoylamino) octadecane-1,3,4-triol by means of spectroscopic and chemical methods. 相似文献
19.
The lipids of the gram-negative bacterium Marinobacter hydrocarbonoclasticus grown in a synthetic seawater medium supplemented with various hydrocarbons as the sole carbon source were isolated, purified,
and their structures determined. The hydrocarbons were normal, iso, anteiso, and mid-chain branched alkanes, phenylalkanes, cyclohexylalkanes, and a terminal olefin. According to the sequential procedure
used for lipid extraction, three pools were isolated: unbound lipids extracted with organic solvents (corresponding to metabolic
lipids and to the main part of membrane lipids), OH− labile lipids [mainly ester-bound in the lipopolysaccharides (LPS)], and H+ labile lipids (mainly amide-bound in the LPS). Each pool contained FA, fatty alcohols, and β-hydroxy acids. The proportions
of these lipids in the unbound lipid pools were 84–98%, 1.1–11.6%, and 0.1–3.6% (w/w), respectively. The chemical structures
of the lipids were strongly correlated with those of the hydrocarbons fed; analytical data suggested a metabolism essentially
through oxidation into primary alcohol, then into FA and degradation via the β-oxidation pathway. Subterminal oxidation of the hydrocarbon chains, α-oxidation of FA or double-bond oxidation in the
case of the terminal olefin, were minor, although sometimes substantial, routes of hydrocarbon degradation. Cyclohexyldodecanedid
not support growth, likely because of the toxicity of cyclohexylacetic acid formed in the oxidation of the alkyl side chain.
In the OH− and H+ labile lipid pools, β-hydroxy acids, the lipophilic moiety of LPS, generally dominated (28–72% and 64–98%, w/w, respectively).
The most remarkable feature of these cultures on hydrocarbons was the incorporation in LPS of β-hydroxy acids with Codd, ω-unsaturated, iso, or anteiso alkyl chains in addition to the specific β-hydroxy acid of M. hydrocarbonoclasticus, 3-OH-n-12∶0. These β-hydroxy acids were tolerated insofar as their geometry and steric hindrance were close to those of the 3-OH-n-12∶0 acid. 相似文献
20.
Incubation of linoleic acid with crude homogenate of tomato fruit gave a high yield (69%) of linoleic acid hydroperoxides
with a ratio of 9- to 13-hydroperoxide isomers of 96∶4. After chromatography of the products, as free acids or methyl esters,
hydroperoxides with 9- to 13-isomeric ratios of >99∶1 were obtained. The major product was characterized as 9-d-hydroperoxy-octadeca-trans-10,cis-12-dienoic acid. The results demonstrate the positional specificity of lipoxygenase from tomato fruit. 相似文献