Synthesis, properties, and identification of epimeric hepoxilins (−)-(10R)-B3 and (+)-(10S)-B3

Vasiljeva, L. L.; Manukina, T. A.; Demin, Peter; Lapitskaja, M. A.; Pivnitsky, K. K.

doi:10.1016/s0040-4020(01)89921-x

Cited by 35 publications

(21 citation statements)

References 11 publications

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“…On either side of the first of these are the two less abundant 9,10- cis -epoxide isomers labeled as peaks 6 and 8, the stereochemistry of which can be deduced from earlier studies as the 9 S ,10 R - cis -epoxy-13 R -hydroxy diastereomer followed by the 9 S ,10 R ,13 S (Gao et al, 2009). We also identified two 9 S ,10 S - trans -epoxy-11-hydroxy diastereomers (Figure 1A, peaks 4 and 5): the 11 S - erythro isomer elutes earlier at ~9.3 min, and the 11 R - threo -hydroxy isomer co-elutes with the first cis -epoxide at 11.0 min (see Supplementary Tables S9 and S10 for 1 H NMR assignments); this is consistent with previous findings that the erythro diastereomers are the less polar on SP-HPLC or TLC (Corey and Mehrotra, 1983; Corey et al, 1983; Dix and Marnett, 1985; Gardner and Kleiman, 1981; Vasiljeva et al, 1993). …”

Section: Resultssupporting

confidence: 89%

Steric analysis of epoxyalcohol and trihydroxy derivatives of 9-hydroperoxy-linoleic acid from hematin and enzymatic synthesis

Thomas

Boeglin

Garcia-Diaz

et al. 2013

Chemistry and Physics of Lipids

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We characterize the allylic epoxyalcohols and their trihydroxy hydrolysis products generated from 9R- and 9S-hydroperoxy-octadecenoic acid (HPODE) under non-enzymatic conditions, reaction with hematin and subsequent acid hydrolysis, and enzymatic conditions, incubation with Beta vulgaris containing a hydroperoxide isomerase and epoxide hydrolase. The products were resolved by HPLC and the regio and stereo-chemistry of the transformations were determined through a combination of 1H NMR and GC-MS analysis of dimethoxypropane derivatives. Four trihydroxy isomers were identified upon mild acid hydrolysis of 9S,10S-trans-epoxy-11E-13S-hydroxyoctadecenoate: 9S,10R,13S, 9S,12R,13S, 9S,10S,13S and 9S,12S,13S-trihydroxy-octadecenoic acids, in the ratio 40:26:22:12. We also identified a prominent -ketol rearrangement product from the hydrolysis as mainly the 9-hydroxy-10E-13-oxo isomer. Short incubation (5 min) of 9R- and 9S-HPODE with Beta vulgaris extract yielded the 9R- and 9S-hydroxy-10E-12R,13S-cis-epoxy products respectively. Longer incubation (60 min) gave one specific hydrolysis product via epoxide hydrolase, the 9R/S,12S,13S-trihydroxyoctadecenoate. These studies provide a practical approach for the isolation and characterization of allylic epoxy alcohol and trihydroxy products using a combination of HPLC, GC-MS and 1H NMR.

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Section: Resultssupporting

confidence: 89%

Steric analysis of epoxyalcohol and trihydroxy derivatives of 9-hydroperoxy-linoleic acid from hematin and enzymatic synthesis

Thomas

Boeglin

Garcia-Diaz

et al. 2013

Chemistry and Physics of Lipids

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“…1 H NMR (400 MHz, in deuterated benzene), assigned from the H,H-COSY analysis, defined the covalent structure and provided key details of the stereochemistry (Table 2, which is published as supporting information on the PNAS web site). For the proton signals from the 10-hydroxy-11,12-epoxy moiety, it was clear that the product from the reaction of 12S-HPETE with eLOX3 has a similar visual appearance and similar coupling constants to the 10R diastereomer (19,20). The coupling constant between H11 and H12 (Ϸ2.2 Hz) indicates the 11,12-trans epoxide configuration, i.e., 11S,12S-epoxy in this case.…”

Section: Identification Of the Two Main Products From 12s-hpetementioning

confidence: 80%

The lipoxygenase gene ALOXE3 implicated in skin differentiation encodes a hydroperoxide isomerase

Schneider

Boeglin

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

139

152

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Herein we identify a logical link of the biochemistry to the genetics. eLOX3 functions as a hydroperoxide isomerase (epoxyalcohol synthase) by using the product of 12R-LOX as the preferred substrate. 12R-Hydroperoxyeicosatetraenoic acid (12R-HPETE) is converted to 8R-hydroxy-11R,12R-epoxyeicosa-5Z,9E,14Z-trienoic acid, one of the isomers of hepoxilin A 3, and to 12-ketoeicosatetraenoic acid in a 2:1 ratio. Other hydroperoxides, including 8R-HPETE, 12S-HPETE, and 15S-HPETE, as well as the 13S-and 13R-hydroperoxides of linoleic acid are converted less efficiently. Mass spectrometric analysis of the epoxyalcohol formed from [ 18 O]15S-HPETE showed that both hydroperoxy oxygens are retained in the product. We propose that the ferrous form of eLOX3 initiates a redox cycle, unprecedented among LOX in being autocatalytic, in which the hydroperoxy substrate is isomerized to the epoxyalcohol or keto product. Our results provide strong biochemical evidence for a functional linkage of 12R-LOX and eLOX3 and clues into skin biochemistry and the etiology of ichthyosiform diseases in humans. L ipoxygenases (LOXs) are a family of nonheme ironcontaining enzymes that oxygenate unsaturated fatty acids such as arachidonic acid to specific hydroperoxide products (1). These may be metabolized further to various bioactive lipid mediators including leukotrienes, lipoxins, hydroxyeicosatetraenoic acids (HETEs), and hepoxilins (2). Although LOX enzymes are catalytically active with free fatty acid substrates, some will also oxygenate esterified substrates such as the phospholipid or cholesterol esters. LOX metabolites play important roles in cell signaling or modification of membrane structures (1, 3).There are five active LOXs found in human beings: 5-LOX, 12S-LOX, 12R-LOX, 15-LOX-1, and 15-LOX-2. A sixth gene family member, epidermal LOX type 3 (eLOX3, gene symbol ALOXE3) was described first in the mouse (4), and in humans in 2001 (5). The amino acid sequence of human eLOX3 shows the closest similarity to 12R-LOX (54% identity) and 15-LOX-2 (51%). It contains the characteristic well conserved amino acid residues found in all LOXs including the putative iron-binding ligands and additional structure-determining residues. These features clearly indicate that eLOX3 belongs to the LOX gene family. The question of the catalytic activity of eLOX3, nonetheless, has remained elusive. No enzymatic activity has been detected by using linoleic or arachidonic acids, the prototypical C18 and C20 LOX substrates, nor with methyl arachidonate or cholesteryl arachidonate (4). In the first section of Results we confirm and extend these findings.Studies in humans and the mouse indicate that eLOX3 has a limited scope of tissue expression, being mainly confined to keratinized epithelia such as skin. From PCR evidence it seems to be coexpressed in tissues that express the 12R-LOX (5). A functional relationship to skin pathophysiology is strongly suggested by a recent genetic study reporting that eLOX3 or 12R-LOX are mutated in six families affected by nonbul...

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“…Such synthesis was recently described in detail [15]. HxB 3 epimers were separated and purified by high-performance flash chromatography and preparative thin-layer chromatography.…”

Section: Methodsmentioning

confidence: 99%

“…HxB 3 epimers were separated and purified by high-performance flash chromatography and preparative thin-layer chromatography. The resultant high-purity samples possessed [aiD 25 -62.6 ~ (CHCI3) for (10R)-HxB 3 and +61.9 ~ (CHC13) for (10S)-HxB 3 [15]. The substances were dissolved in absolute ethanol and stored at -30~ The final concentration of ethanol in the growth medium of isolated islet cells was 0.17%.…”

Section: Methodsmentioning

confidence: 99%

On the mechanism of insulinotropic action of hepoxylins: Evidence of a direct, glucose-independent effect of hepoxylins B3 on insulin secretion

et al. 1995

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The effects of lipoxygenase metabolites of arachidonic acid, hepoxylin B 3 epimers, on insulin secretion by a culture of isolated islet cells were studied. The effect was assessed at hepoxylin B 3 concentrations of 0.2 to 5.0 ~tM and different glucose concentrations in the culture medium. Both hepoxylin B 3 epimers were shown to boost the stimulating effect of glucose on insulin secretion. This effect manifests itself at glucose concentrations of 5.5 and 11 mM and disappears at an above normal glucose content in the medium (20 mM). The capacity of hepoxylin B 3 to stimulate the secretion of insulin by a culture of islet cells in a glucose-free medium has also been demonstrated. This direct, not glucose-mediated, insulinotropic effect may serve as proof that the hepoxylins belong to the category of intracellular messengers.

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Synthesis, properties, and identification of epimeric hepoxilins (−)-(10R)-B3 and (+)-(10S)-B3

Cited by 35 publications

References 11 publications

Steric analysis of epoxyalcohol and trihydroxy derivatives of 9-hydroperoxy-linoleic acid from hematin and enzymatic synthesis

Steric analysis of epoxyalcohol and trihydroxy derivatives of 9-hydroperoxy-linoleic acid from hematin and enzymatic synthesis

The lipoxygenase gene ALOXE3 implicated in skin differentiation encodes a hydroperoxide isomerase

On the mechanism of insulinotropic action of hepoxylins: Evidence of a direct, glucose-independent effect of hepoxylins B3 on insulin secretion

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