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Revising the structure of a new eicosanoid from human platelets to 8,9-11,12-diepoxy-13-hydroxyeicosadienoic acid.

ABSTRACT: Eicosanoids are critical mediators of fever, pain, and inflammation generated by immune and tissue cells. We recently described a new bioactive eicosanoid generated by cyclooxygenase-1 (COX-1) turnover during platelet activation that can stimulate human neutrophil integrin expression. On the basis of mass spectrometry (MS/MS and MS³), stable isotope labeling, and GC-MS analysis, we previously proposed a structure of 8-hydroxy-9,11-dioxolane eicosatetraenoic acid (DXA₃). Here, we achieved enzymatic synthesis and ¹H NMR characterization of this compound with results in conflict with the previously proposed structural assignment. Accordingly, by using LC-MS, we screened autoxidation reactions of 11-hydroperoxy-eicosatetraenoic acid (11-HpETE) and thereby identified a candidate sharing the precise reverse-phase chromatographic and MS characteristics of the platelet product. We optimized these methods to increase yield, allowing full structural analysis by ¹H NMR. The revised assignment is presented here as 8,9-11,12-diepoxy-13-hydroxyeicosadienoic acid, abbreviated to 8,9-11,12-DiEp-13-HEDE or DiEpHEDE, substituted for the previous name DXA₃ We found that in platelets, the lipid likely forms via dioxolane ring opening with rearrangement to the diepoxy moieties followed by oxygen insertion at C13. We present its enzymatic biosynthetic pathway and MS/MS fragmentation pattern and, using the synthetic compound, demonstrate that it has bioactivity. For the platelet lipid, we estimate 16 isomers based on our current knowledge (and four isomers for the synthetic lipid). Determining the exact isomeric structure of the platelet lipid remains to be undertaken.

SUBMITTER: Kornilov A

PROVIDER: S-EPMC6556573 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Revising the structure of a new eicosanoid from human platelets to 8,9-11,12-diepoxy-13-hydroxyeicosadienoic acid.

Kornilov Andrei A Kennedy Paul D PD Aldrovandi Maceler M Watson Andrew J A AJA Hinz Christine C Harless Bryan B Colombo Joseph J Maxey Kirk M KM Tyrrell Victoria J VJ Simon Matthew M Aggarwal Varinder K VK Boeglin William E WE Brash Alan R AR Murphy Robert C RC O'Donnell Valerie B VB

The Journal of biological chemistry 20190506 23

Eicosanoids are critical mediators of fever, pain, and inflammation generated by immune and tissue cells. We recently described a new bioactive eicosanoid generated by cyclooxygenase-1 (COX-1) turnover during platelet activation that can stimulate human neutrophil integrin expression. On the basis of mass spectrometry (MS/MS and MS<sup>3</sup>), stable isotope labeling, and GC-MS analysis, we previously proposed a structure of 8-hydroxy-9,11-dioxolane eicosatetraenoic acid (DXA<sub>3</sub>). Her ...[more]

PMID: 31061099

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Project description:UNLABELLED: BACKGROUND:Thromboxane A2 is derived from arachidonic acid through the action of cyclooxygenases and thromboxane synthase. It is mainly formed in blood platelets upon activation and plays an important role in aggregation. Aspirin is effective in reducing the incidence of complications following acute coronary syndrome and stroke. The anti-thrombotic effect of aspirin is obtained through the irreversible inhibition of cyclooxygenases. Analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid were shown previously to modulate platelet activation and to block thromboxane receptors. RESULTS AND DISCUSSION:We synthesized 10 compounds based on the structures of analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid and evaluated their effect on platelet aggregation triggered by arachidonic acid. The structure activity relationship was evaluated. Five compounds showed a significant inhibition of platelet aggregation and highlighted the importance of the lipidic hydrophobic hydrocarbon chain and the phenol group. Their IC50 ranged from 7.5?±?0.8 to 14.2?±?5.7 ?M (Mean ± S.E.M.). All five compounds decreased platelet aggregation and thromboxane synthesis in response to collagen whereas no modification of platelet aggregation in response to thromboxane receptor agonist, U46619, was observed. Using COS-7 cells overexpressing human cyclooxygenase-1, we showed that these compounds are specific inhibitors of cyclooxygenase-1 with IC50 ranging from 1.3 to 12 ?M. Docking observation of human recombinant cyclooxygenase-1 supported a role of the phenol group in the fitting of cyclooxygenase-1, most likely related to hydrogen bonding with the Tyr 355 of cyclooxygenase-1. CONCLUSIONS:In conclusion, the compounds we synthesized at first based on the structures of analogues of 12 lipoxygenase metabolites showed a role of the phenol group in the anti-platelet and anti-cyclooxygenase-1 activities. These compounds mediate their effects via blockade of cyclooxygenase-1.

Dataset Information

Revising the structure of a new eicosanoid from human platelets to 8,9-11,12-diepoxy-13-hydroxyeicosadienoic acid.

Publications

Revising the structure of a new eicosanoid from human platelets to 8,9-11,12-diepoxy-13-hydroxyeicosadienoic acid.

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