Prostaglandin H₂

Prostaglandin H2
Names
	Other names PGH2, Endoperoxide H2, Prostaglandin R2
Identifiers
CAS Number	42935-17-1 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:15554 ;
ChemSpider	392800 ;
IUPHAR/BPS	4483;
MeSH	Prostaglandin+H2
PubChem CID	445049;
UNII	J670X3LRU2 ;
CompTox Dashboard (EPA)	DTXSID80903949 ;
	InChI InChI=1S/C20H32O5/c1-2-3-6-9-15(21)12-13-17-16(18-14-19(17)25-24-18)10-7-4-5-8-11-20(22)23/h4,7,12-13,15-19,21H,2-3,5-6,8-11,14H2,1H3,(H,22,23)/b7-4-,13-12+/t15-,16+,17+,18-,19+/m0/s1 Key: YIBNHAJFJUQSRA-YNNPMVKQSA-N ; InChI=1/C20H32O5/c1-2-3-6-9-15(21)12-13-17-16(18-14-19(17)25-24-18)10-7-4-5-8-11-20(22)23/h4,7,12-13,15-19,21H,2-3,5-6,8-11,14H2,1H3,(H,22,23)/b7-4-,13-12+/t15-,16+,17+,18-,19+/m0/s1 Key: YIBNHAJFJUQSRA-YNNPMVKQBN;
	SMILES O=C(O)CCC/C=C\C[C@H]2[C@H]1OO[C@H](C1)[C@@H]2/C=C/[C@@H](O)CCCCC;
Properties
Chemical formula	C20H32O5
Molar mass	352.465 g/mol
Density	1.129 ± 0.06 g/mL
Boiling point	490 ± 40.0 °C
Solubility in water	0.034 g/L
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Prostaglandin H₂ is a type of prostaglandin and a precursor for many other biologically significant molecules. It is synthesized from arachidonic acid in a reaction catalyzed by a cyclooxygenase enzyme.[1] The conversion from Arachidonic acid to Prostaglandin H2 is a two step process. First, COX-1 catalyzes the addition of two free oxygens to form the 1,2-Dioxane bridge and a peroxide functional group to form Prostaglandin G2.[2] Second, COX-2 reduces the peroxide functional group to a Secondary alcohol, forming Prostaglandin H2. Other peroxidases like Hydroquinone have been observed to reduce PGG2 to PGH2.[3] PGH2 is unstable at room temperature, with a half life of 90-100 seconds,[4] so it is often converted into a different prostaglandin.

Eicosanoid synthesis - prostaglandin H₂ near center

It is acted upon by:

Prostacyclin synthase to create prostacyclin
Thromboxane-A synthase to create thromboxane A2 and 12-(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) (see 12-Hydroxyheptadecatrienoic acid)
Prostaglandin D2 synthase to create prostaglandin D2
Prostaglandin E synthase to create prostaglandin E2

It rearranges non-enzymatically to:

A mixture of 12-(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) and 12-(S)-hydroxy-5Z,8Z,10E-heptadecatrienoic acid (see 12-Hydroxyheptadecatrienoic acid)

Use of prostaglandin H₂:

regulating the constriction and dilation of blood vessels
stimulating platelet aggregation
- binds to Thromboxane receptor on platelets' cell membranes to trigger platelet migration and adhesion to other platelets.[5]

Effects of Aspirin on prostaglandin H₂:

Aspirin has been hypothesized to block the conversion of arachidonic acid to prostaglandin

Figure 1: Synthetic pathways from PGH₂ (the parent compound) to prostaglandins, prostacyclin and thromboxanes

References

van der Donk WA, Tsai AL, Kulmacz RJ (December 2002). "The cyclooxygenase reaction mechanism". Biochemistry. 41 (52): 15451–8. doi:10.1021/bi026938h. PMID 12501173.
Salomon RG, Miller DB, Zagorski MG, Coughlin DJ (October 1984). "Prostaglandin endoperoxides. 14. Solvent-induced fragmentation of prostaglandin endoperoxides. New aldehyde products from PGH2 and a novel intramolecular 1,2-hydride shift during endoperoxide fragmentation in aqueous solution". Journal of the American Chemical Society. 106 (20): 6049–6060. doi:10.1021/ja00332a049. ISSN 0002-7863.
Hla T, Neilson K (August 1992). "Human cyclooxygenase-2 cDNA". Proceedings of the National Academy of Sciences of the United States of America. 89 (16): 7384–8. Bibcode:1992PNAS...89.7384H. doi:10.1073/pnas.89.16.7384. PMC 49714. PMID 1380156.
"Human Metabolome Database: Showing metabocard for Prostaglandin H2 (HMDB0001381)". www.hmdb.ca. Retrieved 2019-11-19.
Woodward DF, Jones RL, Narumiya S (September 2011). "International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress". Pharmacological Reviews. 63 (3): 471–538. doi:10.1124/pr.110.003517. PMID 21752876.

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[1] van der Donk WA, Tsai AL, Kulmacz RJ (December 2002). "The cyclooxygenase reaction mechanism". Biochemistry. 41 (52): 15451–8. doi:10.1021/bi026938h. PMID 12501173.

[2] Salomon RG, Miller DB, Zagorski MG, Coughlin DJ (October 1984). "Prostaglandin endoperoxides. 14. Solvent-induced fragmentation of prostaglandin endoperoxides. New aldehyde products from PGH2 and a novel intramolecular 1,2-hydride shift during endoperoxide fragmentation in aqueous solution". Journal of the American Chemical Society. 106 (20): 6049–6060. doi:10.1021/ja00332a049. ISSN 0002-7863.

[3] Hla T, Neilson K (August 1992). "Human cyclooxygenase-2 cDNA". Proceedings of the National Academy of Sciences of the United States of America. 89 (16): 7384–8. Bibcode:1992PNAS...89.7384H. doi:10.1073/pnas.89.16.7384. PMC 49714. PMID 1380156.

[4] "Human Metabolome Database: Showing metabocard for Prostaglandin H2 (HMDB0001381)". www.hmdb.ca. Retrieved 2019-11-19.

[5] Woodward DF, Jones RL, Narumiya S (September 2011). "International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress". Pharmacological Reviews. 63 (3): 471–538. doi:10.1124/pr.110.003517. PMID 21752876.