Thromboxane A2 (57576-52-0) Physical and Chemical Properties
Thromboxane A2
A short‑lived eicosanoid (thromboxane) mediator involved in platelet activation and vasoconstriction, supplied and used principally as a biochemical reagent or stabilized analog in preclinical research and assay development.
| CAS Number | 57576-52-0 |
| Family | Thromboxanes (eicosanoid) |
| Typical Form | Powder or oily solid |
| Common Grades | EP |
Thromboxane A2 is an eicosanoid of the thromboxane subclass (fatty acyl-derived signaling lipid) characterized by a substituted bicyclic oxane–oxetane (epoxy) core attached to a heptenoic acid side chain. Structurally it is an epoxy monocarboxylic acid derived from arachidonic acid: the molecule contains multiple stereocenters, a strained epoxy-containing bicyclic ring system and a terminal carboxylic acid group that confer both chemical reactivity and receptor-mediated bioactivity. The molecular skeleton combines a hydrophobic aliphatic chain with localized polar functionality (epoxide, secondary alcohol, carboxylic acid), producing an amphipathic profile typical of platelet-derived lipid mediators.
Electronically, the epoxide and hydroxyl substituents create localized polar sites capable of hydrogen bonding and nucleophilic attack, while the conjugated alkene portions of the side chain provide sites for isomerization and oxidative metabolism. The terminal carboxyl group behaves as a weak acid; at physiological pH the anionic (deprotonated) form is significantly populated, enhancing interactions with protein receptors and transport proteins. As a short-lived intermediate in prostanoid biosynthesis, thromboxane A2 exhibits high intrinsic reactivity (epoxide hydrolysis / ring opening, oxidation, and rapid enzymatic turnover) and limited chemical stability in aqueous and biological matrices.
Functionally, thromboxane A2 is a potent prothrombotic and vasoconstrictive mediator produced by activated platelets. It acts via the thromboxane A2 receptor (TBXA2R) to promote platelet activation, increase expression of platelet surface integrins (GPIIb/IIIa), and induce vascular smooth muscle contraction. Because of its biological potency and labile nature, it is primarily of importance in physiological and pharmacological studies of hemostasis, vascular tone, and arachidonic-acid-derived signaling. Common commercial grades reported for this substance include: EP.
Molecular Attributes
Molecular Weight and Composition
- Molecular formula: \(C_{20}H_{32}O_5\)
- Molecular weight (reported): \(352.5\ \mathrm{g}\,\mathrm{mol}^{-1}\)
- Exact mass / Monoisotopic mass: 352.22497412
- Heavy atom count: 25
- Topological polar surface area (TPSA): \(76\ \text{Å}^2\)
- Formal charge: 0
- Defined atom stereocenter count: 5
- Defined bond stereocenter count: 2
- Complexity: 459
These attributes reflect a mid-sized lipid mediator with multiple stereocenters and a moderate polar surface area associated with the epoxy, hydroxyl and carboxyl functionalities. The combination of a hydrophobic carbon framework and discrete polar sites determines membrane partitioning and protein interactions.
LogP and Amphiphilicity
- XLogP (XLogP3-AA): 3.4
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 5
- Rotatable bond count: 12
The reported XLogP of 3.4 indicates moderate lipophilicity consistent with an amphipathic eicosanoid: a predominantly hydrophobic backbone favors partitioning into lipid bilayers, while the epoxy, hydroxyl and carboxyl moieties provide polar interaction points at membrane interfaces or with protein binding sites. The presence of a carboxylic acid gives the molecule pH-dependent ionization; at physiological pH a significant fraction exists as the anion, reducing aqueous-to-lipid partitioning relative to the neutral form but enhancing receptor and carrier protein recognition. The relatively high rotatable bond count reflects conformational flexibility for receptor binding but also can influence metabolic susceptibility.
Biochemical Properties
Biosynthesis and Metabolic Context
Thromboxane A2 is biosynthesized enzymatically from arachidonic-acid-derived prostaglandin endoperoxides in activated platelets. Specifically, prostaglandin H2 (PGH2) is converted to thromboxane A2 by thromboxane synthase in platelet cytoplasm and endoplasmic reticulum compartments. It functions as a short-lived signaling intermediate between prostaglandin endoperoxides and thromboxane B2, and it is recognized as a principal platelet-derived mediator that stimulates additional platelet activation and aggregation.
Tissue and cellular localization reported includes platelets and vascular smooth muscle, with cellular distribution in cytoplasm, endoplasmic reticulum, membrane and extracellular compartments. Thromboxane A2 participates in arachidonic acid metabolism and is implicated in multiple prostanoid-related pathways relevant to hemostasis and vasomotor control.
Reactivity and Transformations
Thromboxane A2 is chemically labile: the bicyclic epoxy-containing core and the conjugated alkene system are susceptible to hydrolytic ring opening, isomerization and oxidative transformations. Biologically, thromboxane A2 is rapidly converted to thromboxane B2, a more stable, inactive hydrolysis product; this conversion is a primary route for loss of activity in vivo and in vitro. Enzymatic generation from prostaglandin endoperoxides is catalyzed by thromboxane synthase in platelets; subsequent enzymatic and non-enzymatic pathways (hydrolysis, reduction, oxidation) furnish a range of metabolites that terminate signaling. Because of the strained epoxide and the carboxylate functionality, the molecule is chemically reactive under aqueous and nucleophilic conditions and is therefore short-lived outside controlled, low-temperature, or solvent-stabilized environments.
Stability and Degradation
Chemical and Enzymatic Degradation Pathways
No experimentally established value for this property is available in the current data context.
Qualitatively, thromboxane A2 exhibits rapid degradation in aqueous and biological environments. Major degradation pathways include hydration or nucleophilic opening of the epoxy-containing bicyclic ring system, non-enzymatic rearrangement, and rapid conversion to thromboxane B2. Enzymatic catabolism in tissues involves enzymes of prostanoid metabolism that produce oxidized or reduced derivatives with reduced receptor activity. Practically, handling and measurement of thromboxane A2 require measures to limit aqueous exposure, control temperature, and quench enzymatic activity to prevent artifactual loss.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 57576-52-0
- InChIKey: DSNBHJFQCNUKMA-SCKDECHMSA-N
- InChI: InChI=1S/C20H32O5/c1-2-3-6-9-15(21)12-13-17-16(18-14-20(24-17)25-18)10-7-4-5-8-11-19(22)23/h4,7,12-13,15-18,20-21H,2-3,5-6,8-11,14H2,1H3,(H,22,23)/b7-4-,13-12+/t15-,16+,17+,18-,20+/m0/s1
- SMILES: CCCCCC@@HO
- UNII: 4C2A5G825S
- ChEBI ID: CHEBI:15627
- ChEMBL ID: CHEMBL5283529
- DSSTox Substance ID: DTXSID201317452
- HMDB ID: HMDB0001452
- KEGG ID: C02198
- LIPID MAPS ID (LM_ID): LMFA03030001
- Metabolomics Workbench ID: 2590
- NCI Thesaurus Code: C122988
- Nikkaji Number: J40.890E
- PharmGKB ID: PA166178672
- Wikidata: Q774909
Synonyms and Lipid Nomenclature
Common and depositor-supplied synonyms include (exact strings preserved):
- Thromboxane A2
- TXA2
- 57576-52-0
- TXA-2
- 4C2A5G825S
- DTXSID201317452
- 9S,11S-epoxy,15S-hydroxy-thromboxa-5Z,13E-dien-1-oic acid
- Thromboxa-5,13-dien-1-oic acid, 9,11-epoxy-15-hydroxy-, (5Z,9alpha,11alpha,13E,15S)-
- (Z)-7-[(1S,3R,4S,5S)-3-[(E,3S)-3-hydroxyoct-1-enyl]-2,6-dioxabicyclo[3.1.1]heptan-4-yl]hept-5-enoic acid
- (5Z,13E)-(15S)-9alpha,11alpha-Epoxy-15-hydroxythromboxa-5,13-dienoate
- (5Z,9alpha,11alpha,13E,15S)-9,11-Epoxy-15-hydroxythromboxa-5,13-dien-1-oic acid
- Rabbit aorta contracting substance
- RCS
- UNII-4C2A5G825S
- DSNBHJFQCNUKMA-SCKDECHMSA-N
- SCHEMBL34165
- THROMBOXANE A2 [MI]
- LMFA03030001
(Additional systematic and registry synonyms are documented; the list above includes principal nomenclature and identifiers as reported.)
Industrial and Biological Applications
Roles in Formulations or Biological Systems
Thromboxane A2 is principally relevant as a biological signaling mediator rather than as an industrial chemical. Biologically, it is a key platelet-derived eicosanoid that promotes platelet aggregation and vasoconstriction via TBXA2R signaling, and it contributes to hemostatic plug formation through induction of GPIIb/IIIa expression and fibrinogen-mediated platelet crosslinking. It also affects vascular smooth muscle and renal glomerular cell function through receptor-mediated pathways.
In practice, thromboxane A2 and its stable analogs or measurement of its stable metabolite (thromboxane B2) are used in pharmacological and physiological research to probe platelet activation, evaluate effects of antiplatelet agents, and study arachidonic-acid metabolism. No concise application summary is available in the current data context; in practice this substance is selected based on its general properties described above.
Safety and Handling Overview
Handling and Storage of Lipid Materials
Thromboxane A2 is a biologically active, chemically labile eicosanoid. General handling recommendations for such materials include: minimize exposure to aqueous environments and heat, store under inert atmosphere and at low temperature where possible, protect from light and oxidative conditions, and use anhydrous organic solvents for prolonged storage. Because thromboxane A2 is a potent platelet activator and vasoconstrictor, avoid skin contact and inhalation; use appropriate personal protective equipment (gloves, eye protection, lab coat) and work in a certified chemical fume hood or biological safety cabinet as applicable. Waste and spills should be handled as bioactive chemical waste according to institutional procedures.
For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
