Thromboxane B3 (TXB3), the stable hydrolysis product of TXA3, is synthesized from eicosapentaenoic acid (EPA) through the action of COX and thromboxane synthase enzymes. This compound is biosynthesized in several tissues, including seminal vesicles, lungs, polymorphonuclear leukocytes (PMNL), and ocular tissues.

Thromboxane B2 (TXB2) is a compound significantly released from aggregating platelets and undergoes metabolic transformation during circulation into 11-dehydro TXB2 and 2,3-dinor TXB2. The latter, 2,3-dinor TXB2, serves as a prevalent urinary metabolite of TXB2 and acts as an indicator for in vivo TXA2 synthesis. Studies have shown that in healthy male volunteers, the median excretion rate of 2,3-dinor TXB2 is measured at 10.3 ng/hour, equivalent to 138 pg/mg of creatinine.

11-Dehydro-2,3-dinor Thromboxane B2 (11-dehydro-2,3-dinor TXB2) is a metabolite derived from the inactive TXA2 metabolite, TXB2. Its formation involves the action of cytosolic aldehyde dehydrogenase (ALDH) and β-oxidation processes. Remarkably, levels of 11-dehydro-2,3-dinor TXB2 have been observed to increase by 5.2-fold in a surgery-induced rat model of tendon overuse, highlighting its potential role in physiological stress responses.

Pirodomast is a thromboxane A (TXA2) synthase inhibitor. Pirodomast inhibits leukotriene (LT) D4, C4, E4 formation and thromboxane B2 (TXB2) activity, but is weakly or ineffectively antagonistic to guinea pig bronchospasm induced by histamine, methacholine, serotonin, LTC4, or platelet-activating factor. Pirodomast is a potential antiallergic compound. Pirodomast had only weak relaxant activity on guinea pig trachea in vitro. Pirodomast is a potential antiallergic compound that inhibits the protein hydrolyzing activity of trypsin in vitro, prevents antigen-induced immediate and late asthmatic responses in allergic sheep in vivo, and inhibits antigen-induced airway hyperresponsiveness to histamine and carbachol in allergic sheep.

Glutinone (IC50=24 microM) shows a significant effect on thromboxane B2 (TXB2)-release induced by calcium ionophore in human platelets.

Vedaprofen (PM 150) inhibits COX-1 and reduces prostaglandin H2 synthesis with anti-inflammatory activities. Vedaprofen is an inhibitor of Escherichia coli sliding clamp with the IC50 of 222 μM and Ki of 131 μM.

CI-949 is an allergic mediator release inhibitor, which inhibits leukotriene C4/D4 (LTC4/LTD4), histamine, and thromboxane B2 (TXB2) release (IC50s: 0.5 μM, 11.4 μM and 0.1 μM).

Thromboxane B2 (TXB2) is released in substantial quantities from aggregating platelets and metabolized during circulation to 11-dehydro TXB2 and 2,3-dinor TXB2. In rats and rabbits, 2,3-dinor TXB1 has been identified as another urinary metabolite of TXB2. However in human urine, only trace amounts of 2,3-dinor TXB1 have been identified. In rats, 2,3-dinor TXB1 is excreted at a much higher rate than 2,3-dinor TXB2 (19.2 ± 4.9 ng/24 hr and 1.6 ± 0.3 ng/24 hr, respectively). Therefore, urinary 2,3-dinor TXB1 is a suitable marker of thromboxane biosynthesis in rats.

p-Hydroxycinnamic acid (NSC-59260) can inhibit platelet activity, with IC50s of 371 μM, 126 μM for thromboxane B2 production and lipopolysaccharide-induced prostaglandin E2 generation, respectively.

2,3-Dinor-8-iso Prostaglandin F1α (2,3-dinor-8-iso PGF1α), an isoprostane and active metabolite of arachidonic acid deriving its formation from non-enzymatic free radical peroxidation, acts as an active metabolite of the platelet aggregation inhibitor 8-iso PGF2α. This compound exhibits vasoconstrictive properties in isolated porcine retinal and brain microvessels with EC50 values of 12.8 and 18.5 nM, respectively, yet it does not cause contraction in isolated rat aortic rings at a concentration of 31 µM. Further, at a concentration of 1 µM, it raises thromboxane B2 (TXB2) levels in isolated porcine brain slices, an effect reversible by thromboxane A synthase inhibitor CGS 12970, voltage-gated calcium channel inhibitor SKF 96365, or the nicotinic acetylcholine receptor (nAChR) antagonist α-conotoxin.

Otenaproxesul (ATB 346) is a novel hydrogen sulphide-releasing derivative of naproxen with markedly reduced toxicity.

Protectin conjugates in tissue regeneration 1 (PCTR1) is a specialized pro-resolving mediator (SPM) synthesized from docosahexaenoic acid . DHA is oxidized to 16S,17S-epoxy-protectin, which is then converted to PCTR1 by glutathione S-transferase. PCTR1 levels increase during resolution of acute microbial-induced peritonitis in mice. PCTR1 (30 ng, i.p.) administration 12 hours post-infection increases macrophage numbers and activity and shortens the resolution phase of inflammation by 57%. It also reduces the levels of PGE2 , PGD2 , and TXB2 in peritoneal exudates.

KF 13218 is a selective, potent and long lasting thromboxane B2 (TXB2) synthase inhibitor with an IC50 value of 5.3±1.3 nM.

Maresin conjugates in tissue regeneration 3 (MCTR3) is a specialized pro-resolving mediator (SPM) synthesized from docosahexaenoic acid in macrophages. DHA is oxidized to maresin 1 , which is converted to MCTR1 by glutathione S-transferase Mu 4 or leukotriene C4 synthase, then to MCTR2 by γ-glutamyl transferase, and to MCTR3 by dipeptidase. MCTR3 accelerates tissue regeneration in planaria (1 and 100 nM) approximately as potently as MCTR2 and more potently than MCTR1. Pretreatment with MCTR3 prior to E. coli administration in mice reduces neutrophil infiltration, shortens the inflammatory resolution period, and increases phagocytosis of E. coli by macrophages. When administered at a dose of 100 ng 12h post E. coli infection in a mouse model of peritonitis, MCTR3 selectively reduces the amount of the eicosanoids PGD2 , PGE2 , PGF2α , and TXB2 in the exudate.

Thiazinamium chloride possesses potent anticholinergic and antiallergic activity and inhibits synthesis of TxB2(IC50 value of 0.2 µM).

Bunaprolast (U66858) is a novel and potent leukotriene B4 (LTB4) inhibitor.Bunaprolast exhibits oxidative degradation activity and inhibits lipoxygenase and TXB2 release.