leukotriene

14,15-Leukotriene D4 (14,15-LTD4) is a member of an alternate class of LTs synthesized by a pathway involving the dual actions of 15- and 12-lipoxygenases (15- and 12-LOs) on arachidonic acid via 15-HpETE and 14,15-LTA4 intermediates. 14,15-LTD4 is classified as an eoxin (EXD4), because it is formed mostly by eosinophils. However, mast cells and nasal polyps can synthesize 14,15-LTD4 as well. Little is known about the physiological actions of 14,15-LTD4. It has weak contractile activity on both guinea pig ileum and pulmonary parenchyma in contrast to the effects of 5-LO-derived LTs. However, in an in vitro permeability assay, 14,15-LTD4 can increase vascular permeability of human endothelial cell monolayers, with similar potency to that of 5-LO-derived LTs, resulting in plasma leakage, a hallmark of inflammation.

Leukotriene B4 (LTB4) is a dihydroxy fatty acid derived from arachidonic acid through the 5-LO pathway. It promotes a number of leukocyte functions including aggregation, stimulation of ion fluxes, enhancement of lysosomal enzyme release, superoxide anion production, chemotaxis, and chemokinesis. 12-oxo LTB4 is an initial metabolite of LTB4 formed via the LTB4 12-hydroxydehydrogenase pathway. It is rapidly converted to 10,11-dihydro-12-oxo-LTB4, followed by reduction of the 12-oxo group to give 10,11-dihydro-LTB4. 12-oxo-LTB4 (EC50 = 33 nM) is about 70-fold less potent than LTB4 (EC50 = 0.46 nM) at stimulating Ca2+ mobilization in human neutrophils. It is also significantly less potent than LTB4 at stimulating neutrophil migration with EC50 values of 170 and 2.7 nM for 12-oxo-LTB4 and LTB4, respectively.

LTB3 is the LTA hydrolase metabolite of LTA3 in the leukotriene biosynthetic pathway. LTB3 and LTB4 are equipotent in their pro-inflammatory effects. However, LTB3 is five times less potent than LTB4 in eliciting chemotaxis of human neutrophils.

Leukotriene C4 (LTC4) is an arachidonate lipid mediator that regulates leukocyte recruitment and function at sites of inflammation.Leukotriene C4 is a mediator of bronchoconstriction, mucus hypersecretion, and eosinophilia, and has a mediating role in urticaria.

11-trans Leukotriene C4 (11-trans LTC4) is a C-11 double bond isomer of LTC4. LTC4 undergoes slow temperature-dependent isomerization to 11-trans LTC4 during storage. 11-trans LTC4 is produced in smaller amounts relative to LTC4 in ionophore-stimulated HMC-1 cells (a human mast cell line) and equine eosinophils, but not in human neutrophils or RBL-1 cells. It is nearly equipotent with LTC4 for contraction of guinea pig parenchymal and ileum. In a radioligand binding assay using guinea pig ileum as a cysteinyl leukotriene receptor preparation, the pKis for LTC4 and 11-trans LTC4 were determined to be 6.42 and 6.58, respectively.

Leukotrienes (LTs) are a group of acute inflammatory mediators derived from arachidonic acid in leukocytes. The majority of these metabolites are formed through the 5-lipoxygenase (5-LO) pathway. 14,15-LTE4 is a metabolite of 14,15-LTC4 and 14,15-LTD4, an alternate class of LTs synthesized by a pathway involving the dual actions of 15- and 12-LOs on arachidonic acid via 15-HpETE and 14,15-LTA4 intermediates. These metabolites are classified as eoxins because they are formed mostly by eosinophils. Mast cells and nasal polyps can synthesize 14,15-LTC4 as well, however metabolism to 14,15-LTE4 in these cells and tissue has not been documented. 14,15-LTE4 increases vascular permeability of human endothelial cell monolayers with about 10-fold less potency than LTC4, but approximately 100-fold greater potency than histamine.

Leukotriene B4 (LTB4) compounds are produced by both enzymatic and non-enzymatic processes. The products of enzymatic origin, via Leukotriene A4 (LTA4) hydrolase, are stereospecifically 12(R). Non-enzymatic hydrolysis products are 50:50 mixtures at C-12, but are almost exclusively trans at C-6. Thus, the non-enzymatic hydrolysis product of LTA4 is 6-trans-12-epi LTB4. 12-epi LTB4 is an isomer which would not be expected to occur in either non-enzymatic hydrolysis products, or in the enzymatic products of LTA4 hydrolase. Compared to LTB4, 12-epi LTB4 has significantly reduced activity for the LTB4 receptor on human neutrophils (IC50 of 7.5 mM), and on guinea pig lung membranes with a (Ki of 4.7 mM). 12-epi LTB4 is an weak agonist at both the recombinant human BLT1 and BLT2 receptors, requiring approximately 10 mM for full activation of the receptor.

N-acetyl LTE4 is the major inactive metabolite of LTE4 found in bile. This route of metabolism is prominent in the rat, but of minor importance in humans. N-acetyl LTE4 is 100 times less potent than LTC4 as a vasoconstricting agent. In healthy human subjects urinary excretion of N-acetyl LTE4 is about 1.5 nmol/mol creatinine, which is considerably less than that of LTE4 (12 nmol/mol creatinine).

20-Carboxy-Leukotriene B4 (20-COOH LTB4), a metabolite of Leukotriene B4 (LTB4), exhibits high affinity binding to the BLT1 receptor. It notably inhibits LTB4-mediated neutrophil responses, including migration, degranulation, and leukotriene biosynthesis [1].

Leukotriene C4 (LTC4) is the parent cysteinyl-leukotriene produced by the LTC4 synthase-catalyzed conjugation of glutathione to LTA4. LTC4 is produced by neutrophils, macrophages, and mast cells, and by transcellular metabolism in platelets. It is one of the constituents of slow-reacting substance of anaphylaxis (SRS-A) and exhibits potent smooth muscle contracting activity. LTC4-induced bronchoconstriction and enhanced vascular permeability contribute to the pathogenesis of asthma and acute allergic hypersensitivity. The concentration of LTC4 required to produce marked contractions of lung parenchymal strips and isolated tracheal rings is about 1 nM. LTC4 methyl ester is a more lipid soluble form of LTC4. The biological activity of LTC4 methyl ester has not been reported.

Leukotriene A4 methyl ester can be converted into leukotriene C4 monomethyl ester catalyzed by the major alkaline cytosolic glutathione transferase in rat liver, which can be used in metabolism-related studies.

The effects of Leukotriene B4 (LTB4) are mediated by two known receptors, BLT1 and BLT2. LTB4 is a high affinity ligand for BLT1, and many of its pro-inflammatory effects are believed to be transduced through this receptor. The BLT2 is more enigmatic, in that LTB4 is not a high-affinity ligand, nor is it clear that BLT2 activation promotes inflammation. LTB4 ethanolamide (LTB4-EA) is a theoretical 5-LO metabolite of arachidonoyl ethanolamide (AEA). In CHO cells transfected with human BLTR1, LTB4-EA was a potent antagonist with about three times greater affinity for the receptor than LTB4 (Ki = 1.22 nM versus 3.88 nM). LTB4-EA antagonizes the LTB4-induced contractions of guinea pig lung parenchyma with an EC50 of 10 nM. LTB4-EA thus represents a potential endogenous anti-inflammatory compound functioning as a natural antagonist of BLTR1.

Leukotriene B5 (LTB5) is a leukotriene with diverse biological activities. It is a metabolite of eicosapentaenoic acid formed through the 5-lipoxygenase (5-LO) pathway. LTB5 increases contraction of bullfrog lung strips ex vivo in a concentration-dependent manner. In vivo, LTB5 (100 nM) reduces tumor volume in mice injected with Tm1 murine melanoma cells. LTB5 also elicits chemokinesis and lysosomal enzyme release from polymorphonuclear leukocytes (PMNLs) 20- to 30-fold less, and induces platelet aggregation 8-fold less, potently than LTB4 .

20-hydroxy LTB4 is a metabolite of LTB4 in human neutrophils. In human leukocytes, LTB4 is inactivated by the enzyme LTB4 20-hydroxylase. 20-hydroxy LTB4 is not only much less active (~5%) compared to LTB4 in causing degranulation of PMNL, but actually inhibits LTB4-induced degranulation of human neutrophils (Ki = 13.3 nM). However, 20-hydroxy LTB4 is as active as LTB4 in contracting parenchymal strips from guinea pig lung. 20-hydroxy LTB4 retains considerable ligand binding affinity at the BLT2 receptor, but does not appear to function as an agonist.

11-trans Leukotriene D4 (11-trans LTD4) is a C-11 double bond isomer of LTD4. LTD4 undergoes slow temperature-dependent isomerization to 11-trans LTD4 during storage. 11-trans LTD4 retains about 10-25 % of the potency for contraction of guinea pig ileum, trachea and parenchyma compared to LTD4. It exhibits an ED50 ranging between 12-60 nM for contraction of guinea pig trachea.

Leukotriene E4 (LTE4) (LTE4) is produced by the action of dipeptidyl peptidase on LTD4 and is a component of the Slow Reactive Substance of Anaphylaxis (SRS-A).LTE4 is present in plasma and urine and can be used to detect asthma.

Leukotriene D4 (LTD4) is a potent pro-inflammatory mediator formed from arachidonic acid, a bronchoconstrictor, and induces osteoclast senescence.Leukotriene D4 induces transcriptional activity of potentially oncogenic genes and can be used in the study of asthma.

Leukotriene B4 (LTB4)-3-aminopropylamide is an analog of LTB4 that exhibits potent and selective binding to the BLT1 receptor with Ki values of 5.1 nM at BLT1 and 1,227 nM at BLT2, indicating its high affinity for BLT1 over BLT2. This compound's effects are mediated through interactions with two receptors, BLT1 and BLT2.

Slow isomerization of the C-11 double bond of LTE4 leads to the formation of 11-trans LTE4. 11-trans LTE4 is equipotent to LTE4 in contracting guinea pig ileum.

LTF4 is a cysteinyl-leukotriene produced in vitro, but not reported to date in vivo. It is formed by the incubation of LTE4 with γ-glutamyl transpeptidase and glutathione. LTF4 is a weak agonist in its ability to contract vascular smooth muscle. [1] The rank order of potency of the cysteinyl-leukotrienes to contract vascular smooth muscle is LTD4 > LTC4 > LTE4 >> LTF4. [1] [2]

Produced by neutrophils, macrophages, mast cells, and by transcellular metabolism in platelets, leukotriene C4 (LTC4) is the parent cysteinyl leukotriene formed by the LTC4 synthase-catalyzed conjugation of glutathione to LTA4. It is one of the constituents of slow-reacting substance of anaphylaxis (SRS-A) and exhibits potent smooth muscle contracting activity. LTC4, however, is rapidly metabolized to LTD4 and LTE4, which makes the characterization of LTC4 pharmacology difficult. N-methyl Leukotriene C4 (N-methyl LTC4) is a synthetic analog of LTC4 that is not readily metabolized to LTD4 and LTE4.It acts as a potent and selective CysLT2 receptor agonist exhibiting EC50 values of 122 and > 2,000 nM at the human CysLT2 and CysLT1 receptors, respectively. It has essentially the same potency as LTC4 at both the human and murine receptors CysLT2 receptors. N-methyl LTC4 is potent and active in vivo, causing vascular leak in mice overexpressing the human CysLT2 receptor but not in CysLT2 receptor knockout mice.

Leukotriene F-4 sulfone induces vascular permeability changes.

Leukotriene C4 (14,15-LTC4) is an inflammatory mediator synthesized from arachidonic acid through the actions of 15- and 12-lipoxygenases (LOs), involving intermediates such as 15-HpETE and 14,15-LTA4. Unlike the majority of leukotrienes formed via the 5-LO pathway, 14,15-LTC4 is an eoxin predominantly produced by eosinophils, although mast cells and nasal polyps can also synthesize it. While its physiological roles are not well understood, 14,15-LTC4 exhibits limited contractile activity on guinea pig ileum and pulmonary parenchyma. However, it can increase vascular permeability in human endothelial cell monolayers in vitro with potency comparable to 5-LO-derived leukotrienes, contributing to plasma leakage characteristic of inflammation.

18-Carboxy dinor Leukotriene B4 (18-carboxy dinor LTB4) represents a β-oxidation metabolite of Leukotriene B4 (LTB4). Initially, LTB4 is metabolized in the liver to 20-carboxy LTB4, which subsequently undergoes β-oxidation to form 18-carboxy dinor LTB4.

5-Oxo Leukotriene B4 (5-oxo LTB4) serves as an intermediate metabolite in the production of 12-oxo LTB4.

LTB4 dimethyl amide is a moderate inhibitor of LTB4-induced degranulation of human neutrophils (Ki = 130 nM) and lysozyme release from rat PMNL. LTB4 dimethyl amide appears to be an antagonist of the LTB4 receptor on guinea pig lung membranes.

Leukotriene B4 is an alkyl chain-based PROTAC linker that can be used in the synthesis of PROTACs[1].

Leukotriene B4 (LTB4) is a dihydroxy fatty acid derived from arachidonic acid through the 5-lipoxygenase pathway. It promotes a number of leukocyte functions including aggregation, stimulation of ion fluxes, enhancement of lysosomal enzyme release, superoxide anion production, chemotaxis, and chemokinesis. At least two LTB4 receptors, termed BLT1 and BLT2, have been identified. 14,15-dehydro LTB4 is a LTB4 receptor antagonist that has a higher binding affinity for BLT1, demonstrating a Ki value of 27 nM, compared to BLT2, which has a Ki value of 473 nM. 14,15-dehydro LTB4 inhibits LTB4-induced release of lysozymes from rat polymorphonuclear leukoctyes with an IC50 value of 1 μM.

Leukotriene E-4 sulfone is a synthetic leukotriene.

Biosynthesis of LTA3 occurs from 5,8,11-eicosatrienoic acid via the 5-LO pathway and it is the putative intermediate in the biosynthesis of 3-series leukotrienes. LTA3 as a free acid is highly unstable. The methyl ester is stable and can be readily hydrolyzed to the free acid as needed.

6-trans-12-epi-Leukotriene B4, a metabolite of arachidonic acid, serves as a potent anti-inflammatory agent.

Amlexanox (AA673) is an anti-aphthous ulcer drug. Amlexanox inhibits the synthesis and release of inflammatory mediators, including leukotrienes and histamine, from mast cells, neutrophils, and mononuclear cells. Amlexanox also acts as a leukotriene D4 antagonist and a phosphodiesterase inhibitor. Amlexanox decreases the time ulcers take to heal as well as the pain associated with the ulcers.

Gemilukast (ONO-6950) is an orally active and potent dual inhibitor of cysteinyl leukotriene 1 and 2 receptors (CysLT1 and CysLT2), inhibits LTC 4-induced bronchoconstriction, and is inhibitory to human CysLT1 and CysLT2, and may be used in the treatment of asthma.

Montelukast sodium (MK0476) is an orally available leukotriene receptor antagonist which is widely used for the prophylaxis and chronic treatment of asthma and has been linked to rare cases of clinically apparent liver injury.

LTB4-IN-1 (Anti-inflammatory agent 2) with IC50 of 70 nM is an inhibitor of leukotriene synthesis (LTB4).

ABT-080 (VML 530), a leukotriene synthesis inhibitor, is used potentially for treatment of asthma.

FPL 55712 is a leukotriene receptor and SRS-A antagonist that inhibits bronchoconstriction and can be used in studies of asthma and coronary artery thrombosis.

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.

Croconazole exhibited dose-dependent inhibitory activity on the 5-lipoxygenase (5-LOX) of neutrophils. Croconazole is an antimycotic agent. The IC50s for the synthesis of leukotriene B4 (LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE) is 7.8 +/- 1.7 and

Parogrelil Free Base (NM-702 Free Base) is a selective phosphodiesterase 3 inhibitor with bronchodilatory and anti-inflammatory effects, inhibits leukotriene (LT)D(4) and histamine-induced constriction of isolated guinea pig tracheal strips, and can be used in the study of bronchial asthma.

Ticolubant is orally active leukotriene B4 antagonist with high affinity for the human neutrophil LTB4 receptor (Ki = 0.78 nM), blocks LTB4-induced Ca2+ migration with an IC50 of 6.6 ± 1.5 nM, and shows topical anti-inflammatory activity in a mouse model of skin inflammation.

Moxilubant HCl is a small molecule leukotriene B4 receptor 1 (LTB4R) antagonist for the treatment of immune system disorders, skin and musculoskeletal disorders, and may be used in studies of psoriasis and rheumatoid arthritis.

L 674573 is an inhibitor of leukotriene biosynthesis.

YM 16638 is an orally active leukotriene (LT) antagonist with triglyceride-lowering and peroxisome-increasing effects that can be used to study antigen-induced early and late airway responses in allergic sheep.

ONO4057 is a potent and orally active Leukotriene B4 receptor antagonist with an IC50 value of 0.7±0.3 μM. Immunosuppressive effect of ONO4057 on rat allografts.

Linetastine (TMK-688) is a 5-lipoxygenase inhibitor (5-LOX) that inhibits leukotriene production and antagonizes the effects of histamine.Linetastine is used in studies of asthma, atherosclerosis, and peptic ulcers.

SC-22716 is an orally active leukotriene A4 (LTA4) hydrolase inhibitor.SC-22716 has potential anti-inflammatory activity and may be used in the study of inflammatory bowel disease and psoriasis.

BIRM 271 is a novel arachidonic acid release inhibitor that blocks leukotriene B4 and platelet-activating factor biosynthesis in human neutrophils. BIRM 271 and BIRM 270 are enantiomers that inhibit the production of leukotriene B4 with IC50 of 40 nM.

RS-601 is a potent dual leukotriene D4/thromboxane A2 inhibitor that inhibits antigen-induced airway hyperresponsiveness (AHR) and shows asthmatic effects in a guinea pig model of asthma.

5(S),12(S)-DiHETE is a natural bioactive lipid derived from arachidonic acid . It is synthesized by glycogen-induced rabbit peritoneal polymorphonuclear leukocytes (PMNLs) incubated with AA. 5(S),12(S)-DiHETE can be produced by successive oxygenation of AA by 5-lipoxygenase (5-LO) in platelets and 12-LO in leukocytes. It can also be synthesized from 12(S)-HETE by 5-LO, in the presence of 5-LO activating protein (FLAP), activated with calcium ionophore. 5(S),12(S)-DiHETE is an epimer of leukotriene B4 that is weakly chemotactic for PMNL.