Reaction Process: WikiPathways:WP5171
Leukotriene metabolic pathway related metabolites
find 16 related metabolites which is associated with chemical reaction(pathway) Leukotriene metabolic pathway
16-COOH-tetranor-LTE3 ⟶ 14-COOH-hexanor-LTE4
Arachidonic acid
Arachidonic acid is a polyunsaturated, essential fatty acid that has a 20-carbon chain as a backbone and four cis-double bonds at the C5, C8, C11, and C14 positions. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is synthesized from dietary linoleic acid. Arachidonic acid mediates inflammation and the functioning of several organs and systems either directly or upon its conversion into eicosanoids. Arachidonic acid in cell membrane phospholipids is the substrate for the synthesis of a range of biologically active compounds (eicosanoids) including prostaglandins, thromboxanes, and leukotrienes. These compounds can act as mediators in their own right and can also act as regulators of other processes, such as platelet aggregation, blood clotting, smooth muscle contraction, leukocyte chemotaxis, inflammatory cytokine production, and immune function. Arachidonic acid can be metabolized by cytochrome p450 (CYP450) enzymes into 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs), their corresponding dihydroxyeicosatrienoic acids (DHETs), and 20-hydroxyeicosatetraenoic acid (20-HETE). The production of kidney CYP450 arachidonic acid metabolites is altered in diabetes, pregnancy, hepatorenal syndrome, and in various models of hypertension, and it is likely that changes in this system contribute to the abnormalities in renal function that are associated with many of these conditions. Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (PMID: 12736897, 12736897, 12700820, 12570747, 12432908). The beneficial effects of omega-3 fatty acids are believed to be due in part to selective alteration of arachidonate metabolism that involves cyclooxygenase (COX) enzymes (PMID: 23371504). 9-Oxononanoic acid (9-ONA), one of the major products of peroxidized fatty acids, was found to stimulate the activity of phospholipase A2 (PLA2), the key enzyme to initiate the arachidonate cascade and eicosanoid production (PMID: 23704812). Arachidonate lipoxygenase (ALOX) enzymes metabolize arachidonic acid to generate potent inflammatory mediators and play an important role in inflammation-associated diseases (PMID: 23404351). Essential fatty acid. Constituent of many animal phospholipids Arachidonic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=506-32-1 (retrieved 2024-07-15) (CAS RN: 506-32-1). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Arachidonic acid is an essential fatty acid and a major constituent of biomembranes. Arachidonic acid is an essential fatty acid and a major constituent of biomembranes.
Leukotriene B4
A leukotriene composed of (6Z,8E,10E,14Z)-icosatetraenoic acid having (5S)- and (12R)-hydroxy substituents. It is a lipid mediator of inflammation that is generated from arachidonic acid via the 5-lipoxygenase pathway. Chemical was purchased from CAY20110 (Lot 0439924-0).; Diagnostic ions: 335.1, 317.2, 195.1, 129.0, 115.0, 111.5
Leukotriene C4
Leukotriene C4 (LTC4) is a cysteinyl leukotriene (CysLT), a family of potent inflammatory mediators. Eosinophils, one of the principal cell types recruited to and activated at sites of allergic inflammation, is capable of elaborating lipid mediators, including leukotrienes derived from the oxidative metabolism of arachidonic acid (AA). Potentially activated eosinophils may elaborate greater quantities of LTC4, than normal eosinophils. These activated eosinophils thus are primed for enhanced LTC4 generation in response to subsequent stimuli. Some recognized priming stimuli are chemoattractants (e.g. eotaxin, PAF) that may participate in the recruitment of eosinophils to sites of allergic inflammation. The mechanisms by which chemoattractants and other activating cytokines (e.g. interleukin (IL)-5) or extracellular matrix components (e.g. fibronectin) enhance eosinophil eicosanoid formation are pertinent to the functions of these eicosanoids as paracrine mediators of allergic inflammation. Some eosinophil-derived eicosanoids may be active in down-regulating inflammation. It is increasingly likely that eicosanoids synthesized within cells, including eosinophils, may have intracellular (e.g. intracrine) roles in regulating cell functions, in addition to the more recognized activities of eicosanoids as paracrine mediators of inflammation. Acting extracellularly, the cysteinyl leukotrienes (CysLTs) LTC4 and its extracellular derivatives, LTD4 and LTE4 are key paracrine mediators pertinent to asthma and allergic diseases. Based on their receptor-mediated capabilities, they can elicit bronchoconstriction, mucus hypersecretion, bronchial hyperresponsiveness, increased microvascular permeability, and additional eosinophil infiltration. Eosinophils are a major source of CysLTs and have been identified as the principal LTC4 synthase expressing cells in bronchial mucosal biopsies of asthmatic subjects (PMID: 12895596). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent, able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis, through receptor-mediated G-protein linked signalling pathways. Leukotriene c4, also known as ltc4 or 5s,6r-ltc(sub 4), is a member of the class of compounds known as oligopeptides. Oligopeptides are organic compounds containing a sequence of between three and ten alpha-amino acids joined by peptide bonds. Thus, leukotriene c4 is considered to be an eicosanoid lipid molecule. Leukotriene c4 is practically insoluble (in water) and a moderately acidic compound (based on its pKa). Leukotriene c4 can be synthesized from icosa-7,9,11,14-tetraenoic acid. Leukotriene c4 is also a parent compound for other transformation products, including but not limited to, leukotriene C4 methyl ester, 11,12-dihydro-(12R)-hydroxyleukotriene C4, and 11,12-dihydro-12-oxoleukotriene C4. Leukotriene c4 can be found in a number of food items such as gram bean, maitake, caraway, and burbot, which makes leukotriene c4 a potential biomarker for the consumption of these food products. Leukotriene c4 can be found primarily in blood and cerebrospinal fluid (CSF), as well as throughout most human tissues. In humans, leukotriene c4 is involved in several metabolic pathways, some of which include trisalicylate-choline action pathway, antipyrine action pathway, nepafenac action pathway, and fenoprofen action pathway. Leukotriene c4 is also involved in a couple of metabolic disorders, which include leukotriene C4 synthesis deficiency and tiaprofenic acid action pathway. Moreover, leukotriene c4 is found to be associated with eczema. Leukotriene C4 (LTC4) is a leukotriene. LTC4 has been extensively studied in the context of allergy and asthma. In cells of myeloid origin such as mast cells, its biosynthesis is orchestrated by translocation to the nuclear envelope along with co-localization of cytosolic phospholipase A2 (cPLA2), Arachidonate 5-lipoxygenase (5-LO), 5-lipoxygenase-activating protein (FLAP) and LTC4 synthase (LTC4S), which couples glutathione to an LTA4 intermediate.The MRP1 transporter then secretes cytosolic LTC4 and cell surface proteases further metabolize it by sequential cleavage of the γ-glutamyl and glycine residues off its glutathione segment, generating the more stable products LTD4 and LTE4. All three leukotrienes then bind at different affinities to two G-protein coupled receptors: CYSLTR1 and CYSLTR2, triggering pulmonary vasoconstriction and bronchoconstriction .
Leukotriene D4
Leukotriene D4 (LTD4) is a cysteinyl leukotriene. Cysteinyl leukotrienes (CysLTs) are a family of potent inflammatory mediators that appear to contribute to the pathophysiologic features of allergic rhinitis. LTD4 is a pro-inflammatory mediator known to mediate its effects through specific cell-surface receptors belonging to the G-protein-coupled receptor family, namely the high-affinity CysLT1 (cysteinyl leukotriene 1) receptor. LTD4 is present at high levels in many inflammatory conditions, and areas of chronic inflammation have an increased risk for subsequent cancer development. LTD4 is associated with the pathogenesis of several inflammatory disorders, such as asthma and inflammatory bowel disease. Exposure to LTD4 increases survival and proliferation in intestinal epithelial cells. CysLT1 regulator is up-regulated in colon cancer tissue and LTD4 signalling facilitates the survival of cancer cells. LTD4 could reduce apoptosis in non-transformed epithelial cells. LTD4 causes up-regulation of beta-catenin through the CysLT1 receptor, PI3K (phosphoinositide 3-kinase), and GSK-3β (glycogen synthase kinase 3β). LTD4 induces beta-catenin translocation to the nucleus and activation of TCF/LEF family of transcription factors. LTD4 causes accumulation of free beta-catenin in non-transformed intestinal epithelial cells through the CysLT1 receptor, and this accumulation is dependent upon the activation of PI3K as well as GSK-3β inactivation (PMID: 16042577, 12607939). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent and are able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis through receptor-mediated G-protein linked signaling pathways. Leukotriene D4 (LTD4) is a cysteinyl leukotriene a family of potent inflammatory mediators. LTD4 is a pro-inflammatory mediator known to mediate its effects through specific cell-surface receptors belonging to the G-protein-coupled receptor family, namely the high-affinity CysLT1 (cysteinyl leukotriene 1) receptor. LTD4 is present at high levels in many inflammatory conditions, and areas of chronic inflammation have an increased risk for subsequent cancer development; LTD4 is associated with the pathogenesis of several inflammatory disorders, such as asthma and inflammatory bowel disease. Exposure to LTD4 increases survival and proliferation in intestinal epithelial cells. CysLT1 regulator is up-regulated in colon cancer tissue and LTD4 signalling facilitates the survival of cancer cells. LTD4 could reduce apoptosis in non-transformed epithelial cells. LTD4 causes up-regulation of b-catenin through the CysLT1 receptor, PI3K (phosphoinositide 3-kinase) and GSK-3b (glycogen synthase kinase 3b). LTD4 induces b-catenin translocation to the nucleus and activation of TCF/LEF family of transcription factors. LTD4 causes accumulation of free b-catenin in non-transformed intestinal epithelial cells through the CysLT1 receptor, and this accumulation is dependent upon the activation of PI3K as well as GSK-3b inactivation. (PMID: 16042577, 12607939)
5(S)-Hydroperoxyeicosatetraenoic acid
5(S)-Hydroperoxyeicosatetraenoic acid is a lipid hydroperoxide precursor of leukotrienes. The first step of biosynthesis of leukotrienes is conversion of arachidonic acid into 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid [5(S)-HpETE] by 5- lipoxygenases (5-LOX). Lipid hydroperoxides undergo homolytic decomposition into bifunctional electrophiles, which react with DNA bases to form DNA adducts. These DNA modifications are proposed to be involved in the etiology of cancer, cardiovascular disease, and neurodegeneration. 5-LOX, the enzyme responsible for the formation of 5(S)-HpETE in vivo, is expressed primarily in leukocytes, including monocytes and macrophages. Studies have implicated the 5-LOX pathway as an important mediator in the pathology of atherosclerosis. (PMID: 15777099). Endogenously generated 5-hydroperoxyeicosatetraenoic acid is the preferred substrate for human leukocyte leukotriene A4 synthase activity. Thus, the arachidonic acid moiety is preferentially converted to LTA4 in a concerted reaction without dissociation of a 5-HPETE intermediate. (PMID: 3036580). 5(S)-Hydroperoxyeicosatetraenoic acid is a lipid hydroperoxide precursor of leukotrienes. The first step of biosynthesis of leukotrienes is conversion of arachidonic acid into 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid [5(S)-HpETE] by 5- lipoxygenases (5-LOX). Lipid hydroperoxides undergo homolytic decomposition into bifunctional electrophiles, which react with DNA bases to form DNA adducts. These DNA modifications are proposed to be involved in the etiology of cancer, cardiovascular disease, and neurodegeneration.
Leukotriene A4
Leukotriene A4 (LTA4) is the first metabolite in the series of reactions leading to the synthesis of all leukotrienes. 5-Lipoxygenase (5-LO) catalyzes the two-step conversion of arachidonic acid to LTA4.The first step consists of the oxidation of arachidonic acid to the unstable intermediate 5-hydroperoxyeicosatetraenoic acid (5-HPETE), and the second step is the dehydration of 5-HPETE to form LTA4. Leukotriene A4, an unstable epoxide, is hydrolyzed to leukotriene B4 or conjugated with glutathione to yield leukotriene C4 and its metabolites, leukotriene D4 and leukotriene E4. The leukotrienes participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. Recent studies also suggest a neuroendocrine role for leukotriene C4 in luteinizing hormone secretion. (PMID: 10591081, 2820055). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent, able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis, through receptor-mediated G-protein linked signalling pathways. Leukotriene A4 (LTA4) is the first metabolite in the series of reactions leading to the synthesis of all leukotrienes. 5-Lipoxygenase (5-LO) catalyzes the two-step conversion of arachidonic acid to LTA4.The first step consists of the oxidation of arachidonic acid to the unstable intermediate 5-hydroperoxyeicosatetraenoic acid (5-HPETE), and the second step is the dehydration of 5-HPETE to form LTA4. Leukotriene A4, an unstable epoxide, is hydrolyzed to leukotriene B4 or conjugated with glutathione to yield leukotriene C4 and its metabolites, leukotriene D4 and leukotriene E4. The leukotrienes participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. Recent studies also suggest a neuroendocrine role for leukotriene C4 in luteinizing hormone secretion. (PMID: 10591081, 2820055)
20-Hydroxy-leukotriene E4
20-Hydroxy-leukotriene E4 is a metabolite that can originate from the lipid oxidation of leukotriene E4 (LTE4). LTE4 is a cysteinyl leukotriene. Cysteinyl leukotrienes (CysLTs) are a family of potent inflammatory mediators that appear to contribute to the pathophysiologic features of allergic rhinitis. Nasal blockage induced by CysLTs is mainly due to dilatation of nasal blood vessels which can be induced by the nitric oxide produced through CysLT1 receptor activation. LTE4 activates contractile and inflammatory processes via specific interactions with putative seven transmembrane-spanning receptors that couple to G proteins and subsequent intracellular signaling pathways. LTE4 is metabolized from leukotriene C4 in a reaction catalyzed by gamma-glutamyl transpeptidase and a particulate dipeptidase from kidney (PMID: 12607939, 12432945, 6311078). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent and are able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis through receptor-mediated G-protein linked signaling pathways.
12-Keto-leukotriene B4
12-Keto-leukotriene B4 is formed when leukotriene B4 (LTB4) is metabolized by beta-oxidation. LTB4 is the major metabolite in neutrophil polymorphonuclear leukocytes. Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of 5-LO to the perinuclear region and phosphorylation to either enhance or inhibit the activity of 5-LO. Biologically active LTB4 is metabolized by w-oxidation carried out by specific cytochrome P450s (CYP4F) followed by beta-oxidation from the w-carboxy position and after CoA ester formation. (PMID: 8632343, 9667737)Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent, able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis, through receptor-mediated G-protein linked signalling pathways. 12-Keto-leukotriene B4 is formed when leukotriene B4 (LTB4) is metabolized by beta-oxidation. LTB4 is the major metabolite in neutrophil polymorphonuclear leukocytes. Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of 5-LO to the perinuclear region and phosphorylation to either enhance or inhibit the activity of 5-LO. Biologically active LTB4 is metabolized by w-oxidation carried out by specific cytochrome P450s (CYP4F) followed by beta-oxidation from the w-carboxy position and after CoA ester formation. (PMID: 8632343, 9667737)
20-Carboxy-leukotriene B4
20-Carboxyleukotriene B4 is an omega-oxidized metabolite of leukotriene B4 (LTB4). Neutrophil microsomes are known to oxidize 20-hydroxy-LTB4 (20-OH-LTB4) to its 20-oxo and 20-carboxy derivatives in the presence of NADPH. This activity has been ascribed to LTB4 omega-hydroxylase (cytochrome P-450LTB omega). Leukotriene B4 release from polymorphonuclear granulocytes of severely burned patients was reduced as compared to healthy donor cells. This decrease is due to an enhanced conversion of LTB4 into the 20-hydroxy- and 20-carboxy-metabolites and further to a decreased LTB4-synthesis. LTB4 is the major metabolite in neutrophil polymorphonuclear leukocytes. Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of 5-LO to the perinuclear region and phosphorylation to either enhance or inhibit the activity of 5-LO. Biologically active LTB4 is metabolized by w-oxidation carried out by specific cytochrome P450s (CYP4F) followed by beta-oxidation from the w-carboxy position and after CoA ester formation. Other specific pathways of leukotriene metabolism include the 12-hydroxydehydrogenase/ 15-oxo-prostaglandin-13-reductase that form a series of conjugated diene metabolites that have been observed to be excreted into human urine. Metabolism of LTC4 occurs by sequential peptide cleavage reactions involving a gamma-glutamyl transpeptidase that forms LTD4 (leukotriene D4) and a membrane-bound dipeptidase that converts LTD4 into LTE4 (leukotriene E4) before w-oxidation. These metabolic transformations of the primary leukotrienes are critical for termination of their biological activity, and defects in expression of participating enzymes may be involved in specific genetic disease. (PMID 17623009, 7633595, 2155225, 3039534)Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent, able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis, through receptor-mediated G-protein linked signalling pathways.
Leukotriene E4
Leukotriene E4 (LTE4) is a cysteinyl leukotriene. Cysteinyl leukotrienes (CysLTs) are a family of potent inflammatory mediators that appear to contribute to the pathophysiologic features of allergic rhinitis. Nasal blockage induced by CysLTs is mainly due to dilatation of nasal blood vessels, which can be induced by the nitric oxide produced through CysLT1 receptor activation. LTE4 activates contractile and inflammatory processes via specific interaction with putative seven transmembrane-spanning receptors that couple to G proteins and subsequent intracellular signaling pathways. LTE4 is metabolized from leukotriene C4 in a reaction catalyzed by gamma-glutamyl transpeptidase and a particulate dipeptidase from kidney (PMID: 12607939, 12432945, 6311078). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent and are able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis through receptor-mediated G-protein linked signaling pathways. Leukotriene E4 (LTE4) is a cysteinyl leukotriene. Cysteinyl leukotrienes (CysLTs) are a family of potent inflammatory mediators that appear to contribute to the pathophysiologic features of allergic rhinitis. Nasal blockage induced by CysLTs is mainly due to dilatation of nasal blood vessels, which can be induced by the nitric oxide produced through CysLT1 receptor activation. LTE4, activate contractile and inflammatory processes via specific interaction with putative seven transmembrane-spanning receptors that couple to G proteins and subsequent intracellular signaling pathways. LTE4 is metabolized from leukotriene C4 in a reaction catalyzed by gamma-glutamyl transpeptidase and a particulate dipeptidase from kidney. (PMID: 12607939, 12432945, 6311078)
N-Acetyl-leukotriene E4
N acetyl LTE4 is a minor metabolite of Leukotriene E4 in normal human subjects. (PMID: 2174886) [HMDB] N acetyl LTE4 is a minor metabolite of Leukotriene E4 in normal human subjects. (PMID: 2174886).
20-oxo-leukotriene B4
20-oxo-leukotriene B4 is the metabolite of lipid omega-oxidation of leukotriene B4 (LTB4). LTB4 is the major metabolite in neutrophil polymorphonuclear leukocytes. Omega-oxidation is the major pathway for the catabolism of leukotriene B4 in human polymorphonuclear leukocytes. Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of 5-LO to the perinuclear region, and phosphorylation to either enhance or inhibit the activity of 5-LO. Biologically active LTB4 is metabolized by omega-oxidation carried out by specific cytochrome P450s (CYP4F) followed by beta-oxidation from the omega-carboxy position and after CoA ester formation (PMID: 7649996, 17623009, 2853166, 6088485). Leukotrienes are eicosanoids. The eicosanoids consist of the prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and lipoxins (LXs). The PGs and TXs are collectively identified as prostanoids. Prostaglandins were originally shown to be synthesized in the prostate gland, thromboxanes from platelets (thrombocytes), and leukotrienes from leukocytes, hence the derivation of their names. All mammalian cells except erythrocytes synthesize eicosanoids. These molecules are extremely potent, able to cause profound physiological effects at very dilute concentrations. All eicosanoids function locally at the site of synthesis, through receptor-mediated G-protein linked signalling pathways. 20-oxo-leukotriene B4 is the metabolite of lipid omega-oxidation of leukotriene B4 (LTB4). LTB4 is the major metabolite in neutrophil polymorphonuclear leukocytes. Omega-oxidation is the major pathway for the catabolism of leukotriene B4 in human polymorphonuclear leukocytes. Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of 5-LO to the perinuclear region and phosphorylation to either enhance or inhibit the activity of 5-LO. Biologically active LTB4 is metabolized by w-oxidation carried out by specific cytochrome P450s (CYP4F) followed by beta-oxidation from the w-carboxy position and after CoA ester formation. (PMID: 7649996, 17623009, 2853166, 6088485)
