Leukotriene Synthesis Inhibitor Research Articles

Emerging Anti-inflammatory Therapies for Atherosclerosis

Atherosclerosis remains one of the main causes of cardiovascular disease, which is the leading cause of death worldwide. It is now accepted that atherosclerosis is an inflammatory, dynamic and complex disease involving multiple cell types, and many antiinflammatory strategies have recently emerged as potential therapeutic approaches for atherosclerotic disease. In this review, we discuss the most recent progress in the development of anti-inflammatory strategies. We highlight the beneficial effects of potent antiinflammatory drugs, including recently developed biologics, and we describe diverse emerging approaches that target inflammatory processes involved in atherosclerosis including tumor necrosis factor antagonists, anti-interleukins, viral-derived serpins, P-selectin inhibition and leukotriene synthesis inhibition.

Inhibition of renal cyst progression by montelukast: an in vitro study in MDCK cells

Renal cyst enlargement especially in polycystic kidney disease (PKD) is driven by P2Y receptor‐mediated and cAMP‐mediated chloride secretion into cyst lumen. This study aimed to determine the effect of an anti‐asthmatic drug montelukast, cysteinyl leukotriene (CysLT) 1 receptor antagonist, on renal cyst progression and to investigate underlying mechanisms of such an effect. In MDCK cyst model, montelukast (50 μM) inhibited forskolin‐induced cyst growth and cyst formation by 80%. This effect was not reversed by leukotriene D4 co‐incubation. In addition, zileuton, an inhibitor of leukotriene synthesis, had no effect on cyst growth. As analyzed by short‐circuit current measurements, acute treatment with montelukast (50 μM) inhibited ATP (P2Y agonist)‐induced chloride secretion by 50%, with no effect on cAMP‐induced chloride secretion. Similarly, prolonged treatment with montelukast (50 μM, 24 h) significantly inhibited ATP‐induced chloride secretion. Furthermore, montelukast had no effect on cell viability. Our study indicates that montelukast inhibits MDCK cyst progression by attenuating purinergic signaling in these cells. Therefore, montelukast represents a promising candidate drug for PKD therapy.This work was supported by the Faculty of Science and Medical Scholars Program, Mahidol University.

A Randomized, Comparative, Multicentric Clinical Trial to Assess the Efficacy and Safety of Zileuton Extended-Release Tablets With Montelukast Sodium Tablets in Patients Suffering From Chronic Persistent Asthma

Leukotriene (LT) modifiers are anti-inflammatory drugs that are useful as an add-on therapy with first-line asthma-controller medications. This group includes LT synthesis inhibitors (eg, Zileuton) and receptor antagonists (eg, Montelukast), whose direct comparative clinical data are not available. This study was conducted to assess the comparative efficacy and safety of orally administered Zileuton extended-release (ER) with Montelukast sodium in patients suffering from chronic persistent asthma. Patients of 18-65 years of age with mild to moderate chronic stable asthma were randomized to treatment with Zileuton ER 2400 mg/d or Montelukast 10 mg/d for 12 weeks. Peak expiratory flow rate (PEFR) and asthma symptoms (cough, wheeze, chest tightness, and shortness of breath each on a 4-point scale) were assessed on monthly scheduled out-patient visits. Safety assessments by clinical and laboratory parameters were carried out during the course of the study. Among 210 patients eligible for efficacy assessment, PEFR improved by 64.8 ± 52.8 (95% confidence interval: 54.8-74.7) L/min with Zileuton ER (n = 109) and 40.6 ± 47.5 (31.3-49.9) L/min with Montelukast (n = 101; P < 0.001), whereas percent improvements were 27.0% (22.6%-31.5%) versus 18.4% (14.1%-22.7%), respectively (P = 0.006). Zileuton ER lead to ≥12% PEFR improvements in 74 of 109 [67.9% (59.1%-76.7%)] patients, whereas the same was noted in 52 of 101 [51.5% (41.7%-61.2%)] patients receiving Montelukast (P = 0.015). The reduction in the mean overall symptom intensity score was also significantly better with Zileuton ER [-5.0 ± 2.1 (4.6-5.4) versus -4.2 ± 2.3 (3.8-4.7)] (P = 0.018); however, the same was not observed for the decline in the individual symptom scores. A lesser but not significantly different adverse event rate was reported in the Zileuton ER group than the Montelukast group with the commonest events being headache and gastrointestinal effects in both the groups. Thus, Zileuton ER seems to be more efficacious than Montelukast and well tolerated for the treatment of mild to moderate chronic persistent asthma in adult patient population. Further studies can elucidate the comparative treatment benefits of these LT modifiers in asthma management.

The role of PAF/PAFR signaling in zymosan-induced articular inflammatory hyperalgesia

Platelet-activating factor (PAF) and its receptor (PAFR) have been shown to be involved in several inflammatory events, including neutrophil chemoattraction and nociception. The present study addressed the role of PAF in the genesis of articular hyperalgesia in a model of joint inflammation. Zymosan-induced articular hyperalgesia, oedema and neutrophil migration were dose-dependently reduced following pretreatment with selective PAFR antagonists, UK74505 (5, 10 and 20mg/kg) and PCA4248 (3, 10, 30mg/kg). These parameters were also reduced in PAF receptor-deficient mice (PAFR(-/-)). The hyperalgesic action of PAF was further confirmed by the demonstration that joint injection of PAF induces a dose- (0.3, 1 and 3μg/joint), time- and PAFR-dependent articular hyperalgesia and oedema. The PAF hyperalgesic mechanisms were dependent on prostaglandins, leukotrienes and neutrophils, as PAF-induced articular hyperalgesia was inhibited by indomethacin (COX inhibitor), MK886 (leukotrienes synthesis inhibitor) or fucoidan (leukocyte rolling inhibitor). Furthermore, PAF-induced hyperalgesia was reduced in 5-lypoxigenase-null mice. In corroboration of these findings, intra-articular injection of PAF promotes the production of LTB(4) as well as the recruitment of neutrophils to the joint. These results suggest that PAF may participate in the cascade of events involved in the genesis of articular inflammatory hyperalgesia via stimulation of prostaglandins, leukotrienes and neutrophil migration. Finally, targeting PAF action (e.g., with a PAFR antagonist) might provide a useful therapeutic approach to inhibit articular inflammatory hyperalgesia.

Synthesis and pharmacokinetic profile of rhein- boswellic acid conjugate

Rhein, an active metabolite of diacerein, down-regulates the gene-expression and production of pro-matrix metalloproteinases and up-regulates the tissue inhibitors of metalloproteinase-1 production. The therapeutic effects of diacerein on osteoarthritis are, at least in part, due to the chondroprotective effect of rhein. Boswellic acid is a specific, non-redox inhibitor of leukotriene synthesis. It is claimed to possess good anti-inflammatory, anti-arthritic, analgesic, and anti-ulcer activities. It prevents the destruction of articular cartilage by decreasing degradation of glycosaminoglycans. Therefore, rhein and boswellic acid were linked chemically through a bioreversible ester linkage to synthesize their mutual prodrug by reported procedure. In vitro release profile of this prodrug was extensively studied in aqueous buffers of varied pH, upper GIT homogenates and 80% human plasma. In vivo release studies were undertaken in blood, urine and feces of rats. The prodrug was stable in HCl buffer (pH 1.2) and stomach homogenates of rats. However; in phosphate buffer (pH 7.4) and in intestinal homogenates the prodrug exhibited 91% and 96% release of rhein and 27.5% and 38% release of boswellic acid respectively over a period of 6h following first order kinetics. In 80% human plasma (in vitro) and rat blood (in vivo) also 96.35% and 91% release of rhein and 78% and 86.41% release of boswellic acid respectively was observed. The 24h pooled samples of rat urine revealed presence of 6.2% intact prodrug, 7.1% of rhein and 8.9% of boswellic acid indicating their renal excretion. Samples of rat feces pooled over a period of 24h showed absence of rhein and presence of 3.1% of intact boswellic acid and 4.6% of boswellic acid emphasizing their intestinal excretion. The in vivo release kinetics of prodrug in rat clearly indicated activation of prodrug to be occurring in blood, being catalyzed by the weak alkaline pH of blood (7.4) in combination with esterases present therein.

An inhibitor of leukotriene synthesis affects vasopressin secretion following osmotic stimulus in rats

Previous studies revealed the presence of LTC4 synthase in paraventricular vasopressinergic neurons, suggesting a role for leukotrienes (LTs) in certain neuroendocrine system functions. Our aim was to study the effect of an inhibitor of LT synthesis in the release of arginine vasopressin (AVP) following an osmotic stimulus in rats. Male Wistar rats received an intra-cerebroventricular injection of 2μl of the LT synthesis inhibitor MK-886 (1, 2, or 4μg/kg), or vehicle (DMSO 5%), 1h before an intraperitoneal injection of hypertonic saline (NaCl 2M) or isotonic saline (NaCl 0.01M) in a volume corresponding to 1% of body weight. Thirty minutes after the osmotic stimulus, the animals were decapitated and blood was collected for determining hematocrit, plasma osmolality and plasma AVP levels. As expected, the injection of hypertonic saline significantly increased (P<0.05) the hematocrit, plasma osmolality and plasma AVP levels. While inhibiting LT synthesis by central administration of MK-886 did not cause any additional increase in hematocrit or osmolality, plasma AVP levels were augmented (P<0.05). We conclude that central leukotrienes may have a modulatory role in AVP secretion following an osmotic stimulus, this deserving future studies.

Aspirin Exacerbated Respiratory Disease

Aspirin Exacerbated Respiratory Disease

Identification of novel benzimidazole derivatives as inhibitors of leukotriene biosynthesis by virtual screening targeting 5-lipoxygenase-activating protein (FLAP)

Pharmacological suppression of leukotriene biosynthesis by 5-lipoxygenase (5-LO)-activating protein (FLAP) inhibitors is a promising strategy to intervene with inflammatory, allergic and cardiovascular diseases. Virtual screening targeting FLAP based on a combined ligand- and structure-based pharmacophore model led to the identification of 1-(2-chlorobenzyl)-2-(1-(4-isobutylphenyl)ethyl)-1H-benzimidazole (7) as developable candidate. Compound 7 potently suppressed leukotriene formation in intact neutrophils (IC50=0.31μM) but essentially failed to directly inhibit 5-LO suggesting that interaction with FLAP causes inhibition of leukotriene synthesis. For structural optimization, a series of 46 benzimidazole-based derivatives of 7 were synthesized leading to more potent analogues (70–72, 82) with IC50=0.12–0.19μM in intact neutrophils. Together, our results disclose the benzimidazole scaffold bearing an ibuprofen fingerprint as a new chemotype for further development of anti-leukotriene agents.

Influence of adjuvant-induced arthritis on the action of extracellular NAD+ on hepatic gluconeogenesis and related parameters

The influence of arthritis on some metabolic and hemodynamic effects of extracellular NAD+ was investigated in the perfused liver of Holtzman rats with the additional purpose of comparing the present results with previous results obtained with rats from the Wistar strain. Fasted rats were used and glucose plus pyruvate productions from lactate and the associated oxygen uptake increment were measured as well as the portal perfusion pressure. Livers from arthritic rats presented higher transient increments in perfusion pressure upon NAD+ infusion. The metabolic effects of NAD+ consisted in initial inhibitions of glucose and pyruvate production and oxygen uptake, followed by recovery and stimulation. In the arthritis condition, the inhibitions were more accentuated in relative terms and also more persistent in time, but the subsequent stimulations were smaller or even absent. The inhibitory phase was almost abolished by indomethacin, inhibitor of eicosanoid synthesis, but not by nordihydroguaiaretic acid, an inhibitor of leukotriene synthesis. In comparison with Wistar rats, the response to NAD+ of the liver from Holtzman rats in antegrade perfusion was characterized by a shorter and less intense inhibitory phase and by a more vigorous stimulation. In retrograde perfusion, however, where stimulation was the only effect, there was no difference between both strains. This observation suggests that the more accentuated stimulation in Holtzman rats could be the consequence of a short and less intense inhibitory phase. The stronger and more persistent inhibitions of gluconeogenesis and oxygen uptake as well as the enhanced portal pressure increase in the arthritis condition are consistent with an accentuated capacity of producing eicosanoids by animals under the influence of the disease.

Advances in upper airway diseases and allergen immunotherapy in 2011

The purpose of this review is to highlight recently published important articles on upper airway diseases and allergen immunotherapy. We review articles on rhinitis, sinusitis, conjunctivitis, and immunotherapy. New insights into epidemiology, pathophysiology, diagnosis, and therapy are described for each of the above diseases.

Leukotriene Inhibitors in Sinusitis.

It has been recognized for many years that leukotrienes play an important role in mediating various effects of the allergic reaction. Recent evidence has shown that they play a role in other diseases including chronic sinusitis, particularly those sub-types involving eosinophils. Leukotrienes can be separated into the fairly well characterized cysteinyl leukotrienes and less well characterized leukotriene B(4). Effects of the leukotrienes are mediated through receptors that are expressed on a variety of cell types and can be modulated based on the inflammatory environment present. The pharmaceutical industry has long been interested in blocking leukotriene action and as such, two approaches have been developed that led to drugs approved for treatment of allergic disease. The most widely used class is the cysteinyl type 1 receptor antagonists, which block binding of the cysteinyl leukotrienes to the cell. The second class is an inhibitor of the 5-lipoxygenase enzyme that prevents synthesis of both the cysteinyl leukotrienes and leukotriene B(4). This review will focus on the role that leukotrienes play in chronic sinusitis and consider the rationale for choosing either a leukotriene antagonist or synthesis inhibitor as a treatment option. We will also discuss off-label uses for other medications that might be useful in these diseases as they relate to their ability to modulate leukotriene action.

Le syndrôme de Sjögren-Larsson : à propos de 2 cas

Sjögren-Larsson syndrome (SLS) is a neurocutaneous autosomal recessive disease caused by fatty aldehyde dehydrogenase (FADH) deficiency. This enzyme is involved in the biosynthesis pathways of some fatty acids, phytanic acid, and leukotrienes. The main features of the disease are its association with congenital ichthyosis, mental retardation, and spastic tetraplegia. We report on the diagnostic and therapeutic management of 2 cases of SLS. The diagnosis of SLS was suspected in the first patient at 2 years of age before the clinical triad appeared and confirmed at 4 years of age by the culture of fibroblasts and the peak of lipids on 1.3 ppm spectroscopy. After 3 months of treatment with zileuton, an inhibitor of leukotriene synthesis, moderate clinical efficacy for pruritus and ichthyosis was observed. The second patient was diagnosed at 1 year of age with the association of psychomotor retardation and congenital ichthyosis, in accordance with acute Guillain-Barré syndrome. Diagnosis was confirmed with enzymology, and cerebral spectro-MRI featured an abnormal lipidic peak. Zileuton therapy was initiated at the time of diagnosis and was effective for pruritus after 6 months of treatment. We report 2 cases of SLS with delayed diagnosis, due to non neonatal symptoms. Treatment with zileuton shows partial efficacy especially in pruritus. The uncommon association of this rare dysmyelinating disease with Guillain-Barré syndrome in the second patient is discussed.

Leukotriene synthesis inhibitor decreases vasopressin release in the early phase of sepsis

The aim was to analyze the effect of leukotriene synthesis inhibitor administered intraperitoneally in vasopressin release during sepsis. Male Wistar rats received injections of MK-886 (1.0, 2.0 or 4.0mg/kg) or vehicle (DMSO 5%) 1h before cecal ligation and puncture. There was some variation on the survival rate depending on the dose used but the drug did not modify the hematocrit, osmolality, serum sodium and nitrate, plasma protein, and neutrophil recruitment, in any dose. Nevertheless, vasopressin (AVP) release decreased in a dose–response manner in the early phase of sepsis. These results support the suggestion that leukotrienes (LTs) are involved in AVP release during sepsis.

2‐(4‐(Biphenyl‐4‐ylamino)‐6‐chloropyrimidin‐2‐ylthio)octanoic acid (HZ52) – a novel type of 5‐lipoxygenase inhibitor with favourable molecular pharmacology and efficacy in vivo

5-Lipoxygenase (5-LO) is the key enzyme in the biosynthesis of pro-inflammatory leukotrienes (LTs) representing a potential target for pharmacological intervention with inflammation and allergic disorders. Although many LT synthesis inhibitors are effective in simple in vitro test systems, they frequently fail in vivo due to lack of efficacy. Here, we attempted to assess the pharmacological potential of the previously identified 5-LO inhibitor 2-(4-(biphenyl-4-ylamino)-6-chloropyrimidin-2-ylthio)octanoic acid (HZ52). We evaluated the efficacy of HZ52 in vivo using carrageenan-induced pleurisy in rats and platelet-activating factor (PAF)-induced lethal shock in mice. We also characterized 5-LO inhibition by HZ52 at the cellular and molecular level in comparison with other types of 5-LO inhibitor, that is, BWA4C, ZM230487 and hyperforin. HZ52, 1.5 mg·kg⁻¹ i.p., prevented carrageenan-induced pleurisy accompanied by reduced LTB(4) levels and protected mice (10 mg·kg⁻¹, i.p.) against PAF-induced shock. Detailed analysis in cell-based and cell-free assays revealed that inhibition of 5-LO by HZ52 (i) does not depend on radical scavenging properties and is reversible; (ii) is not impaired by an increased peroxide tone or by elevated substrate concentrations; and (iii) is little affected by the cell stimulus or by phospholipids, glycerides, membranes or Ca²⁺. HZ52 is a promising new type of 5-LO inhibitor with efficacy in vivo and with a favourable pharmacological profile. It possesses a unique 5-LO inhibitory mechanism different from classical 5-LO inhibitors and seemingly lacks the typical disadvantages of former classes of LT synthesis blockers.

Plasmin Inhibitors Prevent Leukocyte Accumulation and Remodeling Events in the Postischemic Microvasculature

Clinical trials revealed beneficial effects of the broad-spectrum serine protease inhibitor aprotinin on the prevention of ischemia-reperfusion (I/R) injury. The underlying mechanisms remained largely unclear. Using in vivo microscopy on the cremaster muscle of male C57BL/6 mice, aprotinin as well as inhibitors of the serine protease plasmin including tranexamic acid and ε-aminocaproic acid were found to significantly diminish I/R-elicited intravascular firm adherence and (subsequent) transmigration of neutrophils. Remodeling of collagen IV within the postischemic perivenular basement membrane was almost completely abrogated in animals treated with plasmin inhibitors or aprotinin. In separate experiments, incubation with plasmin did not directly activate neutrophils. Extravascular, but not intravascular administration of plasmin caused a dose-dependent increase in numbers of firmly adherent and transmigrated neutrophils. Blockade of mast cell activation as well as inhibition of leukotriene synthesis or antagonism of the platelet-activating-factor receptor significantly reduced plasmin-dependent neutrophil responses. In conclusion, our data suggest that extravasated plasmin(ogen) mediates neutrophil recruitment in vivo via activation of perivascular mast cells and secondary generation of lipid mediators. Aprotinin as well as the plasmin inhibitors tranexamic acid and ε-aminocaproic acid interfere with this inflammatory cascade and effectively prevent postischemic neutrophil responses as well as remodeling events within the vessel wall.

Leukotrienes are not essential for the efficacy of a heterologous vaccine against Mycobacterium tuberculosis infection

Leukotrienes are reported to be potent proinflammatory mediators that play a role in the development of several inflammatory diseases such as asthma, rheumatoid arthritis and periodontal disease. Leukotrienes have also been associated with protection against infectious diseases. However, the role of leukotrienes in Mycobacterium tuberculosis infection is not understood. To answer this question, we studied the role of leukotrienes in the protective immune response conferred by prime-boost heterologous immunization against tuberculosis. We immunized BALB/c mice (4-11/group) with subcutaneous BCG vaccine (1 x 10(5) M. bovis BCG) (prime) followed by intramuscular DNA-HSP65 vaccine (100 microg) (boost). During the 30 days following the challenge, the animals were treated by gavage daily with MK-886 (5 mg x kg(-1) x day(-1)) to inhibit leukotriene synthesis. We showed that MK-886-treated mice were more susceptible to M. tuberculosis infection by counting the number of M. tuberculosis colony-forming units in lungs. The histopathological analysis showed an impaired influx of leukocytes to the lungs of MK-886-treated mice after infection, confirming the involvement of leukotrienes in the protective immune response against experimental tuberculosis. However, prime-boost-immunized mice treated with MK-886 remained protected after challenge with M. tuberculosis, suggesting that leukotrienes are not required for the protective effect elicited by immunization. Protection against M. tuberculosis challenge achieved by prime-boost immunization in the absence of leukotrienes was accompanied by an increase in IL-17 production in the lungs of these animals, as measured by ELISA. Therefore, these data suggest that the production of IL-17 in MK-886-treated, immunized mice could contribute to the generation of a protective immune response after infection with M. tuberculosis.

Impaired phagocytosis by alveolar macrophages from diabetic rats is related to the deficient coupling of LTs to the FcγR signaling cascade

Diabetic individuals are more susceptible to infections and this seems to be related to impaired phagocyte function. Alveolar macrophages (AMs) are the first barrier to prevent respiratory infections. Leukotrienes (LTs) increase AM phagocytic activity via FcγR. In this study, we compared AMs from diabetic and non-diabetic rats for phagocytosis via FcγR and the roles of LTs and insulin. Diabetes was induced in male Wistar rats by alloxan (42 mg/kg, i.v.); macrophages were obtained by bronchoalveolar lavage and IgG-opsonised sheep red blood cells (IgG-SRBC) were used as targets. LTs were added to the AMs 5 min before the addition of IgG-SRBC. AMs were treated with a LT synthesis inhibitor (zileuton, 10 μM), or antagonists of the LTB 4 receptor (CP105.696, 10 μM) or cys-LT receptor (MK571, 10 μM), 30 or 20 min before the addition of IgG-SRBC, respectively. We found that the phagocytosis of IgG-SRBC by AMs from diabetic rats is impaired compared with non-diabetic rats. Treatment with the LT inhibitor/antagonists significantly reduced AM phagocytosis in non-diabetic but not diabetic rats. During the phagocytosis of IgG-SRBC LTB 4 and LTC 4 were produced by AMs from both groups. The addition of exogenous LTB 4 or LTD 4 potentiated phagocytosis similarly in both groups. Phagocytosis was followed by the phosphorylation of PKC-δ, ERK and Akt. This was reduced by zileuton treatment in AMs from non-diabetic but not diabetic rats. The addition of insulin to AMs further increased the phagocytosis by increasing PKC-δ phosphorylation. These results suggest that the impaired phagocytosis found in AMs from diabetic rats is related to a deficient coupling of LTs to the FcγR signaling cascade and that insulin has a key role in this coupling. An essential role for insulin in innate immunity is suggested.

Regulation of TNFα and IL1β in rheumatoid arthritis synovial fibroblasts by leukotriene B4

Arachidonic acid metabolites, such as leukotriene B4 (LTB4), are known to play an important role in pathogenesis of rheumatoid arthritis (RA). Apart from leukocytes, RA synovial fibroblasts (RASF) produce a broad array of inflammatory mediators to recruit, retain and activate immune cells and resident mesenchymal cells in the joints to promote ongoing inflammation and tissue destruction. To determine how LTB4 may contribute to this process, RASF was cultured from synovial tissues collected from RA patients undergoing total knee replacement. The level of LTB4 in culture medium was determined using ELISA, and expression of LTB4 receptors (BLT1 and BLT2) by RT-PCR. In the presence of exogenous LTB4, mRNA and protein levels of tumor necrosis factor-alpha (TNFalpha) and interleukin 1beta (IL1beta) were determined by real-time PCR and ELISA. Furthermore, we examined the effects of leukotrienes synthesis inhibitors, MK886 and bestatin, on mRNA and protein levels of TNFalpha and IL1beta in RASF. We found that LTB4 was present at a low concentration in the culture medium of RASF, and the major LTB4 receptor expressed in RASF was BLT2. LTB4 synthesis was activated by treatment with LIT (LPS, ionomycin and thapsogargin), and suppressed by MK886 and bestatin. Exogenous LTB4 remarkably increased the expression of TNFalpha and IL1beta at both the mRNA level and the protein level. In contrast, MK886 and bestatin significantly inhibited their expression. These data suggested that LTB4 contributed to RA by regulating the expression of TNFalpha and IL1beta in RASF. BLT2 was probably the major receptor mediating such effects.

5-Lipoxygenase-Activating Protein Inhibitors: Development of 3-[3-tert-Butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid (AM103)

The potent and selective 5-lipoxygenase-activating protein leukotriene synthesis inhibitor 3-[3-tert-butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid (11j) is described. Lead optimization was designed to afford compounds with superior in vitro and in vivo inhibition of leukotriene synthesis in addition to having excellent pharmacokinetics and safety in rats and dogs. The key structural features of these new compounds are incorporation of heterocycles on the indole N-benzyl substituent and replacement of the quinoline group resulting in compounds with excellent in vitro and in vivo activities, superior pharmacokinetics, and improved physical properties. The methoxypyridine derivative 11j has an IC(50) of 4.2 nM in a 5-lipoxygenase-activating protein (FLAP) binding assay, an IC(50) of 349 nM in the human blood LTB(4) inhibition assay, and is efficacious in a murine ovalbumin model of allergen-induced asthma. Compound 11j was selected for clinical development and has successfully completed phase 1 trials in healthy volunteers.

Inhibitors of the 5-Lipoxygenase Pathway in Atherosclerosis

The inflammatory environment within the atherosclerotic lesion stimulates the 5-lipoxygenase pathway of arachidonic acid metabolism, leading to the biosynthesis of the potent lipid inflammatory mediators leukotrienes. The present review summarizes the components of this pathway; the enzymes 5-lipoxygenase (5-LO, ALOX5) with its activating protein, FLAP (ALOX5AP), LTA(4) hydrolase and LTC(4) synthase, as well as the receptors for leukotriene B(4) (BLT(1) and BLT(2)) and cysteinyl-leukotrienes (CysLT(1) and CysLT(2)), respectively. Genetic variations within the genes encoding these proteins have been associated with cardiovascular risk. Inhibiting the 5-lipoxygenase pathway through either leukotriene synthesis inhibitors or leukotriene receptor antagonists in experimental models of atherosclerosis has however generated contradictory results. Several inhibitors of the 5-lipoxygenase pathway are now evaluated in clinical trials of patients with cardiovascular disease.