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Structure–Activity Relationship of Nonacidic Quinazolinone Inhibitors of Human Microsomal Prostaglandin Synthase 1 (mPGES 1)

Microsomal prostaglandin E synthase 1 (mPGES-1) is a key enzyme of the arachidonic acid cascade. Its product PGE(2) plays an important role in various inflammatory processes, pain, fever, and cancer. Selective inhibition of mPGES-1 might be a promising step to avoid cyclooxygenase-related effects of NSAIDs. We studied a class of quinazolinone derivatives of the lead structure FR20 for their effects on the isolated human and murine enzymes, human HeLa cells, and in various settings of the whole blood assay. Novel compounds with direct enzyme inhibiting activity in the submicromolar range (IC(50): 0.13-0.37 μM) were designed using a bioisosteric replacement strategy and proved to be effective in both cells and human whole blood. Furthermore, pharmacological profiling of toxicity and eicosanoid screening with LC/MS-MS was applied to characterize this new class of mPGES-1 inhibitors.

SAR-study on a new class of imidazo[1,2-a]pyridine-based inhibitors of 5-lipoxygenase.

A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridine scaffold, a cyclohexyl moiety and an aromatic system, is presented. This scaffold was identified in a virtual screening study and exhibits promising inhibitory potential on the 5-LO. Here, we investigate the structure-activity relationships of this compound class. With N-cyclohexyl-6-methyl-2-(4-morpholinophenyl)imidazo[1,2-a]pyridine-3-amine (14), we identified a potent 5-LO inhibitor (IC(50)=0.16μM (intact cells) and 0.1μM (cell-free)), which may possess potential as an effective lead compound intervening with inflammatory diseases and certain types of cancer.

Dual-target virtual screening by pharmacophore elucidation and molecular shape filtering.

Dual-target inhibitors gained increased attention in the past years. A novel in silico approach was employed for the discovery of dual 5-lipoxygenase/soluble epoxide hydrolase inhibitors. The ligand-based approach uses excessive pharmacophore elucidation and pharmacophore alignment in conjunction with shape-based scoring. The virtual screening results were verified in vitro, leading to nine novel inhibitors including a dual-target compound.

Molecular characterization of EP6—A novel imidazo[1,2-a]pyridine based direct 5-lipoxygenase inhibitor

5-Lipoxygenase (5-LO) is a crucial enzyme of the arachidonic acid (AA) cascade and catalyzes the formation of bioactive leukotrienes (LTs) which are involved in inflammatory diseases and allergic reactions. The pathophysiological effects of LTs are considered to be prevented by 5-LO inhibitors. In this study we present cyclohexyl-[6-methyl-2-(4-morpholin-4-yl-phenyl)-imidazo[1,2-a]pyridin-3-yl]-amine (EP6), a novel imidazo[1,2-a]pyridine based compound and its characterization in several in vitro assays. EP6 suppresses 5-LO activity in intact polymorphonuclear leukocytes with an IC(50) value of 0.16μM and exhibits full inhibitory potency in cell free assays (IC(50) value of 0.05μM for purified 5-LO). The efficacy of EP6 was not affected by the redox tone or the concentration of exogenous AA, characteristic drawbacks known for the class of nonredox-type 5-LO inhibitors. Furthermore, EP6 suppressed 5-LO activity independently of the cell stimulus or the activation pathway of 5-LO contrary to what is known for some nonredox-type inhibitors. Using molecular modeling and site-directed mutagenesis studies, we were able to derive a feasible binding region within the C2-like domain of 5-LO that can serve as a new starting point for optimization and development of new 5-LO inhibitors targeting this site. EP6 has promising effects on cell viability of tumor cells without mutagenic activity. Hence the drug may possess potential for intervention with inflammatory and allergic diseases and certain types of cancer including leukemia.

5-Lipoxygenase Is a Candidate Target for Therapeutic Management of Stem Cell–like Cells in Acute Myeloid Leukemia

Nonsteroidal anti-inflammatory drugs such as sulindac inhibit Wnt signaling, which is critical to maintain cancer stem cell-like cells (CSC), but they also suppress the activity of 5-lipoxygenase (5-LO) at clinically feasible concentrations. Recently, 5-LO was shown to be critical to maintain CSC in a model of chronic myeloid leukemia. For these reasons, we hypothesized that 5-LO may offer a therapeutic target to improve the management of acute myeloid leukemia (AML), an aggressive disease driven by CSCs. Pharmacologic and genetic approaches were used to evaluate the effects of 5-LO blockade in a PML/RARα-positive model of AML. As CSC models, we used Sca-1(+)/lin(-) murine hematopoietic stem and progenitor cells (HSPC), which were retrovirally transduced with PML/RARα. We found that pharmacologic inhibition of 5-LO interfered strongly with the aberrant stem cell capacity of PML/RARα-expressing HSPCs. Through small-molecule inhibitor studies and genetic disruption of 5-LO, we also found that Wnt and CSC inhibition is mediated by the enzymatically inactive form of 5-LO, which hinders nuclear translocation of β-catenin. Overall, our findings revealed that 5-LO inhibitors also inhibit Wnt signaling, not due to the interruption of 5-LO-mediated lipid signaling but rather due to the generation of a catalytically inactive form of 5-LO, which assumes a new function. Given the evidence that CSCs mediate AML relapse after remission, eradication of CSCs in this setting by 5-LO inhibition may offer a new clinical approach for immediate evaluation in patients with AML. Cancer Res; 74(18); 5244-55. ©2014 AACR.

Synthesis and structure-activity relationship studies of novel dual inhibitors of soluble epoxide hydrolase and 5-lipoxygenase.

Current research leads to the assumption that drugs affecting more than one target could result in a more efficient treatment of diseases and fewer safety concerns. Administration of drugs inhibiting only one branch of the arachidonic acid cascade is usually accompanied by side effects. We therefore designed and synthesized a library of hybrid molecules incorporating an imidazo[1,2-a]pyridine and an urea moiety as novel soluble epoxide hydrolase (sEH)/5-lipoxygenase (5-LO) dual inhibitors. Evaluation of the compounds was accomplished by in vitro testing using recombinant enzyme assays.

From a multipotent stilbene to soluble epoxide hydrolase inhibitors with antiproliferative properties.

Inspired by nature: Natural product isopropylstilbene was identified as an inhibitor of soluble epoxide hydrolase exhibiting antiproliferative properties. Following the natural product inspired design approach, a library of (E)-styryl-1H-benzo[d]imidazoles was synthesized and evaluated with recombinant enzyme and on several cancer cell lines.

Design and synthesis of dual modulators of soluble epoxide hydrolase and peroxisome proliferator-activated receptors.

Metabolic syndrome is a complex condition which often requires the use of multiple medications as a treatment. The resulting problems of polypharmacy are increase in side effects, drug-drug interactions, and its high economic cost. Development of multitarget compounds is a promising strategy to avoid the complications arising from administration of multiple drugs. Modulators of peroxisome proliferator-activated receptors (PPARs) are established agents in the treatment of dyslipidaemia, hyperglycaemia, and insulin resistance. Inhibitors of soluble epoxide hydrolase (sEH) are under evaluation for their use in cardiovascular diseases. In the present study, a series of dual sEH/PPAR modulators containing a pyrrole acidic headgroup and a urea pharmacophore were designed, synthesized, and evaluated in vitro using recombinant enzyme and cell-based assays. Compounds with different activity profiles were obtained which could be used in the treatment of metabolic syndrome.

Structure-activity relationship and in vitro pharmacological evaluation of imidazo[1,2-a]pyridine-based inhibitors of 5-LO.

BACKGROUND 5-LO is an important enzyme involved in the biosynthesis of leukotrienes, which are lipid mediators of immune and inflammation responses, with important roles in respiratory disease, cardiovascular disease, immune responses and certain types of cancer. Therefore, this enzyme has been investigated as a potential target for the treatment of these pathophysiological conditions. RESULTS 5-LO inhibitory potential was investigated in intact polymorphonuclear leukocytes, a cell-free assay, in human whole blood and rodent cells to both elucidate structure-activity relationships and in vitro pharmacological evaluation. Chemical modifications for lead optimization via straight forward synthesis was used to combine small polar groups, which led to a suitable candidate (IC50 [polymorphonuclear leukocytes] = 1.15 µM, IC50 [S100] = 0.29 µM) with desired in vitro biopharmaceutical profiles in terms of solubility (451.9 µg/ml) and intrinsic clearance without demonstrating any cytotoxicity. CONCLUSION Compound 9l is a novel, potent and selective 5-LO inhibitor with favorable preclinical drug-like properties.

Design of dual ligands using excessive pharmacophore query alignment

Dual- or multi-target ligands have gained increased attention in the past years due to several advantages, including more simple pharmacokinetic and phamarcodynamic properties compared to a combined application of several drugs. Furthermore multi-target ligands often possess improved efficacy [1]. We present a new approach for the discovery of dual-target ligands using aligned pharmacophore models combined with a shape-based scoring. Starting with two sets of known active compounds for each target, a number of different pharmacophore models is generated and subjected to pairwise graph-based alignment using the Kabsch-Algorithm [2,3]. Since a compound may be able to bind to different targets in different conformations, the algorithm aligns pairs of pharmacophore models sharing the same features which are not necessarily at the exactly same spatial distance. Using the aligned models, a pharmacophore search on a multi-conformation-database is performed to find compounds matching both models. The potentially “dual” ligands are scored by a shape-based comparison with the known active molecules using ShaEP [4]. Using this approach, we performed a prospective fragment-based virtual screening for dual 5-LO/sEH inhibitors. Both enzymes play an important role in the arachidonic acid cascade and are involved in inflammatory processes, pain, cardiovascular diseases and allergic reactions [5,6]. Beside several new selective inhibitors we were able to find a compound inhibiting both enzymes in low micromolar concentrations. The results indicate that the idea of aligned pharmacophore models can be successfully employed for the discovery of dual-target ligands.