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ABSTRACT: Microsomal prostaglandin E(2) synthase-1 (mPGES-1) is an enzyme, which is induced during the inflammatory response. Therefore, inhibitors of this enzyme are considered to be potential anti-inflammatory drugs. We have identified 3-(4-dodecanoyl-1,3,5-trimethylpyrrol-2-yl)propionic acid (12) as submicromolar inhibitor of mPGES-1. Surprisingly, structural variations made around this lead only resulted in a relatively small change of enzyme inhibitory potency. Such flat structure-activity relationships are reported to be typical for so called nuisance inhibitors, which exert their action not by directly binding to the enzyme, but by forming colloid-like aggregates at micromolar and sometimes submicromolar concentrations, which somehow sequester and inhibit enzyme targets without specificity. Since aggregate-based inhibition is highly sensitive to non-ionic detergents such as Triton X-100, we investigated some of our compounds for inhibition of human recombinant mPGES-1 also in presence of this detergent. The pyrrole derivatives 12, 67 and 81, which exhibited IC(50) values in absence of Triton X-100 in the range of 0.1 and 1μM, were virtually inactive at the highest test concentration of 10μM when 0.1% of the detergent was added. In the same way, the published mPGES-1 inhibitor 2-[(4-{[(1,1'-biphenyl)-4-ylmethyl]amino}-6-chloropyrimidin-2-yl)thio]octanoic acid (Cay10589) (6) totally lost its activity under these conditions. Therefore, these compounds have to be judged as nuisance inhibitors of the enzyme. In contrast, the known indole derivative 3-[3-(tert-butylthio)-1-(4-chlorobenzyl)-5-isopropylindol-2-yl]-2,2-dimethylpropionic acid (MK-886) (2) showed a considerable activity (75% inhibition at 10μM) also in the presence of Triton X-100.
European journal of medicinal chemistry 12/2011; 48:153-63. · 3.27 Impact Factor
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ABSTRACT: Indole-5-carboxylic acids with 3-aryloxy-2-oxopropyl residues in position 1 were previously reported to be potent inhibitors of human cytosolic phospholipase A(2)alpha (cPLA(2)alpha). In continuation of our attempts to develop clinical active cPLA(2)alpha inhibitors, a series of structurally related indole-5-carboxylic acids with reduced lipophilicity was synthesized and tested for cPLA(2)alpha-inhibitory potency. Furthermore, the thermodynamic solubility of these compounds and their metabolic stability in rat liver microsomes were evaluated. With an IC(50) of 0.012 microM against the isolated enzyme, compound 36 was one of the most potent cPLA(2)alpha inhibitors that emerged during the structure-activity relationship study. Concomitantly, 36 possessed the highest water solubility (212 microg/mL at pH 7.4) of all new target compounds. Despite these favorable properties, peroral application of 36 (100 mg/kg) in mice only led to low concentrations of the substance in blood plasma. A very high plasma clearance was observed after intravenous administration of 36 (10 mg/kg). However, in a topical murine model of contact dermatitis, 36 showed a pronounced anti-inflammatory in vivo activity.
Journal of Medicinal Chemistry 07/2010; 53(14):5165-78. · 4.80 Impact Factor
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Jörg Fabian
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ABSTRACT: A rapid, robust and selective on-line solid-phase extraction-liquid chromatographic method with ultra-violet detection (on-line SPE-LC-UV) for microsomal prostaglandin E(2) synthase-1 (mPGES-1) inhibitor screening was developed and validated. Disrupted A549 cells were used as mPGES-1 source and the formation of prostaglandin E(2) (PGE(2)) out of the substrate prostaglandin H(2) (PGH(2)) was determined at 195 nm. Direct on-line sample clean up was achieved by automated column switch (C18 trap column) prior isocratic separation using a C18 analytical column. The on-line SPE-LC-UV method was accurate, precise and reproducible in the range of 71-1763 ng/ml for PGE(2) and met the generally accepted criteria for bioanalytical methods. The method was successfully applied to determine the IC(50) value of the known mPGES-1 inhibitor NS-398.
Journal of Chromatography B 11/2008; 875(2):557-61. · 2.89 Impact Factor
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ABSTRACT: Indole-5-carboxylic acids with 3-aryloxy-2-oxopropyl residues in position 1 were previously reported to be potent inhibitors of cytosolic phospholipase A(2)alpha (cPLA(2)alpha) isolated from human platelets. In continuation of our attempts to develop novel cPLA(2)alpha inhibitors, a series of structurally related indole-2-carboxylic acids containing 3-aryloxy-2-oxopropoxy residues in position 5 were synthesized and tested for their cPLA(2)alpha-inhibitory potency. Furthermore, the thermodynamic solubility of these compounds and their metabolic stability against rat liver microsomes were evaluated.
Bioorganic & medicinal chemistry 05/2008; 16(7):3489-500. · 2.82 Impact Factor
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ABSTRACT: A nonradioactive spectrometric assay for the evaluation of inhibitors of phosphatidylinositol-specific phospholipase C (PI-PLC) is described. l-alpha-Phosphatidylinositol from bovine liver was used as substrate in the presence of the micelle-forming detergent deoxycholic acid. PI-PLC isolated from Bacillus cereus and crude cytosol fractions from porcine brain were used as enzyme sources. PI-PLC activity was determined by measuring the release of 1-stearoyl-2-arachidonoyl-sn-glycerol with reversed-phase HPLC and UV detection at 200 nm. PI-PLC from B. cereus was not inhibited by the putative PI-PLC inhibitors U-73122 and ET-18-OCH(3) at 100 microM, whereas the isobenzofuranone derivative 5 blocked the enzyme with an IC(50) of 75 microM. PI-PLC activity present in porcine brain cytosol was decreased by all three test compounds at 100 microM to approximately 30 to 50%.
Analytical Biochemistry 05/2008; 375(2):291-8. · 3.00 Impact Factor
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ABSTRACT: Inhibition of cytosolic phospholipase A(2)alpha (cPLA(2)alpha) is assumed to provide a novel therapeutic approach for the treatment of many inflammatory diseases. 1-[3-(4-Octylphenoxy)-2-oxopropyl]indole-5-carboxylic acid (2) is a potent inhibitor of cPLA(2)alpha. An important part of the pharmacophore of 2 is its activated electrophilic ketone moiety. Since it is known that activated ketones may be metabolically unstable, the metabolism of 2 by rat liver microsomes was investigated. For quantification of the metabolites normal-phase HPLC/UV on a cyano column was used, because under reversed-phase conditions with aqueous solvents 2 was partly transformed into its hydrate resulting in chromatograms with splitted peaks. Under the conditions applied about 30% of 2 were metabolized. The main metabolite was the alcohol 4 as shown by LC/MS(n).
Journal of Pharmaceutical and Biomedical Analysis 02/2007; 43(2):601-5. · 2.97 Impact Factor
