The emerging pharmacological target soluble epoxide hydrolase (sEH) is a bifunctional enzyme exhibiting two different catalytic activities that are located in two distinct domains. Although the ...physiological role of the C-terminal hydrolase domain is well-investigated, little is known about its phosphatase activity, located in the N-terminal phosphatase domain of sEH (sEH-P). Herein we report the discovery and optimization of the first inhibitor of human and rat sEH-P that is applicable in vivo. X-ray structure analysis of the sEH phosphatase domain complexed with an inhibitor provides insights in the molecular basis of small-molecule sEH-P inhibition and helps to rationalize the structure-activity relationships. 4-(4-(3,4-Dichlorophenyl)-5-phenyloxazol-2-yl)butanoic acid (
, SWE101) has an excellent pharmacokinetic and pharmacodynamic profile in rats and enables the investigation of the physiological and pathophysiological role of sEH-P in vivo.
The soluble epoxide Hydrolase (sEH) is an emerging pharmacological target. The enzyme is an antiparallel homodimer, where each of the two subunits is composed of a C‐terminal hydrolase domain ...connected to an N‐terminal phosphatase domain by a proline‐rich linker. (Cronin et al. 2003) Although the physiological role of the hydrolase domain is well‐investigated (Harris und Hammock 2013, S. 61), little is known about the phosphatase activity. One of the main reasons for this is the lack of high‐affinity inhibitors, which can be used as chemical probes (Arrowsmith et al. 2015) to investigate its physiological role. In this paper, we present a new series of inhibitors for the human sEH‐phosphatase domain. Starting from an HTS hit Oxaprozin we expanded the SAR using a fluorescence‐based activity assay (Klingler et al. 2016). For one of the most potent inhbitors SWE101, we made ITC measurements to further characterize the interactions of the compound with the phosphatase. The compound binds with a Kd of 0.3 μM with balanced enthalpic and entropic contributions. In differential scanning fluorimetry (DSF) experiments a strong stabilizing effect of the two most potent inhibitors SWE101 and SWE102 on the phosphatase domain was visible, while there was only a slight effect on the stability of the hydrolase domain. These two inhibitors have been further tested on a number of potential lipid signaling targets including PPARα, PPARδ, PPARγ, FXR, RXRα, LXRα, LXRβ, COX 1, and COX 2. Additionally, we were able to co‐crystalize the phosphatase domain with one of our most potent inhibitors SWE102 under acidic conditions and without phosphate in the buffer. To our best knowledge, this study is the first description of the interactions of small‐molecule inhibitor with the N‐terminal domain of soluble epoxide hydrolase.
Support or Funding Information
German Research Foundation (DFG; SFB 1039 Teilprojekt A07; Heisenberg‐Professur PR 1405/4‐1)
X‐ray structure of N‐terminal domain of soluble epoxide hydrolase in complex with sEH‐phosphatase inhibitor SWE102.
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5-Lipoxygenase (5-LO, EC1.13.11.34) has been implicated in the pathogenesis of inflammatory and immune diseases. Recently, aminothiazole comprising inhibitors have been discovered for ...this valuable target. Yet, the molecular mode of action of this class of substances is only poorly understood. Here, we present the detailed molecular mechanism of action of the compound class and the in vitro pharmacological profile of two lead compounds ST-1853 and ST-1906. Mechanistic studies with recombinant proteins as well as intact cell assays enabled us to define this class as a novel type of 5-LO inhibitors with unique characteristics. The parent compounds herein presented a certain reactivity concerning oxidation and thiol binding: Unsubstituted aminophenols bound covalently to C159 and C418 of human 5-LO. Yet, dimethyl substitution of the aminophenol prevented this reactivity and slowed down phase II metabolism. Both ST-1853 and ST-1906 confirmed their lead likeness by retaining their high potency in physiologically relevant 5-LO activity assays, high metabolic stability, high specificity and non-cytotoxicity.
Leukotrienes are pivotal lipid mediators in various immune and inflammatory reactions. Herein, 5-LO is a validated target. 2-Aminothiazoles, as a privileged structure, implicate known 5-LO inhibitors ...like ST-1083 (IC50 polymorphonuclear leukocytes (PMNL) = 0.68 μM), yet deep structure-activity relationships (SAR) have not been established.
Compounds were synthesized via Hantzsch thiazole synthesis. Inhibitory activities were evaluated using intact PMNL and purified 5-LO together with cytotoxicity measurements in U937 cells.
We introduced novel functionalities at 2-, 3-, 4- and 5-position of the 2-aminothiazole scaffold and conducted bioisosteric replacement to optimize the parent scaffold. SARs of the 2-aminothiazole scaffold were deduced and extended primarily for inhibition of the 5-LO enzyme.
SAR studies provided at least two optimized leads (ST-1853, ST-1906) with high potency (IC50 polymorphonuclear leukocytes = 0.05 μM), specificity and noncytotoxic behavior.
A ceramic body with hierarchical meso–macro‐porosity was prepared by depositing a mesoporous silica coating on the walls of a macroporous silicon oxycarbide (SiOC) foam. Scanning electron microscopy, ...transmission electron microscopy, and small‐angle X‐ray scattering revealed that a uniform mesoporous coating was deposited on the walls of the macropores, with the mesopores arranged in a highly ordered cubic lattice. Nitrogen adsorption measurements showed a bimodal pore size distribution and revealed that the specific surface area is one order of magnitude higher than in macroporous SiOC foams. Therefore, interesting applications in adsorption and catalysis can be devised.
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