Structure-Based Design of Dual Partial Peroxisome Proliferator-Activated Receptor γ Agonists/Soluble Epoxide Hydrolase Inhibitors

Polypharmaceutical regimens often impair treatment of patients with metabolic syndrome (MetS), a complex disease cluster, including obesity, hypertension, heart disease, and type II diabetes. Simultaneous targeting of soluble epoxide hydrolase (sEH) and peroxisome proliferator-activated receptor γ (PPARγ) synergistically counteracted MetS in various in vivo models, and dual sEH inhibitors/PPARγ agonists hold great potential to reduce the problems associated with polypharmacy in the context of MetS. However, full activation of PPARγ leads to fluid retention associated with edema and weight gain, while partial PPARγ agonists do not have these drawbacks. In this study, we designed a dual partial PPARγ agonist/sEH inhibitor using a structure-guided approach. Exhaustive structure-activity relationship studies lead to the successful optimization of the designed lead. Crystal structures of one representative compound with both targets revealed potential points for optimization. The optimized compounds exhibited favorable metabolic stability, toxicity, selectivity, and desirable activity in adipocytes and macrophages.

RhII -Catalyzed De-symmetrization of Ethane-1,2-dithiol and Propane-1,3-dithiol Yields Metallo-β-lactamase Inhibitors

Diversity-oriented synthesis (DOS) is a rich source for novel lead structures in Medicinal Chemistry. In this study, we present a DOS-compatible method for synthesis of compounds bearing a free thiol moiety. The procedure relies on Rh(II)-catalyzed coupling of dithiols to diazo building blocks. The synthetized library was probed against metallo-β-lactamases (MBLs) NDM-1 and VIM-1. Biochemical and biological evaluation led to identification of novel potent MBL inhibitors with antibiotic adjuvant activity.

Dual Farnesoid X Receptor/Soluble Epoxide Hydrolase Modulators Derived from Zafirlukast

The nuclear farnesoid X receptor (FXR) and the enzyme soluble epoxide hydrolase (sEH) are validated molecular targets to treat metabolic disorders such as non-alcoholic steatohepatitis (NASH). Their simultaneous modulation in vivo has demonstrated a triad of anti-NASH effects and thus may generate synergistic efficacy. Here we report dual FXR activators/sEH inhibitors derived from the anti-asthma drug Zafirlukast. Systematic structural optimization of the scaffold has produced favorable dual potency on FXR and sEH while depleting the original cysteinyl leukotriene receptor antagonism of the lead drug. The resulting polypharmacological activity profile holds promise in the treatment of liver-related metabolic diseases.

Computer-Aided Selective Optimization of Side Activities of Talinolol

Selective optimization of side activities is a valuable source of novel lead structures in drug discovery. In this study, a computer-aided approach was used to deorphanize the pleiotropic cholesterol-lowering effects of the beta-blocker talinolol, which result from the inhibition of the enzyme soluble epoxide hydrolase (sEH). X-ray structure analysis of the sEH in complex with talinolol enables a straightforward optimization of inhibitory potency. The resulting lead structure exhibited in vivo activity in a rat model of diabetic neuropatic pain.

Gliotoxin from Aspergillus fumigatus Abrogates Leukotriene B4 Formation through Inhibition of Leukotriene A4 Hydrolase

The epidithiodioxopiperazine gliotoxin is a virulence factor of Aspergillus fumigatus, the most important airborne fungal pathogen of humans. Gliotoxin suppresses innate immunity in invasive aspergillosis, particularly by compromising neutrophils, but the underlying molecular mechanisms remain elusive. Neutrophils are the first responders among innate immune cells recruited to sites of infection by the chemoattractant leukotriene (LT)B₄ that is biosynthesized by 5-lipoxygenase and LTA₄ hydrolase (LTA₄H). Here, we identified gliotoxin as inhibitor of LTA₄H that selectively abrogates LTB₄ formation in human leukocytes and in distinct animal models. Gliotoxin failed to inhibit the formation of other eicosanoids and the aminopeptidase activity of the bifunctional LTA₄H. Suppression of LTB₄ formation by gliotoxin required the cellular environment and/or reducing conditions, and only the reduced form of gliotoxin inhibited LTA₄H activity. Conclusively, gliotoxin suppresses the biosynthesis of the potent neutrophil chemoattractant LTB₄ by direct interference with LTA₄H thereby impairing neutrophil functions in invasive aspergillosis.

A coupled fluorescence-based assay for the detection of protein arginine N-methyltransferase 6 (PRMT6) enzymatic activity

The protein arginine N-methyltransferase 6 (PRMT6) is overexpressed in a variety of different cancer types and plays a role in human immunodeficiency virus (HIV) infections. Furthermore, the PRMT6 activity might also influence the pathogenesis of neurodegenerative, inflammatory, and cardiovascular diseases, whereby it becomes an interesting target for drug development. Previously reported activity assays for PRMT6 activity are either expensive, time-consuming or use radioactive substrates. To overcome these challenges, we developed a coupled fluorescence-based activity assay using recombinant PRMT6 expressed in E. coli. In the first step of the assay, the fluorogenic substrate Nα-Benzoyl-L-arginine-7-amido-4-methylcoumarin (Bz-Arg-AMC) is methylated by PRMT6, while in a second step the remaining un-methylated substrate is cleaved by trypsin, producing the fluorescent 7-amino-4-methylcoumarin.

Rhabdopeptides as insect-specific virulence factors from entomopathogenic bacteria

Six novel linear peptides, named "rhabdopeptides", have been identified in the entomopathogenic bacterium Xenorhabdus nematophila after the discovery of the corresponding rdp gene cluster by using a promoter trap strategy for the detection of insect-inducible genes. The structures of these rhabdopeptides were deduced from labeling experiments combined with detailed MS analysis. Detailed analysis of an rdp mutant revealed that these compounds participate in virulence towards insects and are produced upon bacterial infection of a suitable insect host. Furthermore, two additional rhabdopeptide derivatives produced by Xenorhabdus cabanillasii were isolated, these showed activity against insect hemocytes thereby confirming the virulence of this novel class of compounds.

Structure and biosynthesis of fimsbactins A-F, siderophores from Acinetobacter baumannii and Acinetobacter baylyi

Novel chatechol/hydroxamate siderophores (named "fimsbactins") were identified in Acinetobacter baumannii ATCC 17978 and Acinetobacter baylyi ADP1. The major compound, fimsbactin A, was isolated from low-iron cultures of A. baylyi ADP1, and its chemical structure was elucidated by mass spectrometry, and detailed (1)H, (13)C and (15)N NMR spectroscopy. From inverse feeding experiments following HPLC-MS analysis, the structures of five additional derivatives were elucidated. The gene cluster encoding the fimsbactin synthetase (fbs) was identified in both genomes, and mutants in fbs genes in A. baylyi were analyzed, thus allowing prediction of the fimsbactin biosynthesis pathway.