Discovery and Evaluation of Enantiopure 9H-pyrimido[4,5-b]indoles as Nanomolar GSK-3ß Inhibitors with Improved Metabolic Stability.

Glycogen synthase kinase-3ß (GSK-3ß) is a potential target in the field of Alzheimer's disease drug discovery. We recently reported a new class of 9H-pyrimido[4,5-b]indole-based GSK-3ß inhibitors, of which 3-(3-((7-chloro-9H-pyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)propanenitrile (1) demonstrated promising inhibitory potency. However, this compound underwent rapid degradation by human liver microsomes. Starting from 1, we prepared a series of amide-based derivatives and studied their structure-activity relationships against GSK-3ß supported by 1 µs molecular dynamics simulations. The biological potency of this series was substantially enhanced by identifying the eutomer configuration at the stereocenter. Moreover, the introduction of an amide bond proved to be an effective strategy to eliminate the metabolic hotspot. The most potent compounds, (R)-3-(3-((7-chloro-9H-pyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)-3-oxopropanenitrile ((R)-2) and (R)-1-(3-((7-bromo-9Hpyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)propan-1-one ((R)-28), exhibited IC50 values of 480 nM and 360 nM, respectively, and displayed improved metabolic stability. Their favorable biological profile is complemented by minimal cytotoxicity and neuroprotective properties.

Discovery of potent p38α MAPK inhibitors through a funnel like workflow combining in silico screening and in vitro validation.

This work describes the rational discovery of novel chemotypes of p38α MAPK inhibitors using a funnel approach consisting of several computer-aided drug discovery methods and biological experiments. Among the identified hits, four compounds belonging to different chemical families showed IC50 values lower than 10 µM. In particular, the 1,4-benzodioxane derivative 5 turned out to be a potent and efficient p38α MAPK inhibitor having IC50 = 0.07 µM, and LEexp and LipE values of 0.38 and 4.8, respectively; noteworthy, the compound had also a promising kinase selectivity profile and the capability to suppress p38α MAPK effects in human immune cells. Overall, the collected findings highlight that the applied strategy has been successful in generating chemical novelty in the inhibitor kinase field, providing suitable chemical candidates for further inhibitor optimization.

Natural chromones as potential anti-inflammatory agents: Pharmacological properties and related mechanisms.

Chromones are a group of natural substances with a diversity of biological activities. Herein we assessed the pharmacological potential of three chromones (1, 2 and 3) isolated from Dictyoloma vandellianum as anti-inflammatory agents using in vitro and in vivo approaches. During in vitro screening, the production of NO and cytokines by macrophages stimulated with LPS and IFN-γ was inhibited by all chromones at concentrations (5-20 µM) that did not induce cytotoxicity. Analysis of pharmacokinetic parameters (in vitro half-life and intrinsic clearance) using human liver microsomes revealed that 3 has a superior pharmacokinetic profile, compared to 1 and 2. Treatment with 3 (100 mg/kg, ip) did not affect the mice motor performance, while 1 and 2 induced motor deficit. Taking into account the pharmacokinetic profile and absence of motor impairment, 3 was selected for further pharmacological characterization. Corroborating the data from in vitro screening, treatment of cell cultures with 3 (5-20 µM) reduced TNF-α, IL-6 and IL-1ß production by stimulated macrophages. In the complete Freund's adjuvant-induced paw inflammation model in mice, 3 (25 and 50 mg/kg, ip) inhibited mechanical hyperalgesia, edema and cytokine production/release (IL-1ß, IL-6 and TNF-α). 3 (5-20 µM) also reduced the transcriptional activity of NF-κB in stimulated macrophages. Furthermore, treatment with RU486, a glucocorticoid receptor (GR) antagonist, partially prevented the inhibitory effect of 3 on macrophages, indicating that this chromone exerts its anti-inflammatory effects in part through the activation of GR. The results presented herein demonstrate the pharmacological potential of natural chromones, highlighting 3 as a possible candidate for the drug discovery process targeting new anti-inflammatory drugs.

Development, Optimization, and Structure-Activity Relationships of Covalent-Reversible JAK3 Inhibitors Based on a Tricyclic Imidazo[5,4- d]pyrrolo[2,3- b]pyridine Scaffold.

Janus kinases are major drivers of immune signaling and have been the focus of anti-inflammatory drug discovery for more than a decade. Because of the invariable colocalization of JAK1 and JAK3 at cytokine receptors, the question if selective JAK3 inhibition is sufficient to effectively block downstream signaling has been highly controversial. Recently, we discovered the covalent-reversible JAK3 inhibitor FM-381 (23) featuring high isoform and kinome selectivity. Crystallography revealed that this inhibitor induces an unprecedented binding pocket by interactions of a nitrile substituent with arginine residues in JAK3. Herein, we describe detailed structure-activity relationships necessary for induction of the arginine pocket and the impact of this structural change on potency, isoform selectivity, and efficacy in cellular models. Furthermore, we evaluated the stability of this novel inhibitor class in in vitro metabolic assays and were able to demonstrate an adequate stability of key compound 23 for in vivo use.

Design and Development of Microsomal Prostaglandin E2 Synthase-1 Inhibitors: Challenges and Future Directions.

Microsomal prostaglandin E2 synthase (mPGES)-1 is responsible for the massive prostaglandin E2 (PGE2) formation during inflammation. Increasing evidence reveals mPGES-1 inhibitors as a safe alternative to nonsteroidal anti-inflammatory drugs. The first selective mPGES-1 inhibitors recently entered clinical trials. Major challenges for drug development have been the high plasma protein binding of lead structures, interspecies discrepancies, nuisance inhibition, sophisticated enzyme assays, and limited structural information about the mPGES-1 inhibitor binding site. Since most of these drawbacks could be solved during the past few years, we are standing at the threshold of a new era of mPGES-1-targeting anti-inflammatory drugs. This perspective introduces mPGES-1 as a key player within the network of eicosanoid biosynthesis and summarizes our current understanding of its structure and mechanism. Moreover, we present high-throughput and in silico screening techniques and discuss the structure-activity relationship and pharmacological potential of major mPGES-1 inhibitor classes in light of recent insights from pharmacophore models and cocrystallization studies.

Entada africana fraction CH2Cl2/MEOH 5% inhibits inducible nitric oxide synthase and pro-inflammatory cytokines gene expression induced by lipopolysaccharide in microglia.

BACKGROUND: Inflammatory response in the CNS mediated by microglia cells play an important role in host defense and is implicated in the pathology of neurodegenerative diseases. We investigated the capacity of Entada africana to protect microglia from inflammatory insults by exploring the effect of the CH2Cl2/MEOH 5% fraction (Ea5) on pro-inflammatory cytokines mRNA expression. Finally, we studied the effect of Ea5 on the inhibition of p38 MAPK Kinase. The results were compared to those obtained with Baicalin, a well reported anti-inflammatory flavonoid. METHODS: Barks from E. africana were harvested in 2010, in the west region of Cameroon. A crude extract was prepared using CH2Cl2/MEOH 1:1 V/V. The crude extract obtained was further fractionated by flash chromatography. A mouse microglia cell line (N9) was stimulated by LPS with or without different concentrations of Baicalin and Ea5. The release of NO was evaluated using the Griess method. The expression of pro-inflammatory cytokines mRNA (TNFα, IL-1ß, IL-6) and iNOS/NO were measured by RT- PCR. The inhibition of p38 MAPK Kinase was assessed using ELISA. RESULTS: We found that Ea5, as well as Baicalin inhibited LPS-induced NO production in a dose dependent manner. Ea5 was most active in term of NO inhibition (87.07%), in comparison to Baicalin (70.85%). The expression of TNFα, IL-1ß, IL-6 and iNOS was strongly suppressed by Ea5 in microglia. Ea5 also inhibited the activity of p38MAPK Kinase, up to 30% for the concentrations tested, whereas a prominent inhibition was obtained with Baicalin. CONCLUSION: These results suggest that E. africana may contain promising compounds useful for the treatment of diseases cause by over-activation of microglia such as Alzheimer disease and other neurological diseases.