Design, synthesis and preliminary biological evaluation of rivastigmine-INDY hybrids as multitarget ligands against Alzheimer's disease by targeting butyrylcholinesterase and DYRK1A/CLK1 kinases.

Based on a multitarget approach implementing rivastigmine-INDY hybrids 1, we identified a set of pseudo-irreversible carbamate-type inhibitors of eqBuChE that, after carbamate transfer at the active site serine residue, released the corresponding INDY analogues 2 endowed with hDYRK1A/hCLK1 kinases inhibitory properties. A SAR study and molecular docking investigation of both series of compounds 1 and 2 revealed that appropriate structural modifications at the carbamate moiety and at the N-appendage of the benzothiazole core led to potent and selective eqBuChE inhibitors with IC50 up to 27 nM and potent hDYRK1A and hCLK1 inhibitors with IC50 up to 106 nM and 17 nM respectively. Pleasingly, identification of the matched pair of compounds 1b/2b with a good balance between inhibition of eqBuChE and hDYRK1A/hCLK1 kinases (IC50 = 68 nM and IC50 = 529/54 nM, respectively) further validated our multitarget approach based on a sequential mechanism of action. In addition, target compound 1b exhibited a suitable ADMET profile, including good brain permeability and high stability in PBS, encouraging further biological investigation as a drug candidate.

Synthesis of 2-Cyanobenzothiazoles via Pd-Catalyzed/Cu-Assisted C-H Functionalization/Intramolecular C-S Bond Formation from N-Arylcyanothioformamides.

We report herein on a catalytic system involving palladium and copper to achieve the cyclization of N-arylcyanothioformamides and the synthesis of 2-cyanobenzothiazoles. The C-H functionalization/intramolecular C-S bond formation reaction was achieved in the presence of air, using 2.0 equiv of an inorganic additive (KI). In many cases, the reaction led to a sole product regioselectively obtained in good yields, allowing the synthesis of a wide range of substituted 2-cyanobenzothiazole derivatives, providing valuable building blocks for the design of more complex heterocyclic or molecular labeling systems.

Relieving DYRK1A repression of MKL1 confers an adult-like phenotype to human infantile megakaryocytes.

Infantile (fetal and neonatal) megakaryocytes (Mks) have a distinct phenotype consisting of hyperproliferation, limited morphogenesis, and low platelet production capacity. These properties contribute to clinical problems that include thrombocytopenia in neonates, delayed platelet engraftment in recipients of cord blood stem cell transplants, and inefficient ex vivo platelet production from pluripotent stem cell-derived Mks. The infantile phenotype results from deficiency of the actin-regulated coactivator, MKL1, which programs cytoskeletal changes driving morphogenesis. As a strategy to complement this molecular defect, we screened pathways with the potential to affect MKL1 function and found that DYRK1A inhibition dramatically enhanced Mk morphogenesis in vitro and in vivo. Dyrk1 inhibitors rescued enlargement, polyploidization, and thrombopoiesis in human neonatal Mks. Mks derived from induced pluripotent stem cells responded in a similar manner. Progenitors undergoing Dyrk1 inhibition demonstrated filamentous actin assembly, MKL1 nuclear translocation, and modulation of MKL1 target genes. Loss-of-function studies confirmed MKL1 involvement in this morphogenetic pathway. Expression of Ablim2, a stabilizer of filamentous actin, increased with Dyrk1 inhibition, and Ablim2 knockdown abrogated the actin, MKL1, and morphogenetic responses to Dyrk1 inhibition. These results delineate a pharmacologically tractable morphogenetic pathway whose manipulation may alleviate clinical problems associated with the limited thrombopoietic capacity of infantile Mks.

Therapeutic antibody glycosylation impacts antigen recognition and immunogenicity.

In this study we show that glycosylation is relevant for immune recognition of therapeutic antibodies, and that defined glycan structures can modulate immunogenicity. Concerns regarding immunogenicity arise from the high heterogeneity in glycosylation that is difficult to control and can deviate from human glycosylation if produced in non-human cell lines. While non-human glycosylation is thought to cause hypersensitivity reactions and immunogenicity, less is known about effects of Fc-associated glycan structures on immune cell responses. We postulated that glycosylation influences antigen recognition and subsequently humoral responses to therapeutic antibodies by modulating 1) recognition and uptake by dendritic cells (DCs), and 2) antigen routing, processing and presentation. Here, we compared different glycosylation variants of the antibody rituximab (RTX) in in vitro assays using human DCs and T cells as well as in in vivo studies. We found that human DCs bind and internalize unmodified RTX stronger compared to its aglycosylated form suggesting that glycosylation mediates uptake after recognition by glycan-specific receptors. Furthermore, we show that DC-uptake of RTX increases or decreases if glycosylation is selectively modified to recognize activating (by mannosylation) or inhibitory lectin receptors (by sialylation). Moreover, glycosylation seems to influence antigen presentation by DCs because specific glycovariants tend to induce either stronger or weaker T cell activation. Finally, we demonstrate that antibody glycosylation impacts anti-drug antibody (ADA) responses to RTX in vivo. Hence, defined glycan structures can modulate immune recognition and alter ADA responses. Glyco-engineering may help to decrease clinical immunogenicity and ADA-associated adverse events such as hypersensitivity reactions.

Review on the Synthesis and Therapeutic Potential of Pyrido[2,3-d], [3,2-d], [3,4-d] and [4,3-d]pyrimidine Derivatives.

The objective of this review is to list the structures composed of a pyridopyrimidine moiety which have shown a therapeutic interest or have already been approved for use as therapeutics. We consider all the synthetic protocols to prepare these pyridopyrimidine derivatives. The review is organized into four sections, successively pyrido[2,3-d]pyrimidines, pyrido[3,4-d]pyrimidines, pyrido[4,3-d]pyrimidines and pyrido[3,2-d]pyrimidines. For each compound we present the biological activity and the synthetic route reported. To produce this manuscript, the bibliographic research was done using Reaxys and Scifinder for each kind of pyridopyrimidine.

Straightforward Access to a New Class of Dual DYRK1A/CLK1 Inhibitors Possessing a Simple Dihydroquinoline Core.

The DYRK (Dual-specificity tyrosine phosphorylation-regulated kinase) family of protein kinases is involved in the pathogenesis of several neurodegenerative diseases. Among them, the DYRK1A protein kinase is thought to be implicated in Alzheimer's disease (AD) and Down syndrome, and as such, has emerged as an appealing therapeutic target. DYRKs are a subset of the CMGC (CDK, MAPKK, GSK3 and CLK) group of kinases. Within this group of kinases, the CDC2-like kinases (CLKs), such as CLK1, are closely related to DYRKs and have also sparked great interest as potential therapeutic targets for AD. Based on inhibitors previously described in the literature (namely TG003 and INDY), we report in this work a new class of dihydroquinolines exhibiting inhibitory activities in the nanomolar range on hDYRK1A and hCLK1. Moreover, there is overwhelming evidence that oxidative stress plays an important role in AD. Pleasingly, the most potent dual kinase inhibitor 1p exhibited antioxidant and radical scavenging properties. Finally, drug-likeness and molecular docking studies of this new class of DYRK1A/CLK1 inhibitors are also discussed in this article.

Recent Advances in Transition-Metal-Free Late-Stage C-H and N-H Arylation of Heteroarenes Using Diaryliodonium Salts.

Transition-metal-free direct arylation of C-H or N-H bonds is one of the key emerging methodologies that is currently attracting tremendous attention. Diaryliodonium salts serve as a stepping stone on the way to alternative environmentally friendly and straightforward pathways for the construction of C-C and C-heteroatom bonds. In this review, we emphasize the recent synthetic advances of late-stage C(sp2)-N and C(sp2)-C(sp2) bond-forming reactions under metal-free conditions using diaryliodonium salts as arylating reagent and its applications to the synthesis of new arylated bioactive heterocyclic compounds.

Microwave-Assisted Sequential One-Pot Synthesis of 8-Substituted Pyrazolo[1,5-a][1,3,5]triazines.

This paper reports a convenient sequential one-pot approach for the synthesis of an array of 14 pyrazolo[1,5-a][1,3,5]triazines, substituted in C8 by halogen (Br), various functions (CN and CO2Et) and alkyl or (het)aryl groups. This study confirms the interest of combining the efficient heating obtained under dielectric microwave heating and the achievement of sequential one-pot reactions, avoiding the tedious work-up and purification of intermediate compounds, achieving sustainable synthesis processes. Considering usual conventional methods, this microwave protocol is featured by advantages in terms of yields, reaction times, and convenient gram scale synthesis.

Demonstration of Green Solvent Performance on O,S,N-Heterocycles Synthesis: Metal-Free Click Chemistry and Buchwald-Hartwig Coupling.

The development of new and greener approaches to organic synthesis has been a trend in recent years. Continuing the latest publications of our team, in this work, we demonstrate the efficiency of three solvents: eucalyptol (1,8-cineole), cyclopentyl methyl ether (CPME), and 2-methyltetrahydrofuran (2-MeTHF) for the synthesis of O,S,N-heterocyclic compounds.

DYRK1A regulates B cell acute lymphoblastic leukemia through phosphorylation of FOXO1 and STAT3.

DYRK1A is a serine/threonine kinase encoded on human chromosome 21 (HSA21) that has been implicated in several pathologies of Down syndrome (DS), including cognitive deficits and Alzheimer's disease. Although children with DS are predisposed to developing leukemia, especially B cell acute lymphoblastic leukemia (B-ALL), the HSA21 genes that contribute to malignancies remain largely undefined. Here, we report that DYRK1A is overexpressed and required for B-ALL. Genetic and pharmacologic inhibition of DYRK1A decreased leukemic cell expansion and suppressed B-ALL development in vitro and in vivo. Furthermore, we found that FOXO1 and STAT3, transcription factors that are indispensable for B cell development, are critical substrates of DYRK1A. Loss of DYRK1A-mediated FOXO1 and STAT3 signaling disrupted DNA damage and ROS regulation, respectively, leading to preferential cell death in leukemic B cells. Thus, we reveal a DYRK1A/FOXO1/STAT3 axis that facilitates the development and maintenance of B-ALL.

Microwave-Assisted Synthesis of Potential Bioactive Benzo-, Pyrido- or Pyrazino-thieno[3,2-d]pyrimidin-4-amine Analogs of MPC-6827.

Efficient microwave-assisted chemical processes were applied to the synthesis of an array of novel N-(4-methoxyphenylamino)-2-methyl benzo-, pyrido- or pyrazino-thieno[3,2-d]pyrimidin-4-amine derivatives. These heteroaromatic systems were envisioned as potent bioisosteric analogues of MPC-6827, an anticancer agent previously developed until phase II clinical studies. A brief evaluation and comparison of their antiproliferative activity on HT-29 and Caco-2, two human colorectal cancer cell lines, were also reported. At the tested concentrations (5 and 10 µM), thieno[3,2-d]pyrimidin-4-amines 4a and 4c exhibited an inhibitory effect similar to MPC-6827 on human colorectal cancer cell proliferation.

Exploring Kinase Inhibition Properties of 9H-pyrimido[5,4-b]- and [4,5-b]indol-4-amine Derivatives.

We previously highlighted the interest in 6,5,6-fused tricyclic analogues of 4-aminoquinazolines as kinase inhibitors in the micromolar to the nanomolar range of IC50 values. For the generation of chemical libraries, the formamide-mediated cyclization of the cyanoamidine precursors was carried out under microwave irradiation in an eco-friendly approach. In order to explore more in-depth the pharmacological interest in such tricyclic skeletons, the central five member ring, i.e., thiophène or furan, was replaced by a pyrrole to afford 9H-pyrimido[5,4-b]- and [4,5-b]indol-4-amine derivatives inspired from harmine. The inhibitory potency of the final products was determined against four protein kinases (CDK5/p25, CK1/ε, GSK3 and DYRK1A). As a result, we have identified promising compounds targeting CK1/ε and DYRK1A and displaying micromolar and submicromolar IC50 values.

Biological Characterization of 8-Cyclopropyl-2-(pyridin-3-yl)thiazolo[5,4-f]quinazolin-9(8H)-one, a Promising Inhibitor of DYRK1A.

Dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs) hyperactivity has been linked to the development of a number of human malignancies. DYRK1A is the most studied family member, and the discovery of novel specific inhibitors is attracting considerable interest. The 8-cyclopropyl-2(pyridin-3-yl)thiazolo[5,4-f]quinazolin-9(8H)-one (also called FC162) was found to be a promising inhibitor of DYRK1A and was characterized in biological experiments, by western transfer and flow cytometry on SH-SY5Y and pre-B cells. Here, the results obtained with FC162 are compared to well-characterized known DYRK1A inhibitors (e.g., Leucettine L41 and EHT1610).

26th Annual GP2A Medicinal Chemistry Conference & 32nd Journées Franco-Belges de Pharmacochimie.

As a joint meeting, the 26th Medicinal Chemistry Conference of GP2A and 32nd Journées Franco-Belges de Pharmacochimie took place between 13th and 15th June at Asnelles sur Mer (Normandie, France), providing a unique opportunity for a wide group of European medicinal chemists to engage. Topics included chemical tools for medicinal chemistry, protein-protein interactions, epigenetics, natural product-inspired molecules, computer-aided drug design, and new strategies for the design and development of drugs. Abstracts of invited lectures, proffered young researcher communications, flash communications and posters presented during the meeting are collected in this report.

Development of Kinase Inhibitors via Metal-Catalyzed C⁻H Arylation of 8-Alkyl-thiazolo[5,4-f]-quinazolin-9-ones Designed by Fragment-Growing Studies.

Efficient metal catalyzed C⁻H arylation of 8-alkyl-thiazolo[5,4-f]-quinazolin-9-ones was explored for SAR studies. Application of this powerful chemical tool at the last stage of the synthesis of kinase inhibitors allowed the synthesis of arrays of molecules inspired by fragment-growing studies generated by molecular modeling calculations. Among the potentially active compounds designed through this strategy, FC162 (4c) exhibits nanomolar IC50 values against some kinases, and is the best candidate for the development as a DYRK kinase inhibitor.

Synthesis of 2-Mercapto-(2-Oxoindolin-3-Ylidene)Acetonitriles from 3-(4-Chloro-5H-1,2,3-Dithiazol-5-Ylidene)Indolin-2-ones.

Alkylidene oxindoles are important functional moieties and building blocks in pharmaceutical and synthetic chemistry. Our interest in biologically active compounds focused our studies on the synthesis of novel oxindoles, bearing on the exocyclic double bond at the C8, CN, and S groups. Extending the potential applications of Appel's salt, we developed a new synthetic approach by investigating the reactions of C5-substituted 2-oxindoles with 4,5-dichloro-1,2,3-dithiazolium chloride (Appel's salt) to give original (Z)-3-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)indolin-2-one derivatives, and new 2-mercapto-(2-oxoindolin-3-ylidene)acetonitriles via a dithiazole ring-opening reaction. The work described in this article represents further applications of Appel's salt in the conception of novel heterocyclic rings, in an effort to access original bioactive compounds. Fifteen new compounds were prepared and fully characterized.

Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) inhibitors: a survey of recent patent literature.

INTRODUCTION: Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a eukaryotic serine-threonine protein kinase belonging to the CMGC group. DYRK1A hyperactivity appears to contribute to the development of a number of human malignancies and to cognitive deficits observed in Down syndrome and Alzheimer's disease. As a result, the DYRK1A kinase represents an attractive target for the synthesis and optimization of pharmacological inhibitors of potential therapeutic interest. Like most tyrosine kinase inhibitors developed up to the market, DYRK1A inhibitors are essentially acting by competing with ATP for binding at the catalytic site of the kinase. Areas covered: This paper reviews patent activity associated with the discovery of synthetic novel heterocyclic molecules inhibiting the catalytic activity of DYRK1A. Expert opinion: Despite the important role of DYRK1A in biological processes and the growing interest in the design of new therapeutic drugs, there are only few patented synthetic DYRK1A inhibitors and most of them were and are still developed by academic research groups, sometimes with industrial partners.

An Unusual Binding Model of the Methyl 9-Anilinothiazolo[5,4-f] quinazoline-2-carbimidates (EHT 1610 and EHT 5372) Confers High Selectivity for Dual-Specificity Tyrosine Phosphorylation-Regulated Kinases.

Methyl 9-anilinothiazolo[5,4-f]quinazoline-2-carbimidates 1 (EHT 5372) and 2 (EHT 1610) are strong inhibitors of DYRK's family kinases. The crystal structures of the complex revealed a noncanonical binding mode of compounds 1 and 2 in DYRK2, explaining the remarkable selectivity and potency of these inhibitors. The structural data and comparison presented here provide therefore a template for further improvement of this inhibitor class and for the development of novel inhibitors selectively targeting DYRK kinases.

Pd-Catalyzed and Copper Assisted Regioselective Sequential C2 and C7 Arylation of Thiazolo[5,4-f]quinazolin-9(8H)-one with Aryl Halides.

A selective functionalization of thiazolo[5,4-f]quinazolin-9(8H)-one has been developed through sequential activation of C-H bonds to furnish diarylated compounds. This strategy allows the regioselective C2 and C7 arylation by a judicious choice of coupling partners and bases, requiring no additional ligands or directing groups. Differently substituted N(8)-benzylated-2,7-diaryl-thiazoloquinazolin-9(8H)-ones were thereby obtained in a facile manner. A one-pot procedure was also performed. These protocols provide a synthetically useful route for late-stage functionalization of this highly valuable scaffold, required in drug discovery.