A new series of pyridinyl-alkynes as antagonists of the metabotropic glutamate receptor 5 (mGluR5)

Catalytic Degradation of 4-Ethylpyridine in Water by Heterogeneous Photo-Fenton Process

In this work, the degradation of 4-ethylpyridine (4EP) in water by a heterogeneous photo-Fenton process (H2O2/Fe3O4/ultraviolet irradiation (UV)) was investigated. More rapid and effective 4EP degradation was obtained with H2O2/Fe3O4/UV than Fenton-like (H2O2/Fe3O4) and UV/H2O2, which is due to the larger production of hydroxyl radicals from the chemical and photolytic decomposition of H2O2. The operational conditions were varied during 4EP degradation experiments to evaluate the effects of pH, catalyst, concentration, and temperature on the kinetics and efficiency of H2O2/Fe3O4/UV oxidation. Under optimal conditions (100 mg/L 4EP, [H2O2] = 1000 mg/L, Fe3O4 = 40 mg/L, pH = 3 and room temperature, 300 rpm), 4EP was totally declined and more than 93% of the total organic carbon (TOC) was eliminated. Liquid chromatography analysis confirmed the formation of aromatic and aliphatic intermediates (4-hydroxypyridine, 4-pyridone, malonic, oxalic, and formic acids) that resulted in being mineralized. Ion chromatography analysis demonstrated the stoichiometric release of NH4+ ions during 4EP degradation by heterogeneous photo-Fenton oxidation. The reuse of the heterogeneous catalyst was evaluated after chemical and heat treatment at different temperatures. The heat-treated catalyst at 500 °C presented similar activity than the pristine Fe3O4. Accordingly, heterogeneous photo-Fenton oxidation can be an alternative method to treat wastewaters and groundwater contaminated with pyridine derivatives and other organic micropollutants. The combination of heterogeneous photo-Fenton oxidation with classical biological methods can be proposed to reduce the overall cost of the treatment in large-scale water treatment plants.

Metabotropic glutamate receptors: potential drug targets for psychiatric disorders

Metabotropic glutamate receptors (mGlu receptors) have emerged as new therapeutic targets for psychiatric disorders, such as schizophrenia, depression and anxiety with their regulatory roles in glutamatergic transmissions. To date, several ligands selective for each mGlu receptor have been synthesized, and pharmacological significances of these ligands have been demonstrated in animal models. Among them, mGlu2/3 receptor agonists have been proven to be effective for treating schizophrenia and anxiety disorders in clinical studies, which may prove utilities of mGlu receptor ligands for the treatment of psychiatric disorders. This article reviews recent advances in development of each mGlu receptor ligands and their therapeutic potential.

Structure-activity relationships in a novel series of 7-substituted-aryl quinolines and 5-substituted-aryl benzothiazoles at the metabotropic glutamate receptor subtype 5

The metabotropic glutamate receptor subtype 5 (mGluR5) has been implicated in numerous neuropsychiatric disorders including addiction. We have discovered that the rigid diaryl alkyne template, derived from the potent and selective noncompetitive mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP), can serve to guide the design of novel quinoline analogues and pharmacophore optimization has resulted in potent mGluR5 noncompetitive antagonists (EC(50) range 60-100 nM) in the quinoline series.

Synthesis of organochalcogen propargyl aryl ethers and their application in the electrophilic cyclization reaction: an efficient preparation of 3-halo-4-chalcogen-2H-benzopyrans

We herein described the synthesis of various organochalcogen propargyl aryl ethers via reaction of lithium acetylide intermediate with electrophilic chalcogen (sulfur, selenium, tellurium) species. Various aryl and alkyl groups directly bonded to the chalcogen atom were used as electrophile. The results revealed that the reaction does not significantly depend on the electronic effects of substituents in the aromatic ring bonded to the chalcogen atom of the electrophilic chalcogen species. Additional versatility in this process was demonstrated with respect to a diverse array of functionality in the aromatic ring at propargyl aryl ethers. These propargyl aryl ethers, bearing the chalcogen group, underwent highly selective intramolecular cyclizations when treated with I(2) or ICl affording 3-iodo-4-chalcogen-2H-benzopyrans. The results demonstrated that the cyclization efficiency was significantly influenced by the steric effects of aromatic ring, since the cyclization reaction gave low yields with aromatic rings having a substituent at orto position than those having no substituent. The reactivity of 3-iodo-4-chalcogen-2H-benzopyrans was also studied. 4-Selenobutyl benzopyrans were treated under Neghishi cross-coupling conditions providing the corresponding 3-aryl benzopyran derivatives in good yields. In addition, using the copper catalyzed cross-coupling reactions with thiols, in the absence of any cocatalyst, we were able to introduce a thiol function in 3-iodo-benzopyran derivatives.

Structure-activity relationships comparing N-(6-methylpyridin-yl)-substituted aryl amides to 2-methyl-6-(substituted-arylethynyl)pyridines or 2-methyl-4-(substituted-arylethynyl)thiazoles as novel metabotropic glutamate receptor subtype 5 antagonists

The metabotropic glutamate receptor subtype 5 (mGluR5) has been implicated in anxiety, depression, pain, mental retardation, and addiction. The potent and selective noncompetitive mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP, 1) has been a critically important tool used to further elucidate the role of mGluR5 in these CNS disorders. In an effort to provide novel and structurally diverse selective mGluR5 antagonists, we previously described a set of analogues with moderate activity wherein the alkyne bond was replaced with an amide group. In the present report, extended series of both amide and alkyne-based ligands were synthesized. MGluR5 binding and functional data were obtained that identified (1) several novel alkynes with comparable affinities to 1 at mGluR5 (e.g., 10 and 20-23), but (2) most structural variations to the amide template were not well tolerated, although a few potent amides were discovered (e.g., 55 and 56). Several of these novel analogues show drug-like physical properties (e.g., cLogP range = 2-5) that support their use for in vivo investigation into the role of mGluR5 in CNS disorders.

Synthesis and SAR of 2-aryl pyrido[2,3-d]pyrimidines as potent mGlu5 receptor antagonists

A novel series of potent 2-aryl pyrido[2,3-d]pyrimidine mGlu5 receptor antagonists are described. The synthesis and pharmacological activities of these analogs are discussed.

Rational design of 7-arylquinolines as non-competitive metabotropic glutamate receptor subtype 5 antagonists

Rational replacement of the alkyne linker of mGluR5 antagonist MPEP gave 7-arylquinolines. SAR optimization gave an orally active compound with high affinity for the MPEP binding site.

Structure–activity relationships for the linker in a series of pyridinyl-alkynes that are antagonists of the metabotropic glutamate receptor 5 (mGluR5)

Studies of structure-activity relationships for the linker in a new series of metabotropic glutamate receptor 5 antagonists are presented together with in vitro and in vivo pharmacokinetic data.