New 2-Pyrazoline and Hydrazone Derivatives as Potent and Selective Monoamine Oxidase A Inhibitors.

Thirty compounds having 1-[2-(5-substituted-2-benzoxazolinone-3-yl) acetyl]-3,5-disubstitutedphenyl-2-pyrazoline structure and nine compounds having N'-(1,3-disubstitutedphenylallylidene)-2-(5-substituted-2-benzoxazolinone-3-yl)acetohydrazide skeleton were synthesized and evaluated as monoamine oxidase (MAO) inhibitors. All of the compounds exhibited selective MAO-A inhibitor activity in the nanomolar or low micromolar range. The results of the molecular docking for hydrazone derivatives supported the in vitro results. Five compounds, 6 (0.008 µM, Selectivity Index (SI): 9.70 × 10-4), 7 (0.009 µM, SI: 4.55 × 10-5), 14 (0.001 µM, SI: 8.00 × 10-4), 21 (0.009 µM, SI: 1.37 × 10-5), and 42 (0.010 µM, SI: 5.40 × 10-6), exhibiting the highest inhibition and selectivity toward hMAO-A and nontoxic to hepatocytes were assessed for antidepressant activity as acute and subchronic in mice. All of these five compounds showed significant antidepressant activity with subchronic administration consistent with the increase in the brain serotonin levels and the compounds crossed the blood-brain barrier according to parallel artificial membrane permeation assay. Compounds 14, 21, and 42 exhibited an ex vivo MAO-A profile, which is highly consistent with the in vitro data.

Evaluation of selective human MAO inhibitory activities of some novel pyrazoline derivatives.

A series of 1-[2-((5-methyl/chloro)-2-benzoxazolinone-3-yl)acetyl]-3,5-diaryl-4,5-dihydro-1H-pyrazole derivatives were prepared by reacting 2-((5-methyl/chloro)-2-benzoxazolinone-3-yl)acetylhydrazine with appropriate chalcones. The chemical structures of all compounds were confirmed by elemental analyses, IR, (1)H NMR and ESI-MS. All the compounds were investigated for their ability to selectively inhibit monoamine oxidase (MAO) by in vitro tests. MAO activities of the compounds were compared with moclobemide and selegiline and all the compounds were found to inhibit human MAO-A selectively. The inhibition profile was found to be competitive and reversible for all compounds by in vitro tests. Among the compounds examined, compounds 5ae, 5af and 5ag were more selective than moclobemide, with respect to the K i values experimentally found. In addition, the compound 5bg showed MAO-A inhibitor activity as well as moclobemide. A series of experimentally tested compounds (5ae-5ch) were docked computationally to the active site of the MAO-A and MAO-B isoenzyme. The AUTODOCK 4.01 program was employed to perform automated molecular docking.

Synthesis, molecular modeling, and in vitro screening of monoamine oxidase inhibitory activities of some novel hydrazone derivatives.

Thirteen 2-[2-(5-methyl-2-benzoxazolinone-3-yl)acetyl]-3/4/5-substituted benzylidenehydrazine derivatives were synthesized by reacting 2-(5-methyl-2-benzoxazolinone-3-yl)acetylhydrazine and substituted benzaldehydes in neutral and acid/base catalyzed conditions, and a comparison was made in terms of their yields and reaction times. The structures of all compounds were confirmed by IR, (1)H NMR, (13)C NMR, mass spectral data, and elemental analyses. All the compounds were investigated for their ability to selectively inhibit MAO isoforms by in vitro tests and were found to inhibit recombinant human MAO-B selectively and reversibly in a competitive manner. Among the compounds examined, compound 16 was found to be more selective than selegiline, a known MAO-B inhibitor, in respect to the K i values experimentally found. Additionally, compounds 9 and 15 showed moderate MAO-B inhibitor activity. The interaction of compounds with MAO isoforms was investigated by molecular docking studies using recently published crystallographic models of MAO-A and MAO-B. The results obtained from the docking studies were found to be in good agreement with the experimental values.

1-Acylthiosemicarbazides, 1,2,4-triazole-5(4H)-thiones, 1,3,4-thiadiazoles and hydrazones containing 5-methyl-2-benzoxazolinones: synthesis, analgesic-anti-inflammatory and antimicrobial activities.

Acetic acid hydrazide containing 5-methyl-2-benzoxazolinone (4) was synthesized by the condensation of 2-(5-methyl-2-benzoxazolinone-3-yl)acetate with hydrazine hydrate. Thiosemicarbazide derivatives (5a-5d) were afforded by the reaction of corresponding compound 4 with substituted isothiocyanates. The cyclization of compounds 5a-5d in the presence of triethylamine resulted in the formation of compounds 6a-6d containing 1,2,4-triazole ring. On the other hand, the treatment of compounds 5a-5d with orthophosphoric acid caused the conversion of side chain of compounds 5a-5d into 1,3,4-thiadiazole ring: thus, compounds 7a-7c were obtained. The treatment of compound 4 with aromatic aldehydes resulted in the formation of arylidene hydrazides as cis-trans conformers (8a-8e). The structures of the compounds were elucidated by spectral and elemental analysis. While most compounds were exhibiting high activity in the analgesic-anti-inflammatory field, most of them were found to be inactive against bacteria and fungi.