Human Monoamine Oxidase Inhibitory Activity Research Articles

Synthesis and human monoamine oxidase inhibitory activity of novel C2-, C3- and C4-substituted phthalonitriles

Development of new selective reversible monoamine oxidase (MAO) B inhibitors is still essential for the treatment of Alzheimer’s and Parkinson’s disease. Phthalonitrile compounds have been shown to display MAO inhibitory activity with MAO-B selectivity. In this study, we synthesized and evaluated the inhibitory activities of a new series of phthalonitrile compounds. Compound 3, 4 and 5 presented selective MAO-B inhibition, compound 5 being the most selective (75.16-fold). Additionally, molecular docking simulations were carried out. Investigation of binding modes of each compound with both isoforms were carried out to elaborate structure–activity relationships. Druglikeness was calculated for each compound, revealing that the lipophilicity of compound 5 (logP = 3.37) is optimal to cross membranes.

Synthesis, molecular modelling and biological activity of some pyridazinone derivatives as selective human monoamine oxidase-B inhibitors.

Since brain neurotransmitter levels are associated with the pathology of various neurodegenerative diseases like Parkinson and Alzheimer, monoamineoxidase (MAO) plays a critical role in balancing these neurotransmitters in the brain. MAO isoforms appear as promising drug targets for the development of central nervous system agents. Pyridazinones have a broad array of biological activities. Here, six pyridazinone derivatives were synthesized and their human monoamine oxidase inhibitory activities were evaluated by molecular docking studies, in silico ADME prediction and in vitro biological screening tests. The compounds were synthesized by the reaction of different piperazine derivatives with 3 (2H)-pyridazinone ring and MAO-inhibitory effects were investigated. Docking studies were conducted with Maestro11.8 software. Most of the synthesized compounds inhibited hMAO-B selectively except compound 4f. Compounds 4a-4e inhibited hMAO-B selectively and reversibly in a competitive mode. Compound 4b was found as the most potent (ki = 0.022 ± 0.001µM) and selective (SI (Ki hMAO-A/hMAO-B) = 206.82) hMAO-B inhibitor in this series. The results of docking studies were found to be consistent with the results of the in vivo activity studies. Compounds 4a-4e were found to be non-toxic to HepG2 cells at 25μM concentration. In silico calculations of ADME properties indicated that the compounds have good pharmacokinetic profiles. It was concluded that 4b is possibly recommended as a promising nominee for the design and development of new pyridazinones which can be used in the treatment of neurological diseases.

Discovery of potent and reversible MAO-B inhibitors as furanochalcones

A series of twelve furanochalcones (F1-F12) was synthesized and investigated for their human monoamine oxidase inhibitory activities. Among the series, compound (2E, 4E)-1-(furan-2-yl)-5-phenylpenta-2, 4-dien-1-one (F1), which was analyzed by single-crystal X-ray diffraction, showed potent and selective MAO-B inhibitory activity with an inhibition constant (Ki) value of 0.0041 μM and selectivity index of (SI) 172.4, and exhibited competitive inhibition. Introduction of a cinnamyl group to the furanochalcone significantly increased the inhibitory activity. In the dilution-recovery experiments, the residual activities of MAO-A and MAO-B by F1 under the diluted condition fully recovered as compared with the undiluted condition, indicating F1 is a reversible inhibitor. The Ki value of F1 is the lowest among the values of chalcone derivatives and furthermore lower than that (0.0079 μM) of the reversible MAO-B inhibitor, lazabemide, a marketed drug. Molecular docking study against hMAO-B provided the binding site interactions of the lead compound, including strong π-π stacking between the phenyl system and FAD nucleus.

Monoamine oxidase inhibitory activity of methoxy-substituted chalcones

The MAO-B inhibitory activity of chalcone (1, 3- diphenyl-2-propen-1-one) based compounds arise from its structural similarity with 1, 4-diphenyl-2-butene, a known MAO-B inhibitor. Based on our previous report, the methoxy-substituted with fluorine containing chalcones are promising reversible MAO-B inhibitors, while in the present study, a series of methoxylated chalcones (C1-C9) bearing substitution on the para position of ring B was synthesized and evaluated for their human monoamine oxidase inhibitory activity. With the exception of (2E)-1-(4-methoxyphenyl)-3-(4-nitrophenyl) prop-2-en-1-one (C7), which is a nonselective inhibitor, the chalcones exhibited competitive, selective, and reversible inhibition of hMAO-B. The most potent compound, (2E)-3-[4-(dimethylamino) phenyl]-1-(4-methoxyphenyl) prop-2-en-1-one (C5), showed the best inhibitory activity towards hMAO-B (IC50=0.29±0.011μM;Ki=0.14±0.001μM). The reversibility of MAO-B inhibition by compound C5 was demonstrated by the recovery of enzyme activity after dialysis of mixtures containing enzyme and inhibitor. The reversiblity of C5 was 25.38±1.40 and 92.00±3.87% before and after dialysis, respectively. PAMPA was carried out to evaluate the blood-brain barrier effects of the designated compounds. Moreover, the most potent MAO-B inhibitor, C5, was found to be nontoxic towards cultured hepatic cells at 5 and 25μM, with 97 and 90% viability. Molecular docking study was performed against hMAO-B to observe the binding site interactions of the lead compound.

Evaluation of Natural and Synthetic 1,4-naphthoquinones as Inhibitors of Monoamine Oxidase.

Previous reports have documented that 1,4-naphthoquinones act as inhibitors of the monoamine oxidase (MAO) enzymes. In particular, fractionation of the extracts of cured tobacco leafs has led to the characterization of 2,3,6-trimethyl-1,4-naphthoquinone, a non-selective MAO inhibitor. To derive structure-activity relationships for MAO inhibition by the 1,4-naphthoquinone class of compounds, this study investigates the human MAO inhibitory activities of fourteen structurally diverse 1,4-naphthoquinones of natural and synthetic origin. Of these, 5,8-dihydroxy-1,4-naphthoquinone was found to be the most potent inhibitor with an IC50 value of 0.860 μm for the inhibition of MAO-B. A related compound, shikonin, inhibits both the MAO-A and MAO-B isoforms with IC50 values of 1.50 and 1.01 μm, respectively. It is further shown that MAO-A and MAO-B inhibition by these compounds is reversible by dialysis. In this respect, kinetic analysis suggests that the modes of MAO inhibition are competitive. This study contributes to the discovery of novel MAO inhibitors, which may be useful in the treatment for disorders such as Parkinson's disease, depressive illness, congestive heart failure and cancer.

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 and Evaluation of Human Monoamine Oxidase Inhibitory Activities of Some 3,5‐Diaryl‐N‐substituted‐4,5‐dihydro‐1H‐pyrazole‐1‐carbothioamide Derivatives

Sixteen 3-aryl-5-(4-fluorophenyl)-N-substituted-4,5-dihydro-1H-pyrazole-1-carbothioamide derivatives were synthesized and their structure were identified by UV, IR, (1) H NMR, mass spectra, and microanalyses. The compounds were evaluated in vitro for their human monoamine oxidase (hMAO) inhibitory activities and their MAO-A and -B selectivity. All the compounds were found to potently inhibit MAO-A isoforms. 5-(4-Fluorophenyl)-3-(4-methoxyphenyl)-N-methyl-4,5-dihydro-1H-pyrazole-1-carbothioamide (1.0 × 10(-3) µM) was found to inhibit hMAO-A most selectively and potently. The binding mode of 5-(4-fluorophenyl)-3-(4-methoxyphenyl)-N-methyl-4,5-dihydro-1H-pyrazole-1-carbothioamide to hMAO-A was also predicted using docking studies.

Synthesis, human monoamine oxidase inhibitory activity and molecular docking studies of 3-heteroarylcoumarin derivatives

Monoamine oxidase (MAO) is an important drug target for the treatment of neurological disorders. Series of 3-indolyl and 3-thiophenylcoumarins were synthesized and evaluated as inhibitors of the two human MAO isoforms, hMAO-A and hMAO-B. In general, the derivatives were found to be selective hMAO-B inhibitors with IC 50 values in the nanoMolar (nM) to microMolar (μM) range. Docking experiments were carried out in order to compare the theoretical and experimental affinity of these compounds to the hMAO-B protein. According to our results, docking experiments could be an interesting approach to try to predict the activity of this class of coumarins against MAO-B receptors.

Synthesis and selective inhibition of human monoamine oxidases of a large scaffold of (4,5-substituted-thiazol-2-yl)hydrazones

A large class of (4,5-substituted-thiazol-2-yl)hydrazone derivatives (1–66) was synthesized in good yield (82–99%) and characterized by elemental analysis and 1H NMR studies. The compounds were assayed for their in vitro human monoamine oxidase inhibitory activity and selectivity. Most of them showed IC50 values in the micromolar range. Our aim was to evaluate the importance of a bulky group at C2, C4, and C5 positions of the thiazole nucleus in modulating the biological activity of this scaffold.