Interaction of rat lung SSAO with the novel 1-N-substituted thiocarbamoyl-3-substituted phenyl-5-(2-pyrolyl)-2-pyrazoline derivatives

Absolute configuration and biological profile of pyrazoline enantiomers as MAO inhibitory activity

A new racemic pyrazoline derivative was synthesized and resolved to its enantiomers using analytic and semipreparative high-pressure liquid chromatography. The absolute configuration of both fractions was established using vibrational circular dichroism. The in vitro monoamine oxidase (MAO) inhibitory profiles were evaluated for the racemate and both enantiomers separately for the two isoforms of the enzyme. The racemic compound and both enantiomers were found to inhibit hMAO-A selectively and competitively. In particular, the R enantiomer was detected as an exceptionally potent and a selective MAO-A inhibitor (K_i  = 0.85 × 10^-3  ± 0.05 × 10^-3  μM and SI: 2.35 × 10^-5 ), whereas S was determined as poorer compound than R in terms of K_i and SI (0.184 ± 0.007 and 0.001). The selectivity of the enantiomers was explained by molecular modeling docking studies based on the PDB enzymatic models of MAO isoforms.

Selected aryl thiosemicarbazones as a new class of multi-targeted monoamine oxidase inhibitors

A series of 13 phenyl substituted thiosemicarbazones (SB1-SB13) were synthesized and evaluated for their inhibitory potential towards human recombinant monoamine oxidase A and B (MAO-A and MAO-B, respectively) and acetylcholinesterase. The solid state structure of SB4 was ascertained by the single X-ray diffraction technique. Compounds SB5 and SB11 were potent for MAO-A (IC50 1.82 ± 0.14) and MAO-B (IC50 0.27 ± 0.015 μM), respectively. Furthermore, SB11 showed a high selectivity index (SI > 37.0) for MAO-B. The effects of fluorine orientation revealed that SB11 (m-fluorine) showed 28.2 times higher inhibitory activity than SB12 (o-fluorine) against MAO-B. Furthermore, inhibitions by SB5 and SB11 against MAO-A and MAO-B, respectively, were recovered to near reference levels in reversibility experiments. Both SB5 and SB11 showed competitive inhibition modes, with K i values of 0.97 ± 0.042 and 0.12 ± 0.006 μM, respectively. These results indicate that SB5 and SB11 are selective, reversible and competitive inhibitors of MAO-A and MAO-B, respectively. Compounds SB5, SB7 and SB11 showed moderate inhibition against acetylcholinesterase with IC50 values of 35.35 ± 0.47, 15.61 ± 0.057 and 26.61 ± 0.338 μM, respectively. Blood-brain barrier (BBB) permeation was studied using the parallel artificial membrane permeation assay (PAMPA) method. Molecular docking studies were carried out using AutoDock 4.2.

Monoamine oxidase inhibitory activity of 3,5-biaryl-4,5-dihydro-1H-pyrazole-1-carboxylate derivatives

Ethyl and phenyl carbamate derivatives of pyrazoline (3a-3h) were synthesized and tested for their MAO inhibitory activity. All the compounds were found to be selective towards MAO-A. Phenyl carbamates (3e-3h) were better than ethyl carbamates (3a-3d) and displayed the best selectivity index. Compound 3f (KiMAO-A; 4.96 ± 0.21 nM) was found to be equally potent as that of standard drug, Moclobemide (KiMAO-A; 5.01 ± 0.13 nM) but with best selectivity index (8.86 × 10(-5)). Molecular docking studies with R &S conformer of 3f revealed S-enantiomer is better than R-enantiomer as reported earlier by other groups. It is proposed that VdW's radii of the substitution (bulkiness) in ring B determine the potency of phenyl carbamates.

Gold-catalyzed three-component annulation: efficient synthesis of highly functionalized dihydropyrazoles from alkynes, hydrazines, and aldehydes or ketones

Polysubstituted dihydropyrazoles were directly obtained by a gold-catalyzed three-component annulation. This reaction consists of a Mannich-type coupling of alkynes with N,N'-disubstituted hydrazines and aldehydes/ketones followed by intramolecular hydroamination. Cascade cyclization using 1,2-dialkynylbenzene derivatives as the alkyne component was also performed producing fused tricyclic dihydropyrazoles in good yields.

Synthesis, in vitro activity, and three-dimensional quantitative structure-activity relationship of novel hydrazine inhibitors of human vascular adhesion protein-1

Vascular adhesion protein-1 (VAP-1) belongs to the semicarbazide-sensitive amine oxidases (SSAOs) that convert amines into aldehydes. SSAOs are distinct from the mammalian monoamine oxidases (MAOs), but their substrate specificities are partly overlapping. VAP-1 has been proposed as a target for anti-inflammatory drug therapy because of its role in leukocyte adhesion to endothelium. Here, we describe the synthesis and in vitro activities of novel series of VAP-1 selective inhibitors. In addition, the molecular dynamics simulations performed for VAP-1 reveal that the movements of Met211, Ser496, and especially Leu469 can enlarge the ligand-binding pocket, allowing larger ligands than those seen in the crystal structures to bind. Combining the data from molecular dynamics simulations, docking, and in vitro measurements, the three-dimensional quantitative structure-activity relationship (3D QSAR) models for VAP-1 (q(2)(LOO): 0.636; r(2): 0.828) and MAOs (q(2)(LOO): 0.749, r(2): 0.840) were built and employed in the development of selective VAP-1 inhibitors.

Development of selective and reversible pyrazoline based MAO-A inhibitors: Synthesis, biological evaluation and docking studies

3,5-Diaryl pyrazolines analogs were synthesized and evaluated for their monoamine oxidase (MAO) inhibitory activity. The compounds were found reversible and selective towards MAO-A with selectivity index in the magnitude of 10(3)-10(5). The docking studies were carried out to gain further structural insights of the binding mode and possible interactions with the active site of MAO-A. Interestingly, the theoretical (K(i)) values obtained by molecular docking studies were in congruence with their experimental (K(i)) values.

New pyrazoline bearing 4(3H)-quinazolinone inhibitors of monoamine oxidase: synthesis, biological evaluation, and structural determinants of MAO-A and MAO-B selectivity

A new series of pyrazoline derivatives were prepared starting from a quinazolinone ring and evaluated for antidepressant, anxiogenic and MAO-A and -B inhibitory activities by in vivo and in vitro tests, respectively. Most of the synthesized compounds showed high activity against both the MAO-A (compounds 4a-4h, 4j-4n, and 5g-5l) and the MAO-B (compounds 4i and 5a-5f) isoforms. However, none of the novel compounds showed antidepressant activity except for 4b. The reason for such biological properties was investigated by computational methods using recently published crystallographic models of MAO-A and MAO-B. The differences in the intermolecular hydrophobic and H-bonding of ligands to the active site of each MAO isoform were correlated to their biological data. Compounds 4i, 4k, 5e, 5i, and 5l were chosen for their ability to reversibly inhibit MAO-B and MAO-A and the availability of experimental inhibition data. Observation of the docked positions of these ligands revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. Among the pyrazoline derivatives, it appears that the binding interactions for this class of compounds are mostly hydrophobic. All have potential edge-to-face hydrophobic interactions with F343, as well as pi-pi stacking with Y398 and other hydrophobic interactions with L171. Strong hydrophobic and H-bonding interactions in the MAO recognition of 4i could be the reason why this compound shows selectivity toward the MAO-B isoform. The very high MAO-B selectivity for 4i can be also explained in terms of the distance between the FAD and the compound, which was greater in the complex of MAO-A-4i as compared to the corresponding MAO-B complex.