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On the basis of the recent findings about the biological properties of thiazolidinones and taking into account the encouraging results about the antifungal activity of some (thiazol-2-yl)hydrazines, new N-substituted heterocyclic derivatives were designed combining the thiazolidinone nucleus with the hydrazonic portion. In details, 1,3-thiazolidin-4-ones bearing (cyclo)aliphatic or (hetero)aromatic moieties linked to the N1-hydrazine at C2 were synthesized and classified into three series according to the aromatic or bicyclic rings connected to the lactam nitrogen of the thiazolidinone. These molecules were assayed for their anti-Candida effects in reference to the biological activity of the conventional topic (clotrimazole, miconazole, tioconazole) and systemic drugs (fluconazole, ketoconazole, amphotericin B). Finally, we investigated the selectivity against fungal cells by testing the compounds endowed with the best MICs on Hep2 cells in order to assess their cell toxicity (CC50) and we noticed that two derivatives were less cytotoxic than the reference drug clotrimazole. Moreover, a preliminary molecular modelling approach has been performed against lanosterol 14-α demethylase (CYP51A1) to rationalize the activity of the tested compounds and to specify the target protein or enzyme., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

We designed and synthesized a large number of novel thiazolidin-4-one derivatives for the evaluation of their anti-Toxoplasma gondii activity. This scaffold was functionalized at the N1-hydrazine portion with aliphatic, cycloaliphatic and (hetero)aromatic moieties. Then, a benzyl pendant was introduced at the lactamic NH of the core nucleus to evaluate the influence of this chemical modification on biological activity. The compounds were subjected to several in vitro assays to assess their anti-parasitic efficacy, cytotoxicity on fibroblasts, inhibition of tachyzoite invasion/attachment and replication after treatment. Results showed that fourteen of these thiazole-based compounds compare favorably to control compound trimethoprim in terms of parasite growth inhibition., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Acetylation, which targets a broad range of histone and non-histone proteins, is a reversible mechanism and plays a critical role in eukaryotic genes activation/deactivation. Acetyltransferases are very well conserved through evolution. This allows the use of a simple model organism, such as budding yeast, for the study of their related processes and to discover specific inhibitors. Following a simple yeast-based chemogenetic approach, we have identified a novel HAT (histone acetyltransferase) inhibitor active both in vitro and in vivo. This new synthetic compound, 1-(4-(4-chlorophenyl)thiazol-2-yl)-2-(propan-2-ylidene)hydrazine, named BF1, showed substrate selectivity for histone H3 acetylation and inhibitory activity in vitro on recombinant HAT Gcn5 and p300. Finally, we tested BF1 on human cells, HeLa as control and two aggressive cancer cell lines: a neuroblastoma from neuronal tissue and glioblastoma from brain tumour. Both global acetylation of histone H3 and specific acetylation at lysine 18 (H3AcK18) were lowered by BF1 treatment. Collectively, our results show the efficacy of this novel HAT inhibitor and propose the utilization of BF1 as a new, promising tool for future pharmacological studies., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Monoamine oxidases (MAOs) are mitochondrial bound enzymes, which catalyze the oxidative deamination of monoamine neurotransmitters. Inside the brain, MAOs are present in two isoforms: MAO-A and MAO-B. The activity of MAO-B is generally higher in patients affected by neurodegenerative diseases like Alzheimer's and Parkinson's. Therefore, the search for potent and selective MAO-B inhibitors is still a challenge for medicinal chemists. Nature has always been a source of inspiration for the discovery of new lead compounds. Moreover, natural medicine is a major component in all traditional medicine systems. In this review, we present the latest discoveries in the search for selective MAO-B inhibitors from natural sources. For clarity, compounds have been classified on the basis of structural analogy or source: flavonoids, xanthones, tannins, proanthocyanidins, iridoid glucosides, curcumin, alkaloids, cannabinoids, and natural sources extracts. MAO inhibition values reported in the text are not always consistent due to the high variability of MAO sources (bovine, pig, rat brain or liver, and human) and to the heterogeneity of the experimental protocols used.

Thirty-eight new (4-(4-substituted-phenyl/2,4-disubstituted-phenyl)-thiazol-2-yl)hydrazine derivatives were synthesized in good yield and assayed for their in vitro anti-Candida activity, compared to topical and systemic antifungal drugs, against twenty-two clinical isolates of Candida spp. The concurrent presence of aliphatic chains or cycloaliphatic rings at N1-hydrazine and a 4-methyl/4-methoxyphenyl at C4 position of the thiazole nucleus exhibited an interesting anti-Candida inhibitory activity. Moreover, some of the most active compounds showed synergistic antifungal effects and lower cell toxicity when combined with clotrimazole., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

A large series of (4-substituted-thiazol-2-yl)hydrazine derivatives was synthesized in good yield and assayed for their in vitro human monoamine oxidase (hMAO) inhibitory activity and selectivity. Most of them showed inhibitory activity in the nanomolar range and hMAO-B selective inhibition higher than reference drugs, demonstrating our interest in this privileged scaffold. The structure-activity relationship of the different rings on the N1-hydrazine position indicated that a pyridine ring was preferred with the presence of electron-withdrawing substituents on the aryl group at C4 of the thiazole nucleus. The substituent on the α-carbon to the N1-hydrazine moiety (methyl or hydrogen) had a great influence on the activity and hMAO-B selectivity. Moreover, the reversibility of the enzyme inhibition for the best active compound was reported., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Novel 1-(4-ethyl carboxylate-thiazol-2-yl)-3,5-di(hetero)aryl-2-pyrazoline derivatives were obtained by reacting 3,5-di(hetero)aryl-1-thiocarbamoyl-2-pyrazolines with the ethyl ester of α-bromo-pyruvic acid. The synthesized compounds were confirmed by spectroscopic data and assayed to evaluate their in vitro ability to inhibit both isoforms of human cyclooxygenase (hCOX). Some derivatives (compounds 5, 6, 13, 16, and 17) displayed promising selectivity against hCOX-1 in the micromolar range and were shown to have a selectivity index similar or better than the reference drugs (indometacin, diclofenac). The introduction of a phenyl or a 4-F-phenyl ring on the C5 associated with a 4-substituted phenyl or a heteroaryl group on the C3 of (4-substituted-thiazol-2-yl)pyrazoline derivatives improved the activity against hCOX-1. Thanks to these preliminary results it could be possible to extend our knowledge of the pharmacophoric requirements for the discovery of new pyrazoline-based hCOX-1 inhibitors., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Introduction: Monoamine oxidase (MAO) plays an important role in the control of intracellular concentration of monoaminergic neurotransmitters or neuromodulators and dietary amines. The rapid degradation of these molecules ensures the proper functioning of synaptic neurotransmission and is critical for the regulation of several mental and cognitive functions. The by-products of MAO-mediated reactions comprehend reactive and toxic chemical species. As a consequence of this, the development of human MAO inhibitors led to important discoveries in the treatment of several neuropsychiatric and neurodegenerative disorders., Areas Covered: This review highlights the recent MAO inhibitors-related patents (2010-2012) and reports on new associations of already known MAO inhibitors with other drugs, innovative therapeutic targets, MAO inhibitors obtained by plants extraction, alternative administration routes and synthetic processes., Expert Opinion: MAO inhibitors appear promising for further clinical development being often endowed with other pharmacological functions (iron-chelating property, cholinesterase inhibition). A new 'golden age' of MAO inhibitors recently started from (i) the discovery of new therapeutic targets (prostate cancer, diabetes, ischemia/reperfusion injury, tobacco dependence, transmissible spongiform encephalopathy); (ii) the recognized role of MAO as biomolecular markers (insomnia, chronic alcoholism, obsessive-compulsive behavior); (iii) the activity of these enzymes in other tissues (platelets, prostate cells).

Novel (4-(4-iodophenyl)-thiazol-2-yl)hydrazine derivatives were assayed for their in vitro anti-Candida activity, compared to topical and systemic antifungal drugs, against twenty-seven clinical isolates. The presence of aliphatic chains or specific heteroaromatic rings on hydrazone moiety at position C2 and a 4-iodophenyl at C4 of the thiazole ring gave a promising inhibitory activity especially against Candida albicans and Candida krusei. The most active compounds have been also evaluated for their cytotoxicity and in association with clotrimazole for anti-Candida activity., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

A computer-aided design of novel asymmetric pyrazoles with improved enantioselective properties was performed by docking experiments starting from a model of Chiralcel OJ chiral in the stationary phase. Synthesis and HPLC experiments confirmed the theoretical prediction and led to a detailed investigation of the enantioselective recognition process. For the first time, looking at the time spent by each enantiomer in contact with the CSP during long molecular dynamic simulations, the experimental analytical trend has been reproduced., (© 2012 American Chemical Society)

Monoamine oxidase B (MAO-B) is a promising target for the treatment of neurodegenerative disorders. We report the synthesis and the biological evaluation of halogenated derivatives of 1-aryliden-2-(4-phenylthiazol-2-yl)hydrazines. The fluorinated series shows interesting activity and great selectivity toward the human recombinant MAO-B isoform expressed in baculovirus infected BTI insect cells. The multiple crystal structures alignment of the enzyme highlighted pronounced induced fit (IF) adaptations with respect to bound ligands. Therefore, IF docking (IFD) experiments and molecular dynamic (MD) simulations were carried out to reveal the putative binding mode and to explain the experimentally observed differences in the activity of 1-(aryliden-2-(4-(4-chlorophenyl)thiazol-2-yl)hydrazines. The importance of water molecules within the binding site was also investigated. These are known to play an important role in the binding site cavity and to mediate protein-ligand interactions. Detailed analyses of the trajectories provide insights on the chemical features required for the activity of this scaffold. In particular it was highlighted the importance of fluorine atom interacting with the water close to the cofactor and the influence of steric bulkiness of substituents in the arylidene moiety. Free energy perturbation (FEP) analysis confirmed experimental data. The information we deduced will help to develop novel high-affinity MAO-B inhibitors., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Purpose: We previously identified novel thiazole derivatives able to reduce histone acetylation and histone acetyltransferase (HAT) activity in yeast. Among these compounds, 3-methylcyclopentylidene-[4-(4'-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) has been selected and used throughout this study., Experimental Design: The effect of CPTH6 on histone acetylation, cell viability and differentiation, cell-cycle distribution, and apoptosis in a panel of acute myeloid leukemia and solid tumor cell lines has been evaluated., Results: Here, we showed that CPTH6 leads to an inhibition of Gcn5 and pCAF HAT activity. Moreover, it inhibits H3/H4 histones and α-tubulin acetylation of a panel of leukemia cell lines. Concentration- and time-dependent inhibition of cell viability, paralleled by accumulation of cells in the G(0)/G(1) phase and depletion from the S/G(2)M phases, was observed. The role of mitochondrial pathway on CPTH6-induced apoptosis was shown, being a decrease of mitochondrial membrane potential and the release of cytochrome c, from mitochondria to cytosol, induced by CPTH6. Also the involvement of Bcl-2 and Bcl-xL on CPTH6-induced apoptosis was found after overexpression of the two proteins in leukemia cells. Solid tumor cell lines from several origins were shown to be differently sensitive to CPTH6 treatment in terms of cell viability, and a correlation between the inhibitory efficacy on H3/H4 histones acetylation and cytotoxicity was found. Differentiating effect on leukemia and neuroblastoma cell lines was also induced by CPTH6., Conclusions: These results make CPTH6 a suitable tool for discovery of molecular targets of HAT and, potentially, for the development of new anticancer therapies, which warrants further investigations., (©2011 AACR.)

Among different heterocyclic chemotypes incorporating two nitrogen atoms, pyrazolines could be considered a valid pharmacophore for the synthesis of selective monoamine oxidase (MAO) inhibitors because they were developed by the cyclization of the early hydrazine derivatives such as isocarboxazid. Substituted pyrazolines, decorated with different functional groups, are important lead compounds endowed with a large amount of biological activities. As a matter of this, most of them were also evaluated as dual inhibitors with a synergistic action towards different classes of enzymes (ciclooxygenase, acetylcholinesterase, butyrylcholinesterase). Moreover due to the direct correlation with the recognized MAO inhibition, this scaffold displayed antidepressant and anticonvulsant properties in animal models.

Several 3-carbonyl (1-26), 3-acyl (27-52), and 3-carboxyhydrazido (53-58) coumarins have been synthesized in high yields (72-99%) and tested in vitro for their human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitory activity. Different substituents on the coumarin nucleus were evaluated for their effect on biological activity and isoform selectivity. Substitution at position C7 of the 3-ethyl ester coumarin ring, or the introduction of a hydrazido substituent at C3, were important to obtain highly potent and selective hMAO-B inhibitors with IC(50) values in the nanomolar range. Some derivatives were also submitted to a stability test and showed no chemical cleavage in vitro., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

A set of ten C5-chiral 4,5-dihydro-(1H)-pyrazole derivatives was synthesized and analyzed by high-performance liquid chromatography (HPLC) on the polysaccharide-based Chiralcel OJ-H chiral stationary phase (CSP). The enantioseparations were carried out using pure ethanol as eluent. Different structural elements of the investigated compounds were recognized for obtaining a very high enantioselectivity. In order to clarify some aspects of the chiral discrimination process, the thermodynamic parameters associated to the enantiorecognition and the enantiomer elution order were established., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A series of homoisoflavonoids [(E)-3-benzylidenechroman-4-ones 1a-w, 3-benzyl-4H-chromen-4-ones 2a-g, and 3-benzylchroman-4-ones 3a-e] have been synthesized and tested in vitro as inhibitors of human monoamine oxidase isoforms A and B (hMAO-A and hMAO-B). Most of the compounds were found to be potent and selective MAO-B inhibitors. In general, the (E)-3-benzylidenechroman-4-ones 1a-w showed activities in the nano- or micromolar range coupled with high selectivity against hMAO-B. The reduction of the exocyclic double bond results in compounds 3a-e selective against isoform B and active in the micromolar range. In contrast, the endocyclic migration of the double bond (compounds 2a-g) generally produces the loss of the inhibitory activity or a marked reduction in potency. (E)-3-(4-(Dimethylamino)benzylidene)chroman-4-one (1l) and (E)-5,7-dihydroxy-3-(4-hydroxybenzylidene)chroman-4-one (1h) were the most interesting compounds of the entire series of inhibitors, showing hMAO-B affinity better than the selective inhibitor selegiline. Molecular modeling studies have been carried out to explain the selectivity of the most active homoisoflavonoids 1h and 1l.

A new series of [4-(4'-substituted-phenyl)thiazol-2-yl]hydrazine derivatives were synthesized in good yield (86-99%) and characterized by elemental analysis, IR, (1)H NMR, and mass spectral studies. The compounds were assayed for their in vitro broad-spectrum antifungal activity, compared to clotrimazole and fluconazole, against 20 clinical isolates of pathogenic Candida spp., representing five different species. The results showed that the presence of heterocyclic or bicyclic rings on hydrazone moiety in position C2 of thiazole revealed a promising selective inhibitory activity especially against Candida albicans and Candida glabrata., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Eighteen new 1-N-substituted-3,5-diphenyl-2-pyrazoline derivatives have been synthesized and cyclooxygenase (COX-1 and COX-2) inhibitory activities have been evaluated. The results of these biological assays showed that all of new derivatives are not endowed with improved anti-inflammatory activity against COX-1, but some of them showed a good activity against COX-2. To evaluate the binding mode of the most significative compounds (2d, 2f, 2g and 2k) docking studies were carried out. These studies confirmed biological data, in fact these compounds were able to fit into the active site of COX-2., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

A series of N-substituted-3-[(2'-hydroxy-4'-prenyloxy)-phenyl]-5-phenyl-4,5-dihydro-(1H)-pyrazolines were synthesized and tested on human monoamine oxidase-A and -B isoforms. Structure-activity relationships and molecular modelling showed that some substitutions, such as benzyloxy or chlorine atom, improve the best interaction with active site of hMAO-B., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Novel 1-(4-arylthiazol-2-yl)-2-(3-methylcyclohexylidene)hydrazine derivatives have been investigated for their ability to inhibit selectively the activity of the human B isoform of monoamine oxidase. These compounds were obtained as racemates and (R)-enantiomers by a stereoconservative synthetic pattern in high yield and enantiomeric excess. The (S)-enantiomers of the most active derivatives have been separated by enantioselective HPLC. All compounds showed selective activity against hMAO-B with IC(50) ranging between 21.90 and 0.018 microM.

N-substituted-3-carboxamido-coumarin derivatives were prepared and evaluated for selective antibacterial activity against 20 isolates of Helicobacter pylori clinical strains, including five metronidazole resistant ones. Some of them possessed the best activity against H. pylori metronidazole resistant strains with MIC values lower than the drug reference (metronidazole). Furthermore, anti-inflammatory activity through the inhibition of the IL-8 production was investigated., (2010 Elsevier Ltd. All rights reserved.)

A new series of [4-(3-methoxyphenyl)-thiazol-2-yl]hydrazyne derivatives were synthesized in good yield (71-99%) and characterized by elemental analysis and (1)H NMR studies. The compounds were assayed for their in vitro human monoamine oxidase (hMAO) inhibitory activity and selectivity and most of them showed IC(50) values in the nanomolar range, thus demonstrating our interest in this privileged scaffold. The most active and selective derivative (20), bearing a pyridine moiety on the CN, displayed IC(50)=3.81+/-0.12 nM and selectivity ratio=119 toward hMAO-B. Molecular modeling studies were carried out on recent and high resolution hMAO-A and hMAO-B crystallographic structures to better justify the enzyme-inhibitor interaction toward hMAO isoforms and to explain the structure-activity relationship of this kind of inhibitors., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

The present study reports on synthesis in high yields (70-99%), HPLC enantioseparation, inhibitory activity against human monoamino oxidases, and molecular modeling including 3D-QSAR studies, of a large series of (4-aryl-thiazol-2-yl)hydrazones (1-45). Most of the synthesized compounds proved to be potent and selective inhibitors of hMAO-B isoform in the micromolar or nanomolar range, thus demonstrating that hydrazothiazole could be considered a good pharmacophore to design new hMAO-B inhibitors. Due to the presence in some derivatives of a chiral center, we also performed a semipreparative chromatographic enantioseparation of these compounds obtained by a stereoconservative pattern. The separated enantiomers were submitted to in vitro biological evaluation to point out the stereorecognition of the active site of the enzyme towards these structures. Finally, a 3D-QSAR study was carried out using Comparative Molecular Field Analysis (CoMFA), aiming to deduce rational guidelines for the further structural modification of these lead compounds., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Importance of the Field: Monoamine oxidase (MAO) plays a significant role in the control of intracellular concentration of monoaminergic neurotransmitters or neuromodulators and dietary amines. The rapid degradation of these molecules ensures the proper functioning of synaptic neurotransmission and is critically important for the regulation of emotional and other brain functions. Furthermore, modulators of neurotransmitters exert pleiotropic effects on mental and cognitive functions. The by-products of MAO-mediated reactions include several chemical species with neurotoxic potential. It is widely speculated that prolonged or excessive activity of these enzymes may be conducive to mitochondrial damages and neurodegenerative disturbances. In keeping with these premises, the development of human MAO inhibitors has led to important breakthroughs in the therapy of several neuropsychiatric disorders., Areas Covered in This Review: This review highlights the recent MAO inhibitors related patents published from July 2005 to December 2009. It also reports on new associations of already known MAO inhibitors with other drugs, innovative therapeutic targets, MAO inhibitors obtained by plants extraction, alternative administration routes and synthetic processes., What the Reader Will Gain: The reader will gain an overview of the main structures being investigated and their biological activities., Take Home Message: Several of these MAO inhibitors appear promising for further clinical development.

In vivo biotransformation experiments were performed by using a cell suspension culture of Morus nigra expressing a high PT (prenyltransferase) activity, fed with the target substrate 2',4'-dihydroxychalcone. In order to improve the reaction yields by enhancing the chalcone solubility, three different cyclodextrins have been used to host the substrate. The respective complexes have been studied by means of both spectroscopic and calorimetric techniques (Fourier-transform infrared, 1H-NMR and differential scanning calorimetry) and the solution behaviours have been characterized by solubility phase studies. The hydroxypropyl-beta-cyclodextrin complex was found to be the most suitable for biotransformation, and the reaction of prenylation resulted in a 6-fold higher yield of the final product when compared with the use of the free substrate. The reaction provided as the sole product the 3'-dimethylallyl derivative isocordoin, a biologically active plant compound. The results obtained allow the development of systems based on the use of biofermentors or the use of immobilized cells in order to enhance the biotransformation yields.

A series of N1-thiocarbamoyl-3,5-di(hetero)aryl-4,5-dihydro-(1H)-pyrazole derivatives has been synthesized and assayed for their ability to inhibit the activity of the A and B isoforms of human monoamine oxidase (hMAO). Some of these compounds were endowed with a selective inhibitory activity against hMAO-B in the micromolar range. The most active of the series is the compound 13, N1-thiocarbamoyl-3-(fur-2'-yl)-5-(4'-fluoro-phenyl)-4,5-dihydro-(1H)-pyrazole, with IC(50) 2.75+/-0.81muM value and selectivity ratio of 25, which is the best candidate for further investigations., (Copyright 2009 Elsevier Masson SAS. All rights reserved.)

A new series of synthetic flavones, thioflavones, and flavanones has been synthesized and evaluated as potential inhibitors of monoamine oxidase isoforms (MAO-A and -B). The most active series is the flavanone one with higher selective inhibitory activity against MAO-B. Some of these flavanones (mainly the most effective) have been separated and tested as single enantiomers. In order to investigate the MAOs recognition of the most active and selective compounds, a molecular modeling study has been performed using available Protein Data Bank (PDB) structures as receptor models for docking experiments., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

A new series of 4-acyl-2-thiazolylhydrazone derivatives was synthesized and screened for its in vitro activity against Toxoplasma gondii. We evaluated parasite growth inhibition and cytotoxicity, inhibition of replication, and inhibition of parasite invasion of host cells. The biological results indicated that some substances had an antiproliferative effect against intracellular T. gondii tachyzoites cultivated in vitro.

A large series of substituted chalcones have been synthesized and tested in vitro for their ability to inhibit human monoamine oxidases A and B (hMAO-A and hMAO-B). While all the compounds showed hMAO-B selective activity in the micro- and nanomolar ranges, the best results were obtained in the presence of chlorine and hydroxyl or methoxyl substituents. To better understand the enzyme-inhibitor interaction and to explain the selectivity of the most active compounds toward hMAO-B, molecular modeling studies were carried out on new, high resolution, hMAO-B crystallographic structures. For the only compound that also showed activity against hMAO-A as well as low selectivity, the molecular modeling study was also performed on the hMAO-A crystallographic structure. The docking technique provided new insight on the inhibition mechanism and the rational drug design of more potent/selective hMAO inhibitors based on the chalcone scaffold.

A large series of 3-carboxamido-7-substituted coumarins have been synthesized and tested in vitro for their human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitory activity. Taking into account all the relevant structural information on MAOs reported in the literature, we made some changes in the coumarin nucleus and examined with particular attention the effect on activity and selectivity of substituting at position 3 with N-aryl or N-alkyl carboxamide and at position 7 with a benzyloxy or a 4'-F-benzyloxy group. Some of the assayed compounds proved to be potent, selective inhibitors of hMAO-B with IC(50) values in the micromolar range. To better understand the enzyme-inhibitor interaction and to explain the selectivity of the most active compounds toward hMAOs, molecular modeling studies were carried out on new, high resolution, hMAO-A and hMAO-B crystallographic structures.

Acetylation is a key modulator of genome accessibility through decondensation of the chromatin structure. The balance between acetylation and opposite deacetylation is, in fact, a prerequisite for several cell functions and differentiation. To find modulators of the histone acetyltransferase Gcn5p, we performed a phenotypic screening on a set of newly synthesized molecules derived from thiazole in budding yeast Saccharomyces cerevisiae. We selected compounds that induce growth inhibition in yeast strains deleted in genes encoding known histone acetyltransferases. A novel molecule CPTH2, cyclopentylidene-[4-(4'-chlorophenyl)thiazol-2-yl)hydrazone, was selected based on its inhibitory effect on the growth of a gcn5Delta strain. We demonstrated a specific chemical-genetic interaction between CPTH2 and HAT Gcn5p, indicating that CPTH2 inhibits the Gcn5p dependent functional network. CPTH2 inhibited an in vitro HAT reaction, which is reverted by increasing concentration of histone H3. In vivo, it decreased acetylation of bulk histone H3 at the specific H3-AcK14 site. On the whole, our results demonstrate that CPTH2 is a novel HAT inhibitor modulating Gcn5p network in vitro and in vivo.

A series of N1-propanoyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives were synthesized and assayed as inhibitors of MAO-A and MAO-B isoforms. Most of the tested compounds showed inhibitory activity with micromolar values and MAO-A selectivity. In addition a computational work was carried out on the most selective compound 3b to highlight the most relevant interactions in the mechanism of recognition within both the MAO-A and the MAO-B enzyme active sites.

A series of 2-methylcyclohexylidene-(4-arylthiazol-2-yl)hydrazones have been investigated for their ability to inhibit selectively the activity of the human A and B isoforms of monoamine oxidase (MAO). The target compounds, which present a stereogenic center on the cyclohexane ring, were obtained as pure (R) and (S) enantiomers by enantioselective HPLC. The absolute configuration of homochiral forms isolated on a semipreparative scale was obtained by a combined strategy based on chemical correlation and single-crystal X-ray diffraction. All compounds showed higher activity against the human MAO-B isoform with IC50 values ranging between 26.81 +/- 2.74 microM and 14.20 +/- 0.26 nM, and the assays carried out on the pure enantiomers showed higher activity for the (R) form. A computational study was performed by molecular mechanics, DFT-based quantomechanics, and docking techniques on the most active and human MAO-B selective inhibitor 8.

In this paper, we report on the synthesis of a novel series of 2-thiazolylhydrazone derivatives and the influence of the substituents on the thiazole ring on antifungal activity. All synthesized compounds were screened for their in vitro activities against 22 clinical isolates of Candida spp., representing six different species, compared to clotrimazole as a reference compound. Some of the tested compounds were found to possess significant antifungal activity when compared to clotrimazole, in particular compound 14 which exhibited higher potency against most of the Candida spp. considered. The compounds that were most active as anti-Candida agents were also submitted to cytotoxic screening by the Trypan Blue dye exclusion assay and in general they were shown to induce low cytotoxic effects.

A novel class of selective anti-Helicobacter pylori agents, 2-oxo-2H-chromene-3-carboxamide derivatives, were prepared and evaluated for their anti-bacterial activity. All synthesized compounds showed little or no activity against different species of Gram-positive and Gram-negative bacteria and against various strains of pathogenic fungi. Some of them exhibited a potent and specific inhibitory effect on the growth of H. pylori, including metronidazole-resistant strains, in the 0.0039-16 microg/mL MIC range. A cytotoxic screening by the Trypan blue dye exclusion assay was also carried out on the most active compounds as anti-H. pylori agents. Among the derivatives examined for their cytotoxic potential, a number of them induced low cytotoxic effects.

A series of 2-thiazolylhydrazone derivatives have been investigated for the ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO) selectively. All of the compounds showed high activity against both the MAO-A and the MAO-B isoforms with pKi values ranging between 5.92 and 8.14 for the MAO-A and between 4.69 and 9.09 for the MAO-B isoforms. Both the MAO-A and the MAO-B isoforms, deposited in the Protein Data Bank as model 2BXR and 1GOS, respectively, were considered in a computational study performed with docking techniques on the most active and MAO-B-selective inhibitor, 18.

A series of 3,5-diaryl pyrazoles were prepared and assayed for their ability to inhibit reversibly monoamine oxidase-A (MAO-A) and monoamine oxidase B (MAO-B). Several compounds show inhibitory activity with concentration values in the nanomolar range. A computational work was carried out on the two most selective inhibitors that have tautomeric pyrazole forms. The binding free energies of these compounds for each MAO isoform were influenced by the tautomeric equilibria.

A novel series of N,N'-bis[2-oxo-2H-1-benzopyran]-3-carboxamide derivatives have been synthesized and investigated for the ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). Some of the synthesized compounds show good selective inhibitory activity against the MAO-A isoform. Both the MAO-A and -B isoforms, deposited in the Protein Data Bank as the 2BXR and 1GOS models, respectively, were considered in a computational study performed with docking techniques on the most active and selective inhibitors.

The methanol extract from Hypericum hircinum leaves exhibited in vitro inhibition of monoamine oxidases (MAO). Bioassay-guided fractionation led to the isolation of quercetin and five compounds identified for the first time from H. hircinum. Quercetin was the only compound with a selective inhibitory activity against MAO-A, with an IC50 value of 0.010 microM. To explain MAO selective inhibition at the molecular level, a computational study was carried out by conformational search and docking techniques using recently determined crystallographic models of both enzymatic isoforms. An in vivo study in mice was carried out using the forced swimming test in order to elucidate the behavioral effects of quercetin.

This report describes novel pyrazoline derivatives investigated for their ability to selectively inhibit the activity of the A and B isoforms of monoamine oxidase. These new synthetic compounds proved to be reversible, potent, and selective inhibitors of monoamine oxidase-A rather than of monoamine oxidase-B, and are promising candidates to further advance drug discovery efforts. The most active compounds show inhibitory activity on monoamine oxidase-A in the 1.0x10(-8)-8.6x10(-9) M range. Moreover, it should be pointed out that for some compounds a high IC50>or=10(-9) M value is associated with a high A-selectivity (Selectivity Index monoamine oxidase-B/monoamine oxidase-A in the 10,000-12,500 range). Further insight to understand enzyme-inhibitor molecular interaction was obtained by docking experiments with the monoamine oxidase-A and monoamine oxidase-B isoforms.

In order to develop new anti-Helicobacter pylori agents, five new and three already known N-substituted-2-oxo-2H-1-benzopyran-3-carboxamides (coumarin-3-carboxamides) were prepared and evaluated for their antibacterial activity. All synthesized compounds showed little or no activity against different species of Gram-positive and Gram-negative bacteria of clinical relevance and against various strains of pathogenic fungi. Among the prepared compounds those with a 4-acyl-phenyl group showed the best activity against H. pylori metronidazole resistant strains in the 0.25-1 microg/ml MIC range, indicating the presence of an acyl function as an important feature for activity.

The present report provides a extended study of the chemistry, the inhibitory activity against monoamino oxidases (MAO), and molecular modeling including the 3D-QSAR hypothesis of 1,3,5-trisubstituted-4,5-dihydro-(1H)-pyrazole derivatives. Four series of about eighty novel pyrazoline derivatives were prepared and investigated for their ability to inhibit the activity of the A and B isoforms of MAO selectively. Most of the new synthesized compounds proved more reversible, potent, and selective inhibitors of MAO-A than of MAO-B, and could be taken into account to develop the search further in this field, knowing that reversible and selective MAO-A inhibitors are used as antidepressant and antianxiety drug. The 30 most active compounds show inhibitory activity on MAO-A in the 8.6 x 10(-8) - 9.0 x 10(-9)M range. Moreover, it should be pointed out that for most of them a high IC(50) > or = 10(-9)M value is associated with a high A-selectivity (Selectivity Index MAO-B/MAO-A in the 10,000-16,250 range). Furthermore, due to the presence of a chiral centre at the C5 position of the pyrazole moiety, we performed the semi-preparative chromatographic enantioseparation of the most potent, selective, and chiral compounds. The separated enantiomers were then submitted to in vitro biological evaluation, and from the results of these experiments it has been possible to point out a difference in inhibiting the two isoforms selectively between the racemic mixture and the single enantiomers. The molecular modeling work was carried out combining the Glide docking approach with CoMFA with the aim to rationalize the structure-activity relationships of each pyrazoline inhibitor toward MAO-A and MAO-B isoforms and to derive a suitable selectivity model.

A novel series of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesized and investigated for the ability to inhibit selectively the activity of the A and B isoforms of monoamine oxidase (MAO). All the synthesized compounds show high activity against both the MAO-A and the MAO-B isoforms with Ki values between 27 and 4 nM and between 50 and 1.5 nM, respectively, except for a few derivatives whose inhibitory activity against MAO-B was in the micromolar range. Knowing that stereochemistry may be an important modulator of biological activity, we performed the semipreparative chromatographic enantioseparation of the most potent, selective, and chiral compounds. The separated enantiomers were then submitted to in vitro biological evaluation. The selectivity of the (-)-(S)-1 enantiomer against MAO-B increases twice and a half, while the selectivity of the (-)-(S)-4 enantiomer against MAO-A triples. Both the MAO-A and MAO-B isoforms respectively of the 1O5W and 1GOS models deposited in the Protein Data Bank were considered in the computational study. The docking study was carried out using several computational approaches with the aim of proposing possible binding modes of the MAO enantioselective compounds 1 and 4.

A series of substituted pyrazolines were synthesized and evaluated for their anticancer activity and for their ability to inhibit P-glycoprotein-mediated multidrug resistance by direct binding to a purified protein domain containing an ATP-binding site and a modulator interacting region. Compounds 2a and e have been found to bind to P-glycoprotein with greater affinity.

The HPLC enantiomer separation of a novel series of C(5)-chiral 1-acetyl-3-(4-hydroxy- and 2,4-dihydroxyphenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole derivatives, with inhibitory activity against monoamine oxidases (MAO) type A and B, was accomplished using polysaccharide-based chiral stationary phases (CSPs: Chiralpak AD, Chiralcel OD, and Chiralcel OJ). Pure alcohols, such as ethanol and 2-propanol, and typical normal-phase binary mixtures, such as n-hexane and alcohol modifier, were used as mobile phases. Single enantiomers of several analytes examined were isolated on a semipreparative scale, and their chiroptical properties were measured. The assignment of the absolute configuration was established for one compound by single-crystal X-ray diffraction method and for the other three by CD spectroscopy. The inhibitory activity against MAO of racemic samples and single enantiomers were evaluated in vitro., ((c) 2004 Wiley-Liss, Inc.)

A series of coumarin-3-acyl derivatives have been synthesized and investigated for the ability to inhibit selectively monoamine oxidases. The coumarin-3-carboxylic acids, 2a-e, proved to be reversible and selective inhibitors of the MAO-B isoform, displaying pIC(50) values of particular interest: 2a shows pIC(50) 7.76 and a selectivity index (pS.I.) 2.94 and 2b shows pIC(50) 7.72 and a pS.I. of 2.80. The coumarin-3-acyl chlorides 3a-e showed high pIC(50) values against both MAO-A and MAO-B isoforms, 3d being the highest against MAO-B with a pIC(50) value of 8.00. In order to rationalize the activity/selectivity results, molecular descriptors were generated. Further insight about enzyme-inhibitor interaction was obtained by docking experiments with the MAO-B isoform.

A novel series of 1-acetyl-3-(4-hydroxy- and 2,4-dihydroxyphenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole derivatives 1-12 have been synthesized and investigated for the ability to selectively inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). The new synthesized compounds 1-12 proved to be more reversible, potent, and selective inhibitors of MAO-A than of MAO-B. Knowing that stereochemistry may be an important modulator of biological activity, we performed the semipreparative chromatographic enantioseparation of the most potent, selective, and chiral compounds, 6 and 11. The separated enantiomers were then submitted to in vitro biological evaluation while increasing their inhibitory activity and A selectivity. The (-)-6 enantiomer shows K(i(MAO-A)) = 2 nM and SI = 165 000, (+)-6 shows K(i(MAO-A)) = 6 nM and SI = 166 666, (-)-11 shows K(i(MAO-A)) = 4 nM and SI = 80 000, and (+)-11 shows K(i(MAO-A)) = 7 nM and SI = 38 571.

A novel series of 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesised and investigated for the ability to inhibit selectively monoamine oxidases, swine kidney oxidase, and bovine serum amine oxidase. The newly synthesised compounds 1-6 proved to be reversible and non-competitive inhibitors of all types of the assayed amine oxidases. Compounds inhibit monoamine oxidases potently, displaying low I(50) values of particular interest. In particular 1-acetyl-3-(2,4-dihydroxyphenyl)-5-(3-methylphenyl)-4,5-dihydro-(1H)-pyrazole 6 showed to be a potent monoamine oxidase inhibitor with a K(i) of about 10(-8)M. Further insights in the theoretical evaluation of the possible interactions between the compounds and monoamine oxidase B have been developed through a computational approach.