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, 1H 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.

AbstractThe most promising derivatives in terms of potent broad‐spectrum anti‐Candida spp.

A new series of 3-acyl-6,7,8-substituted coumarin derivatives has been synthesized in high yields (79-99%) and characterized by means of elemental analysis, mass spectrometry, IR, and (1)H NMR spectroscopy. We examined with particular attention the presence of an acyl group at position 3 (ethyl ester, carboxylic acid, and acyl chloride), and of a hydroxyl group at position 7 or a functionalized one like benzyloxy or phthalimido. The hydroxyl group has been modified by an etherification in presence of crown ether with substituted benzyl bromide or chloride to evaluate the influence on chemical characteristics and lipophilicity of coumarin nucleus. Halogens (Cl, Br) and methyl group were introduced in position 6 and 8 of the coumarin ring, respectively, in order to study their effect on reaction feasibility. Some of these 3-acyl derivatives have been recently assayed as MAO inhibitors and as intermediates (i.e. reactive chloride derivative) to design new anti-Helicobacter pylori agents.

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.

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 H-1 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.

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 1H NMR studies. The compounds were assayed for their in vitro human monoamine oxidase (hMAO) inhibitory activity and selectivity and most of them showed IC50 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 IC50=3.81±0.12nM 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.

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.

A novel class of coumarin-thiazole conjugated systems (1-31) were synthesized by Hantzsch condensation between alpha-bromo-3-acetyl coumarin and several thiosemicarbazone intermediates. This scaffold was also evaluated for selective antibacterial activity against 20 isolates of H. pylori clinical strains, including four metronidazole resistant ones.

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.

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.

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 IC50 2.75 ± 0.81 μM value and selectivity ratio of 25, which is the best candidate for further investigations.

Seven new 2,4-disubstituted thiazoles have been synthesized by Hantzsch condensation and assayed for several biological activities for a preliminary screening. They have been fully characterized by elemental analysis, UV-Vis spectroscopy, TG-DTA, IR, and H-1 NMR its well. These structures display different pharmacological (antimicrobic activity, citotoxicity, and hMAO inhibition) and industrial properties (complete transparency in the region between 465-800 nm and high thermal stability) varying oil their substituents and could be considered as good lead compounds for further developments.

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.

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.

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.