Search results for "Azoles"
showing 10 items of 899 documents
Host−Guest Interactions between β-Cyclodextrin and the (Z)-Phenylhydrazone of 3-Benzoyl-5-phenyl-1,2,4-oxadiazole: The First Kinetic Study of a Ring…
2002
The effect of beta-cyclodextrin (beta-CD) on the mononuclear heterocyclic rearrangement of the (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1) in aqueous borate buffer at pH = 9.6 has been analyzed at temperatures ranging from 293.15 to 313.15 K. The trend of the absorption spectra of 1 as a function of time has been accounted for with the formation of two different 1:1 complexes between beta-CD and 1, the first, "unreactive" complex being formed faster than the "reactive" one. The occurrence of negative activation enthalpy values for the studied interconversion evidences the kinetic relevance of inclusion processes. Computational models elaborated using the MM2 molecular mec…
Discovery and structure-activity relationship studies of irreversible benzisothiazolinone-based inhibitors against Staphylococcus aureus sortase A tr…
2014
Gram-positive bacteria, in general, and staphylococci, in particular, are the widespread cause of nosocomial and community-acquired infections. The rapid evolvement of strains resistant to antibiotics currently in use is a serious challenge. Novel antimicrobial compounds have to be developed to fight these resistant bacteria, and sortase A, a bacterial cell wall enzyme, is a promising target for novel therapies. As a transpeptidase that covalently attaches various virulence factors to the cell surface, this enzyme plays a crucial role in the ability of bacteria to invade the host's tissues and to escape the immune response. In this study we have screened a small molecule library against rec…
In vitro anti-biofilm activity of Boswellia spp. oleogum resin essential oils
2009
Aims: To evaluate the anti-biofilm activity of the commercially available essential oils from two Boswellia species. Methods and Results: The susceptibility of staphylococcal and Candida albicans biofilms was determined by methyltiazotetrazolium (MTT) staining. At concentrations ranging from 217·3 μg ml−1 (25% v/v) to 6·8 μg ml−1 (0·75% v/v), the essential oil of Boswellia papyrifera showed considerable activity against both Staphylococcus epidermidis DSM 3269 and Staphylococcus aureus ATCC 29213 biofilms. The anti-microbial efficacy of this oil against S. epidermidis RP62A biofilms was also tested using live/dead staining in combination with fluorescence microscopy, and we observed that …
4-Diazopyrazole Derivatives as Potential New Antibiofilm Agents
2008
<i>Background:</i> The recognition that chronic infections and infections associated with medical devices are biofilm related has been the impulse for investigating the antibiofilm properties of some diazopyrazoles biologically active as antimicrobials. <i>Methods:</i> The susceptibility of staphylococcal biofilms was determined at concentrations ranging from 25 to 1.5 µg/ml using crystal violet and methylthiazotetrazolium (MTT) staining. In the case of <i>Candida albicans,</i> we first assessed the anti-germ tube formation effect of 4-NO<sub>2</sub> (compound 1c) and then we evaluated its antibiofilm activity at concentrations ranging from 10…
A new palladium(II)-catalyzed [3,3] aza-Claisen rearrangement of 3-allyloxy-5-aryl-1,2,4-oxadiazoles
2011
Abstract A new efficient palladium(II)-catalyzed [3,3] aza-Claisen, formal sigmatropic rearrangement of 3-allyloxy-5-aryl-1,2,4-oxadiazoles was developed. The mechanism was studied by analyzing the regiochemical and stereochemical course of the reaction. The results obtained indicated the intervention of a cationic pallada-cycle similar to the one postulated for the Cope rearrangement of 1,5-dienes.
Membrane D-lactate oxidase in Zymomonas mobilis: evidence for a branched respiratory chain.
1998
Respiratory chain composition of the ethanol-producing bacterium Zymomonas mobilis was studied. Its membrane D-lactate oxidase was characterised. With NADH, but not D-lactate as substrate, a cytochrome o-like component was seen in CO difference spectra. Chlorpromazine specifically inhibited reduction of cytochrome d, while myxothiazol eliminated the cytochrome o-like features in CO difference spectra. It is suggested that electrons from NADH are distributed between branches terminated by the cytochrome o-like component, cytochrome a, and cytochrome d. With D-lactate, electrons are transported to cytochrome a, or an unidentified CN(-)-sensitive oxidase, and cytochrome d.
Synthesis and in vitro antileukemic activity of new 4-triazenopyrazole derivatives
2003
Several new 4-(3,3-dimethyltriazeno)-5-benzamidopyrazole derivatives were prepared by reacting 4-diazo-5-benzamidopyrazole derivatives with dimethylamine. The compounds were tested at 10 microM for their vitro antileukemic activity against K562 (Human chronic myelogenous leukemia) and Raji (human Burkitt limphoma ) cell lines. Dacarbazine and methotrexate were used for comparative purpose. The 3-methyl-4-(3,3-dimethyltriazeno)-5-(substituted benzamido)pyrazoles, bearing the pyrazole nucleus free at 1 position, resulted more active than the 1-(substituted phenyl)-3-methyl-4-(3,3-dimethyltriazeno)-5-benzamidopyrazoles. Dacarbazine at 10 microM showed no activity in the above tests. The observ…
Synthesis and Characterization of New Bivalent Agents as Melatonin- and Histamine H3-Ligands
2014
Melatonin is an endogenous molecule involved in many pathophysiological processes. In addition to the control of circadian rhythms, its antioxidant and neuroprotective properties have been widely described. Thus far, different bivalent compounds composed by a melatonin molecule linked to another neuroprotective agent were synthesized and tested for their ability to block neurodegenerative processes in vitro and in vivo. To identify a novel class of potential neuroprotective compounds, we prepared a series of bivalent ligands, in which a prototypic melatonergic ligand is connected to an imidazole-based H3 receptor antagonist through a flexible linker. Four imidazolyl-alkyloxy-anilinoethylami…
A deep insight into the mechanism of the acid-catalyzed rearrangement of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole in a non-polar s…
2010
The conversion of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole (1a) into the relevant 1,2,3-triazole (2a) has been quantitatively studied in toluene in the presence of several halogenoacetic acids (HAAs, 3a–h). Again, the occurrence of two reaction pathways has been pointed out: they require one or two moles of acid, respectively, thus repeating the situation previously observed in the presence of trichloroacetic acid. The observed rate constant ratios (kIII/kII) are only slightly affected by the nature of the acid used. To gain a deeper insight into the action of the acids used we have measured the association constants of the HAAs (3a–h) with 4-nitroaniline (4) in toluene. …
Synthesis, properties, antitumor and antibacterial activity of new Pt(II) and Pd(II) complexes with 2,2′-dithiobis(benzothiazole) ligand
2017
Mono- and binuclear Pt(II) and Pd(II) complexes with 2,20-dithiobis(benzothiazole) (DTBTA) ligand are reported. [Pt(DTBTA)(DMSO)Cl]Cl∙CHCl3 (1) and [Pd2(m-Cl)2(DTBTA)2]Cl2 (2) have been synthesized and structurally characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, MS spectrometry and the content of platinum and palladium was determined using a flame atomic spectrometer. Two different coordination modes of 1 and 2 complexes were found; in both complexes, the coordination of Pt(II) and Pd(II) ions involves the N(3) atoms of the ligand but the binuclear complex 2, is a cis-chloro-bridged palladium complex. Evaluation of their in vitro antitumor activity against two human tu…