Search results for "Pyrrole"

In vitro anti-Gram-positive and anti-staphylococcal biofilm activity of newly halogenated pyrroles related to Pyrrolomycins

2007

3,4,5,3’,5’-pentabromo-2-(2’-hydroxybenzoyl) pyrrole: a potential lead compound as anti Gram-positive and anti biofilm agent

2005

The activity against Gram-positive bacteria of 3,4,5,3 ,5 -pentabromo-2-(2 -hydroxybenzoyl)pyrrole I, a synthetic anti-bacterial compound related to pyrrolomycins, was tested in vitro using seven reference bacterial strains and Staphylococcus epidermidis and Staphylococcus aureus preformed biofilms. Compound I was active against all strains tested, with minimum inhibitory concentration (MIC) values ranging from 0.002 to 0.097 mg/l and minimum bactericidal concentrations (MBCs) from 0.37 to 12.5 mg/l. Compound I was also active at low concentrations against preformed S. epidermidis and S. aureus biofilms.

Fe- but not Mg-protophorphyrin IX binds to a transmembrane b-type cytochrome.

2013

Transmembrane b-type cytochromes, which are crucially involved in electron transfer chains, bind one or more heme (Fe-protoporphyrin IX) molecules non-covalently. Similarly, chlorophylls are typically also non-covalently bound by several membrane integral polypeptides involved in photosynthesis. While both, chlorophyll and heme, are tetrapyrrole macrocycles, they have different substituents at the tetrapyrrole ring moiety. Furthermore, the central metal ion is Mg(2+) in chlorophyll and Fe(2+/3+) in heme. As heme and chlorophyll a have similar structures and might both be ligated by two histidine residues of a polypeptide chain, and as the local concentration of chlorophyll a might be up to …

Confinement inside a Crystalline Sponge Induces Pyrrole To Form N−H⋅⋅⋅π Bonded Tetramers

2021

Based on the DFT‐level calculated molecular volume (V mol ) of pyrrole and its liquid density, pyrrole manifests the highest liquid density coefficient LD c (defined as [V mol • density • 0.6023]/FW) value of 0.7. Normal liquids have LD c < 0.63. This very high LD c is due to the strong N‐H … π interactions in solution and hence pyrrole can be considered to be a pseudo‐crystalline liquid. When trapped inside the confined space of the crystalline sponge a reorientation of the N‐H … π interaction is observed leading to specific cyclic N‐H … π tetramers and N‐H … π dimers, verified by single crystal X‐ray crystallographic and computational methods. These tetramers are of the same size as four …

Design, Synthesis, and Biological Evaluation of 3,4-Diarylmaleimides as Angiogenesis Inhibitors

2006

The new analogue 2 of combretastatin A-4 was discovered to be an inhibitor of tubulin polymerization with an IC50 of 7.6 microM and reduced angiogenesis in the in vivo chick embryo model. Interestingly, in a series of 2,3-diarylmaleimides closely related to this lead, no other compound was found to be active in the tubulin polymerization assay. However, by screening in the in vivo chick embryo assay 10 was identified as a potent angiogenesis inhibitor indicating an alternative target. Indeed, molecular modeling studies suggest a reasonable binding mode of 10 at the ATP-binding site of the model kinase CDK2. Motivated by these results, analogues of 10 were screened for inhibitory activity in…

Molybdenum Complex with Bulky Chelates as a Functional Model for Molybdenum Oxidases

2014

The novel bulky Schiff base chelate ligand [(4,5-diisopropyl-1H-pyrrole-2-yl)methylene]-4-(tert-butyl)aniline ((iPr2)HL) bearing two isopropyl groups close to the pyrrole nitrogen atom reacts with MoCl2(dme)O2 (dme = 1,2-dimethoxyethane) to give the sterically congested complex Mo(VI)((iPr2)L)2O2 ((iPr2)1; OC-6-4-4 configuration). In spite of the increased steric shielding of the [MoO2] unit (iPr2)1 is active in oxygen-atom transfer to PMe3 and PPh3 to give OPMe3 and OPPh3, respectively. Because of the increased steric bulk of the chelate ligand, formation of dinuclear complexes [Mo(V)((iPr2)L)2O]2(μ-O) ((iPr2)3) by comportionation is effectively prevented in contrast to the highly favored …

Stepwise sequential redox potential modulation possible on a single platform.

2011

Step by step: The cluster [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) is an excellent platform for making a stepwise tunable redox potential system by dehydroiodination. With the addition of up to eight iodine substituents (purple; see picture), there is a fall in the E(1/2)(Co(III)/Co(II)) value from -1.80 V to -0.68 V (vs. Fc(+)/Fc; Fc = ferrocene). A practical application of this tunability has been observed in the growth of polypyrrole.

A new approach to inhibit human β-tryptase by protein surface binding of four-armed peptide ligands with two different sets of arms

2013

A series of six new tetravalent ligands (1-6) with two different sets of arms bind to the surface of β-tryptase, a tetrameric enzyme with an A(2)B(2) arrangement of its four monomers and two different binding sites on its protein surface (as suggested by a docking study). Besides proteinogenic amino acids also the guanidiniocarbonyl pyrrole cation (abbreviated as GCP), as an artificial arginine analog, was introduced into the arms of the ligands to investigate its influence on protein surface binding and enzyme inhibition. Furthermore, four ligands (7-10) with four identical arms also containing the GCP group were additionally synthesized to study the influence of the GCP moiety on the inhi…

A DFT study of [3 + 2] cycloaddition reactions of an azomethine imine with N-vinyl pyrrole and N-vinyl tetrahydroindole

2016

The mechanism and selectivities of the [3+2] cycloaddition (32CA) reactions of azomethine imine (AI) 8 with two N-vinyl five-membered heterocycles (NVFH), 9a and 9b, have been theoretically studied using DFT methods at the MPWB1K/6-31G(d) computational level. The possible ortho/meta regio- and endo/exo stereoselective channels were explored and characterised. The low polar character of these 32CA reactions, which is the consequence of the high nucleophilic character of both reagents, as well as the non-effective reactivity of these NVFH as nucleophiles, accounts for the high calculated activation energies, 16.1 (9a) and 16.8 (9b) kcalmol-1 in chlorobenzene. Analysis of the relative electron…

Structural and Molecular Characterization of meso-Substituted Zinc Porphyrins: A DFT Supported Study

2011

Structural parameters of a range of over 100 meso-substituted zinc porphyrins were reviewed and compared to show how far the nature of the functional group may affect the interatomic distances and bond angles within the porphyrin core. It was proved that even despite evident deformations of the molecular structure, involving twisting of the porphyrin's central plane, the coupled π-bonding system remains flexible and stable. DFT calculations were applied to a number of selected porphyrins representative for the reviewed compounds to emphasize the relevance of theoretical methods in structural investigations of complex macrocyclic molecular systems. Experimental and DFT-simulated IR spectral …