Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PYRROLES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2002

Hydrogen-bonding and C-H...pi interactions in ethyl 4-acetyl-5-methyl-3-phenyl-1H-pyrrole-2-carboxylate monohydrate.

In the title compound, C(16)H(17)NO(3).H(2)O, the pyrrole ring is distorted slightly from ideal C(2v) symmetry. Three strong hydrogen bonds link the substituted pyrrole and water molecules to form infinite chains, in which the hydrogen bonds form rings and chain patterns. Two intermolecular C-H.pi interactions maintain the internal cohesion between these chains. The molecular structure differs slightly from that of the isolated molecule calculated by ab initio quantum-mechanical calculations. In the latter model, the non-H substituent atoms share the plane of the pyrrole ring, except for the phenyl group, which lies almost perpendicular to this plane.

Journal Article↗
PubMed2003

6-(2-Hydroxybenzoyl)-5-(pyrrol-2-yl)-3H-pyrrolizine.

The title compound, 2-hydroxyphenyl 5-(pyrrol-2-yl)-3H-pyrrolizin-6-yl ketone, C(18)H(14)N(2)O(2), was isolated from the base-catalyzed 1:2 condensation of 2-hydroxyacetophenone with pyrrole-2-carbaldehyde. The pyrrole N-H and hydroxybenzoyl O-H groups are hydrogen bonded to the benzoyl O atom. The allylic C=C double bond of the 3H-pyrrolizine system is located between ring positions 1 and 2, the C atom at position 3 (adjacent to the N atom) being single bonded.

Journal Article↗
PubMed1997

Two-component flavin-dependent pyrrole-2-carboxylate monooxygenase from Rhodococcus sp.

Pyrrole-2-carboxylate can serve as the sole source of carbon, nitrogen, and energy for a strain tentatively identified to belong to the genus Rhodococcus. An NADH-dependent oxygenase activity was detected in cell extracts that initiated the degradation of the substrate. During purification of the enzyme, this activity was separated into two protein components which were both purified to apparent homogeneity. A small monomeric 18.7-kDa protein designated as reductase, catalyzed in vitro the NADH and FAD-dependent reduction of cytochrome c and had an NADH-oxidase activity. The second component, a 54-kDa protein with a trimeric native structure had no enzymatic activity by itself, but exhibited a pyrrole-2-carboxylate-dependent oxygen consumption when it was complemented with the reductase component, FAD, and NADH. This indicated that the large protein referred to as oxygenase was responsible for the oxygen-dependent hydroxylation of the substrate. The rate of an uncoupled NADH oxidation without hydroxylation of the substrate was found to be strongly dependent on the molar ratio of both components. The uncoupling was nearly completely suppressed by a 5-7-fold molar excess of the oxygenase component. The small protein was N-terminally blocked. It was thus proteolytically digested and four of the resulting peptides were sequenced comprising 47 amino acids. The sequences of these fragments were similar to the sequences reported for the small component of different two-component flavin monooxygenases. Furthermore, the N-terminus of the oxygenase component showed high sequence similarity to the second, usually large subunit of these enzymes and to two single-component flavin monooxygenases. Thus, the enzyme from Rhodococcus sp. designated as pyrrole-2-carboxylate monooxygenase belongs to the recently discovered new class of two-component flavin aromatic monooxygenases. Some of the basic properties of both components were determined and their interaction during catalysis was investigated.

Amino Acid Sequence↗
PubMed1985

Metabolic pathways of the anti-hypertensive agent, N-(2,5-dimethyl-1H-pyrrol-1-yl)-6-(4-morpholinyl)-3-pyridazinamine+ ++ hydrochloride. I. Studies in the rat.

The metabolic fate of a new anti-hypertensive, 1-pyrrolyl pyridazinamine, was studied in male Wistar rats after both p.o. and i.v. administration (1 mg/kg). The compound undergoes rapid metabolism, disappearing from the central compartment with a half-life of about 0.5 h. Plasma concn. of the parent drug and its major metabolite I following i.v. and p.o. administration suggest a route-dependent first-pass metabolism. Ten metabolites were isolated from the urine and identified by u.v., i.r., mass and 1H-n.m.r. spectroscopy. The structure of some was confirmed by 13C-n.m.r. and chemical synthesis. All biotransformations are restricted to the pyrrole ring which undergoes oxidative cleavage followed by a series of chemical rearrangements. A minor pathway leads to the formation of methyl sulphinyl and methyl sulphonyl pyrroles. It is suggested that, as with natural indoles, the pyrrole might be oxidized by a 2,3-dioxygenase. The three major metabolites, I, II and IX, along with two minor ones, VI and VII, were inactive when tested i.v. for antihypertensive activity.

Administration, Oral↗
PubMed2000

GC/MS/MS detection of pyrrolic metabolites in animals poisoned with the pyrrolizidine alkaloid riddelliine.

Pyrrolic metabolites from pyrrolizidine alkaloids (PAs) were detected in liver and dried blood samples using a gas chromatography/tandem mass spectrometry (GC/MS/MS) selected product-ion-monitoring method. A calibration curve was constructed using a protein-metabolite conjugate spiked into dried bovine blood. These spiked samples served as a model for tissues from animals poisoned by the toxic metabolite of PAs. Tissue samples from pigs fed various amounts of the PA alkaloid riddelliine (from Senecio riddellii) were analyzed for pyrrolic metabolites, and the results were applied to the calibration curve to provide a measure of the degree of PA poisoning. Pyrrolic metabolites were detected in liver and blood samples of all poisoned animals at levels between 2 and 64 ppm. Although differences in metabolite levels could be discerned under the reported experimental conditions, the amount detected did not correlate with the dose of riddelliine given; and livers fixed with formalin gave greatly reduced recovery than those same livers either frozen or freeze dried.

Animals↗
PubMed1991

The effects of monocrotaline pyrrole on cultured bovine pulmonary artery endothelial and smooth muscle cells.

Monocrotaline pyrrole (MCTP), a reactive electrophile, induces delayed and progressive pulmonary edema, vascular remodeling, and pulmonary hypertension after a single intravenous administration to rats. The effects of a single exposure of cultured bovine pulmonary artery endothelial cells (BEC) and bovine pulmonary artery smooth muscle cells (BSMC) to MCTP were examined. Monocrotaline pyrrole caused a dose-dependent, delayed, and progressive cell detachment and release of lactate dehydrogenase activity from monolayers of BECs but not BSMCs. Monolayers of BECs also released increased concentrations of 6-keto-prostaglandin F1 degrees, the stable metabolite of prostacyclin, as the post-treatment interval increased. Progressive and marked endothelial cell hypertrophy occurred after exposure to a nominal concentration of 5 or 50 micrograms/ml of MCTP but not after 0.5 micrograms/ml. Morphologic changes in monolayers of BSMCs were minimal, even up to 2 weeks after exposure. Ultrastructurally the hypertrophic, MCTP-treated BECs had enlarged cell profiles with enlarged nuclei. The nucleoli were prominent, occasionally multiple, and had separation of granular and fibrillar components. Cytoplasmic microtubules and perinuclear intermediate filaments were prominent in some cells, as were the golgi apparatus and endoplasmic reticulum. Degenerative changes were not prominent in cells that remained in the monolayer. Monocrotaline pyrrole inhibited proliferation of both cell types at concentrations (0.5 micrograms/ml) that were not cytotoxic. These findings indicate that MCTP induces direct, dose-dependent injury to cells in culture that is delayed and progressive, and the expression of this injury depends, in part, on the cell type.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Synthesis, neuropsychopharmacological effects and analgesic-antiinflammatory activities of pyrrole analogues of lefetamine.

The synthesis of pyrrole analogues of the analgesic drug lefetamine is reported. These derivatives bear the 1-phenyl-2-(1H-pyrrol-1-yl)ethylamino moiety. Compounds were evaluated for analgesic activities in mice by the hot plate and Randall-Selitto tests. Antiinflammatory activity was tested by the carrageenan-induced rat paw edema method. General neuropsychopharmacological effects were also screened. The most interesting compound, N,N-dimethyl-1-phenyl-2-(1H-pyrrol-1-yl)ethylamine, showed an analgesic effect comparable to that of lefetamine, but devoid of the neurotoxicity of this drug.

Animals↗
PubMed1985

1-Ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1H-pyrrol-1-yl)-quinoline-3-carb oxylic acid, a new fluorinated compounds of oxacin family with high broad-spectrum antibacterial activities.

The synthesis of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1H-pyrrol-1-yl)quinoline-3-carboxy lic acid, a new fluorinated high broad-spectrum antibacterial agent related to nalidixic acid is described. The title compound has been prepared by the reaction of 4-fluoro-3-(1H-pyrrol-1-yl)aniline with diethyl ethoxymethylenemalonate, cyclization of the malonate obtained to the quinolinecarboxylate ester, ethylation of the ester, followed by hydrolysis with aqueous sodium hydroxide. The new derivative proved very active against both gram-positive and gram-negative bacteria. Its activities in comparison with those of nalidixic acid, pipemidic acid, piromidic acid and enoxacin were found to be greatly superior with regard to the unfluorinated compounds and somewhat superior also to enoxacin. The known 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(pyrrolidin-1-yl)quinoline-3- carboxylic acid, here prepared by catalytic hydrogenation of the pyrrole moiety of the title compound, has been found to be less active as an antibacterial agent.

Anti-Bacterial Agents↗
PubMed1983

Researches on antibacterial and antifungal agents. I. Analogs of nalidixic acid with a pyrrole moiety.

The synthesis and antibacterial activities of 4-hydroxyquinoline-3-carboxylic acid and 1,4-dihydro-1-ethyl-4-oxoquinoline-3-carboxylic acid containing a pyrrole or 2,5-dimethylpyrrole group at 6 position are reported. Reaction of 1-(4-aminophenyl)pyrrole or 2,5-dimethyl-1-(4-aminophenyl)-pyrrole with ethoxymethylenemalonate diethyl ester (EMME) afforded the related pyrroleanilinomethylenemalonates, which were subjected to thermal cyclization to give the required quinoline derivatives. These compounds on ethylation furnished at last the quinolonecarboxylic analogs of nalidixic acid.

Anti-Bacterial Agents↗
PubMed1995

In vitro production of long chain pyrrole fatty esters from carbonyl-amine reactions.

The reaction of lipoxygenase pathway products methyl 9,10(Z)-epoxy-13-oxo-11(E)-octadecenoate (13-MZEO) and methyl 12,13(Z)-epoxy-9-oxo-10(E)-octadecenoate (9-MZEO), with butylamine and lysine was studied in order to investigate whether some oxidized fatty acids are able to react with amino groups, analogously to volatile aldehydes, and, therefore, contribute to the overall protein damage produced during oxidative stress. The reaction mixtures were incubated at room temperature or 37 degrees C; the products were fractionated by semipreparative high performance liquid chromatography, and characterized by 1H and 13C nuclear magnetic resonance spectroscopy and mass spectrometry. The products identified were methyl 9-hydroxy-9-(5-pentyl-N-alkylpyrrole-2-)nonanoate and N-alkyl-2-pentylpyrrole for the 13-MZEO, and methyl 8-[5-(1'-hydroxyhexyl)-N-alkyl-pyrrole-2-]octanoate and methyl 8-(N-alkylpyrrole-2-)octanoate for the 9-MZEO. Formation of these pairs of analogs suggested that compounds were produced by one mechanism with the loss of the 5-substituent as a short-chain aldehyde, which was identified for the 13-MZEO. A reaction mechanism that explains the formation of all these compounds is proposed and the biological significance of these findings in relation to low density lipoprotein oxidation is discussed. Although these results do not demonstrate the formation of long-chain pyrrole fatty acids in vivo, they suggest that these pyrroles could be produced as an ultimate step in the lipid peroxidation process.

Amines↗
PubMed1989

Researches on antibacterial and antifungal agents, X. Synthesis and antifungal activities of 1-(p-methyl-alpha-[4-(1H-pyrrol-1-yl)phenyl]benzyl)azoles and some related products.

The synthesis and antifungal activities against Candida albicans and Candida spp. of some pyrrole analogues of bifonazole are reported. 1-(p-Methyl-alpha-[4-(1H-pyrrol-1-yl)phenyl]benzyl)imidazole was found to be equipotent or sometimes superior to bifonazole and ketoconazole, and lightly inferior to miconazole. Substitution of the imidazole moiety with other azoles retained some activities. No activity was shown when the azole aromatic rings were replaced by the heteroalicyclic ones.

Antifungal Agents↗
PubMed2006

Synthesis, acute toxicity, and analgesic activity of new derivatives of pyrrole.

Ten pyrrole derivatives (including six new compounds) were synthesized and evaluated as potential platform for analgesic agents' development. Acute intraperitoneal toxicity and analgesic activity studies (acetic acid writhing test) were performed on mice with acetylsalicylic acid used as a reference substance. Products 3c, 3d, 3e, and 3h exhibited a dose-dependent activity demonstrating 1.5 to 2.5-fold better protections than the reference. The most prospective compounds comprised salicylic acid moieties, whose 4-substituted derivatives were related to lower acute toxicity and considerable activity. 4-[3-(Ethoxycarbonyl)-2-methyl-5-(3,4-dimethoxy-phenyl)-1H-pyrrol-1-yl]-2-hydroxy-benzoic acid 3c was pointed out as the most prospective substance due to its lower acute toxicity (378 mg/kg body weight, intraperitoneally) and highest analgesic activity (up to 89.3% protection) in a dose range of 1/10 to 1/40 parts of LD(50).

Acetic Acid↗
PubMed2005

Utility of the ammonia-free Birch reduction of electron-deficient pyrroles: total synthesis of the 20s proteasome inhibitor, clasto-lactacystin beta-lactone.

A new synthesis of the 20S proteasome inhibitor clasto-lactacystin beta-lactone is described. Our route to this important natural product involves the partial reduction of an electron deficient pyrrole as a key step. By judicious choice of enolate counterion, we were able to exert complete control over the stereoselectivity of the reduction/aldol reaction. Early attempts to complete the synthesis by using a C-4 methyl substituted pyrrole are described in full, together with our attempts to promote regioselective elimination of a tertiary alcohol. The lessons learnt from this first approach led us to develop another, and ultimately successful, route that introduced the C-4 methyl group at a late stage in the synthesis. Our successful route is then described and this contains several highly stereoselective steps including a cis-dihydroxylation and an enolate methylation. The final synthesis proceeds in just 13 steps and in 15 % overall yield making it an extremely efficient route to this valuable compound.

Ammonia↗
PubMed2007

Bifurcated hydrogen-bonding effect on the shielding and coupling constants in trifluoroacetyl pyrroles as studied by 1H, 13C and 15N NMR spectroscopy and DFT calculations.

According to the (1)H, (13)C and (15)N NMR spectroscopic data and DFT calculations, bifurcated N--H...N and N--H...O intramolecular hydrogen bond is shown to be present in 2-trifluoroacetyl-5-(2'-pyridyl)-pyrrole. This bifurcated hydrogen bond causes an increase in the absolute size of the (1)J(N,H) coupling constant by about 6 Hz, and the deshielding of the bridge proton by 2 ppm. DFT calculations show that the influence of the N--H...N and N--H...O intramolecular hydrogen bonds on the (1)J(N,H) coupling and proton shielding is almost additive, although the components of the bifurcated hydrogen bond slightly weaken each other. In 2-trifluoroacetyl-5-(2'-pyridyl)-pyrrole, the coupling constants involving the fluorine and the N--H covalent bond nuclei depend dramatically on the spatial position of the pyridine ring. The pyridine ring rotation operates as a quantum switch controlling the spin information transfer between the (19)F and (15)N nuclei, as well as the proton.

Carbon Isotopes↗
PubMed1988

Pharmacokinetics of pirprofen and its pyrrol metabolite in elderly patients.

Plasma concentrations of pirprofen and of its pyrrol metabolite were assessed in 9 elderly patients (3 males, 6 females; mean age 76 years) suffering from chronic degenerative disease. Pirprofen 400 mg in 4 ml was administered i.m. and the pharmacokinetic profile of the drug and the metabolite was calculated. The AUC, Cmax and t1/2 of pirprofen were similar to those found in previous studies, and, as expected, those parameters for the pyrrol metabolite were lower (Cmax = 2.8 micrograms/ml-1; tmax = 6.4 h; AUC(0-32) = 56.5 micrograms.h.ml-1). One patient (n = 8) showed different pharmacokinetic behaviour, which is discussed. The data suggest that age has little influence on the pharmacokinetic of pirprofen, although unpredictable responses should always be considered in clinical practice.

Aged↗
PubMed2002

An innovative strategy for immobilization of receptor proteins on to an optical fiber by use of poly(pyrrole-biotin).

We report an innovative and useful procedure for immobilization of antibodies on to a fiber-optic silica surface. The procedure consists in the chemical oxidation of pyrrole-biotin monomers that are readily deposited as a thin film of poly(pyrrole-biotin) polymer on to the end-face of the fiber. The film was shown to be sufficiently translucent to enable photon coupling within the fiber transducer and its presence was demonstrated by means of fluorescent micrographs of bound rhodamine-labeled avidin. Fiber-optics modified with cholera toxin B subunit molecules were tested for sensitivity, non-specificity, and overall practicality. It was shown that the fiber-optic immuno-assay for the detection of anti-cholera toxin antibody was up to three orders of magnitude more sensitive than the classical enzyme-linked immunosorbent assay (ELISA).

Biotin↗
PubMed2005

A simple approach to the synthesis of highly functionalized pyrrole derivatives.

The reaction of dibenzoylacetylene and enaminocarbonyl compounds leads to 3-alkylidene-2,3-dihydro-1H-pyrrol-2-ol derivatives in nearly quantitative yields. The reaction of this heterocyclic system with alcohols in the presence of a catalytic amount of HCl produces highly functionalized pyrroles in good yields.

Alkylation↗
PubMed1995

In situ polymerization of pyrrole in animal tissue in the formation of hybrid biomaterials.

Porcine pericardium was impregnated with pyrrole or its derivative, sodium 4-(3-pyrrolyl)butanesulphonate (SPBS), by soaking the animal tissue in the monomer. Subsequent in situ chemical polymerization of the monomer-rich tissue using FeCl3 as initiator produced black polypyrrole-tissue hybrid biomaterials. The rate and extent of polymerization was found to be greater in 0.5 M acetic acid than in Hepes-buffered saline (HBS) and also greater for SPBS than for pyrrole. However, better tissue integrity was obtained for polymerization in HBS. Histological examination showed that the monomers do not permeate through the entire tissue, restricting polymerization to the surface layers of the tissue. The samples so formed do not exhibit detectable electrical conductivity.

Acetates↗