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Results for “Pyridinium Compounds”

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At least 19 recordsLinked to original sources
PubMed1987

Protective effect of bis-pyridinium compounds on the rat brain acetylcholinesterase inhibition by carbamate in vitro.

The inhibition of the rat brain acetylcholinesterase by quaternary bis-pyridinium compounds and the protection against acetylcholinesterase inhibition by 3-diethyl-aminophenyl-N-methylcarbamate methiodide was studied with three bis-pyridinium compounds. These compounds have two pyridinium rings connected by a dimethylether link and alkyl groups in position 4 of both pyridinium rings. Toxogonin was used as a reference compound. Bis-pyridinium compounds studied are weak reversible inhibitors of acetylcholinesterase (I50 from 10(-4) to 10(-3) M) and exert also the ability to protect acetylcholinesterase against inhibition by 3-diethyl-aminophenyl-N-methylcarbamate methiodide in vitro at a concentration of 0.1 mM. Negligible protection was obtained with Toxogonin.

Animals↗
PubMed1977

Inhibition of C1s-induced vascular leakage in guinea pigs by substituted benzamidine and pyridinium compounds.

A variety of benzamidine and pyridinium compounds were examined for their ability to inhibit irreversibly C1s-induced vascular leakage in guinea pig skin. Vascular leakage was compared with esterolysis of N-Z-L-Tyr-Np and catalysis of EAC42 formation by C1s. Vascular leakage correlated significantly better with esterolytic activity than with EAC42 formation. The presence of a sulfonyl fluoride moiety in the compounds is important in the inhibition of C1s-induced vascular leakage.

Amidines↗
PubMed1991

[Rough sets theory in structure-activity relationship analysis of quaternary pyridinium compounds].

Relationship between chemical structure and antimicrobial activity of 53 quaternary pyridinium compounds is analysed using the theory of rough sets. The compounds are described by 8 attributes concerning structure and are divided into 5 classes of activity. The description builds up an information system. Using the rough sets approach a smallest set of attributes significant for a high quality of classification has been found. A decision algorithm has been derived from the information system showing important relations between structure and activity. It may be helpful in supporting decisions concerning synthesis of new antimicrobial compounds.

Algorithms↗
PubMed1999

Inhibition of acetylcholinesterase by three new pyridinium compounds and their effect on phosphonylation of the enzyme.

Three new mono-pyridinium compounds were prepared: 1-phenacyl-2-methylpyridinium chloride (1), 1-benzoylethylpyridinium chloride (2) and 1-benzoylethylpyridinium-4-aldoxime chloride (3) and assayed in vitro for their inhibitory effect on human blood acetylcholinesterase (EC 3.1.1.7, AChE). All the three compounds inhibited AChE reversibly; their binding affinity for the enzyme was compared with their protective effect (PI) on AChE phosphonylation by soman and VX. Compound 1 was found to bind to both the catalytic and the allosteric (substrate inhibition) sites of the enzyme with estimated dissociation constants of 6.9 microM (Kcat) and 27 microM (Kall), respectively. Compound 2 bound to the catalytic site with Kcat = 59 microM and compound 3 only to the allosteric site with Kall = 328 microM. PI was evaluated from phosphonylation measured in the absence and in presence of the compounds applied in a concentration corresponding to their Kcat or Kall value, and was also calculated from theoretical equations deduced from the reversible inhibition of the enzyme. Compounds 1 and 3 protected the enzyme from phosphonylation by soman and VX, whereas no protection was observed in the presence of compound 2 under the same conditions. Irrespective of the binding sites to AChE, PI for compounds 1 and 3 evaluated from phosphonylation agreed with PI calculated from reversible inhibition. Compound 3 was found to be a weak reactivator of methylphosphonylated AChE with Kr = 1.1 x 10(2) L mol-1 min-1.

Acetylcholinesterase↗
PubMed1999

Structural Effects on the Interaction between cis-Dialkoxyazobenzene and a Pyridinium Compound at the Glass-Heptane Interface as Studied by in Situ Second Harmonic Generation.

The in situ optical second harmonic generation (SHG) technique was applied to the direct investigation of interactions between cis-dialkoxyazobenzene and a pyridinium compound at the glass-heptane interface. The SHG response due to noncentrosymmetric adsorption of the SHG-active cis-isomer was profoundly dependent on the structure of the pyridinium compound preadsorbed at the glass surface. It is suggested that the cis-isomer can interact preferentially with a bipyridinium compound in which the two pyridinium moieties are spatially separated to be able to interact snugly with the two phenoxy moieties of cis-dialkoxyazobenzene. Copyright 1999 Academic Press.

Journal Article↗
PubMed1995

Application of the rough sets theory to the analysis of structure-activity-relationships of antimicrobial pyridinium compounds.

Relationship between chemical structure and antimicrobial activity of 80 quaternary pyridinium chlorides were analysed using the method of rough sets. The compounds are described by eight conditions attributes (substituents in pyridine) and divided into three classes of activity (MIC). Using the rough sets approach a smallest set of four condition attributes significant for a high quality of classification and accuracy of classes has been found. The resulting decision rules describe relations between structure and antibacterial activity of pyridinium chlorides in terms of significant condition attributes. This may be helpful in predicting structures of new antibacterial compounds to be synthesized.

Anti-Infective Agents↗
PubMed1975

Clinical neuromuscular pharmacology of AH 8165 D, an azobis-arylimidazo-pyridinium-compound.

The neuromuscular blocking properties of AH 8165 D (1,1'azobis-(3-methyl-2-phenyl-1H-imidazo-1,2a-pyridinium)dibromide) were quantitatively studied in 50 patients, undergoing extra-abdominal surgery and anaesthetized with barbiturates, nitrous oxide, fentanyl and droperidol, by means of mechanograms of the hand muscles obtained by ulnar nerve stimulation. AH 8165 D is a rapid-acting nondepolarizing agent (full effect within 1--2 min) providing good intubation conditions similar to those obtained with suxamethonium. AH 8165 D may be considered to be indicated for emergency intubation in patients with full stomach when the risk of regurgitation is high. The duration of action of clinically useful doses (0.4-0.8 mg/kg body weight) is shorter than that of equi-effective doses of other nondepolarizing muscle relaxants. Repeated doses show a cumulative effect. The neuromuscular blockade can easily be reversed by an anticholinesterase drug. AH 8165 D-induced muscle relaxation is always accompanied by a dose-dependent tachycardia limiting the clinical usefulness of this new drug.

Adult↗
PubMed1997

Lipofuscin in the retina: quantitative assay for an unprecedented autofluorescent compound (pyridinium bis-retinoid, A2-E) of ocular age pigment.

The pyridinium bis-retinoid, A2-E, has been discovered as one of the major autofluorescent components of retinal pigment epithelial lipofuscin. Due to its chemical characteristics, A2-E may contribute to cellular and molecular changes leading to age-related macular degeneration. Because A2-E is the first lipofuscin component that has been identified, purified, and its structure analysed, it represents an important marker molecule for studying lipofuscin formation under various conditions. In order to investigate the role of A2-E in ageing processes of the retinal pigment epithelium, we developed an HPLC assay for this compound using single wavelength UV-absorbance detection with continuous light emission. Standard A2-E was synthetized and purified by sequential TLC. In our assay, A2-E can be detected in amounts lower than 10 pmol. The assay has been applied to quantitative determination of A2-E amounts in albino rat eyes of different age groups. Our results demonstrate that there is a marked increase of A2-E levels in older animals. The method described is the first to allow quantification of this unusual retinoid from small amounts of biological samples.

Aging↗
PubMed1972

Microbial metabolism of pyridinium compounds. Metabolism of 4-carboxy-1-methylpyridinium chloride, a photolytic product of paraquat.

1. A bacterium, Achromobacter D, isolated from garden soil by elective culture, utilized N-methylisonicotinic acid (4-carboxy-1-methylpyridinium chloride) as sole carbon source. 2. Extracts of N-methylisonicotinate-grown cells oxidized this substrate only after supplementation with a source of nicotinamide nucleotides and then consumed 1 mol of O(2) and released 1 mol of CO(2)/mol of N-methylisonicotinate supplied. 3. The N-methyl group of the substrate was released as methylamine whereas the five C atoms of the pyridine ring were accounted for as succinate and formate. The CO(2) evolved by extracts was believed to derive from the carboxyl group on C-4 of the heterocyclic ring. 4. The immediate precursor of the succinate end-product was succinic semialdehyde; the inducible nature of succinic semialdehyde dehydrogenase in N-methylisonicotinate-grown cells supported this finding. 5. There was no evidence for monohydroxylation of the ring, but the time sequence of the appearance of the end-products indicated that the oxygen-requiring, NADH-requiring and decarboxylation steps clearly preceded the formation of methylamine and succinate. 6. The results are consistent with the oxidative cleavage of a partially reduced heterocyclic ring followed by several hydrolytic and dehydrogenase steps resulting in the appearance of the end-products.

Alcaligenes↗
PubMed1972

Microbial metabolism of pyridinium compounds. Radioisotope studies of the metabolic fat of 4-carboxy-1-methylpyridinium chloride.

Extracts of Achromobacter D formed CO(2), methylamine, succinate and formate as metabolic end-products from N-methylisonicotinic acid (4-carboxy-1-methylpyridinium chloride). The origin of the CO(2) in the 4-carboxyl group and of the methylamine in the N-methyl group of N-methylisonicotinate was demonstrated with carboxyl-(14)C- and N-Me-(14)C-labelled substrates respectively. The carbon skeletons of formate and succinate were shown to arise from the C-2 and the C-3-C-6 atoms of the heterocyclic ring respectively by using N-methyl[2,3-(14)C(2)]isonicotinate. This result is consistent with ring cleavage by the organism between C-2 and C-3.

Alcaligenes↗
PubMed2000

Chlorination of pyridinium compounds. Possible role of hypochlorite, N-chloramines, and chlorine in the oxidation of pyridinoline cross-links of articular cartilage collagen type II during acute inflammation.

Reactive oxygen species produced by activated neutrophils and monocytes are thought to be involved in mediating the loss of collagen and other matrix proteins at sites of inflammation. To evaluate their potential to oxidize the pyridinoline (Pyd) cross-links found in collagen types I and II, we reacted hydrogen peroxide (H(2)O(2)), hypochlorous acid/hypochlorite (HOCl/OCl(-)), and singlet oxygen (O(2)((1)delta g)) with the Pyd substitutes, pyridoxamine dihydrochloride and vitamin B(6), which share the same chemical structure and spectral properties of Pyd cross-links. Neither H(2)O(2) (125-500 microm) nor O(2)((1)delta g) (10-25 microm) significantly changed the spectral properties of pyridoxamine or vitamin B(6). Reaction of HOCl/OCl(-) (12.5-50 microm) with pyridoxamine at pH 7.2 resulted in a concentration-dependent appearance of two new absorbance peaks and a decrease in fluorescence at 400 nm (excitation 325 nm). The new absorbance peaks correlated with the formation of an N-chloramine and the product of its subsequent reaction with pyridoxamine. In contrast, the extent to which HOCl reacted with vitamin B(6), which lacks a primary amine group, was variable at this pH. At lysosomal pH 5.5, Cl(2)/HOCl/OCl(-) reacted with both pyridoxamine and vitamin B(6). Four of the chlorinated products of this reaction were identified by gas chromatography-mass spectrometry and included 3-chloropyridinium, an aldehyde, and several chlorinated products with disrupted rings. To evaluate the effects of Cl(2)/HOCl/OCl(-) on Pyd cross-links in collagen, we exposed bone collagen type I and articular cartilage type II to HOCl. Treatment of either collagen type with HOCl at pH 5. 0 or 7.2 resulted in the oxidation of amine groups and, for collagen type II, the specific decrease in Pyd cross-link fluorescence, suggesting that during inflammation both oxidations may be used by neutrophils and monocytes to promote the loss of matrix integrity.

Cartilage, Articular↗
PubMed1994

[Application of the rough sets theory to the analysis of structure-activity relationships of pyridinium antifungal compounds].

Relationships between chemical structure and antifungal activity of 72 quaternary pyridinium chlorides were analysed using the method of rough sets. In the information system the compounds are described by eight condition attributes and divided into three classes of activity. Using the rough sets approach a smallest set of four condition attributes significant for a high quality of classification and accuracy of classes has been found. The resulting decision algorithm describes relations between structure and antifungal activity in terms of significant condition attributes. It may be helpful in predicting structures of new antifungal compounds to be synthesized.

Algorithms↗