Quaternary Pyridinium Compounds Research Articles

Recent Advances in Electron Donor‐Acceptor (EDA)‐Complex Reactions involving Quaternary Pyridinium Derivatives

AbstractQuaternary pyridinium compounds are valuable intermediates in organic synthesis, which have gained immense popularity in the synthetic community. The application of transition metal or photoredox catalysis in transforming quaternary pyridinium compounds into various C−C and C−X bonds is well established. A majority of these methods require high temperatures, expansive catalysts, and delicate conditions for successful execution. On the other hand, the use of transition metal‐free and photocatalysis‐free strategies in constructing C−C and C−X bonds using quaternary pyridinium derivatives has been sought‐after. In this context, the electron‐donor‐acceptor (EDA)‐complex reactions have emerged as a state‐of‐the‐art organic synthetic methodology, which do not require any photocatalyst for their successful execution. EDA‐complex photochemistry takes advantage of the electron‐acceptor ability of quaternary pyridinium derivatives, which can quickly generate a radical precursor via the deaminative process. These newly generated radical intermediates are useful in several valuable transformations. We hereby, in this review, discuss an area of major progress in EDA‐complex mediated reactions involving quaternary pyridinium compounds with mechanism, substrate scope, and limitations.magnified image

Modification of chitosan and chitosan nanoparticle by long chain pyridinium compounds: Synthesis, characterization, antibacterial, and antioxidant activities

Chitosan is an antibacterial biopolymer and conjugation of it with other antimicrobial agents can be a valuable method to improve the potential application of the resultant materials in the various industries such as cosmetics, food and packaging materials. In this work, a series of quaternary pyridinium compounds were synthesized; then to achieve developed biological properties, they were attached to the chitosan and chitosan nanoparticles. The formation of chitosan derivatives was evinced by FT-IR, 1H and 13C NMR, UV–vis and EDX spectroscopy. The morphology of samples was detected by FE-SEM, TEM and AFM images. The QAC-chitosan hybrids were investigated for antibacterial activity against two Gram-positive and two Gram-negative bacteria, and they showed a significant effect on the Gram-positive bacteria. DPPH-radical scavenging assay shows mild improvement in antioxidant activity of new chitosan derivatives.

Antibacterial activity of N-methylbenzofuro[3,2-b]quinoline and N-methylbenzoindolo[3,2-b]-quinoline derivatives and study of their mode of action

The emergence of multidrug-resistant bacteria causes an urgent need for new generation of antibiotics, which may have a different mechanism of inhibition or killing action from the existing. Targeting at the inhibition of bacterial cell division via the control of FtsZ function is one of the effective and promising approaches. Some natural extracts from plants such as sanguinarine and berberine (analogs of pyridinium compounds) are known to alter FtsZ function. In this study, a series of novel quaternary pyridinium compounds was constructed based on the N-methylbenzofuro[3,2-b]quinoline and N-methylbenzoindolo[3,2-b]-quinoline derivatives and their antibacterial activity against nine significant pathogens was investigated using broth microdilution method. In the in vitro assay, the compounds showed strong antibacterial activities against various testing strains, which include some drug-resistant strains such as methicillin-resistant S. aureus and vancomycin-resistant E. faecium. Our results of morphology change of B. subtilis cells and molecular docking proved that the compounds functioned as an effective inhibitor to suppress FtsZ polymerization and FtsZ GTPase activity and thus the compound stops cell division and cause cell death through interacting with C-terminal interdomain cleft of FtsZ.

Dienals derived from pyridinium salts and their subsequent application in natural product synthesis.

Transformation of quaternary pyridinium compounds into functionalized conjugated dienes can be adapted to natural product synthesis with great effect. Most conspicuously, the transformation has been employed in the preparation of polyenic structures. However, in a more convoluted application, polycyclic systems have arisen from elaboration of the diene motif. The goal of the present account is to survey the utility of dienals derived from pyridinium salts as the means to establish molecular architecture featured in natural products.

Adsorption of quaternary pyridinium compounds at Pt electrodes in neutral and weakly alkaline solutions

Two quaternized pyridinium compounds being considered for application as corrosion inhibitors, N-butyl-3-(hydroxynonyl) pyridinium bromide (Quat 1) and N-butyl-3-( N-octylcarbamyl)pyridinium bromide (Quat 2), differing only in the nature of the linkage between the pyridinium ring and the group attached at the meta position, have been investigated for their adsorptive properties at polycrystalline Pt electrodes in pH 7 and 11 solutions. It is seen that both Quats are strongly adsorbing, even at a concentration of <50 μM, completely blocking the Pt surface and fully suppressing both Pt electrochemistry and hydrogen evolution. In situ mass measurements, carried out together with electrochemistry, reveal that one to two monolayers of Quats 1 and 2 are deposited when cycling between the potentials of oxygen and hydrogen evolution. Notably, once the Pt surface and its electrochemistry are fully blocked, the potential can be extended more negatively, allowing the reduction of Quats in solution, forming a multilayer film on the Pt surface. Concurrent mass measurements show that the equivalent of up to 100 monolayers of reduced Quat can then be deposited, probably as a mixture of monomers and dimers.

Quaternary pyridinium compounds formed by reaction of primary amines with alkanals and their antimicrobial activities.

Seventeen alkyl-substituted quaternary pyridinium compounds were synthesized by the condensation reaction of amino acids and primary amines with alkanals. The growth-inhibitory capabilities of these pyridiniums were investigated against gram-negative and gram-positive bacteria (Escherichia coli and Streptococcus thermophilus), as well as against a mold (Neurospora crassa) and yeast (Candida utilis). Most of the pyridiniums appreciably inhibited the growth of the microorganisms tested. l-Carboxymethyl-2-hexyl-3, 5-dipentylpyridinium betaine and l-(2hydroxyethyl)-2-hexyl-3, 5-dipentylpyridiriium chloride showed the greatest inhibitory activity. Least growth inhibition by pyridinium ions was observed for E. coli.

Antigenic specificity of glutaraldehyde-treated rabbit albumin

Rabbit albumin treated with glutaraldehyde is immunogenic in rabbits due to the new antigenic determinants induced into the molecule by glutaraldehyde (Onicǎ et al., 1978 a, b). Hardy et al. (1976 a, 1977) isolated quaternary pyridinium compounds from the acid hydrolysis products of glutaraldehyde-reacted ovalbumin, which are responsible for the strong chromophore absorbing at 265 nm exhibited by glutaraldehyde-treated proteins. Our data have shown that such structures are involved in the antigenic determinants of glutaraldehyde-treated rabbit albumin. As a consequence, the reaction between the modified albumin and the specific antibodies is inhibited by: (1) peptides with molecular weights of 7800 and 11,000 daltons, and having an absorption maximum at 265 nm, isolated from the pronase digest of glutaraldehyde-treated albumin; (2) compounds with pyridinium structures obtained by the reaction of glutaraldehyde and the amino groups of 6-aminohexanoic acid and (3) other proteins (human and bovine albumin, ovalbumin, rabbit immunoglobulin G, peroxidase) treated with glutaraldehyde. Since glutaraldehyde-treated albumin shows a reaction of identity with albumin aged in vivo or in vitro, it is possible that the physiologic aging of albumin involves the formation of pyridinium-like structures. The molecular rearrangements around such structures may represent the new antigenic sites specific for the aged albumin. These sites could be recognized as non-self by the immunocompetent cells, stimulating the production of physiologic autoantibodies which remove the modified albumin from the circulation.

ChemInform Abstract: The Nature of the Cross‐linking of Proteins by Glutaraldehyde. Part 2. The Forma‐tion of Quaternary Pyridinium Compounds by the Action of Glutaraldehyde on Proteins and the Identification of a 3‐(2‐Piperidyl)‐pyridinium Derivative, Anabilysine, as a Cross‐linking Entity.

AbstractAus den Säurehydrolysaten von mit Glutaraldehyd (II) behandelten Ovalbumin (I) werden die Pyridiniumchloride (III) und (IV) (Anabilysin) isoliert, deren Strukturen durch die angegebenen Synthesen bestätigt werden; bei der Synthese von (IV) entsteht auch das Monoalkylierungsprodukt (VIII).

The nature of the cross-linking of proteins by glutaraldehyde. Part 2. The formation of quaternary pyridinium compounds by the action of glutaraldehyde on proteins and the identification of a 3-(2-piperidyl)-pyridinium derivative, anabilysine, as a cross-linking entity

1-(5-Amino-5-carboxypentyl)pyridinium chloride (3) and 1-(5-amino-5-carboxypentyl)-3-[1-(5-amino-5-carboxypentyl)-2-piperidyl]pyridinium chloride, anabilysine (4), have been isolated from acid hydrolysates of glutaraldehyde-treated ovalbumin and their structures confirmed by synthesis. It is concluded that the strong chromophore at ca. 265 nm shown by glutaraldehyde-treated proteins is due to the formation of such quaternary pyridinium compounds and that anabilysine residues are important in the cross-linking of proteins by glutaraldehyde.

Formation of quaternary pyridinium compounds by the action of glutaraldehyde on proteins

1-(5-Amino-5-carboxypentyl)pyridinium chloride hydrochloride (2) has been isolated by acid hydrolysis of the product of the action of glutaraldehyde on ovalbumin, supporting the view that the chromophore with λmax ca. 265 nm formed when glutaraldehyde reacts with proteins is due to the formation of quaternary pyridinium compounds.

Identification of a new crosslinking amino acid in elastin

Recently, Partridge et al . (1963) described the occurrence in elastin of two hitherto unrecognized amino acids for which evidence has now accrued to show their origin from lysine residues in a “pre-elastin” (Partridge et al ., 1964; Miller et al ., 1964). These substances, called desmosine and isodesmosine, are in fact quaternary pyridinium compounds with four side-chain substituents that function in crosslinking of elastin chains (Thomas et al ., 1964). An examination of peptide fractions of elastin selected for enrichment with respect to the desmosines revealed the presence of an additional amino acid, called X 4′ also previously undescribed (Franzblau et al ., 1965). The present communication presents data to show that X 4 can be represented by the formula, N ϵ-(5-amino 5-carboxypentanyl)-lysine.

Paper chromatography of nicotinic acid derivatives.

LEIFER et al.1 have reported the paper chromatography of nicotinic acid with the use of microbiological assay. While our work was in progress, Huebner2 described a spot test for detection of some pyridine derivatives. The present work describes sensitive qualitative techniques developed in this Laboratory for the detection of tertiary and quaternary pyridinium compounds. The laborious procedure involved in the microbiological method of Leifer et al.1 is obviated by rapid colour or fluorescent tests. For the colour test, advantage was taken of Konig's3 reaction, namely, the formation of coloured compounds when tertiary pyridine derivatives are treated with cyanogen bromide and a primary aromatic amine. The fluorescence test allows the detection of quaternary nicotinamide derivatives. Use is made of the formation of bluish-white fluorescent substances when quaternary pyridine compounds with a side chain CO—NH—R in the β position are treated with methyl ethyl ketone and ammonia4.