ChemInform Abstract: AMIDES AND RELATED COMPOUNDS

Challis, Brian C.; Challis, J. A.

doi:10.1002/chin.197952348

Cited by 7 publications

(5 citation statements)

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“…The results obtained in the previous sections indicate that aldehyde groups formed in the TEMPO-oxidized cellulose fibers more or less contribute to the wet strength improvement of the sheets prepared with C-PAM, PEI, PVAm, and cationic starch. It is known that NH 2 groups of amides and amines form N -acylcarbinolamine and carbinolamine structures, respectively, with aldehyde groups, which are similar to hemiacetals formed between hydroxyl and aldehyde groups . C-PAM can form the N -acylcarbinolamine structures with aldehyde groups in the TEMPO-oxidized cellulose sheets, while primary amino groups of PVAm and PEI can form carbinolamine structures followed by the formation of Schiff base structures with aldehyde groups in the TEMPO-oxidized cellulose fibers in the sheets by heating (Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…It is known that NH 2 groups of amides and amines form Nacylcarbinolamine and carbinolamine structures, respectively, with aldehyde groups, which are similar to hemiacetals formed between hydroxyl and aldehyde groups. 26 C-PAM can form the N-acylcarbinolamine structures with aldehyde groups in the TEMPO-oxidized cellulose sheets, while primary amino groups of PVAm and PEI can form carbinolamine structures followed by the formation of Schiff base structures with aldehyde groups in the TEMPO-oxidized cellulose fibers in the sheets by heating 8). Formation of a number of these covalent bonds at the TEMPO-oxidized cellulose fiber surfaces with either C-PAM, PEI, PVAm, or C-starch in the sheets is likely to cause their wet strength improvements, reinforcing the interfiber hemiacetal linkages formed between aldehyde and hydroxyl groups of the TEMPO-oxidized cellulose fibers in the sheets (Figure 9).…”

Section: Mechanisms Of Wet Strength Improvement Of Tempo-oxidized Cel...mentioning

confidence: 99%

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Wet Strength Improvement of TEMPO-Oxidized Cellulose Sheets Prepared with Cationic Polymers

Saito

Isogai

2006

Ind. Eng. Chem. Res.

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Cellulose fibers were oxidized with a catalytic amount of 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) in water, and these TEMPO-oxidized cellulose fibers were subjected to sheet making with cationic polymers such as cationic poly(acrylamide) (C-PAM) and poly(vinylamine) (PVAm). The wet strength of the sheets thus prepared was evaluated in terms of the cationic polymer used. It was found that wet tensile strength of the sheets was clearly improved by the cationic polymer addition to the cellulose slurries. Especially, the C-PAM addition was effective in wet strength improvement of the sheets, when the TEMPO-oxidized cellulose fibers were used. The results obtained using the TEMPO-oxidized and then NaBH4-reduced cellulose fibers showed that aldehyde groups present in the TEMPO-oxidized cellulose fibers have some interactions with the cationic polymers in the sheets, contributing to their wet strength improvements. Hemiacetals, N-acylcarbinolamines, carbinolamines, and Schiff bases are the possible structures formed at the interfaces between the TEMPO-oxidized cellulose fibers and cationic polymers in the sheets. Repulping behavior of the once-dried sheets was studied as well.

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Section: Resultsmentioning

confidence: 99%

Section: Mechanisms Of Wet Strength Improvement Of Tempo-oxidized Cel...mentioning

confidence: 99%

Wet Strength Improvement of TEMPO-Oxidized Cellulose Sheets Prepared with Cationic Polymers

Saito

Isogai

2006

Ind. Eng. Chem. Res.

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“…A more general effect on prolyl isomerization could arise from catalysis by functional groups within the polypeptide chain. Specific acid catalysis was found for proline-containing peptides and model compounds but will not affect prolyl isomerization rates under physiological conditions ( − ).…”

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confidence: 99%

Intramolecular Assistance of cis/trans Isomerization of the Histidine−Proline Moiety

Reimer

Schutkowski

et al. 1997

Biochemistry

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Peptidyl-prolyl cis/trans isomerization is a slow conformational interconversion in the polypeptide backbone that is frequently rate-limiting in refolding of proteins and is thought to play a role in cellular restructuring of proteins. In order to probe the influence of positively charged amino acids located in sequence segments adjacent to proline, the rotational barriers of Arg-Pro- and His-Pro-containing peptides were determined by isomer-specific proteolysis and dynamic NMR spectroscopy for Suc-Ala-His-Pro-Phe-NH-Np, Ac-Ala-Arg-Pro-Ala-Lys-NH2, Ac-Ala-His-Pro-Ala-Lys-NH2, angiotensin III, thyrotropin-releasing hormone (TRH), and [His(3-Me)2]TRH in aqueous solution. In contrast to the guanidinium group of arginine, the protonated side chain of histidine preceding proline led to an acceleration of the prolyl isomerization up to 10-fold relative to the unprotonated state. Both arginine and histidine residues succeeding proline in an amino acid sequence proved to be ineffective. Under basic and acidic conditions the kinetic solvent deuterium isotope effects Kc-->tH20/Kc-->tD20 for angiotensin III were 1.0 +/- 0.1 and 2.0 +/- 0.1, respectively. The results are interpreted in terms of intramolecular general acid catalysis of prolyl bond rotation by the imidazolium group that is without precedent in intermolecular catalysis.

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“…These distances measured on Dreiding models gave the order: 15 < 24 < 25 < 25.5 nm, respectively. This trend is confirmed in the 7-mononitro-substituted series with the mercaptoacetic acid 20 as well as with the hydroxamic acid 12 , where the proton attached to the oxygen is considered the ionizable one …”

Section: Resultsmentioning

confidence: 67%

“…This trend is confirmed in the 7-mononitro-substituted series with the mercaptoacetic acid 20 as well as with the hydroxamic acid 12, where the proton attached to the oxygen is considered the ionizable one. 27 Attempts to expand these SARs to include other acidic groups such as the boronic (22) and phosphinic (29) acids led to inactive compounds. Phosphonic acid monoesters are expected to be better mimics of carboxylic acid functions as both are monobasic acids, while the phosphonic acids are dibasic acids.…”

Section: Resultsmentioning

confidence: 99%

Structure−Activity Relationships in a Series of 2(1H)-Quinolones Bearing Different Acidic Function in the 3-Position: 6,7-Dichloro-2(1H)-oxoquinoline-3-phosphonic Acid, a New Potent and Selective AMPA/Kainate Antagonist with Neuroprotective Properties

et al. 1996

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Recently, we reported the synthesis of 3-(sulfonylamino)-2(1H)-quinolones, a new series of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate and N-methyl-D-aspartic acid (NMDA)/glycine antagonists. By exploring the structure-activity relationships (SAR) in this series, we were able to identify the 6,7-dinitro derivative 6 as a potent and balanced antagonist at both receptors. Unfortunately, compound 6 was devoid of in vivo activity in mice anticonvulsant testing. To overcome this critical limitation, new compounds bearing various acidic moieties at the 3-position of the quinolone skeleton were synthesized and evaluated. The SAR of these new analogues indicated that not all acidic groups are acceptable at the 3-position: A rank order of potency going from carboxylic approximately phosphonic > tetrazole > mercaptoacetic > hydroxamic >> other heterocyclic acids was defined. In addition, the selectivity between the AMPA/kainate and NMDA/glycine sites is dependent on the nature of the substitution (nitro > chloro for AMPA selectivity), its position (5,7- > 6,7-pattern for glycine selectivity), and the distance between the quinolone moiety and the heteroatom bearing the acidic hydrogen (the longer the distance the more AMPA selective the compound). Among these new AMPA antagonists, we have identified 6,7-dichloro-2(1H)-oxoquinoline-3-phosphonic acid (24c) as a water soluble and selective compound endowed with an appealing pharmacological profile. Compared with the reference AMPA antagonist NBQX, the phosphonic acid 24c is much less potent in vitro but almost equipotent in vivo in the audiogenic seizures model after intraperitoneal administration. Moreover, unlike NBQX, compound 24c is also active after oral administration. In the gerbil global ischemia model, compound 24c shows a neuroprotective effect at 10 mg/kg/ip, equivalent to the reference NBQX.

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ChemInform Abstract: AMIDES AND RELATED COMPOUNDS

Cited by 7 publications

References 0 publications

Wet Strength Improvement of TEMPO-Oxidized Cellulose Sheets Prepared with Cationic Polymers

Wet Strength Improvement of TEMPO-Oxidized Cellulose Sheets Prepared with Cationic Polymers

Intramolecular Assistance of cis/trans Isomerization of the Histidine−Proline Moiety

Structure−Activity Relationships in a Series of 2(1H)-Quinolones Bearing Different Acidic Function in the 3-Position: 6,7-Dichloro-2(1H)-oxoquinoline-3-phosphonic Acid, a New Potent and Selective AMPA/Kainate Antagonist with Neuroprotective Properties

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