Oxidative effects induced by dediazoniation of the p-hydroxybenzenediazonium ion in a neutral aqueous medium

Quintero, B.; Puentedura, Martínez; Megı́as, M.T.; Cabeza, M. Carmen; Gutiérrez, M.; Parras, P. J. Martinez De Las

doi:10.1016/j.chroma.2004.02.046

Cited by 3 publications

(3 citation statements)

References 56 publications

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“…Our previous results highlight the peroxidative effects involved at the beginning of cell damage. As we have reported elsewhere [15], analysis by reverse-phase HPLC shows that the decomposition of PDQ in a mixed micellar medium containing the surfactant Tween 20 induces the peroxidation of both linoleic acid (LA) and methyl linoleate (MEL), thus causing the appearance of a first group of chromatographic signals consisting of an unsolved couple of peaks, corresponding to isomers 9 and 13-cis-trans, dienic hydroperoxides, characterized by an absorption maximum located at 235 nm, and a second group formed by two well separated peaks, corresponding to isomers 9 and 13-trans-trans, the absorption spectra of which display a maximum at 232 nm. The same products are observed after interaction between LA and the water-soluble 2,2 -azobis (2-amidinopropane), a frequently used initiator of lipid peroxidation.…”

Section: Discussionsupporting

confidence: 68%

“…In previous studies into PDQ dediazoniation [13][14][15] our results have shown that in a neutral aqueous medium in the dark PDQ dediazoniation is a homolytic process. This homolytic degradation is triggered by the hydroxyl anion but the primary products then produce a selfcatalyzed reaction in which aryl, hydroxyphenylperoxyl and semiquinone radicals appear to be involved.…”

Section: Introductionmentioning

confidence: 99%

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Tumor-promoting activity of p-hydroxybenzenediazonium is accelerated in Mg-deficient rats

Quintero

Planells

Cabeza

et al. 2006

Chemico-Biological Interactions

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Tumor-promoting activity caused by the short-term administration of p-hydroxybenzenediazonium (PDQ) has been assayed in rats fed on a Mg-deficient diet as a reference model versus rats fed on a standard diet as controls. For 5 weeks groups of 20 rats, fed either on the Mg-deficient or standard diet, were treated simultaneously with PDQ. A group of 10 Mg-deficient rats remained untreated. Topical application of PDQ was followed by the appearance of macroscopic alterations in the skin, which were more evident in the Mg-deficient rats. No deaths occurred during the treatment. After 5 weeks' PDQ treatment the rats were killed and histological analyses were made. Tissues from the skin, liver, heart, kidney, lung and thymus were screened by conventional staining methods. Both the PDQ-treated Mg-deficient and PDQ-treated control rats presented tissue lesions, although to a different extent. The untreated Mg-deficient rats showed no such lesions. Mg-deficient rats treated with PDQ developed significant incipient fibrosarcomas (p < 0.05) and extended hyperplasia (p < 0.001), particularly in the skin, accompanied by a significant increase in the thickness of collagen (mean value: 445.4 ± 47.2 m, p < 0.05) compared to the control PDQ-treated group (mean values: 258.7 ± 36.4 m). The overall results provide objective proof of tumor-promoting activity after 5 weeks' treatment with PDQ. Such a fast response is interpreted as being linked to the increased vulnerability of the membrane caused by Mg deficiency, which would more readily facilitate the toxic activity of p-hydroxybenzenediazonium ions.

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Section: Discussionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Tumor-promoting activity of p-hydroxybenzenediazonium is accelerated in Mg-deficient rats

Quintero

Planells

Cabeza

et al. 2006

Chemico-Biological Interactions

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“…Recently, we studied the reaction between a number of arenediazonium ions with VC and some of its hydrophobic derivatives in aqueous acid solutions, in the presence and absence of anionic micellar aggregates, at different pH values. − The reactions may have some importance in food and biological systems because antioxidants may be able to directly reduce ArN 2 + ions via one-electron-transfer processes yielding aryl radicals that, in turn, are believed to be responsible, to some extent, for the carcinogenic properties of arenediazonium ions. ,− …”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of the Reaction between Ascorbic Acid Derivatives and an Arenediazonium Salt: Cationic Micellar Effects

2005

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The effects of tetradecyltrimethylammonium bromide, TTAB, and hexadecyl-trimethylammonium bromide, CTAB, micellar systems on the reaction of 3-methylbenzenediazonium, 3MBD, tetrafluoroborate with ascorbic acid, VC, and with the hydrophobic derivatives 6-O-dodecyl-L-ascorbic acid, VC12, and 6-O-palmitoyl-L-ascorbic acid, VC16, were investigated at different pH values by employing a combination of UV-vis spectroscopy and high-performance liquid chromatography, HPLC, techniques. Previous studies in the absence of surfactant showed that the reaction between 3MBD and VC derivatives takes place through a rate-limiting decomposition of a transient diazo ether, DE, formed from reaction between 3MBD and the monoanion form of ascorbic acid, VC-, in a rapid preequilibrium step. In the presence of a fixed [CTAB], the kinetics of the reaction of 3MBD with VC follows a saturation kinetics similar to that observed in its absence, but for the reaction with VC12 and VC16, only the first linear portions of the saturation profiles could be obtained because k(obs) values become too large. HPLC analyses of the reaction mixtures show that no unexpected products are detected, suggesting that cationic micelles do not modify the mechanism of the reaction. Analyses of the kinetic data allowed estimations of the rate constant for the decomposition of the diazo ether and of the equilibrium constant for the formation of DE in the presence of CTAB micelles, which is approximately 6 times higher than in its absence; this suggests that CTAB micelles promote diazo ether formation. At constant [antioxidant], the variations of k(obs) for the reactions with VC, VC12, or VC16 follow bell-shaped curves, with rate enhancements of up to 2-3-fold for VC with respect to the value in the absence of surfactant. The rate maximum for the reaction of 3MBD with VC is reached at [CTAB] = 0.02 M suggesting a CTAB-induced rate increase, i.e., micellar catalysis; meanwhile the rate maximum for the reaction with VC12 and VC16, which may behave as amphiphilic compounds, is reached at [CTAB] approximately 1 x 10(-4) M, a concentration about 10 times lower than its critical micelle concentration, cmc, in pure water, but only approximately 3 times lower than the cmc of VC16, suggesting the formation of reactive CTAB-VC12 and CTAB-VC16 premicellar aggregates. Kinetic and HPLC results are consistent with the predictions of the pseudophase model and are interpreted in terms of 3MBD ions sampling in the aqueous bulk phase and the micellar effects on the different equilibrium involved. The results should contribute to a better understanding of the role of compartmentalized systems on the efficiency with which hydrophilic and hydrophobic reductants such as ascorbic acid derivatives interact with potentially mutagenic and carcinogenic ArN2+ ions.

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Study of the spontaneous attachment of polycyclic aryldiazonium salts onto amorphous carbon substrates

et al. 2012

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Diazonium salts of two nitro-substituted polycyclic aromatic compounds were synthesized and their spontaneous covalent attachment onto amorphous carbon surfaces was studied via electrochemical and spectroscopic techniques. In situ spectroscopic monitoring of the grafting of these compounds at amorphous carbon surfaces via attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR) highlighted a marked difference in adsorption rates, which was also evident via ex situ electrochemical analysis. We show that adsorption rate differences cannot be explained based on differences in the solvolysis rates of these two molecules. It was found instead that the relative position of the -N 2 + groups with respect to the -NO 2 groups affected the reduction potential of the diazonium cations and in turn their adsorption rate at amorphous carbon surfaces. We conclude that differences in the electron density at the carbon atom bound to the diazonium group are responsible for the differences observed in the spontaneous attachment at carbon.

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Oxidative effects induced by dediazoniation of the p-hydroxybenzenediazonium ion in a neutral aqueous medium

Cited by 3 publications

References 56 publications

Tumor-promoting activity of p-hydroxybenzenediazonium is accelerated in Mg-deficient rats

Tumor-promoting activity of p-hydroxybenzenediazonium is accelerated in Mg-deficient rats

Kinetics and Mechanism of the Reaction between Ascorbic Acid Derivatives and an Arenediazonium Salt: Cationic Micellar Effects

Study of the spontaneous attachment of polycyclic aryldiazonium salts onto amorphous carbon substrates

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