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  • 1990-1994  (2)
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  • Prohapten activation  (2)
  • 1
    ISSN: 1432-069X
    Keywords: Allergic contact dermatitis ; Monohydric alkylbenzenes ; Dihydric alkylbenzenes ; Quinols ; Resorcinols ; Catechols ; Urushiols ; Prohapten activation ; NADH ; Cysteine ; Glutathione ; Diphenylpicrylhydrazyl ; 2-Oxo-4-thiazolidine carboxylate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The induction of allergic contact dermatitis to urushiols from poison ivy and related plants is generally believed to involve an initial oxidation event by which a protein-reactive quinone is formed. However, this does not readily account for the contact allergenicity of closely related mono- and dihydric alkylbenzenes such as the alkylphenols and alkylresorcinols which are not so easily oxidised to quinones in vitro. When the redox processes known to occur in living tissues are taken into consideration, a more plausible unifying mechanism involving the formation of protein-reactive radical species becomes apparent. Experiments described here examine the autoxidation of p-benzoquinone and various mono- and dihydric benzenes and alkylbenzenes, and their reactions with the diphenylpicrylhydrazyl radical, cysteine, glutathione, and NADH. We have also demonstrated that administration to mice of 2-oxo-4-thiazolidine carboxylate, a compound known to elevate intracellular glutathione levels, inhibits the irritancy and sensitising activity of 3-pentadecylphenol. This work suggests that redox cycling in the skin following penetration of allergenic mono- and dihydric alkylbenzenes initially depletes local levels of endogenous reducing equivalents such as glutathione and NADH; once depleted, further cycling results in the uncontrolled generation of radical species which may reasonably be expected to exhibit protein reactivity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 284 (1992), S. 400-408 
    ISSN: 1432-069X
    Keywords: Allergic contact dermatitis ; Dinitrohalobenzenes ; Picryl chloride ; Prohapten activation ; Xenobiotic metabolism ; Glutathione status ; Oxidative stress ; NADPH-dependent reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using a selection of ‘classic’ haptens (dinitrohalobenzenes and picryl chloride) and related nonsensitizing analogous, we examined changes in levels of glutathione (GSH) and glutathione disulphide (GSSG) in mouse skin 12 h after their epicutaneous application. We observed that elevation of GSSG levels and/or depletion of GSH levels correlated well with contact allergenic potential. Non-sensitizing analogous failed to perturb GSH/GSSG status. In vitro assays using mouse skin and rat liver microsomal preparations indicated that only the allergenic nitrohalobenzenes initiated NADPH-dependent oxygen utilization, with the activity falling off in the order picryl chloride ≫ DNIB 〉 DNBB 〉 DNCB 〉 DNFB. In addition, an examination of the colour of mouse skin homogenates ex vivo after application of the dinitrohalobenzenes showed significant yellowing (consistent with aromatic nucleophilic substitution) only with DNFB. Our results indicate that, while an aromatic nucleophilic substitution reaction with skin protein can possibly account for the allergenicity of DNFB, it does not seem to occur with DNCB, DNBB or DNIB. These may instead behave mainly as prohaptens which are activated enzymically by NADPH-dependent reductase (s) within the skin, with the concomitant generation of superoxide and hydrogen peroxide, to form potentially protein-reactive free radical and other metabolites. Picryl chloride appears capable of both conjugating directly with proteins by aromatic nucleophilic substitution and undergoing NADPH-dependent metabolism to other potentially protein-reactive metabolites.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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