Antioxidant-Mediated Modulation of Protein Reactivity for 3,4-Dihydroxyphenylacetaldehyde, a Toxic Dopamine Metabolite.
Chem Res Toxicol
; 29(7): 1098-107, 2016 07 18.
Article
em En
| MEDLINE
| ID: mdl-27268734
ABSTRACT
3,4-Dihydroxyphenylacetaldehyde (DOPAL) is an endogenously produced toxic aldehyde. It is a bifunctional electrophile implicated in the loss of dopaminergic cells concomitant with Parkinson's disease and neurodegeneration. DOPAL is known to react with proteins and amino acids such as N-acetyl lysine (NAL); oxidation of the catechol moiety to the quinone of DOPAL increases this reactivity. Here, we demonstrate the ability of the antioxidants N-acetylcysteine, glutathione, and ascorbic acid to mitigate the reactivity of DOPAL with proteins and amino acids in a dose-dependent fashion. Conversely, Trolox did not lessen the observed reactivity with proteins. Interestingly, use of tricine, a buffer and reducing agent, in these systems also decreased the reactivity of DOPAL with amines, yielding tricine-derived free radical species. Modification of amines with aldehydes typically involves Schiff base chemistry; however, the observance of free radicals suggests that an oxidative step is involved in the reaction of DOPAL with lysine. Furthermore, while Schiff base formation is usually optimal at pH 5, the reaction rate of DOPAL with NAL is negligible at pH 5 and is enhanced under basic conditions (e.g., pH 9). Conditions of high pH are also favorable for catechol auto-oxidation, known to occur for DOPAL. The antioxidant-mediated protection demonstrated here suggests that oxidative stress may impart cellular vulnerability to protein modification by DOPAL. Therefore, depleted antioxidants and increased levels of lipid peroxidation products, known to prevent the detoxifying metabolism of DOPAL, may present a survival challenge to dopaminergic cells targeted in Parkinson's disease.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Ácido 3,4-Di-Hidroxifenilacético
/
Dopamina
/
Antioxidantes
Limite:
Animals
Idioma:
En
Revista:
Chem Res Toxicol
Assunto da revista:
TOXICOLOGIA
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Estados Unidos