Bilirubin as an antioxidant in micelles and lipid bilayers: its contribution to the total antioxidant capacity of human blood plasma.
Free Radic Biol Med
; 43(4): 600-9, 2007 Aug 15.
Article
em En
| MEDLINE
| ID: mdl-17640570
ABSTRACT
The antioxidant capacities, antioxidant activities, k(inh), and stoichiometric factors, n, of water-soluble derivatives of bilirubin (BR), BR-human serum albumin (BR-HSA), and BR-ditaurate disodium conjugate (BRC) were determined in aqueous/lipid dispersions of sodium dodecyl sulfate (SDS) micelles/methyl linoleate and in bilayers of dilinoleoylphosphatidylcholine (DLPC) during initiation by water-soluble azo-bis-amidinopropane dihydrochloride (ABAP). The inhibition rate constants for BRC and BR-HSA were similar in micelles (k(inh) approximately 1.3 x 10(4) M(-1) s(-1)), where n approximately 2, whereas the k(inh) for BR-HSA dropped by (1/2) in bilayers. The dimethyl ester of bilirubin (BRDE) gave a k(inh) only one-tenth that of the vitamin E analog, pentamethylhydroxychroman (PMHC) in SDS micelles/methyl linoleate when initiated by lipid-soluble azo-bis-2,4-dimethylvaleronitrile (DMVN). Biliverdin hydrochloride (BVHCl) was NOT an effective peroxyl radical-trapping agent in the micellar phase during initiation by ABAP or DMVN containing methyl linoleate but it inhibited oxygen uptake in the aqueous phase. Both BRC and BR-HSA extended the total radical antioxidant parameter (TRAP) of human blood plasma and their contribution to TRAP was in the range of 5-10% of the natural TRAP of blood plasma, depending on the BR content determined in the blood plasma.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Plasma
/
Bilirrubina
/
Bicamadas Lipídicas
/
Micelas
/
Antioxidantes
Limite:
Humans
Idioma:
En
Revista:
Free Radic Biol Med
Assunto da revista:
BIOQUIMICA
/
MEDICINA
Ano de publicação:
2007
Tipo de documento:
Article