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Mechanisms of flavonoid repair reactions with amino acid radicals in models of biological systems: a pulse radiolysis study in micelles and human serum albumin.
- Source :
-
Biochimica et biophysica acta [Biochim Biophys Acta] 2002 Aug 15; Vol. 1572 (1), pp. 150-62. - Publication Year :
- 2002
-
Abstract
- Neutral tryptophan (*Trp) and tyrosine (TyrO(*)) radicals are repaired by certain flavonoids in buffer, in micelles and in human serum albumin (HSA) with corresponding formation of semioxidized flavonoid radicals. In deaerated buffer, *Trp but not TyrO(*) radicals react with catechin. In micelles, quercetin and rutin repair both *Trp and TyrO(*) radicals. In addition to amino acid reactivity, microenvironmental factors and nature of the flavonoids govern this repair. Electron transfer efficiencies from quercetin to negatively charged *Trp radicals are 100% in the micellar pseudophases of positively charged cetyltrimethylammonium bromide, (CTAB), and neutral Triton X100 (TX100), but 55% in negatively charged sodium dodecyl sulfate (SDS). In oxygen-saturated CTAB micelles, quercetin also reacts with the superoxide radical anion. When bound to domain IIA of HSA, quercetin repairs, by intra- or intermolecular encounter, less than 20% of oxidative damage to HSA. Quercetin can also repair freely circulating oxidized molecules with repair efficiencies falling to 7% for oxidized Trp, Tyr and alpha-MSH and to less than 2% for urate radical. This limited effectiveness is attributed both to the inaccessibility of bound quercetin and rutin toward radicals of circulating molecules and to the diffusion-controlled recombination of these radicals.
- Subjects :
- Catechin chemistry
Electron Transport
Free Radicals chemistry
Hydrogen-Ion Concentration
Micelles
Models, Biological
Oxidation-Reduction
Pulse Radiolysis
Quercetin chemistry
Rutin chemistry
Tryptophan analogs & derivatives
Tyrosine analogs & derivatives
Uric Acid chemistry
alpha-MSH chemistry
Flavonoids chemistry
Serum Albumin chemistry
Tryptophan chemistry
Tyrosine chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0006-3002
- Volume :
- 1572
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biochimica et biophysica acta
- Publication Type :
- Academic Journal
- Accession number :
- 12204344
- Full Text :
- https://doi.org/10.1016/s0304-4165(02)00302-1