Inhibiting amyloid ß-protein assembly: Size-activity relationships among grape seed-derived polyphenols.
J Neurochem
; 135(2): 416-30, 2015 Oct.
Article
em En
| MEDLINE
| ID: mdl-26228682
ABSTRACT
Epidemiological evidence that red wine consumption negatively correlates with risk of Alzheimer's disease has led to experimental studies demonstrating that grape seed extracts inhibit the aggregation and oligomerization of Aß in vitro and ameliorate neuropathology and behavioral deficits in a mouse model of Alzheimer's disease. The active agent in the extracts is a mixed population of polyphenolic compounds. To evaluate the relative potency of each of these compounds, HPLC was used to fractionate the mixture into monomers, dimers, and oligomers. Each fraction was analyzed for its effect on Aß conformational dynamics (circular dichroism), oligomerization (zero-length photochemical cross-linking), aggregation kinetics (Thioflavin T fluorescence), and morphology (electron microscopy). The relative activities of each fraction were determined on the basis of molar concentration (mol/L) or mass concentration (g/L). When molar concentration, the number concentration of each polyphenolic compound, was considered, the oligomer fraction was the most potent inhibitor of Aß oligomerization and aggregation. However, when mass concentration, the number concentration of phenolic groups, was considered, monomers were the most potent inhibitors. To understand these ostensibly contradictory results, a model of polyphenolAß complexation was developed. This model, which was found to be consistent with published X-ray crystallographic studies, offers an explanation for the effects of functional group polyvalency on inhibitor activity. Our data emphasize the importance of an in-depth understanding of the mechanism(s) underlying 'concentration dependence' in inhibitor systems involving polyfunctional agents.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos beta-Amiloides
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Vitis
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Polifenóis
Limite:
Animals
Idioma:
En
Revista:
J Neurochem
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Estados Unidos