Interaction of astringent grape seed procyanidins with oral epithelial cells

Mechanisms underlying astringency perception are not clearly understood. It has been suggested that oral epithelial cells play a role. A cell-based bioassay has been developed to define the interactions of astringent grape seed procyanidins with oral epithelial cells. Procyanidins are visualised and quantified after reaction with 4-(dimethylamino)cinnamaldehyde. This assay has demonstrated, conclusively, that astringent procyanidins bind to oral epithelial cells, and that the binding is concentration-, pH- and temperature-dependent, but is not affected by the presence of up to 13% ethanol. Furthermore, the presence of 13% ethanol did not alter in vivo astringency thresholds. However, a decrease in pH resulted in enhanced binding of grape seed procyanidins to oral epithelial cells, which supports our in vivo findings of decreased astringency recognition threshold at lower pH. These data indicate that the cells of the oral cavity may play a direct role in the astringent sensation.