Interaction between red wine procyanidins and salivary proteins: effect of stomach digestion on the resulting complexes

Abstract

Tannins, a group of polyphenols, are important at sensory (e.g. astringency sensation) and health levels (e.g., anti-cancer and cardiovascular protection). The health benefits are related to tannins' concentration that reaches the gastrointestinal tract (bioaccessible concentration) which could be affected by interaction with other biological molecules, such as salivary proteins (SP). Most of the work that studies tannin's health benefits does not consider these interactions. So, this work intended to mimic the ingestion of red wine condensed tannin fractions and assess the stability of the (in)soluble complexes formed between the different tannins and the different SP in a simulated stomach digestion. The results showed that some of the tannin/SP complexes could be disrupted by gastric digestion leading to the release of tannins. This was observed for the complexes formed with the lowest polymerized tannins (monomers, dimers and trimers). Oppositely, the complexes formed by tannin tetramers and pentamers were significantly more resistant to stomach conditions. Therefore, SP probably influence negatively the concentrations at which tannins tetramers and pentamers reach the stomach and ultimately they may influence negatively some of these procyanidins biological potential health benefits. In the future, these and other biological interactions of tannin compounds should be taken into consideration in bioavailability and health benefits studies.