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Conference Poster Year : 2024

The fate of salivary proteins-apple polyphenols complexes during gastric digestion

Abstract

Despite recognized health benefits, some polyphenols referred to as tannins exhibit anti-nutritional properties. Binding of tannins by proteins prior to the stomach may therefore act as a protective mechanism against their deleterious effects on digestion1. Illustration is provided by the particular case of salivary proteins, especially Proline-Rich Proteins (PRPs) with high affinity for tannins. Polyphenols-salivary proteins complexes are formed in the oral cavity, but it is not entirely clear how they behave in the harsh digestive environment. The overall objective of this study was to describe the interactions between salivary proteins and apple polyphenols, and the impact of gastric digestion on such interactions. A polyphenol extract was obtained from Dous Moën cider apples and mixed with pooled human saliva to reach different ratios of polyphenols to saliva proteins. In parallel, saliva, polyphenols extract or mixtures were subjected to the gastric phase of the INFOGEST static in vitro digestion procedure. Samples were centrifuged at 10000 g, 4 °C for 10 minutes. Protein profiles in supernatants and pellets were analyzed by SDS-PAGE. Proteins contained in bands of interest were identified by nano-LC-ESI MS/MS after in-gel trypsinolysis, and by staining of PRP with Coomassie blue R-250. Native polyphenols were quantified in supernatants by UPLC-UV-MS. Before digestion, increasing the polyphenols load resulted in a rise of turbidity of the mixtures suggesting the formation of progressively larger aggregates. Supernatants showed a protein profile similar to that of saliva while four bands were enriched in pellets. These proteins, identified as carbonic anhydrase 6, PRP and S100-A8, formed insoluble complexes with apple polyphenols. At low polyphenols load, the interaction with saliva induced a significant (p<0.05) concentration decrease in the supernatants of procyanidin oligomers (dimers PA-B1, PA-B2, PA-B5, trimer PA-C1, tetramer DP4), catechins and hydroxycinnamic acids. At a higher polyphenol load, the only affected compound was DP4, indicating that when polyphenols are abundant, highly polymerized procyanidins are preferentially complexed with proteins. After digestion of saliva, samples containing the highest polyphenols load showed specificities, namely the persistance in pellets of two bands at 60 kDa (identified as α-amylase) and at 20kDa (containing PRP). In addition, digestion of low polyphenols-saliva mixtures resulted in a large decrease of procyanidins PA-B5, PA-C1 and DP4 from the soluble fractions of digests compared to digestion of polyphenols alone. This suggests that insoluble complexes between salivary proteins and those tannins are formed and remain stable during gastric digestion. This study supports that saliva modulates the nature and amount of polyphenols that reach the digestive tract in free or soluble form.
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hal-04546322 , version 1 (15-04-2024)

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  • HAL Id : hal-04546322 , version 1

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Müzeyyen Berkel Kasikci, Sophie Guilois-Dubois, Kevin Billet, Julien Jardin, Sylvain Guyot, et al.. The fate of salivary proteins-apple polyphenols complexes during gastric digestion. https://www.icfd2024.com/scientific-program. 8th International Conference on FOOD DIGESTION, Apr 2024, Porto, Portugal. , 2024. ⟨hal-04546322⟩

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