Gastrointestinal fate of phenolic compounds and amino derivatives from the cocoa shell: An in vitro and in silico approach

Abstract

The objective of this study was to assess how in vitro gastrointestinal digestion influenced the bioaccessibility and potential bioavailability of phenolic compounds and methylxanthines in thecocoa shell (CS) in the form of flour (CSF) and aqueous extract (CSE). To comprehend how these phytochemicals behaved during gastrointestinal digestion, we also modeled in silico the colonic microbial biotransformation of the phenolic compounds in the CS. Different groups of phenolic compounds (mainly gallic andprotocatechuic acids, and catechin) and methylxanthines (theobromine and caffeine)could be found in the CS. Methylxanthines and phenolic compounds were released differently during gastrointestinal digestion. Whereas digestion triggered the release of hydroxybenzoic acids (67-73%) and flavan-3-ols (73-88%) during the intestinal phase, it also caused the degradation of flavonols and flavones. Besides, the release of phytochemicals was significantly influenced by the CS matrix type. Phenolic compounds were protected by the CSF matrix. Phenolic acids from CSF were more bioaccessible in the intestinal (1.2-fold, p < 0.05) and colonic (1.3-fold, p < 0.05) phases than those from the CSE. Methylxanthines were also more bioaccessible in the intestinal (1.8-fold, p < 0.01) and colonic phases (1.3-fold, p < 0.001) and bioavailable (1.8-fold, p < 0.001) in the CSF. Colonic metabolism demonstrated that the gut microbiota could biotransform non-absorbed phenolic compounds into other lower molecular weight and more bioavailable metabolites. These findings support the CS's potential as a source of bioaccessible, bioavailable, and active phytochemicals.

Keywords: Bioaccessibility; Bioavailability; Cocoa by-products; Cocoa shell; In vitro digestion; Methylxanthines; N-phenylpropenoyl-L-amino acids; Phenolic compounds.