Bioaccessibility, bioactivity and cell metabolism of dark chocolate phenolic compounds after in vitro gastro-intestinal digestion

The bioaccessibility of phenolic compounds after in vitro gastro-intestinal digestion of dark chocolate, dark chocolate enriched with Sakura green tea and dark chocolate enriched with turmeric powder was studied. The phenolic profile, assessed by accurate mass spectrometry analysis, was modified during in vitro gastro-intestinal digestion, with a considerable decrease of total and individual phenolic compounds. Phenolic acids showed the highest bioaccessibility with hydroxycinnamic acids displaying higher bioaccessibility (from 41.2% to 45.1%) respect to hydroxybenzoic acids (from 28.1% to 43.5%). Isomerisation of caffeoyl-quinic acids and galloyl-quinic acids as well as dimerization of (epi)gallocatechin were also observed after in vitro gastro-intestinal digestion. Antioxidant activity increased after the gastric step and rose further at the end of the digestion. Furthermore, in vitro digested phenolic-rich fractions showed anti-proliferative activity against two models of human colon adenocarcinoma cell lines. Cell metabolism of digested phenolic compounds resulted in the accumulation of coumaric and ferulic acids in the cell media.