Degradation of anthocyanins from grape extract and their uptake in a human intestinal cell monolayer

Anthocyanins are a group of natural polypenols the consumption of which is associated with a reduced risk of chronic diseases. Bioavailability and metabolism of anthocyanins, however, are considered to be an important issue, but not fully understood. The aim of the study was to determine the pH and time dependent stability of anthocyanins (malvidin‐ (M), cyanidin‐ (C), peonidin‐ (P), delphidin‐ (D) and petunidin‐ (Pet) 3‐glucosides (3G)) as well as their uptake by intestinal cells. As a model to differentiate between intestinal and colonic absorption, an in vitro model of Caco‐2 and HT‐29/B6 cells in co‐culture was established. Anthocyanins were determined by HPLC analysis. It was demonstrated that the most frequent glycosides were stable after 5 h incubation in cell–free media at pH 2.0. At pH 7.2, C3G‐ and P3G remained stable, but 24.5 ± 3.9, 36.5 ± 5.8 and 53.3 ± 6.1% of M3G, D3G and Pet3G were degraded, respectively. The rate of disappearance from the apical compartment was not statistically different from that of degradation rate in co‐culturing Caco‐2 and HT‐29/B6 cells. In a Caco‐2 monoculture, however, uptake of anthocyanins appeared to be rapid considering the degradation levels. These data suggest that the stability of anthocyanins and their absorption in the gastrointestinal tract varies in dependency of the compound, the pH and the location within the gut segment. (BMBF 0315379A)