A new approach on the gastric absorption of anthocyanins

The bioavailability of anthocyanins is the most difficult one to assess amongst all flavonoid compounds as a result of their occurrence under different structures in equilibrium depending on pH. Due to their rapid appearance in plasma, the absorption of anthocyanins is likely to occur at the gastric level. Further investigations of the mechanisms by which anthocyanins are absorbed are limited by the lack of testable gastric epithelial cell models that form functional barriers. The methods available to evaluate the absorption of drugs at the gastric level make use of isolated gastric epithelial cells, which is both time and labour consuming. In the present study, a biologically relevant in vitro model of moderately differentiated adenocarcinoma stomach cells (MKN-28) was used as gastric barrier. The transepithelial electrical resistance (TEER) of MKN-28 cell monolayers was evaluated at pH values that cover the physiologic range of the stomach, ensuring the integrity of the cell monolayer. The immunofluorescence assay attested the localization of occludins at the cellular margins, which is associated with a non-disrupted membrane. Anthocyanins were found to cross MKN-28 cells in a time dependent manner and probably via a saturable transport mechanism.