Dephosphorylation of Myo-Inositol Phosphates in the in Vitro Intestinal Caco-2 Cell Model.

Plant and microbial phytases present in raw materials can cause a dephosphorylation of phytate (myo-inositol hexakisphosphate) (InsP(6))) during food processing resulting in a broad range of different myo-inositol phosphates such as pentakisphosphate (InsP(5)) and tetrakisphosphate (InsP(4)) in foods. Here, we investigated whether the human intestinal epithelium is able to dephosphorylate myo-inositol phosphates (InsP(6), InsP(5)-, InsP(4)-, InsP(3)-isomers) using an in vitro model with differentiated human Caco-2 cells cultured on semipermeable inserts. Incubation of InsP(6) and an InsP(5)-isomer with cells for 3 h showed no dephosphorylation of both InsPs. Treatment of cells with a mixture of different InsP(4)-isomers, however, caused a formation of about 3.5% of an InsP(3)-isomer (Ins(1,5,6)P-3) and treatment with a mixture of different InsP(3)-isomers caused about 20% formation of InsP(2)-isomers, respectively. Thus, human intestinal cells can contribute to the dephosphorylation of myo-inositol phosphates of partly dephosphorylated forms such as InsP(3) and InsP(4).