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) (InsP₆)) during food processing resulting in a broad range of different myo-inositol phosphates such as pentakisphosphate (InsP₅) and tetrakisphosphate (InsP₄) in foods. Here, we investigated whether the human intestinal epithelium is able to dephosphorylate myo-inositol phosphates (InsP₆, InsP₅-, InsP₄-, InsP₃-isomers) using an in vitro model with differentiated human Caco-2 cells cultured on semipermeable inserts. Incubation of InsP₆ and an InsP₅-isomer with cells for 3 h showed no dephosphorylation of both InsPs. Treatment of cells with a mixture of different InsP₄-isomers, however, caused a formation of about 3.5% of an InsP₃-isomer (Ins(1,5,6)P₃) and treatment with a mixture of different InsP₃-isomers caused about 20% formation of InsP₂-isomers, respectively. Thus, human intestinal cells can contribute to the dephosphorylation of myo-inositol phosphates of partly dephosphorylated forms such as InsP₃ and InsP₄.