Thermal degradation of phytate produces all four possible inositol pentakisphosphates as determined by ion chromatography and 1H and 31P NMR spectroscopy

Abstract

Decomposition of phytate has recently been shown to occur under mild conditions in the solid state, giving rise to a complex mixture of lower inositol phosphates. In this study, the reaction products of this thermal, abiotic degradation of phytate were separated using ion chromatography and the most highly phosphorylated products subsequently identified using 1D and 2D NMR spectroscopy. Two late eluting fractions were each shown to be a mixture of two specific inositol pentakisphosphate isomers. The peak with shorter retention time contained Ins(1,2,3,4,6)P5 and DL-Ins(1,2,3,4,5)P5, while the later eluting fraction contained Ins(1,3,4,5,6)P5 and DL-Ins(1,2,4,5,6)P5. The formation of all four possible inositol pentakisphosphate isomers by thermal degradation of phytate contrasts with the selective production of unique inositol pentakisphosphate isomers during enzymatic phytate degradation and therefore suggests a method for differentiating abiotic and biotic processes in environmental samples, including soils and decomposing plant biomass.