title: Determination of neo- and D-chiro-inositol hexakisphosphate in soils by solution 31P NMR spectroscopy.
abstract: The inositol phosphates are an abundant but poorly understood group of organic phosphorus compounds found widely in the environment. Four stereoisomers of inositol hexakisphosphate (IP(6)) occur, although for three of these (scyllo, neo, and D-chiro) the origins, dynamics, and biological function remain unknown, due in large part to analytical limitations in their measurement in environmental samples. We synthesized authentic neo- and D-chiro-IP(6) and used them to identify signals from these compounds in three soils from the Falkland Islands. Both compounds resisted hypobromite oxidation and gave quantifiable (31)P NMR signals at δ = 6.67 ppm (equatorial phosphate groups of the 4-equatorial/2-axial conformer of neo-IP(6)) and δ = 6.48 ppm (equatorial phosphate groups of the 2-equatorial/4-axial conformer of D-chiro-IP(6)) in soil extracts. Inositol hexakisphosphate accounted for 46-54% of the soil organic phosphorus, of which the four stereoisomers constituted, on average, 55.9% (myo), 32.8% (scyllo), 6.1% (neo), and 5.2% (D-chiro). Reappraisal of the literature based on the new signal assignments revealed that neo- and D-chiro-IP(6) occur widely in both terrestrial and aquatic ecosystems. These results confirm that the inositol phosphates can constitute a considerable fraction of the organic phosphorus in soils and reveal the prevalence of neo- and D-chiro-IP(6) in the environment. The hypobromite oxidation and solution (31)P NMR spectroscopy procedure allows the simultaneous quantification of all four IP(6) stereoisomers in environmental samples and provides a platform for research into the origins and ecological significance of these enigmatic compounds.
authors.affiliation: Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama. TurnerBL@si.edu
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Turner
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Cheesman
authors.forename: H Yasmin
authors.initials: HY
authors.lastname: Godage
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Riley
authors.forename: Barry V L
authors.initials: BV
authors.lastname: Potter
mesh_terms: D001966:Bromine; D004492:Edetic Acid; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010759:Phosphorus Isotopes; D010833:Phytic Acid / Q000032:analysis* / Q000138:chemical synthesis; D012987:Soil / Q000032:analysis*; D013237:Stereoisomerism
chemical_list: D010759:Phosphorus Isotopes; D012987:Soil; D010833:Phytic Acid; D004492:Edetic Acid; D001966:Bromine