Multinuclear NMR of Calcium Fructoborate Complex – Structure, Stability, and Quantitation in the Presence of Other Ingredients, Excipients or Adulterants

FruiteX-B®- calcium fructoborate (FrxB) plant mineral complex was investigated in this study. Although calcium fructoborate is naturally-occurring and found in commonly ingested fruits and vegetables, the commercially produced FrxB calcium fructoborate complex is formed by a proprietary reaction of boric acid with fructose and calcium carbonate. Liquid and solid-state 13C and 11B NMR were utilized in order to establish a baseline standard of FrxB for product quality purposes, to establish a reliable methodology to positively identify and quantify amounts of FrxB present in tablets and capsules, liquids and powdered blends wherein the FrxB may have been mixed with other ingredients, excipients, or adulterants such as maltodextrin or magnesium stearate, and to establish a robust and reliable testing method for the identification and quantification of the mono- and the di-complexes of calcium fructoborate as well as any free borate and/or free fructose that may be present. The molar ratio of the various components of calcium fructoborate was studied by 11B and 13C NMR in order to establish the relative amounts of free borate, free fructose, and mono-ester/di-ester complex present in the material. A quantitative 11B NMR method was developed to enable quantification of the amount of FrxB present in products wherein it had been tableted or encapsulated in combination with other dietary supplement ingredients, or excipients such as magnesium stearate or maltodextrin. A quantitative 13C NMR method was developed to quantify free fructose content in the complex. Finally, an NMR based product stability study was performed to monitor molecular level stability of the complex at temperatures ranging from 35-70 ºC with exposures lasting from 2-18 hours.