Cyclodextrins as inhibitors of the precipitation of riboflavin-5'-phosphate due to presence of zinc chloride: A NMR investigation.

Several cyclodextrins (CDs) were probed in order to counteract the precipitation of riboflavin-5'-phosphate (or flavin mononucleotide, FMN-P) due to the presence of divalent cations, by exploiting Nuclear Magnetic Resonance (NMR) spectroscopy both for quantitative analyses and stereochemical characterizations. Among CDs, β-cyclodextrin (β-CD) showed the best solubilizing power in virtue of the formation of a 1-2 FMN-P/β-CD complex, the stereochemistry of which was ascertained by ROESY (Rotating-frame Overhauser Enhanced SpectroscopY) measurements.

Stability of hydrophilic vitamins mixtures in the presence of electrolytes and trace elements for parenteral nutrition: a nuclear magnetic resonance spectroscopy investigation.

In total parenteral nutrition (TPN), especially in the case of preterm infants, simultaneous administration of vitamins and trace elements is still a problematic issue: guidelines put in evidence the lack of specific documentation. In this work NMR spectroscopy was applied to the study of vitamins (pyridoxine hydrochloride, thiamine nitrate, riboflavin-5'-phosphate and nicotinamide) stability in presence of salts and trace elements. Vitamins in D2O were first analyzed by (1)H NMR spectroscopy in absence of salts and trace elements; changes in chemical shifts or in diffusion coefficients, measured by NMR DOSY technique, were analyzed.