Characterization and structure by NMR and FTIR spectroscopy, and molecular modeling of chromium(III) picolinate and nicotinate complexes utilized for nutritional supplementation

Chromium picolinate (CrPic) and chromium nicotinate preparations (CrNic1, CrNic2, CrNic3) were investigated with 1H and 13C NMR, FTIR, and molecular modeling. CrPic is crystalline and bidentately coordinated. CrPicA bonding broadens the NMR signal or shifts it so far downfield that it is not detect...

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Bibliographic Details
Published in:Journal of inorganic biochemistry 1997-05, Vol.66 (2), p.119-130
Main Authors: Broadhurst, C.Leigh, Schmidt, Walter F., Reeves, James B., Polansky, Marilyn M., Gautschi, Kurt, Anderson, Richard A.
Format: Article
Language:English
Subjects:
ACIDE ORGANIQUE
ACIDOS ORGANICOS
CHROME
COMPLEMENT ALIMENTAIRE
CROMO
ESPECTROMETRIA
ESPECTROSCOPIA INFRARROJA
ESPECTROSCOPIA RMN
ESTRUCTURA QUIMICA
NICOTINAMIDA
NICOTINAMIDE
NUTRIENTES MINERALES
SPECTROMETRIE
SPECTROSCOPIE INFRAROUGE
SPECTROSCOPIE RMN
STRUCTURE CHIMIQUE
SUBSTANCE NUTRITIVE MINERALE
SUPLEMENTOS
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Summary:Chromium picolinate (CrPic) and chromium nicotinate preparations (CrNic1, CrNic2, CrNic3) were investigated with 1H and 13C NMR, FTIR, and molecular modeling. CrPic is crystalline and bidentately coordinated. CrPicA bonding broadens the NMR signal or shifts it so far downfield that it is not detectable. All CrNic preparations are noncrystalline, and results provide no evidence that nicotinic acid (NiA) is O-coordinated to Cr. The complex colors may be due to O-coordination with H 2O and/or OH, not NicA. 1H NMR spectra of CrNic1 have two sets of peaks. One set has a significant δ with respect to NicA, indicating that NicA is more strongly associated with Cr. CrNic1 13C data show small, uniform δ with respect to NicA, indicating that strong localized CrCOOH bonding is unlikely. The magnitude of δ, 13C, and 1H exchange data suggests that limited CrN bonding may occur in CrNic1. CrNic2 and CrNic3 show little difference from NicA spectra. FTIR spectra of all CrNic complexes, but not CrPic, PicA, or NicA, show bound OH and/or H 2O. CrNic complexes are probably olates, with Cr and NicA OH-polymerized. CrPic exchanges with CrNic1 in DMSO. This exchange may provide a mechanism for the absorption and active transport of Cr in biological systems.
ISSN:0162-0134
1873-3344
DOI:10.1016/S0162-0134(96)00192-4