Chemical properties and biotoxicity of several chromium picolinate derivatives

As a man-made additive, chromium picolinate Cr(pic)₃ has become a popular dietary supplement worldwide. In this paper Cr(pic)₃ and its new derivatives Cr(6-CH₃-pic)₃ (1), [Cr(6-NH₂-pic)₂(H₂O)₂]NO₃ (2) and Cr(3-NH₂-pic)₃ (3) were synthesized, and complexes 1 and 2 were characterized by X-ray crystal structure (where pic=2-carboxypyridine). The relationship between the chemical properties and biotoxicity of these complexes was fully discussed: (1) The dynamics stability of chromium picolinate complexes mainly depends on the CrN bonds length. (2) There is a positive correlation between the dynamics stability, electrochemical potentials and generation of reactive oxygen species through Fenton-like reaction. (3) However, no biological toxicity was observed through MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and sub-chronic oral toxicity study for these chromium picolinate compounds. Together, our findings establish a framework for understanding the structure-property-toxicity relationships of the chromium picolinate complexes.