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.