Biomimetic Oxidation of Chromium( III ): Does the Antidiabetic Activity of Chromium( III ) Involve Carcinogenic Chromium( VI )?

The insulin-enhancing activities of some CrIII complexes, such as [Cr3O(OCOEt)6(OH2)3]+ (1), previously attributed to specific interactions of CrIII ions with cellular insulin receptors, are more likely to be caused by the formation of [CrO4]2− (2). Oxidation of 1 to 2 by biologically relevant oxidants, including enzymes (see scheme), and inhibition of an isolated protein tyrosine phosphatase by a CrVI complex are reported.