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

Abstract

Die Insulin verstärkende Wirkung mancher CrIII‐Komplexe wie [Cr3O(OCOEt)6(OH2)3]+ (1), bisher spezifischen Wechselwirkungen zwischen CrIII‐Ionen und Insulinrezeptoren zugeschrieben, rührt wohl eher von der Bildung von [CrO4]2− (2) her. Die Oxidation von 1 zu 2 durch biologisch relevante Oxidationsmittel (siehe Schema) sowie die Inhibierung einer isolierten Protein‐Tyrosin‐Phosphatase durch einen Modellkomplex werden geschildert.

A sub-acute oral toxicity analysis and comparative in vivo anti-diabetic activity of zinc oxide, cerium oxide, silver nanoparticles, and Momordica charantia in streptozotocin-induced diabetic Wistar rats

“…Many ndings have depicted the key role of metals in glucose metabolism and the relationship of their inadequacy with diabetes. Silver, [9][10][11][12][13] vanadium, chromium, magnesium, and zinc oxide have been reported to play a role in the reduction of glucose levels and included in diabetes therapy and possess many other pharmacological properties. The valuable role of zinc in the treatment of diabetes has been embroiled via investigations of zinc supplies in diabetic rats.…”

An informatics search for the low-molecular weight chromium-binding peptide

“…The earliest models [12], and those advanced by Vincent [18], fall into a structural category and focus on the interactions of Cr(III) with peptides and proteins to affect insulin signaling and glucose metabolism, either directly or indirectly. There is an important redox model recently advanced [33] that suggests higher oxidation states of Cr interact with tyrosine phosphatases to inhibit the down-regulation of the insulin receptor. Finally, the chemical similarity of the Cr(III) and Fe(III) cations, and various in vitro studies suggest that Cr(III) replacement in the physiological iron transport and storage apparatus may lead to some small beneficial outcome for certain diseases [10].…”

“…This model is reminiscent of Mertz and co-workers' original proposal [12] of a ternary interaction between Cr(III), insulin and insulin receptor. It is substantially different from intracellular mechanisms for LMWCr action [16,18], redox mechanisms [33], and the iron homeostasis model [10]. In addition, the cycling of the insulin receptor and insulin degradation [34] may satisfy the problems of cellular distribution of Cr(III) and production of LMWCr via proteolysis.…”

Effects of adjunct therapy of a proprietary herbo-chromium supplement in type 2 diabetes: A randomized clinical trialFNx01

“…Cr (III) complexes with serum proteins, such as albumin and transferrin, could also be oxidized to Cr (VI) under similar conditions. [10] Chromium supplements have also been shown to induce chromosome damage and tend to accumulate in human tissues when consumed in high doses for prolonged period of time. [11,12] Deleterious effects of chromium supplements may occur from its ligand [11] or its higher than trivalent oxidation state.…”