Chromium

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

“…[1] However, 2 is known to be metabolized by hepatic enzymes with the release of more reactive Cr III species. [28] Rapid hydrolysis of CrCl 3 in neutral aqueous media with the formation of insoluble products [16] is a likely reason for its relatively inefficient oxidation to Cr VI (Table 1), as well as for the controversies regarding its biological activity. [1] In conclusion, the ease of oxidation of 1 to carcinogenic Cr VI under biologically relevant conditions (Table 1) warrants further research into the safety of using 1 (or any other Cr III compound) as a nutritional supplement or therapeutic agent.…”

“…[4,7] Complex 1 can also serve as a representative example of numerous polynuclear species formed on hydrolysis of Cr III complexes in neutral aqueous solutions. [16] It is relatively stable at pH 7.4 and 37 8C, although partial hydrolysis (leading to di-and mononuclear species) occurs on the timescale of hours, as revealed by electrospray mass spectrometry (see the Supporting Information).…”

“…Relatively low but detectable levels of Cr VI species were formed upon the oxidation of 2 or hydrolysed CrCl 3 by H 2 O 2 ( Table 1). [16] No detectable levels of Cr V species (! 1 mm, by EPR spectroscopy) [3,11] were formed under the studied conditions ( Table 1).…”

Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate

“…The specific interactions of Cr(III) ions with cellular insulin receptors[ 7 ] are caused by intra-or extracellular oxidations of Cr(III) to Cr(V) and/or Cr(VI) compounds, which act as protein tyrosine phosphatase (PTP) inhibitors. The oxidation of some Cr(III) complexes by H 2 O 2 in neutral or weakly basic aqueous media (pH 7.0–9.0), lead to polynuclear species formed on hydrolysis of Cr(III) complexes in neutral aqueous solutions [ 8 ]. The relative reactivities of various Cr(III) complexes towards H 2 O 2 may correlate with their reported activities as insulin activators [ 9 ].…”

Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: chromium and vanadium

“…In contrast to the V V , soluble Cr VI ions that enter cells are quickly reduced (Standeven and Wetterhan, 1989). As the Cr V and Cr IV species formed are unstable intracellularly (Lay and Lavina, 2004; Nag and Bose, 1985), the ion ultimately present is Cr III . Nevertheless, though unidirectionally-reduced, Cr VI ions are strong oxidants and can undergo redox/ligand displacement reactions with GSH, NAD(P)H, or other HS-bearing entities.…”