Behaviour of the Antitumor Agent Vanadocene Dichloride in Physiological and Therapeutic Media, Blood Plasma and Human Blood - An EPR Study

Abstract

By means of EPR spectroscopy the behaviour of the vanadocene dichloride (I), Cp₂VCl₂ (Cp=η⁵-C₅H₅), in various deoxygenated and non-deoxygenated physiological media and therapeutic solution as well as in blood plasma and stabilized human blood was studied. On the basis of measured values of isotropic spectroscopic splitting factor g_iso and isotropic hyperfine coupling constant A_iso, the vanadocene species, [Cp₂V(H₂O)Cl]⁺ (II; g_iso= 1.985, |A_iso| = 7.68 mT), [Cp₂V(H₂O)₂]²⁺ (III; g_iso= 1.983, |A_iso| = 7.92 mT), [Cp₂V(OH₂ (IV; g_iso= 1.991, |A_iso| = 6.285 mT), [Cp₂VCl(DMSO)]⁺ (V; g_iso= 1.985, |A_iso| = 7.69 mT), the vanadyl species [VO(DMSO)₅]²⁺ (VI; g_iso= 1.964, |A_iso| = 10.78mT) and [VO(H₂O)₅]²⁺ (VII; g_iso= 1.955, |A_iso| = 11.56 mT) have been identified. From the measurements it follows that I does not react in its first coordination sphere with any component of a system used other than water and DMSO, resp. As to water-containing media, its behaviour is fully consistent with that of I in pure aqueous media. It was found the only vanadocene species present after application of the therapeutic solution of I into human blood to be IV not interacting in its first coordination sphere with any blood component.

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