ESR of Copper and Iron Complexes with Antitumor and Cytotoxic Properties

Abstract

The relatively few iron and copper metal complexes which have been examined in cells and tissues for their redox properties, radical generation properties, and antitumor activity are discussed for studies which utilized electron spin resonance spectroscopy (ESR). A common property of a number of metal complexes, which include bleomycin, adriamycin, and thiosemicarbazones described in this review, is that they are readily reduced by thiol compounds and oxidized by oxygen or reduced species of oxygen to produce radicals. Structural features ofthese reactions are identified by ESR spectroscopy in model systems and-often in cells. Furthermore, ESR spectroscopy has been most useful to probe the environment of the complexes in cells and to measure the rate of reduction of their oxidized forms. As a result of these studies, it is anticipated that more attention will be given to the exploration of redox-active metal complexes as drugs.

A comparative study of α- N -pyridyl thiosemicarbazones: Spectroscopic properties, solution stability and copper(II) complexation

“…The pH-potentiometric titration data (Fig. 7) reveal that proton displacement by the metal ion due to complex formation is almost complete already at the starting pH value ($2), and a fairly low amount of free Cu(II) was detected by EPR at this pH in a good accordance with the findings of Antholine et al in pure water [30]. Therefore the overall stability constants for the species were determined by UV-vis spectrophotometric titrations (at pH between 1 and 12) following the changes of the d-d bands partly overlapped by the S ?…”

“…Although several of these data have been already reported in literature, the comparability in most cases is insufficient due to the application of different settings and solvents. Solution chemistry of Cu(II) complexes formed with some a-N-pyridyl TSCs has been characterized in some of our former publications [23][24][25] and also by others research groups [26][27][28][29][30], however surprisingly no comparable stability data are available for the standard thiosemicarbazone compound FTSC. Therefore, stoichiometry, stability and structure of Cu(II) complexes of FTSC were determined in aqueous solution in this study via a combined approach using pH-potentiometry, UV-visible (UV-vis) spectrophotometry and electron paramagnetic resonance (EPR) spectroscopy.…”

Casiopeína IIgly-induced oxidative stress and mitochondrial dysfunction in human lung cancer A549 and H157 cells

“…Previous findings suggest that copper-phenanthroline complexes redox-cycle with thiols and H 2 O 2 , resulting in ROS production (Kobashi and Horecker, 1967; Que et al, 1980; Antholine et al, 1985). On the other hand, intracellular GSH depletion eventually induces mitochondrial GSH depletion and has been associated with increased levels of mitochondrial ROS and mitochondrial dysfunction (Armstrong and Jones, 2002).…”

Diaquabis(8-chloro-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purinato-κN 7)copper(II) dihydrate

“…For related literature, see: Halpert et al (2002); Antholine et al (1985); García-Tojal et al (1996); Okabe et al (1993); Saryan et al (1979); Serafin (1996); Spealman (1988); West et al (1993); Zhao et al (2003).…”