Biological activity of complexes derived from pyridine-2-carbaldebyde thiosemicarbazone - Structure of [Co(C7H7N4S)(2)][NCS]

Biological studies on [Fe(L)(2)](NO3).0.5H(2)O (1), [Fe(L)(2)][PF6] (2), [C o(L)(2)](NCS) (3), [Ni(HL)(2)]Cl-2. 3H(2)O (4) and Cu(L)(NO3) (5), where HL =C7H8N4S, pyridine-2-carbaldehyde thiosemicarbazone, have been carried out. The crystal structure of compound 3 has been solved. It consists of discre te monomeric cationic entities containing cobalt(III) ions in a distorted o ctahedral environment. The metal ion is bonded to one sulfur and two nitrog en atoms of each thiosemicarbazone molecule. The thiocyanate molecules act as counterions. The copper(II) and iron(III) complexes react with reduced g lutathione and 2-mercaptoethanol, The reaction of compound 1 with the above thiols causes the reduction of the metal ion and bis(thiosemicarbazonato)i ron(II) species are obtained. The redox activity, and in particular the rea ction with cell thiols, seems to be related to the cytotoxicity of these co mplexes against Friend erithroleukemia cells and melanoma B16F10 cells. (C) 2001 Elsevier Science B.V. All rights reserved.