Cytotoxic activities of new iron(III) and nickel(II) chelates of some S-methyl-thiosemicarbazones on K562 and ECV304 cells.

The S-methyl-thiosemicarbazones of the 2-hydroxy-R-benzaldehyde (R = H, 3-OH 3-OCH(3) or 4-OCH(3)) reacted with the corresponding aldehydes in the presence of FeCl(3) and NiCl(2). New ONNO chelates of iron(III) and nickel(II) with hydroxy- or methoxy-substituted N(1),N(4)-diarylidene-S-methyl-thiosemicarbazones were characterized by means of elemental analysis, conductivity and magnetic measurements, UV-Vis, IR and (1)H-NMR spectroscopies. Cytotoxic activities of the compounds were determined using K562 chronic myeloid leukemia and ECV304 human endothelial cell lines by MTT assay. It was determined that monochloro N(1)-4-methoxysalicylidene-N(4)-4-methoxysalicylidene-S-methyl-thiosemicarbazidato-iron(III) complex showed selective anti-leukemic effects in K562 cells while has no effect in ECV304 cells in the 0.53 microg/ml (IC(50)) concentrations. Also, some methoxy-substituted nickel(II) chelates exhibit high cytotoxic activity against both of these cell lines in low concentrations. Cytotoxicity data were evaluated depending on cell lines origin and position of the substituents on aromatic rings.