Cytotoxicity,antioxidant and glutathione S-transferase inhibitory activity of palladium(II) chloride complexes bearing nucleobase ligands

Palladium(II) chloride complexes bearing the nucleobases, adenine, cytosine and guanine, have been synthesized and characterized by UV–vis spectrophotometric methods, magnetic susceptibility, molar conductivity, elemental analysis, FTIR and ¹H-NMR. The complexes were found to have the general composition PdCl₂(NH₃L) (where L = adenine, cytosine or guanine). Square-planar geometry is proposed for these Pd(II) complexes based on magnetic evidence and electronic spectra. The complexes as well as the free nucleobase ligands show varying degrees of cytotoxicity on human promyelocytic leukemia (HL60) and human histiocytic leukemia (U937) cell lines, with cis-PdCl₂(NH₃)(Gua)] showing IC₅₀ values of 48.03 ± 9.67 and 11.12 ± 3.42 µM against HL60 and U937, respectively. The complexes as well as the ligands did not show anti-proliferative activity against a normal human cell line (NB1RGB). The complexes also show significant antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl radical as well as glutathione S-transferase inhibitory activity.