Study of the substitution reactions between Pd(II) complexes and biologically significant ligands

Abstract

Considering that Pd(II) complexes in recent yeras have shown the significant antitumor activity against numerous cancer cells, study of the substitution reactions of Pd(II) complexes with nitrogen and sulfur containing biomolecules can help to develop new antitumor drugs with improved characteristics. Kinetics of the substitution reactions of Pd(II) complexes, 3-(1-(2-hydroxypropylamino)-ethylidene)-chroman-2,4-dione-palladium(II) (C1) and 3- (1-(2-mercaptoethylamino)ethylidene)-chroman-2,4-dione-palladium(II) (C2), with biologically relevant ligands, such as L-cysteine (L-cys), L-methionine (L-met) and guanosine-5'-monophosphate (5'-GMP) were studied under the pseudo-first order conditions, using stopped-flow method. All reactions were performed at pH = 7.2 (25 mM Hepes buffer in the presence of 50 mM NaCl) at 37 0C. The obtained kinetic data showed that C2 complex is more reactive than C1, confirming that structural and electronic characteristics of the investigated complexes stongly affect on their reactivity toward selected ligands. The reactivity of the studied nucleophiles decreases in order: L-cys > L-met > 5’-GMP