Synthesis, characterization, biological and radical scavenging activities of new palladium complexes

Palladium complexes bearing chloro, bromo and iodo ligands were designed and synthesized. The iodo complexes were obtained by direct oxidative addition of iodoaryls on Pd(PPh3)4 [1]. Bromo and chloro complexes were prepared by halogen exchange from the iodo complexes with saturated solutions of KBr and KCl. All compounds have been characterized by 1H,13C and 31P NMR and by Xray diffraction.
The radical scavenging effect was carried out according to the method first employed by Re et al [2]. In the ABTS free radical scavenging tests IPd(PPh3)2(C6H4OCOMe) showed the highest activity. By contrast, BrPd(PPh3)2(C6H4OCOMe) and ClPd(PPh3)2(C6H4OCOMe) complexes showed the most interesting free radical scavenging proprieties in DPPH tests. Interestingly, after three hours all compounds showed similar activities at the same concentration. All the tests were compared to cis-platine.
Cells toxicity of complexes is evaluate with using trypan bleu test. Cells are incubated with complexes solutions during one hour. IPd(PPh3)2(C6H4OCOMe) showed the most great toxicity but mortality remains below 25%.
The tetrazolium dyes assays WST-1, that measure cell proliferation, where it is assumed that dye reduction will be proportional to the number of viable cells was realized. BrPd(PPh3)2(C6H4OCOMe) shows the same behavior to that observed for cis-platine.
All these results will be presented and discussed.