Guanine and plasmid DNA binding of mono- and trinuclear fac-[Re(CO)3 ]+ complexes with amino acid Ligands

We have synthesized and fully characterized four new complexes comprising the fac-[Re(CO)(3)](+) moiety and the ligands NH3, (L)-proline (Pro), or N,N-dimethylglycine (dmGly). The reaction of [Re(H2O)(3)(CO)(3)](+) with the two amino acids gives trinucleor complexes of general formula [Re(L)(CO)(3)](3) (where L=omino acid). We have studied the in vitro behavior of these compounds with guanine and DNA in order to understand whether the cytotoxicity exhibited by certain rhenium complexes based on the fac[Re(CO)(3)](+) core is due to the formation of nucleobose complexes and inter- or intrastrand links between DNA bases. We have performed model studies with guanine and studied the structural effects induced by different rhenium(i) tricarbonyl complexes on Phi X774 plasmid DNA by electrophoretic methods. Our results show that rhenium complexes with two available coordination sites interact with plasmid DNA to form a stable adduct that is likely to involve two bases.