Metal-ion binding properties of ( S )-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC, Cidofovir). A nucleotide analogue with activity against DNA viruses

A systematic study of the metal ion-binding properties of the antivirally active acyclic nucleoside phosphonate HPMPC2− reveals, via comparisons with HPMP2− that the cytosine moiety does not participate in metal ion binding; only the ether is involved in addition to the primary phosphonate-binding site. The resulting isomer with a 5-membered chelate reaches, depending on the metal ion, formation degrees of up to 70%. In the complexes of HPMP2− with the heavier alkaline earth ions, the hydroxymethyl group also contributes to binding.