Gadolinium texaphyrin (Gd-Tex)-malonato-platinum conjugates: synthesis and comparison with carboplatin in normal and Pt-resistant cell lines.

The synthesis of a new PEG-solubilized gadolinium texaphyrin (Gd-Tex) conjugate containing a malonate-Pt(NH(3))(2) moiety is described. The effect of the tumor localizing Gd-Tex macrocycle on platinum activity was evaluated in cell culture. The malonate moiety, analogous to that present in carboplatin, is expected to release an aquated Pt(NH(3))(2) species under physiological conditions.