The novel use of Rh(I) complexes with naphthyridine ligands and poly(oxyethylene) as antitumorals

Rh(I) complexes adsorbed on polymers, as a way to improve their transport and solubility properties, were studied as antitumor agents. The binding constants of the complexes to the polymer were evaluated in order to determine the conditions for maximum association to the vehicle. The toxicity of the pure complexes and those bound were determined in vivo using female mice. [Rh(NBD)(2,4N)]CIO4, complex A; where NBD = norbornadiene, (2,4N) = 3,3'-dimethylene-2,2'-di-1,8-naphthyridine, was investigated on primary solid tumors and ascitic tumors. [Rh(NBD)(3,4N)]CIO4, complex B; where (3,4N) = 3,3'-trimethylene-2,2'-di-1,8-naphthyridine, was investigated on ascitic tumors. These Rh(I) complexes appear to be promising drugs because of their solubility in aqueous polymer, which make them easier to handle in comparison with the neutral species. These complexes show a similarity to cisplatin by reducing tumor growth and by increasing the survival life span of mice. Poly (oxyethylene) was used to solubilize these poorly water-soluble compounds and to stabilize the compounds in the solution before injection. These studies suggest that both complexes, A and B, are good candidates for tumor control growth and increase the survival time.