Organo-platinum compoundsOrgano-platinum compounds S 8300 Synthesis, Structure, and Antitumor Properties of Platinum(IV) Complexes with Aminonitroxyl Radicals. -Novel Pt(IV) complexes (I) and (II) are synthesized, which possess high activity against the experimental tumor, viz., P388 leukemia. Complex (I) possesses higher antitumor activity and much more slow rate of the development of drug resistance compared to the standard Cisplatin. The combined use of low doses of (I) and Cisplatin results in the mutual enhancement of the antitumor action of the drugs and leads to 100% cure of animals. -(SEN*, V. D.; TKACHEV, V. V.; VOLKOVA, L. M.; GONCHAROVA, S. A.; RAEVSKAYA, T. A.; KONOVALOVA, N. P.; Russ.

Mixed-ligand platinum comptexes cis-PtfI(R6NH3)(NH3)X., and c:s-PtH(RSNH_~)(NH3)X2 ~,R ~ is 2.2.6,6-tetramethyi-4-piperidyl-l-oxyl and R 5 is 2, 2,5.5-tetramethyl-3-pyrrolidinyl-1-oxyt) were synthesized by either the reaction of aminonitroxides RN H~ with Nat Pt al( N H3)CI21I generated in situ (for X 2 --'-Cll) or by replacement of ~he iodo-chloro ligands in cis-PtH(RNH~)(NH3)CII by dichloro and oxalato ligands. The complexes obtained were characterized by elemental analysis and by IR, UV, and ESR spectra. For cis-PtlI(RSNH~)(NH3)CI2, crystal and molecular structures were determined by X-ray diffraction analysis. Cisplatin accelerates autooxidation of methyl linoleate and the platinum nitroxide complexes synthesized exhibit antioxidant properties. The rate of isolated DNA binding with the new complexes is almost as high as that for cisplatin, cis-PtU(R6NH2)(NH3)CI2 exhibits the highest antitumor activity. The high antitumor activity of platinum nitroxide complexes shows that the possible "radical component" is not a crucial factor in the cyto~oxic action of cisplatin

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