Chem.-Biol. Interactions, 45 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF (1983) l-6 Elsevier Scientific Publishers Ireland Ltd. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM ANTITUMOR EFFECTS OF RHODIUM (I), IRIDIUM (I) AND RUTHENIUM(I1) COMPLEXES IN COMPARISON WITH cis- DICHLORODIAMMINO PLATINUM(I1) IN MICE BEARING LEWIS LUNG CARCINOMA* GIANNI SAVA, TULLIO GIRALDI, GIOVANNI MESTRONIs and GRAZIA ZASSINOVICH’ Zstituto di Farmacologia e Farmacognosia and aZstituto di Chimica, Universita’ di Trieste I-341 00 Trieste (Italy) (Received July 21st, 1982) (Revision received November 26th, 1982) (Accepted November 26th, 1982) SUMMARY The effects of square planar rhodium, [RhacacCOD]” and iridium, [IracacCOD]’ complexes and of octahedral ruthenium, [cis-RuCl, (DMSO), 1” complex have been examined in comparison with cis-dichlorodiammino platinum(I1) (cis-PDD). The toxicity in BDFl mice varies widely and de- creasing LD,, -values, ranging from 0.94 mg/kg to 1000 mg/kg, have been obtained forcis-PDD, [RhacacCOD]“, DracacCOD]” and [cis-RuCl, (DMSO),]“, respectively. All the tested complexes similarly inhibit the growth of sub- cutaneous Lewis lung carcinoma and the development of spontaneous as well as of artificial metasteses, with the exception of [IracacCOD]” which is in- active on metastases. The antitumor activity of [ RhacacCOD]” and [ cis-RuCl, (DMSO),]” appears interesting, since it is of the same magnitude as that of cis-PDD, considering also that they were found to be only marginally nephrotoxic. Key words: Organometallic complexes - Antitumor - Antimetastatic *Supported by Consiglio Naxionale delle Ricerche, Special Project ‘Control of Neoplastic Growth’, Contract no. 81.01380.96 and by a grant from the University of Trieste. Abbreviations: [RhacacCOD]“, acetylacetonate-1,ficyclooctadiene rhodium(I); [Iracac- COD]“, acetylacetonate-1,5cyclooctadiene iridium(I); [cis-RuCl, (DMSO),]“, cis-dich- lorotetrakisdimethylsulphoxide ruthenium(I1); cis-PDD, cis-dichlorodiammino platinum (II). zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 0009--2797/83/$03.00 o Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland