title: Antitumor action of rhodium (I) and iridium (I) complexes.
abstract: Several rhodium(I) and iridium(I) complexes displayed different degrees of antitumour activity when tested in mice bearing Ehrlich ascites carcinoma. Rhodium (I) and iridium (I) acetylacetonate derivatives caused a high percentage of cures. The rhodium (I) dimers were particularly interesting, since (bis(cycloocta-1,5-diene)micromicron' dichlorodirhodium(I) [RhCODCl]2) was highly effective, whereas its analogues, bis(bicyclo[2,2,1]hepta-2,5-diene)micromicron'-dichlorodirhodium(I) [RhNBDCl]2) and bis(1,5-hexadiene)micromicron' dichlorodirhodium(I) [RhEDCl]2) were virtually inactive. The absence of significant inhibition of DNA, RNA and protein syntheses in tumour cells found for [RhCODCl]2 at therapeutically active dosages, indicates that this substance has a different mechanism of action from that of cis-dichlorodiammine Pt(II) (cis-PDD). The amount of rhodium found in tumour cells after administration of active [RhCODCl]2 was higher than that for [RhEDCl]2, while the rhodium concentration in the ascitic fluid was much higher for [RhEDCl]2. A mechanism based on the chemical properties of the complexes is tentatively proposed for explaining these findings and selective toxicity for tumour cells.
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D007495:Iridium / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D009363:Neoplasm Proteins / Q000096:biosynthesis; D009696:Nucleic Acids / Q000096:biosynthesis; D012238:Rhodium / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D008024:Ligands; D009363:Neoplasm Proteins; D009696:Nucleic Acids; D007495:Iridium; D012238:Rhodium