Without external activation, cis- and
trans-dichlorodiammineplatinum(II) (DDP) and the cis, trans(-), and trans(+) forms of
dichloro-1,2-diaminocyclohexaneplatinum(II) (
DDCP) and sulfato-1,2-diaminocyclohexaneplatinum(II) (SHP) showed a 400-fold range of mutagenicity for Salmonella typhimurium TA100 and TA98; they were 2 to 10 times more mutagenic for strain TA100 than for strain TA98. With strain TA100,
trans-DDP was less than 0.5% as mutagenic as the cis isomer, which produced 180 revertants/nmol. For the diaminocyclohexane complexes, mutagenic activity was strongly dependent on the stereoisomer of the diaminocyclohexane in the complex. Thus, with strain TA100, the trans(+) forms of
DDCP and SHP produced 220 and 66 revertants/nmol, respectively, while the cis and trans(-) isomers induced only 10 and 5% as many revertants as the trans(+) forms. The SHP complexes were the most reactive toward
DNA and produced a greater reduction in the transforming activity of Bacillus subtilis
DNA after 3-hr reaction times than did the DDP or
DDCP complexes. With 20-hr reaction times, all of the
platinum complexes showed similar extents of reaction with
DNA and caused approximately equal losses of transforming activity. The stereoisomeric form of the diaminocyclohexane
ligand of the
DDCP or SHP complexes did not affect either the reactivity of the complex with
DNA or its ability to reduce the transforming activity of
DNA. Significant increases in the number of lung
adenomas in A/J mice were induced by multiple i.p.
injections of cis-DDP and each of the
DDCP and SHP complexes (total doses, 21 to 108 mumol/kg
body weight). Similar treatments with cis-DDP caused a significant increase in the number of skin
papillomas in female CD-1 mice given promoting treatments with
croton oil; the
DDCP and SHP complexes had little or no activity in this system. At these levels,
trans-DDP was not active for the induction of either lung
adenomas or skin
tumors. With the systems used for this study, the mutagenicities and tumorigenicities of the
platinum(II) complexes did not correlate with their reported antitumor activities. Further studies appear warranted to determine whether there may be effective antitumor
platinum(II) complexes that are not strongly mutagenic or carcinogenic.