Synthesis and structure-activity relationships of mono- and dialkyl-substituted oxaliplatin derivatives.

In order to improve the pharmacological profile of the anticancer drug oxaliplatin, (trans-R,R-cyclohexane-1,2-diamine)oxalatoplatinum(II), and to explore activity-structure relationships, new mono- and dialkyl substituted oxaliplatin analogues have been synthesized. Following a new synthetic strategy, racemates with a defined stereochemistry at carbon atoms 1, 2, 4, and 5 of the cyclohexane ring could be prepared, which are the bases for reliable structure-activity relationships and the following enantiomer resolution. The cytotoxicity was evaluated in nine tumor cell lines, indicating that bulky substituents have a negative influence on the cytotoxic potency of the oxaliplatin derivatives. With respect to the antiproliferative properties, the 4-methyl-, cis-4,5-dimethyl-, and especially the 4,4-dimethyl-trans-cyclohexane-1,2-diamine(oxalato)platinum(II) complexes are the most promising candidates to be further evaluated.