Cytotoxicity of 2,2':6',2' '-terpyridineplatinum(II) complexes against human ovarian carcinoma

2,2':6',2''-Terpyridineplatinum(II) complexes are shown to possess cytotoxicity against a number of human ovarian tumor cell lines. Many of the complexes show similar activity against cisplatin- and doxorubicin-resistant cell lines as the parental cells suggesting that there is little or no cross-resistance with cisplatin or doxorubicin. The cytotoxicity of bis[2,2':6',2''-terpyridineplatinum(II)] complexes is strongly dependent on the nature of the linker. Bis[2,2':6',2''-terpyridineplatinum(II)] complexes with a flexible linker at the 4'-position show poor cytotoxicity; by contrast bis[2,2':6',2''- terpyridineplatinum(II)] complexes with rigid and short linkers at platinum(II) are strikingly effective. Several of the compounds show greater cytotoxicity against human ovarian cell lines than carboplatin, the therapeutic agent currently advocated for the treatment of human ovarian cancers.