Ring-substituted [1,2-bis(4-hydroxyphenyl)ethylenediamine]dichloroplatinum (II) complexes: compounds with a selective effect on the hormone-dependent mammary carcinoma.

[1,2-Bis(4-hydroxyphenyl)ethylenediamine]dichloroplatinum (II) complexes with one substituent in the 2-position (CH3, CF3, F, Cl, Br, I: meso- and d,l-1-PtCl2, meso-(3-5)-PtCl2, meso-(7 and 8)-PtCl2) or two substituents in the 2,6-positions (CH3, Cl: meso-2-PtCl2, meso- and d,l-6-PtCl2) in both benzene rings were synthesized and tested for estrogenic and cytotoxic activities. Two complexes (meso-6-PtCl2 and meso-7-PtCl2) possess both effects. In comparative tests on estrogen receptor positive and negative mammary tumors in cell culture (MCF 7, ER+ and MDA-MB 231, ER-) and in animals (MXT, ER+ and MXT, ER-, mouse), meso-6-PtCl2 shows a selective effect on the estrogen receptor positive mammary carcinoma. A further increase of efficacy was achieved with the water-soluble (sulfato)platinum(II) derivative (meso-6-PtSO4). On the DMBA-induced hormone dependent mammary carcinoma of the SD rat, meso-6-PtSO4 is significantly more active than its ligand (meso-6) and cisplatin.