Trans- and cis-2-phenylindole platinum(II) complexes as cytotoxic agents against human breast adenocarcinoma cell lines

The synthesis and characterization of the new 2-phenylindole derivative: C 8 H 3 N-2-C 6 H 5 -3NOMe-5OMe ( 3c ) and the trans- and cis- isomers of [Pt( 3c )Cl 2 (DMSO)] complexes ( 4c and 5c , respectively) are described. The crystal structures of 4c ·CH 2 Cl 2 and 5c confirm: (a) the existence of a Pt-N indole bond, (b) the relative arrangement of the Cl − ligands [ trans- (in 4c ) or cis- (in 5c )] and (c) the anti- ( E ) configuration of the oxime. The cytotoxic assessment of C 8 H 3 N-2-(C 6 H 4 -4′R 1 )-3NOMe-5R 2 [with R 1 = R 2 = H ( 3a ); R 1 = Cl, R 2 = H ( 3b ) and R 1 = H, R 2 = OMe ( 3c )] and the geometrical isomers of [Pt(L)Cl 2 (DMSO)] with L = 3a – 3c [ trans- ( 4a – 4c ) and cis- ( 5a – 5c ), respectively] against human breast adenocarcinoma cell lines (MDA-MB231 and MCF-7) is also reported and reveals that all the platinum(II) complexes (except 4a ) are more cytotoxic than cisplatin in front of the MCF7 cell line. Electrophoretic DNA migration studies of the synthesized compounds in the absence and in the presence of topoisomerase-I have been performed, in order to get further insights into their mechanism of action.