Design, synthesis and biological evaluation of naphthalenebenzimidizole platinum (II) complexes as potential antitumor agents

A serial of naphthalenebenzimidizole-Pt complexes 1-6 were designed and synthesized as antitumor agents. In vitro antitumor assay results showed that complexes 1-6 exhibited moderate to high antiproliferative activity against Hela, HepG2, SKOV-3, NCI-H460, BEL-7404 and A549 cancer cell lines, while they displayed obvious sensitivity and selectivity against SMMC-7721 and U251 cell lines and low toxicity against normal HL-7702 cells, in comparison with cisplatin. In vivo antitumor assay results indicated that complex 1 and 5 exhibited important in vivo antiproliferative activity in the NCI-460 and SMMC-7721 models, in comparison with cisplatin, respectively. Complexes 1 and 5 exhibited better antiproliferative activity against A549CDDP and SKOV3CDDP cell lines than cisplatin, with IC₅₀ values of 6.98 ± 0.47 μM, 5.62 ± 0.88 μM and 13.13 ± 2.11 μM, 5.30 ± 0.33 μM, respectively, while they displayed potential antiproliferation against A549 and SKOV3 cell lines, with IC₅₀ values of 7.32 ± 0.51 μM, 5.19 ± 0.49 μM and 14.92 ± 0.11 μM, 12.19 ± 0.92 μM, indicating the introduction of naphthalenebenzimidizole into platinum-metal system may overcome the resistance. Mechanistic studies showed that the representative complexes 1 and 5 exerted the antitumor effect mainly by the obvious covalent binding with DNA and the upregulation of the expression level of intracellular topo I, showing different action mechanism from cisplatin.