Cytotoxicity of four newly synthesized dinuclear complexes [{cis-PtCl(NH3)2(μ-4,4′-bipyridyl)ZnCl(terpy-Cl)}](ClO4)2, [{trans-PtCl(NH3)2(μ-4,4′-bipyridyl)ZnCl(terpy-Cl)}](ClO4)2, [{cis-PtCl(NH3)2(μ-pyrazine)ZnCl(terpy-Cl)}](ClO4)2 and [{trans-PtCl(NH3)2(μ-pyrazine)ZnCl(terpy-Cl)}](ClO4)2, derived from mononuclear [ZnCl(terpy-Cl)], (where terpy-Cl = 4’-chloro-2,2′:6′,2′′-terpyridine) were evaluated on two colon carcinoma cell lines, HCT-116 and SW-480.
The effect of investigated complexes at different concentrations (0.1, 1, 10, 50, 100, 200 μg/ml) on colon carcinoma cell lines (HCT-116 and SW-480) was examined with MTT assay, and the IC50 value was calculated, as a measure of cytotoxicity. Compared with the positive control (cisplatin), on SW-480 colon cancer cells, there is no significant citotoxicity of tested complexes and IC50 values are higher than 200 µg/ml. If we compare IC50 values between HCT-116 and SW-480 colon cancer cells, it is evident that HCT-116 cells are more sensitive on the treatment with these complexes. Tested complexes showed significant anticancer effect on HCT-116 colon carcinoma cell lines, but after 72 h of applied treatments. After 72 h, significant cytotoxic effect was evident only in HCT-116 cells after applied complexes [{cis-PtCl(NH3)2(μ-4,4′-bipyridyl)ZnCl(terpy-Cl)}](ClO4)2, [{trans-PtCl(NH3)2(μ-4,4′-bipyridyl)ZnCl(terpy-Cl)}](ClO4)2 and [{cis-PtCl(NH3)2(μ-pyrazine)ZnCl(terpy-Cl)}](ClO4)2. The best cytotoxic effect of all investigated complexes was pronounced after applying [{trans-PtCl(NH3)2(μ-4,4′-bipyridyl)ZnCl(terpy-Cl)}](ClO4)2 complex on HCT-116 colon cancer cells after 72 h (19.52±0.78 µg/ml).
In comparison with previously studied four analogues of these complexes but without chlorinated terpy ligand, cytotoxic effect of all complexes is lower. Obviously, the presence of the chloride in the structure of [ZnCl(terpy-Cl)] subunit of newly synthesized complexes influenced their behavior due to exchanged electronic communication between metal centers.
