Cyclooxygenase-Inhibiting Platinum(IV) Prodrugs with Potent Anticancer Activity.

Platinum(IV) prodrugs of the [Pt(P)(A)(COXi)(OH)] type scaffold (where P is 1,10-phenanthroline or 5,6-dimethyl-1,10-phenanthroline, A is 1,2-diaminocyclohexane, and COXi is a COX inhibitor, either indomethacin or aspirin) were synthesised and characterised, and their biological activity was explored. MTT assays showed that these complexes exhibit outstanding activity against a range of cancer cell lines, and nanomolar activities were observed. The most potent complex, , exhibited a GI of 3 nM in the Du145 prostate cancer cell line and was observed to display a 1614-fold increased activity against the HT29 colon cancer cell line relative to cisplatin. ICP-MS studies showed a linear correlation between increased cellular accumulation of the complexes and increased cytotoxicity, while an enzyme immunoassay showed that and inhibited COX-2 at 14 and 1.4 µM, respectively, which is comparable to the inhibition exhibited by indomethacin. These results suggest that while the cytotoxicity of prodrugs - was influenced by cellular uptake, it was not entirely dependent on either COX inhibition or lipophilicity.