Photoactivation of trans diamine platinum complexes in aqueous solution and effect on reactivity towards nucleotides

We show that UVA irradiation (365 nm) of the PtIV complex trans,trans,trans-[PtIVCl2(OH)2(dimethylamine)(isopropylamine)] (1), induces reduction to PtII photoproducts. For the mixed amine PtII complex, trans-[PtIICl2(isopropylamine)(methylamine)] (2), irradiation at 365 nm increases the rate and extent of hydrolysis, triggering the formation of diaqua species. Additionally, irradiation increases the extent of reaction of complex 2 with guanosine-5′-monophosphate and affords mainly the bis-adduct, while reactions with adenosine-5′-monophosphate and cytidine-5′-monophosphate give rise only to mono-nucleotide adducts. Density Functional Theory calculations have been used to obtain insights into the electronic structure of complexes 1 and 2, and their photophysical and photochemical properties. UVA-irradiation can contribute to enhanced cytotoxic effects of diamine platinum drugs with trans geometry.

Irradiation at 365 nm induces activation of this trans-PtIV diamine dichlorido dihydroxido anticancer complex via reduction to reactive PtII species. Additionally, light promotes the second aquation of PtII dichlorido species and their interaction with guanosine monophosphate, leading mainly to bis-nucleotide adducts.Figure optionsDownload as PowerPoint slide