A Theoritical Mechanistic Investigation Into the Reduction of PtIV[Cl4(dach)] (dach = diaminocyclohexane) Complex with Ascorbate

Although anticancer properties of platinum(II) complexes have been approved, due to the hydrolysis of these complexes before arriving at the target cell, platinum(IV) complexes are generally used as an anticancer prodrug. Density Functional Theory (DFT) was employed to investigate the reduction of anticancer prodrug PtIV[Cl4(dach)] (dach = diaminocyclohexane) by monoanionic ascorbate via an inner sphere mechanism as proposed by Elding. The results obtained from the reduction by different forms of ascorbate (monomeric, dimeric, and hydrated) showed the dimer to be much more reactive. This was attributed to the one ascorbate acting as a base through partial abstraction of the proton from the other. The results were validated by performing natural bond orbital (NBO) analysis on the theoretical transition structures related to the reduction process.