Abstract
Hydration reactions of two anticancer Pt(IV) complexes JM149 and JM216 (Satraplatin) were studied computationally together with the hydration of the Pt(II) complex JM118, which is a product of the Satraplatin reduction. Thermodynamic and kinetic parameters of the reactions were determined at the B3LYP/6-311++G(2df.2pd)//B3LYP/6-31 + G(d)) level of theory.
The water solution was modeled using the COSMO implicit solvation model, with cavities constructed using Klamt's atomic radii. It was found that hydration of the Pt(IV) complexes is an endergonic/endothermic reaction.
It follows the (pseudo)associative mechanism is substantially slower (k a parts per thousand aEuro parts per thousand 10(-11) s(-1)) than the corresponding reaction of Pt(II) analogues ((k a parts per thousand aEuro parts per thousand 10(-5) s(-1)). Such a low value of the reaction constant signifies that the hydration of JM149 and Satraplatin is with high probability a kinetically forbidden reaction.
Similarly to JM149 and Satraplatin, the hydration of JM118 is an endothermic/endoergic reaction. On the other hand, the kinetic parameters are similar to those of cisplatin Zimmermann et al. (J Mol Model 17:2385-2393, 2011), allowing the hydration reaction to occur at physiological conditions.
These results suggest that in order to become active Satraplatin has to be first reduced to JM118, which may be subsequently hydrated to yield the active species.