Comparative study of hydrolytic and electron-driven processes in carboplatin biotransformation

Area of Science:

• Computational chemistry
• Pharmacology
• Materials science

Background:

• Carboplatin is a crucial chemotherapy drug, but its activation mechanism is not fully understood.
• Understanding carboplatin's transformation from pro-drug to active form is key to optimizing its cytotoxic effects.
• Existing models focus on hydrolysis, but alternative bioactivation pathways may exist.

Purpose of the Study:

• To computationally simulate and compare different pathways for carboplatin bioactivation.
• To investigate carboplatin transformation via hydrolysis versus electron-transfer processes.
• To identify the most effective mechanism for generating carboplatin's active, cytotoxic form.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• A supermolecular approach was used to model reaction courses.
• Geometrical and thermodynamic parameters were calculated to evaluate pathway efficiency.

Main Results:

• Hydrolysis follows a two-stage S_N2 mechanism and is endothermic.
• Electron-driven reactions proceed via dissociative electron attachment (DEA) and are exothermic.
• Hybrid pathways (water followed by electron impact) are predicted to be the most favorable for carboplatin activation.

Conclusions:

• Hybrid carboplatin transformation is more efficient than purely hydrolytic pathways.
• Activated aqua-products exhibit strong electron-affinity, acting as cytotoxic agents and electron acceptors.
• This study proposes novel insights into carboplatin's bioactivation, potentially leading to improved drug design.