DFT studies of camptothecins cytotoxicity IV — active and inactive forms of irinotecan

Abstract Structures of irinotecan (CPT-11) in neutral lactone, carboxyl, and anionic carboxylate forms singlet ground states their complexes with Cu(II) doublet are optimized using B3LYP/6-311G* treatment. Metal ion affinities (MIA), Cu charges Laplacians Cu-ligand bond critical points possible CPT active sites evaluated. The formation the ligand leads to release CO 2 that can cause a decrease concentration lactone form due equilibria between all drug. MIA values electron density transfer increase sequence < carboxyl carboxylate. Both exhibit lower than those camptothecin, unlike form.