Loading...

DFT Study on Mechanism and Kinetic of Thiotepa and Tepa Interaction with its DNA Receptor

Torabifard, Hedieh | 2011

678 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42531 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Fattahi, Alireza
  7. Abstract:
  8. N, N′, N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules which can be carried out via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine of DNA. The second one is the direct nucleophilic ring opening of aziridyl group. Thiotepa and Tepa in pathway 2 act as a cell penetrating carrier for aziridine, which is released via hydrolyses. In this study, we calculated the free activation energy and kinetic rate constant for suggested mechanisms to predict the most probable mechanism by applying density Functional Theory (DFT) using B3LYP method. In addition, solvent effect was introduced using the Conductor-like Polarizable Continuum Model (CPCM) in water, THF and dimethyl ether to simulate the cell condition. Hyper conjugation stabilization factors that effect on stability of generated transition state were investigated by natural bond order (NBO) analysis. Furthermore, quantum Theory of Atoms in Molecules (QTAIM) analysis was performed to extract the bond critical points (BCP) properties, because the electron densities can be considered as a good description of the strength of the different types of interactions.
  9. Keywords:
  10. Kinetics Study ; Hydrolysis ; Triethylenethiophosphoramide (Thiotepa) ; Tepa ; Density Functional Theory (DFT) ; Kinetics

 Digital Object List

 Bookmark

No TOC