Ab initio computational study of vincristine as a biological active compound: NMR and NBO analyses

Vincristine is a biological active alkaloid that has been used clinically against a variety of neoplasms. In the current study we have theoretically investigated the magnetic properties of titled compound to predict physical and chemical properties of vincristine as a biological inhibitor. Ab initio computation using HF and B3LYP with 3-21G(d) and 6-31G(d) level of theory have been performed and then magnetic shielding tensor (, ppm), shielding asymmetry (), magnetic shielding anisotropy (aniso, ppm), the skew of a tensor (K), chemical shift anisotropy () and chemical shift () were calculated to indicate the details of the interaction mechanism between microtubules and vincristine. Moreover, EHOMO, ELUMO and Ebg were evaluated. The maximum and minimum values of Ebg were found in HF/3-21g and B3LYP/3-21g respectively. It was also uggested that O24, O37, O49 and O55 with minimum values of iso, are active sites of titled compound. Furthermore the calculated chemical shifts were compared with experimental data in DMSO and CDCl3 solvents.