Spectral Properties of α and β L Rhamno-Indigo Molecules and Activities Prediction Through NBO Analysis. A DFT Study

Abstract

Structural and physical properties such as some spectral features of α-L rhamno-indigo and β-L rhamno-indigo molecules are presented in this paper. Results are compared with those of 5,5'-dichloro-indigo N-β-glycosidic 4-amino-4,6-didesoxyglucose (Akashine A) that exhibits a strong inhibitory activity against various human tumor cell lines. Density functional theory (DFT) using B3LYP functional and 6-31G+(d,p), 6-311+G(2d,p) and cc-pvdz as basis sets was applied to perform these studies. Calculations were carried out both in gas phase and with DMSO as an implicit solvent. Gauge including atomic orbitals (GIAO) approach was used to calculate ¹H NMR chemical shifts and Time dependent density functional theory (TD-DFT) calculations were performed to determine the electronic transitions and their nature within the molecules. Moreover, stabilization energies of intra and intermolecular interactions were determined using NBO analyses. Local reactivity descriptors were computed to give insight in the nature of reactive sites. Overall, it has been shown that the nature of the glycosidic linkages has a significant influence on the molecular properties.