DFT evaluation of structural, electronic and variation properties for complex carbohydrates with biological interest

Abstract

The synthetic bicyclic bis(hemiacetals) compounds 1,5-pyranose-9,7-pyranoses, with a structural analogy to the bicyclic monosaccharide Bradyrhizose, have been described here based on a theoretical approach, using DFT calculations with the B3LYP functional combined with the 6-311 + G(d,p) basis set. First, we have performed a geometrical and electronic properties description of (1 R,9S), (1S,9S) and (1S,9R)-1,5-pyranose-9,7-pyranoses. Results analysis indicated that, slight differences in the three-dimensional orientations of their atoms lead to an enormous difference in chemical reactivity. Consequently, (1S,9S) and (1S,9R) isomers are predicted to be the most resembling the natural bradyrhizose in structural features. To enhance the performance of these two isomers, a set of modifications through functional groups attached to the reactive sites were determined by local reactivity descriptors. Subsequently, in order to get more information on the obtained derivatives for both isomers, HOMO, LUMO, Egap and four electronic parameters were calculated and compared. The substituted systems show a good performance in chemical reactivity than the unmodified parent compounds.

Communicated by Ramaswamy H. Sarma

Keywords:

• DFT
• biological activity
• chemical reactivity
• carbohydrates
• bradyrhizose
• immunological activity
• LPS
• O-antigen

Acknowledgment

The authors K. Adjir and M. Sekkal Rahal are grateful to the Alexander Von Humboldt-Stiftung Bonn for financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.