Structure and electronic properties of (+)-catechin : aqueous solvent effects

Abstract

We report a study of the structure of (+)-catechin, which belongs to the family of the flavan-3-ols—one of the five most widely distributed phenolic groups. The biological activities and pharmaceutical utility of these compounds are related to antioxidant activity due to their ability to scavenge

free radicals. A breakthrough in the study of the conforma- tional space of this compound, so far absent in the literature, is

presented herein. A detailed analysis of the electronic distri- bution, charge delocalization effects, and stereoelectronic ef- fects is presented following application of the theory of atoms

in molecules (AIM) and natural bond orbital analysis. The stability order, and the effects of electron delocalization in the structures were analyzed in depth. The molecular electrostatic potential (MEP) was also obtained, assessing changes in the electronic distribution in aqueous solution, the effects of the solvent on the intrinsic electronic properties, and molecular geometry. The effect of the aqueous solvent on MEP was also

quantified, and rationalized by charge delocalization mecha- nisms, relating them to structural changes and topological

properties of the electronic charge density. To further analyze

the effects of the aqueous solvent, as well as investigating the molecular and structural properties of these compounds in a biological environment, the polarizabilities for all conformers characterized were also calculated. All results were interpreted on the basis of our accumulated knowledge on (4α→6", 2α→ O→1")-phenylflavans in previous reports, thus enriching and deepening the analysis of both types of structure.