Z-Isomers of (4α→6′′, 2α→O→1′′)-phenylflavan substituted with R′=R=OH. Conformational properties, electronic structure and aqueous solvent effects

• Autores: Bentz, Erika Natalia; Pomilio, Alicia Beatriz; Lobayan, Rosana María
• Año de publicación: 2016
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Journal of Molecular Modeling, 2016, vol. 22, no. 187, p. 1-15.
• Materia: (4α→6′′, 2α→O→1′′)- phenylflavans; Antioxidants; Density functional theory; Aqueous solvent effect; PCM model; Atoms in molecules; Natural bond orbital analysis; Molecular polarizability
• Institución: Universidad Nacional del Nordeste

Fil: Bentz, Erika Natalia. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina.
Fil: Pomilio, Alicia Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; Argentina.
Fil: Lobayan, Rosana María. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina.
Procyanidins are highly hydroxylated polymers known as antioxidant compounds, thereby exhibiting benefi- cial effects. These compounds are protective agents against oxidative stress and the damage induced by free radicals in membranes and nucleic acids. This paper describes a study of the conformational space of (4α→6′′, 2α→O→1′′)- phenylflavan substituted with R′=R=OH as part of a larger study of similar structures with different substitutions. The relationships between aqueous solution–vacuum variations of some properties were studied, as well as the stabilization and reactivity of (4α→6′′, 2α→O→1′′)-phenylflavan substituted with R′=R=H, R′=H, R=OH, R′=R=OH, and (+)- catechin. The variations in geometric parameters and electron- ic properties due to conformational changes, as well as the effects of substituents and polar solvents, were evaluated and analyzed. Bader’s theory of atoms in molecules was applied to characterize intramolecular interactions, along with a natural bond orbital analysis for each conformer described. The mo- lecular electrostatic potential was rationalized by charge delo- calization mechanisms and interatomic intramolecular interac- tions, relating them to the structural changes and topological properties of the electron charge density. Molecular polariz- ability and permanent electric dipole moment values were estimated. The results show the importance of a knowledge of the conformational space, and values for each conformer. Based on our previous results, we showed the existence of electron charge delocalization mechanisms acting coopera- tively as “delocalization routes”, showing interactions be- tween different rings not even sharing the same plane. These “delocalization routes” were more effective for (4α→6′′, 2α→O→1′′)-phenylflavan substituted with R′=R=OH than for (+)-catechin, and are proposed as adding insight into the structure–antioxidant activity relationship of flavans.