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 Maria
• Año de publicación: 2016
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: (4α→6″, 2α→O→1″)- Phenylflavans; Antioxidants; Aqueous Solvent Effect; Atoms in Molecules; Density Functional Theory; Molecular Polarizability; Natural Bond Orbital Analysis; Pcm Model
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Procyanidins are highly hydroxylated polymers known as antioxidant compounds, thereby exhibiting beneficial 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 electronic 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 molecular electrostatic potential was rationalized by charge delocalization mechanisms and interatomic intramolecular interactions, relating them to the structural changes and topological properties of the electron charge density. Molecular polarizability 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 cooperatively as “delocalization routes”, showing interactions between 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.
Fil: Bentz, Erika Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura. Departamento de Física; Argentina
Fil: Pomilio, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; Argentina
Fil: Lobayan, Rosana Maria. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura. Departamento de Física; Argentina