title: The role of structural C--H compared with phenolic OH sites on the antioxidant activity of oleuropein and its derivatives as a great non-flavonoid family of the olive components: a DFT study.
abstract: Oleuropein and its derivatives are the main phenolic compounds of Olea europaea L. leaf and fruit. The structure-antioxidant activity relationship was considered for studying the radical scavenging activity of this non-flavonoid family of the olive components using density functional theory (DFT). The structure of these compounds were optimized employing the B3LYP/6-31G (d,p) and the role of some structural CH positions was compared with phenolic OH sites on radical scavenging. As a result, a radical unique position (C3) in the oleuropein, characterized by low BDE (Bond Dissociation Enthalpy), reasonable spin density and electron distribution, was identified. The experimental results of the previous publications of oleuropein for NO and OH scavenging confirmed the presence of this unique active site in its molecular structure. According to the results, 2,2-diphenylpicrylhydrazyl (DPPH) cannot find this non-marginal active site. Therefore, DPPH may not be a determinant assay for all antioxidant comparisons. Solvent effects were considered in all calculations using a Polarized Continuum Model (PCM) at the B3LYP/6-31G (d,p) level. Solvation calculations were carried out for benzene (ε=2.3) to simulate the oil environment compared to gas phase.
authors.affiliation: Chemistry Department, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran; Young Researchers and Elites Club, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran. Electronic address: keyumars_hassanzadeh@yahoo.com.
authors.forename: Keyumars
authors.initials: K
authors.lastname: Hassanzadeh
authors.affiliation: Physics Department, University of Kurdistan, P.O. Box 416, Sanandaj, Iran. Electronic address: k1akhtari@yahoo.com.
authors.forename: Keivan
authors.initials: K
authors.lastname: Akhtari
authors.affiliation: Biology Department, Science and Research Branch, Islamic Azad University, Sanandaj, Iran.
authors.forename: Halaleh
authors.initials: H
authors.lastname: Hassanzadeh
authors.affiliation: Chemistry Department, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.
authors.forename: Seyed Amir
authors.initials: SA
authors.lastname: Zarei
authors.affiliation: Brian and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Nahid
authors.initials: N
authors.lastname: Fakhraei
authors.affiliation: Physiology and Pharmacology Department, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
authors.forename: Katayoun
authors.initials: K
authors.lastname: Hassanzadeh
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry; D005638:Fruit / Q000737:chemistry; D057888:Iridoid Glucosides; D039823:Iridoids / Q000737:chemistry*; D015394:Molecular Structure; D031658:Olea / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D057888:Iridoid Glucosides; D039823:Iridoids; D010636:Phenols; D010936:Plant Extracts; C002769:oleuropein
keywords: Antioxidant; DPPH; Density functional theory (DFT); Oleuropein; Olive; Radical scavenging activity