title: Molecular mechanisms of silybin and 2,3-dehydrosilybin antiradical activity--role of individual hydroxyl groups.
abstract: The flavonolignans silybin (1) and 2,3-dehydrosilybin (2) are important natural compounds with multiple biological activities operating at various cell levels. Many of these effects are connected with their radical-scavenging activities. The molecular mechanisms of the antioxidant activity of these compounds and even the functional groups responsible for this activity are not yet well known. Their mechanism can be inferred from the structures of the dimeric products obtained from radical-mediated reactions of selectively methylated derivatives of 1 and 2. The radical oxidation of 1 methylated at 7-OH and 2 methylated at both 3-OH and 7-OH yields C-C and C-O dimers that enable the molecular mechanism of their E-ring interaction with radicals to be elucidated and shows the importance of the 20-OH group in this respect. The pivotal role of the 3-OH group in the radical-scavenging activity of 2 was confirmed through the formation of another type of dimer from its selectively methylated derivative.
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, CZ-142 20 Prague, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Gazák
authors.forename: Petr
authors.initials: P
authors.lastname: Sedmera
authors.forename: Marek
authors.initials: M
authors.lastname: Vrbacký
authors.forename: Jitka
authors.initials: J
authors.lastname: Vostálová
authors.forename: Zdenĕk
authors.initials: Z
authors.lastname: Drahota
authors.forename: Petr
authors.initials: P
authors.lastname: Marhol
authors.forename: Daniela
authors.initials: D
authors.lastname: Walterová
authors.forename: Vladimír
authors.initials: V
authors.lastname: Kren
mesh_terms: D019281:Dimerization; D016166:Free Radical Scavengers / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D066298:In Vitro Techniques; D015227:Lipid Peroxidation; D020944:Silybum marianum; D008958:Models, Molecular; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D000077385:Silybin; D012838:Silymarin / Q000737:chemistry
chemical_list: D016166:Free Radical Scavengers; D012838:Silymarin; D017665:Hydroxyl Radical; D000077385:Silybin