title: Phenolic compounds from Hypericum calycinum and their antioxidant activity.
abstract: From the MeOH extract of Hypericum calycinum, two caffeoylquinic acid derivatives, butyl chlorogenate (1), and chlorogenic acid (2), seven flavonoids, quercetin (3), quercitrin (4), hyperoside (5), isoquercitrin (6), miquelianin (7), rutin (8) and I3,II8-biapigenin (9) and two flavanols, (+)-catechin (10) and (-)-epicatechin (11) were isolated. Identification of the isolates was carried out by spectroscopic analysis including 1D and 2D NMR experiments as well as mass spectrometry. Free radical scavenging activities of the isolated compounds were determined in in-vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging models. The compounds showed strong DPPH and moderate NO scavenging activities in a concentration dependent manner. (+)-Catechin and (-)-epicatechin were found to be the most active compounds with IC50 values of 4.16 and 4.67 microM for DPPH and 190 and 170 microM for NO scavenging activities, respectively.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Yeditepe University, TR-34755, Kayişdaği, Istanbul, Turkey. hasankbekmez@yahoo.com
authors.forename: Hasan
authors.initials: H
authors.lastname: Kirmizibekmez
authors.forename: Carla
authors.initials: C
authors.lastname: Bassarello
authors.forename: Sonia
authors.initials: S
authors.lastname: Piacente
authors.forename: Engin
authors.initials: E
authors.lastname: Celep
authors.forename: Irem
authors.initials: I
authors.lastname: Atay
authors.forename: Güldem
authors.initials: G
authors.lastname: Mercanoğlu
authors.forename: Erdem
authors.initials: E
authors.lastname: Yeşilada
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry; D020902:Hypericum / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010851:Picrates / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; D009569:Nitric Oxide; C004931:1,1-diphenyl-2-picrylhydrazyl