title: The corrected structure of depressoside, an antioxidative iridoid glucoside extracted from the flowers of Gentiana urnula Harry Sm.
abstract: Three known iridoid glucosides (gentiournoside A, gentiournoside E and depressoside) were isolated from the flowers of Gentiana urnula Harry Sm. through activity-guided fractionations with a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. All three compounds exhibited excellent DPPH radical scavenging activities (IC50: 10-20 μmol L(-1)) comparable to that of ascorbic acid and Trolox. However, examination of the NMR data revealed that the reported chemical structure of depressoside, previously isolated from the leaves of G. depressa, needed correcting due to incorrect elucidation around C-7 of the iridane skeleton, and was corrected to 6-β-(2,3-dihydroxyphenyl)-D-glucosyl 7-O-(2,3-dihydroxybenzoyl)-loganate. Depressoside exhibited a much higher scavenging activity against superoxide radicals (IC50: 45.5 μmol L(-1)) than the other two extracted compounds (IC50: more than 900 μmol L(-1)) due to the crucial presence of a pyrogallyl unit.
authors.affiliation: a Shiseido Research Center , Yokohama , Japan.|c Department of Agrobioscience, Graduate School of Agricultural Science , Kobe University , Kobe , Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kusakari
authors.affiliation: a Shiseido Research Center , Yokohama , Japan.
authors.forename: Tadao
authors.initials: T
authors.lastname: Fukuhara
authors.affiliation: a Shiseido Research Center , Yokohama , Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Motoyama
authors.affiliation: a Shiseido Research Center , Yokohama , Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Ochiai
authors.affiliation: b Department of Medicinal Plant, Graduate School of Pharmaceutical Sciences , Kumamoto University , Kumamoto , Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: c Department of Agrobioscience, Graduate School of Agricultural Science , Kobe University , Kobe , Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Sugimoto
mesh_terms: D035264:Flowers / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D030012:Gentiana / Q000737:chemistry*; D057888:Iridoid Glucosides / Q000737:chemistry*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry
chemical_list: D016166:Free Radical Scavengers; D057888:Iridoid Glucosides; D010936:Plant Extracts; C000612022:depressoside
keywords: 1,1-diphenyl-2-picrylhydrazyl (DPPH); Gang-ga Chung; Gentiana; antioxidant; depressoside; iridoid