title: Bioactive constituents from Chinese natural medicines. XVII. constituents with radical scavenging effect and new glucosyloxybenzyl 2-isobutylmalates from Gymnadenia conopsea.
abstract: The methanol-eluted fraction of the methanolic extract from the tubers of Gymnadenia conopsea was found to show radical scavenging activities for DPPH and super oxide anion (.O2-) radicals. Three new glucosyloxybenzyl 2-isobutylmalates, gymnosides VIII, IX, and X, were isolated from this natural medicine together with 58 known constituents. The stereostructures of gymnosides were elucidated on the basis of chemical and physicochemical evidence. In addition, the phenanthrene and dihydrostilbene constituents showed radical scavenging activities and suggested the following structural requirements on radical scavenging activities; a) phenanthrenes: 1) dihydrogenation at the 9,10-positions enhances the activities, 2) the 1 or 3-p-hydroxybenzyl group enhances the activities; b) dihydrostilbenes: 1) methylation of the 3'-position reduces the activities, 2) the 2- and/or 6-p-hydroxybenzyl groups enhance the activities.
authors.affiliation: Kyoto Pharmaceutical University, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Morikawa
authors.forename: Haihui
authors.initials: H
authors.lastname: Xie
authors.forename: Hisashi
authors.initials: H
authors.lastname: Matsuda
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yoshikawa
mesh_terms: D001577:Benzophenones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology*; D006865:Hydrogenation; D008293:Malates / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008745:Methylation; D015394:Molecular Structure; D029595:Orchidaceae / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry / Q000378:metabolism; D013267:Stilbenes / Q000737:chemistry / Q000378:metabolism
chemical_list: D001577:Benzophenones; D004365:Drugs, Chinese Herbal; D016166:Free Radical Scavengers; D008293:Malates; D010616:Phenanthrenes; D013267:Stilbenes; C031181:phenanthrene; C005290:oxybenzone