title: Flavonoids in the poisonous plant Oxytropis falcata.
abstract: Three new flavonoids, oxytropisoflavans A (1) and B (2) and (6aR,11aR)-3,8-dihydroxy-9,10-dimethoxypterocarpan (3), together with 30 known flavonoids (4-33), were isolated from the aerial parts and roots of Oxytropis falcata. The absolute configurations of 3 and C-3 in 1 and 2 were deduced by circular dichroism. The structure of flavonoid 2 was confirmed by single-crystal X-ray diffraction analysis and that of flavonoid 3 by total synthesis of its racemate. Oxytropisoflavan A (1) is an unprecedented chalcan-isoflavan biflavonoid, whereas oxytropisoflavan B (2) possesses a rare modified A-ring. Pterocarpan 3 has good radical-scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.
authors.affiliation: Key Laboratory of Chemistry of Northwestern Plant Resources, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China.
authors.forename: Wen-Hao
authors.initials: WH
authors.lastname: Chen
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Shi
mesh_terms: D001713:Biphenyl Compounds / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008968:Molecular Conformation; D015394:Molecular Structure; D033021:Oxytropis / Q000737:chemistry*; D010851:Picrates / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D010947:Plants, Toxic / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C552223:(6aR,11aR)-3,8-dihydroxy-9,10-dimethoxypterocarpan; D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal; D005419:Flavonoids; D016166:Free Radical Scavengers; D010851:Picrates; C552221:oxytropisoflavan A; C552222:oxytropisoflavan B; C004931:1,1-diphenyl-2-picrylhydrazyl