title: Quinones from Chirita eburnea.
abstract: Five new quinone derivatives, (R)-7-hydroxy-alpha-dunnione (1), (R)-8-hydroxy-alpha-dunnione (2), (R)-7,8-dihydroxy-alpha-dunnione (3), (R)-7-methoxy-6,8-dihydroxy-alpha-dunnione (4), and 1,7-dihydroxy-2-hydroxymethylanthraquinone (5), along with seven known compounds, were isolated from Chirita eburnea. All structures were elucidated by spectroscopic techniques (NMR, MS, UV, and IR). The EtOAc fraction of the EtOH extract and compounds 3 and 4 showed free radical (DPPH) scavenging activity, with IC50 values of 101.7 +/- 5.2 microg/mL, 124.82 +/- 8.4 microM, and 45.72 +/- 3.6 microM, respectively, compared with 86.91 +/-6.8 microM for ascorbate.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, People's Republic of China.
authors.forename: Xiang-Hai
authors.initials: XH
authors.lastname: Cai
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Luo
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.forename: Xiao-Jiang
authors.initials: XJ
authors.lastname: Hao
mesh_terms: D000465:Algorithms; D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D019684:Magnoliopsida / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010851:Picrates / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal; D016166:Free Radical Scavengers; D010851:Picrates; D011809:Quinones; C004931:1,1-diphenyl-2-picrylhydrazyl