title: ent-Pimarane diterpenoids from Siegesbeckia orientalis and structure revision of a related compound.
abstract: Six new ent-pimarane diterpenoids, namely, ent-14beta,16-epoxy-8-pimarene-3beta,15alpha-diol (1), 7beta-hydroxydarutigenol (2), 9beta-hydroxydarutigenol (3), 16-O-acetyldarutigenol (4), 15,16-di-O-acetyldarutoside (5), and 16-O-acetyldarutoside (6), were isolated from the ethanol extract of Siegesbeckia orientalis. Their structures were elucidated on the basis of spectroscopic studies, and the absolute configuration of 1 was established by the modified Mosher's method. Furthermore, the structure of ent-12beta,16-epoxy-8-pimarene-2alpha,15beta,19-triol, recently isolated from the same plant, should be revised as ent-14beta,16-epoxy-8-pimarene-2alpha,15alpha,19-triol (10).
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: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Cheng
authors.forename: Ya-Ju
authors.initials: YJ
authors.lastname: Li
authors.forename: Song
authors.initials: S
authors.lastname: Shi
authors.forename: Ji-Kai
authors.initials: JK
authors.lastname: Liu
mesh_terms: D045784:Abietanes / Q000737:chemistry* / Q000302:isolation & purification*; D019659:Asteraceae / Q000737:chemistry*; D004365:Drugs, Chinese Herbal / Q000737:chemistry* / Q000302:isolation & purification*; D006801:Humans; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular
chemical_list: D045784:Abietanes; D004365:Drugs, Chinese Herbal; C433018:pimarane