title: Novel diterpenoids and diterpenoid glycosides from Siegesbeckia orientalis.
abstract: Eight new ent-pimarane diterpenoids and diterpenoid glycosides, namely, ent-12alpha,16-epoxy-2beta,15alpha,19-trihydroxypimar-8-ene (1), ent-12alpha,16-epoxy-2beta,15alpha,19-trihydroxypimar-8(14)-ene (2), ent-2alpha,15,16,19-tetrahydroxypimar-8(14)-ene, ent-15-oxo-2beta,16,19-trihydroxypimar-8(14)-ene, ent-2-oxo-15,16-dihydroxypimar-8(14)-en-16-O-beta-glucopyranoside, ent-2-oxo-15,16,19-trihydroxypimar-8(14)-ene, ent-2-oxo-3beta,15,16-trihydroxypimar-8(14)-en-3-O-beta-glucopyranoside, and ent-2beta,15,16,19-tetrahydroxypimar-8(14)-en-19-O-beta-glucopyranoside, together with seven known diterpenes were isolated from Siegesbeckia orientalis. Compounds 1 and 2 are novel ent-pimarane diterpenoids with an unprecedented 12alpha,16-epoxy group. Their structures were established by spectral methods, especially 1D and 2D NMR spectral methods.
authors.affiliation: State Key Laboratory of Drug Research, Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Zhangjiang Hi-Tech Park, Shanghai 201203, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiang
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Cheng-Qi
authors.initials: CQ
authors.lastname: Fan
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Yue
mesh_terms: D045784:Abietanes / Q000737:chemistry / Q000302:isolation & purification*; D019659:Asteraceae / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry / Q000302:isolation & purification*; D008516:Medicine, Chinese Traditional; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D045784:Abietanes; D006027:Glycosides; C433018:pimarane