title: A pair of epimeric spirosesquiterpenes from the roots of Ligularia fischeri.
abstract: Two new highly oxygenated spirosesquiterpene lactones, ligulactones A (1) and B (2), and one known sesquiterpenoid, 1beta,10beta-epoxy-6beta-isobutyryloxy-9-oxo-furanoeremophilane (3), were isolated from the roots of Ligularia fischeri. Their structures and relative configurations were elucidated by 1D and 2D NMR and MS data and by comparison of their NMR data with those of related compounds. Single-crystal X-ray diffraction analyses confirmed their structures. Compounds 1 and 2 are C-7 epimers. A possible biosynthetic process for their formation is proposed. Structure 3 was proposed as the likely parent compound for the two new epimeric sesquiterpenoids.
authors.affiliation: Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China.
authors.forename: Wen-Juan
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Xue-Hu
authors.initials: XH
authors.lastname: Li
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Shi
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification*; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification*; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018517:Plant Roots / Q000737:chemistry; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification*; D013141:Spiro Compounds / Q000737:chemistry / Q000302:isolation & purification*; D013237:Stereoisomerism
chemical_list: D004365:Drugs, Chinese Herbal; D007783:Lactones; D012717:Sesquiterpenes; D013141:Spiro Compounds; C548087:ligulactone A; C548088:ligulactone B