title: Macropodumines A-C: novel pentacyclic alkaloids with an unusual skeleton or zwitterion moiety from Daphniphyllum macropodum Miq.
abstract: Three novel alkaloids, macropodumines A-C (1-3), were isolated from the stem of Daphniphyllum macropodum Miq. Interestingly, the structure of macropodumine A (1) was characterized as having a fused pentacyclic system including an unusual eleven-membered macrolactone ring, whereas macropodumine B (2) contains a rare cyclopentadienyl carbanion, which is stabilized as a zwitterion by an internal iminium cation. The structures of these new metabolites were established on the basis of their detailed spectroscopic analysis. In particular, the unique structure of zwitterion 2 was further confirmed by using single-crystal X-ray diffraction analysis.
authors.affiliation: State Key Laboratory of Drug Research, Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, P.R. China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Yue-Wei
authors.initials: YW
authors.lastname: Guo
authors.forename: Karsten
authors.initials: K
authors.lastname: Krohn
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010944:Plants / Q000737:chemistry*; D011083:Polycyclic Compounds / Q000737:chemistry* / Q000302:isolation & purification; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000470:Alkaloids; D011083:Polycyclic Compounds; C520038:macropodumine A; C520040:macropodumine B; C520039:macropodumine C