title: Piperidine and tetrahydropyridine alkaloids from Lobelia siphilitica and Hippobroma longiflora.
abstract: The hyphenated technique HPLC-PDA-MS-SPE-NMR was used to assist targeted preparative-scale isolation of constituents of Lobelia siphilitica and Hippobroma longiflora (both Campanulaceae). This resulted in the isolation of two new alkaloids, (S)-2-[(2S,6R)-1-methyl-6-(2-oxo-2-phenylethyl)piperidin-2-yl]-1-phenylethyl acetate (3) and 6-[(E)-2-(3-methoxyphenyl)ethenyl]-2,3,4,5-tetrahydropyridine (4), the latter possessing a skeleton hitherto unseen among alkaloids of Lobelia and related genera. Lobeline (1), (1S,1'S)-2,2'-[(2R,6S)-1-methylpiperidine-2,6-diyl]bis(1-phenylethanol) (2), and lobetyolin (5) were also isolated. The structures of 1-5 were established using spectroscopic methods including homo- and heteronuclear two-dimensional NMR experiments and optical rotation data.
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Julie R
authors.initials: JR
authors.lastname: Kesting
authors.forename: Inge-Lise
authors.initials: IL
authors.lastname: Tolderlund
authors.forename: Anders F
authors.initials: AF
authors.lastname: Pedersen
authors.forename: Matthias
authors.initials: M
authors.lastname: Witt
authors.forename: Jerzy W
authors.initials: JW
authors.lastname: Jaroszewski
authors.forename: Dan
authors.initials: D
authors.lastname: Staerk
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000302:isolation & purification*; D029422:Campanulaceae / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003718:Denmark; D029746:Lobelia / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010880:Piperidines / Q000737:chemistry / Q000302:isolation & purification*; D011725:Pyridines / Q000737:chemistry / Q000302:isolation & purification*; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D010880:Piperidines; D011725:Pyridines