title: Chemotaxonomy of the pantropical genus Merremia (Convolvulaceae) based on the distribution of tropane alkaloids.
abstract: The occurrence and distribution of tropane and biogenetically related pyrrolidine alkaloids in 18 Merremia species of paleo-, neo-, and pantropical occurrence have been studied. The extensive GC-MS study included members of almost all sections of the genus and has been carried out with epigeal vegetative parts as well as with roots. It comprises altogether 74 tropanes and 13 pyrrolidines including nicotine. Along with datumetine known already from a solanaceous species, the study led to the isolation (from M. dissecta and M. guerichii, respectively) and structure elucidation (spectral data) of four novel 3alpha-acyloxytropanes, merresectines A-D: 3alpha-(4-methoxybenzoyloxy)nortropane (A), 3alpha-kurameroyloxytropane (B), 3alpha-nervogenoyloxytropane (C), 3alpha-[4-(beta-D-glucopyranosyloxy)-3-methoxy-5-(3-methyl-2-butenyl)benzoyloxy]tropane (beta-d-glucoside of D). Moreover, the novel 3alpha,6beta-di-(4-methoxybenzoyloxy)tropane (merredissine) has been isolated from M. dissecta and structurally elucidated. In addition the structures of datumetine and merresectine A could be confirmed by synthesis. Spectral data for two known 3alpha-acyloxytropanes (merresectine E beta-D-glucoside, 4'-dihydroconsabatine) and one known 3beta-acyloxytropane (concneorine) are documented for the first time. The structures of three further merresectines (F-H) have been determined by mass spectrometry. Furthermore, the linkage (2',3- and 2',4-, respectively) of two position isomer N-methylpyrrolidinylhygrines was proven by synthesis. The results of the study contribute to the solution of infrageneric taxonomic problems. Whereas all species yield pyrrolidine alkaloids without suitably differentiating results the diverging occurrence of tropane alkaloids leads to three groups of sections: (1) taxa free of tropanes, (2) taxa with simple tropanes, and (3) taxa with merresectines in addition to simple tropanes.
authors.affiliation: Institut für Pharmazie (Pharmazeutische Biologie), Freie Universität Berlin, Königin-Luise-Str. 2+4, D-14195 Berlin, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Jenett-Siems
authors.forename: Robert
authors.initials: R
authors.lastname: Weigl
authors.forename: Anke
authors.initials: A
authors.lastname: Böhm
authors.forename: Petra
authors.initials: P
authors.lastname: Mann
authors.forename: Britta
authors.initials: B
authors.lastname: Tofern-Reblin
authors.forename: Sonja C
authors.initials: SC
authors.lastname: Ott
authors.forename: Azar
authors.initials: A
authors.lastname: Ghomian
authors.forename: Maki
authors.initials: M
authors.lastname: Kaloga
authors.forename: Karsten
authors.initials: K
authors.lastname: Siems
authors.forename: Ludger
authors.initials: L
authors.lastname: Witte
authors.forename: Monika
authors.initials: M
authors.lastname: Hilker
authors.forename: Frank
authors.initials: F
authors.lastname: Müller
authors.forename: Eckart
authors.initials: E
authors.lastname: Eich
mesh_terms: D000470:Alkaloids / Q000145:classification / Q000302:isolation & purification; D002965:Classification; D027722:Convolvulaceae / Q000737:chemistry* / Q000145:classification*; D008401:Gas Chromatography-Mass Spectrometry; D015394:Molecular Structure; D010936:Plant Extracts / Q000302:isolation & purification; D018517:Plant Roots / Q000737:chemistry; D011759:Pyrrolidines / Q000145:classification / Q000302:isolation & purification*; D014326:Tropanes / Q000145:classification / Q000302:isolation & purification*
chemical_list: D000470:Alkaloids; D010936:Plant Extracts; D011759:Pyrrolidines; D014326:Tropanes