title: Loganin and secologanin derived tryptamine-iridoid alkaloids from Palicourea crocea and Palicourea padifolia (Rubiaceae).
abstract: During comparative analysis on Palicourea species from Costa Rica, two unusual loganin derived tryptamine-iridoid alkaloids were isolated from an accession of Palicourea crocea. Besides the already known brachycerine (2), palicroceaine (1) features a novel hexacyclic backbone. A second provenance, however, yielded strictosidinic acid (3), belonging to the more common secologanin derived tryptamine-iridoid alkaloids, such as those found in Palicourea padifolia. From this species, strictosidine (4), lyaloside (5) and its derivative (E)-O-(6')-(4″-hydroxy-3″,5″-dimethoxy)-cinnamoyl lyaloside (6) could be isolated. A herbarium specimen-based screening was performed, indicating some degree of regional differentiation in alkaloid content and biosynthetic pathways within the widespread and variable Pal. crocea. It further shows its differentiation from the related strictosidine containing Palicourea croceoides. The occurrence of loganin derived tryptamine-iridoid alkaloids in Pal. crocea, Psychotria brachyceras and Psychotria brachypoda, all putatively unrelated members of the Palicourea s.l. clade, is a noteworthy exception within the genus, otherwise largely characterized by secologanin-derived tryptamine-iridoid alkaloids.
authors.affiliation: Chemodiversity Research Group, Division of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Berger
authors.affiliation: Chemodiversity Research Group, Division of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
authors.forename: Maria Katharina
authors.initials: MK
authors.lastname: Kostyan
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
authors.forename: Simon Immo
authors.initials: SI
authors.lastname: Klose
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Gastegger
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Lorbeer
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
authors.forename: Lothar
authors.initials: L
authors.lastname: Brecker
authors.affiliation: Chemodiversity Research Group, Division of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria. Electronic address: johann.schinnerl@univie.ac.at.
authors.forename: Johann
authors.initials: J
authors.lastname: Schinnerl
mesh_terms: D003364:Costa Rica; D026121:Indole Alkaloids; D057888:Iridoid Glucosides / Q000737:chemistry / Q000302:isolation & purification*; D039823:Iridoids / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D019666:Rubiaceae / Q000737:chemistry* / Q000235:genetics; D046948:Secologanin Tryptamine Alkaloids / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D026121:Indole Alkaloids; D057888:Iridoid Glucosides; D039823:Iridoids; D046948:Secologanin Tryptamine Alkaloids; C021086:secologanin; C059516:loganin
keywords: Brachycerine; Monoterpene indole alkaloids; Palicourea crocea; Palicourea padifolia; Palicroceaine; Psychotria alliance