title: A revised structure for alkaloid 235C isolated from skin extracts of mantellid (Mantella) frogs of Madagascar.
abstract: Madagascan frogs of the mantellid genus Mantella have been a rich source of alkaloids derived from dietary arthropods. Two species of frogs, inhabiting swamp forest, contain a unique set of alkaloids, previously proposed, based only on GC-MS and GC-FTIR data, to represent dehydro analogues of the homopumiliotoxins. The major alkaloid of this set, alkaloid 235C (2), now has been isolated in sufficient quantities (ca. 0.3 mg) to allow determination of the structure by NMR analysis. The structure of alkaloid 235C proved to be a 7,8-dehydro-8-desmethylpumiliotoxin. A comparison is presented between the mass, infrared, and (1)H NMR spectra of 235C (2) and a synthetic dehydrohomopumiliotoxin (1), initially proposed incorrectly as the structure for 235C.
authors.affiliation: Laboratoire de Chimie Organique "Produits Naturels", Université d'Antananarivo, Antananarivo 1001, Madagascar, School of Chemistry, Queen's University, Belfast BT9 5AG, Northern Ireland, UK.
authors.forename: N Rabe
authors.initials: NR
authors.lastname: Andriamaharavo
authors.forename: Marta
authors.initials: M
authors.lastname: Andriantsiferana
authors.forename: Paul A
authors.initials: PA
authors.lastname: Stevenson
authors.forename: Gavin
authors.initials: G
authors.lastname: O'mahony
authors.forename: Herman J C
authors.initials: HJ
authors.lastname: Yeh
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kaneko
authors.forename: H Martin
authors.initials: HM
authors.lastname: Garraffo
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Spande
authors.forename: John W
authors.initials: JW
authors.lastname: Daly
mesh_terms: D000470:Alkaloids / Q000032:analysis / Q000737:chemistry*; D000818:Animals; D001001:Anura / Q000378:metabolism*; D001181:Arthropods; D004032:Diet; D007212:Indolizines / Q000737:chemistry*; D008270:Madagascar; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D012867:Skin / Q000737:chemistry*
chemical_list: D000470:Alkaloids; D007212:Indolizines; C506977:alkaloid 235C