Planta Med 2013; 79(05): 334-337
DOI: 10.1055/s-0032-1328283
Biological and Pharmacological Activity
Letters
Georg Thieme Verlag KG Stuttgart · New York

Unusual Amino Acids and Monofluoroacetate from Dichapetalum michelsonii (Umutambasha), a Toxic Plant from Rwanda

Virginie Esters
1  Laboratory of Pharmacognosy, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Charles Karangwa
2  Laboratory of Pharmacology and Toxicology, Department of Pharmacy, Faculty of Medicine, National University of Rwanda, Butare, Rwanda
,
Monique Tits
1  Laboratory of Pharmacognosy, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Pierre Francotte
3  Laboratory of Medicinal Chemistry, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Bernard Pirotte
3  Laboratory of Medicinal Chemistry, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Anne-Catherine Servais
4  Laboratory of Analytical Pharmaceutical Chemistry, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Marianne Fillet
4  Laboratory of Analytical Pharmaceutical Chemistry, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Jacques Crommen
4  Laboratory of Analytical Pharmaceutical Chemistry, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Elmar Robbrecht
5  Department of Vascular Plants (Spermatophyta-Pteridophyta), National Botanic Garden of Belgium, Meise, Belgium
,
Arlette Minet
6  Center for Cellular and Molecular Neurobiology (CNCM), University of Liège, Liège, Belgium
,
Thierry Grisar
6  Center for Cellular and Molecular Neurobiology (CNCM), University of Liège, Liège, Belgium
,
Luc Angenot
1  Laboratory of Pharmacognosy, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
,
Michel Frederich
1  Laboratory of Pharmacognosy, Centre Interfacultaire de Recherche du Médicament (CIRM), Department of Pharmacy, University of Liège, Liège, Belgium
› Author Affiliations
Further Information

Publication History

received 19 August 2012
revised 28 January 2013

accepted 30 January 2013

Publication Date:
01 March 2013 (online)

Abstract

In the course of our investigations on Umutambasha in order to identify its convulsant principles, small quantities of monofluoroacetate were observed in stem bark, leaves, and fruits of this plant newly identified as Dichapetalum michelsonii Hauman. Conclusive evidence for a monofluoroacetate presence came from its isolation from the freeze-dried extract of stem bark. Three free unusual amino acids, named N-methyl-α-alanine, N-methyl-β-alanine, and 2,7-diaminooctan-1,8-dioic acid, described for the first time in a plant, and known trigonelline were also isolated from the stem bark of D. michelsonii. Structure elucidations were mainly achieved by spectroscopic methods (1H-NMR, 2D-NMR, MS) and by comparison with authentic references. These unusual amino acids were detected by a fast, reliable TLC analysis in all our batches of Umutambasha, suggesting that they could be used for identification purposes in case of human or livestock intoxications. Finally, EEG recordings and behavioural observations performed in mice suggested that the convulsive patterns produced by Umutambasha are the consequence of monofluoroacetate presence in D. michelsonii.

Supporting Information