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| Heiko Rischer |
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Secondary Metabolism of Triphyophyllum peltatum (Dioncophyllaceae)
Heiko Rischer, Michael Wohlfarth, Jan Schlauer, Gerhard Bringmann Institute of Organic Chemistry • University of Würzburg • Am Hubland, 97074 • Würzburg • Germany
The family Dioncophyllaceae comprises the three monotypic genera Dioncophyllum, Habropetalum and Triphyophyllum. All of them are lianas growing in the tropical forests of West Africa and although they have morphological features like for example the unique hooked leaves and the seeds with their round wings in common, the at least ‘part-time carnivorous’ behaviour is so far only reported from Triphyophyllum peltatum (Bringmann et al., 1996). This contribution is focused on the secondary metabolism of Triphyophyllum. It serves as an excellent example because the prominent naphthylisoquinoline alkaloids, which exhibit a broad range of biological activities (e.g. Boyd et al., 1994; François et al., 1997), are only found in the families Dioncophyllaceae and the closely related Ancistrocladaceae. These alkaloids are chemically characterized by their biaryl axis, which connects the two parts (isoquinoline and naphthoquinone) of each molecule (Bringmann and Pokorny, 1995). Up to now there are about 16 naphthylisoquinolines known from T. peltatum. In addition to the isolation and structural elucidation, we recently proved their unprecedented biosynthetic origin from acetate units by feeding callus cultures with 13C2-labelled sodium acetate and analyzing the metabolites formed, by NMR-techniques (Bringmann et al., 1999).
References Boyd, M. R., Hallock, Y. F., Cardellina, J. H., Manfredi, K. P., Blunt, J. W., McMahon, J. B., Buckheit, R. W., Bringmann, G., Schäffer, M., Cragg, G. M., Thomas, D. W., Jato, J. G. 1994, Anti-HIV Michellamines from Ancistrocladus korupensis. J. Med. Chem. 37: 1740-1745. François, G., Timperman, G., Haller, R. D., Bär, S., Isahakia, M. A., Robertson, S. A., Zhao, C., De souza, N. J., Aké Assi, L., Holenz, J., Bringmann, G. 1997, Growth inhibition of asexual erythrocytic forms of Plasmodium falciparum and P. berghei in vitro by naphthylisoquinoline alkaloid-containing extracts of Ancistrocladus and Triphyophyllum species. Int. J. Pharmacognosy 35: 55-59. Bringmann, G., Pokorny, F. 1995, The Naphthylisoquinoline Alkaloids, in Cordell, G. A. (ed.) The Alkaloids 46, pp. 127-271, New York: Academic Press. Bringmann, G., Wenzel, M., Bringmann, H., Schlauer, J. Aké Assi, L. 1996, Die ‘Teilzeit-fleischfressende’ Pflanze Triphyophyllum peltatum (Dioncophyllaceae): Nutzung der Fangorgane zur Erforschung der Alkaloidbildung. Der Palmengarten 60: 32-37. Bringmann, G., Wohlfarth, M., Rischer, H., Schlauer, J. 1999, A new biosynthetic pathway to alkaloids in plants: acetogenic isoquinolines. Angew. Chem. Int. Ed. Engl. (submitted).
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