Thomas SCHIMMlNG-1, Anuschka BUFACCHI-RICHTER-1,
Kristina JENETT-SIEMS-1, Petra MANN-
1- Institut für Pharmazie II (Pharmazeutische Biologie),
Freie Universität Berlin, Königin-Luise-Strasse 2+4,
D-14195 Berlin;
2- Institut für Pharmazeutische Biologie, Universität
Halle-Wittenberg, D-06120 Halle;
3- Centro de Investigaciones Farmacognósticas de la Flora
Panamena (CIFLORPAN), Facultad de Farmacia, Universidad de Panama;
4- Herbarium, Universidad de Panama / Smithsonian Tropical
Research Institute, Panama
Calystegines, hydrophilic tropane alkaloids characterized by the absence of the N-methyl substituent and a high degree of hydroxylation, had been discovered as secondary metabolites of Calystegia septum and Convolvulus arvensis (Convolvulaceae), in 1988 [1]. Occurrence has also been reported for several species of the Solanaceae [2 ] and two species of the Moraceae [31. The calystegines apparently are certain nutritional mediators in the plant rhizosphere (plant-bacteria relationship) and possess glycosidase inhibiting properties comparable to well-known polyhydroxy alkaloids of different structural types like e.g. swainsonine or castanospermine.
Thus they exhibit important biological effects e.g. in glycoprotein metabolism which may be of therapeutical value (viral diseases, cancer). Moreover they function as antifeedants~for animals and may have detrimental effects on herbivores.
The recent report of Molyneux et al. on the occurrence of calystegine Bz and swainsonine in an Australian Ipomoea species poisonous for sheep and cattle [4] prompted us to examine whether or not the hydrophilic calystegines as well as swainsonine might be widely distributed in the bindweed family. For that purpose we screened (1) samples of all plant organs, (2) samples from many predominantly tropical provenances belonging to the other 4 continents, and (3) 35 species from 21 genera belonging to all 8 tribes. We focussed on the occurrence of the calystegines A3, B1, and B2, respectively, and in addition swainsonine, which have been identified by using TLC and GS-MS analysis comparing Rf,-values, retention times and fragmentation patterns with authentical samples and data from literature [5].
While swainsonine could not be detected in any sample the hydrophylic nortropanes indeed turned out to be common convolvulaceous metabolites and are in principle detectable in all organs of the plant.
LITERATURE