DISTRIBUTION AND TAXONOMIC SIGNIFICANCE OF CALYSTEGINES IN THE CONVOLVULACEAE{ THOMAS SCHIMMING,BRITTA TOFERN,PETRA MANN,ANUSCHKA RICHTER, KRISTINA JENETT-SIEMS,BIRGIT DRA È GER,% NAOKI ASANO,} MAHABIR P. GUPTA, k MIREYA D. CORREA} and ECKART EICH* Institut fuÈr Pharmazie II (Pharmazeutische Biologie), Freie UniversitaÈt Berlin, KoÈnigin-Luise-Straûe 2 + 4, D-14195 Berlin, Germany; %Institut fuÈr Pharmazeutische Biologie, Martin-Luther-UniversitaÈt Halle-Wittenberg, D-06120 Halle/Saale, Germany; }Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa-machi, Kanazawa, Ishikawa, 920-11, Japan; kCentro de Investigaciones FarmacognoÂsticas de la Flora PanamenÄa (CIFLORPAN), Facultad de Farmacia, Universidad de PanamaÂ, Panama City, Republic of Panama; }Herbarium, Universidad de PanamaÂ/Smithsonian Tropical Research Institute, Panama City, Republic of Panama (Received in revised form 14 May 1998) Key Word IndexÐAniseia; Argyreia; Bonamia; Calystegia; Convolvulus; Cuscuta; Dichondra; Erycibe; Evolvulus; Falkia; Hewittia; Ipomoea; Iseia; Jacquemontia; Lepistemon; Maripa; Merremia; Odonellia; Operculina; Porana; Stictocardia; Turbina; Convolvulaceae; GC-MS; tropane alkaloids; calystegines; glycosidase inhibitors; chemotaxonomy. AbstractÐThe GC-MS analysis of 65 convolvulaceous species from many, predominantly tropical prove- nances, belonging to 22 genera (9 tribes), revealed the occurrence of one to ®ve calystegines in 30 species belonging to 15 genera (8 tribes). This indicates the chemotaxonomic signi®cance of these glycosidase inhi- biting polyhydroxy-nortropanes for the Convolvulaceae. # 1998 Published by Elsevier Science Ltd. All rights reserved INTRODUCTION Calystegines, polyhydroxy-nortropanes with a ter- tiary hydroxyl group at the bicyclic ring bridgehead (aminoketal functionality), have been discovered as constituents of Calystegia sepium [2, 3], Convolvulus arvensis (both Convolvulaceae), and Atropa bella- donna (Solanaceae) [2]. They were proposed as nutritional mediators in the plant rhizosphere (plant bacteria relationship). Moreover, they possess gly- cosidase inhibiting properties [4] comparable to polyhydroxy alkaloids of dierent structure, like e.g., the indolizidines swainsonine or castanospermine [5]. To date the structure of nine calystegines has been elucidated including three tri- hydroxy-nortropanes (A 3 ,A 5 ,A 6 ) [3, 6±8], four tet- rahydroxy-nortropanes (B 1 , B 2 , B 3 , B 4 ) [3, 7±10], and two pentahydroxy-nortropanes (C 1 , C 2 ) [6, 8, 11, 12]. Moreover, a ®rst glycoside could be identi®ed as the 3-O-b-D-glucopyranoside of calystegine B 1 [13]. Whereas the occurrence of calystegines in the Solanaceae is documented for nine genera (Atropa, Datura, Duboisia, Hyoscyamus, Mandragora, Nicandra, Physalis, Scopolia, Solanum) [12, 14, 15], there is only one further report of a calystegine in the Convolvulaceae. Thus calystegine B 2 was ident- i®ed in the seeds of Ipomoea polpha R. W. Johnson and another Australian Ipomoea sp. (Q6, a. calo- bra, Weir Vine). These species are found to be toxic to animals [16]. In order to obtain more information on the occurrence and distribution of these compounds in the Convolvulaceae, we studied 65 species from 22 genera belonging to 9 tribes. The largest genus Ipomoea, divided into 13 sections [17], is represented by species from 7 sections. We chose samples of all plant organs and from many predominantly tropical provenances belonging to all continents except Australia. Phytochemistry Vol. 49, No. 7, pp. 1989±1995, 1998 # 1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0031-9422/98/$ - see front matter PII: S0031-9422(98)00430-0 *Authors to whom correspondence should be addressed. {Part 6 in the series ``Phytochemistry and Chemotaxonomy of the Convolvulaceae''. For Part 5, see Ref. [1]. Presented in part at the 13th Annual Meeting of the International Society of Chemical Ecology, 1996, Prague, Czech Republic (Abstract Book, p. 98), at the IOCD/CYTED International Joint Symposium, 1997, PanamaÂ, Republic of Panama (Abstract Book L-5), and at the 45th Annual Congress of the Society for Medicinal Plant Research, 1997, Regensburg, Germany (Abstract Book E12). 1989