Tropane Alkaloids

Other Names Tropanalkaloide, tropanes, tropeine Tropane alkaloids are esters of tropanal combined with various acids. They occur primarily in nightshades (Solanaceae), especially the psychoactive ones. The most important psychoactive tropane alkaloids are atropine, scopolamine, and hyoscyamine. These substances are "quickly absorbed through the mucous membranes but also through the intact skin" (Roth et al. 1994, 944*). For this reason, plant preparations in the form of ointments with these tropane alkaloids can induce psychoactive effects (cf. Datura innoxia, witches' ointments). Atropine, scopolamine, and hyoscyamine are found in the genera Atropa, Brugmansia, Datum, Hyoscyamus, Iochroma, ]uanulloa, Mandragora, Solandra, and Scopolia. The psychoactive tropane alkaloid hyoscyamine (cf. Hyoscyamus niger) occurs in the following nightshades in concentrations that appear to make them useful for psychoactive purposes (Festi 1995, 132 f.*): Anthoceris littorea Labill. (herbage), Crenedium spinescens Haegi (leaves), Cyphanthera anthocercidea (Ev. Muel!.) Haegi (leaves), Mandragora caulescens C.B. Clarke (entire plant; cf. Mandragora spp.), Physochlaina praealta (Decne.) Miers (entire plant), and Scopolia lurida Dunal (roots; cf. Scopolia carniolica). As a plant dries, the hyoscyamine it contains is usually transformed into its analog scopolamine. The profile of effects of hyoscyamine is essentially the same as that of scopolamine. Tropanes and cocaine are chemically related and can under certain conditions elicit similar pharmacological effects (Sauerwein et al. 1993). The tropane alkaloid 2-tropanone is a metabolic product of cocaine. Tropane alkaloids occur in most if not all Erythroxylum species (AI-Said et al. 1989). The bark of Erythroxylum zambesiacum N. Robson has been found to contain various tropanes (Christen et al. 1993). The root bark of Erythroxylum hypericifolium Lam., a species indigenous to Mauritius that is used in folk medicine to treat kidney problems, contains large amounts of hygrine as well as other tropanes (e.g., cuscohygrine) (AI-Said et al. 1989). Both hygrine and cuscohygrine are also found in the leaves and bark of the two coca species Erythroxylum coca and Erythroxylum novogranatense (AI-Said et al. 1989, 672). The leaves of the Southeast Asian species Erythroxylum cuneatum (Wall.) Kurz, which is used in Malaysia as a tonic, were found to contain as their primary alkaloid (±)-3<X,613-dibenzoyloxytropane; another major constituent in the leaves is nicotine. The main alkaloid in the leaves of another ethnomedicinally useful Southeast Asian species, Erythroxylum ecarinatum Burck., is tropacacaine. The root bark of the Australian species Erythroxylum australe Ev. Muell. also contain numerous tropanes (meteloidine) (EI-Imam et al. 1988). Tropane alkaloids also appear to be present in the Proteaceae Family, e.g., in the species Knightia strobolina (EI-Imam et aL 1988:2182). In Australia, several members of the genera Hakea and Banksia are used to produce wine. The recent discovery of tropane alkaloids (tropine, tropinone, cuscohygrine, hygrine) in field bindweed (Convolvulus arvensis 1.; cf. Convolvulus tricolor) is very interesting; the species also contains ergot alkaloids (Todd et al. 1995). Tropane alkaloids have also been found in the hedge bindweed Calystegia sepium (1.) R. Br. [syn. Convolvulus sepium] (Goldmann et al. 1990).

Literature See also the entries for atropine and scopolamine. Bauer, Eduard. 1919. Studium aber die Bedeutung der Alkaloide in pharmakognostisch wichtigen Solanaceen, besonders in Atropa Belladonna und Datura Stramonium. Bern: Hallwag. Christen, P., M. F. Roberts, J. D. Phillipson, and W. C. Evans. 1993. Recent aspects of tropane alkaloid biosynthesis in Erythroxylum zambesiacum stem bark. Planta Medica 59 supp!.: A583-84. Goldmann, Arlette, Marie-Louise Milat, Paul-Henri Ducrot, Jean-Yves Lallemand, Monique Maille, Andree Lepingle, Isabelle Charpin, and David Tepfer. 1990. Tropane derivates from Calistegia sepium. Phytochemistry 29 (7): 2125-27. Imam, Yahia M. A. e1-, William C. Evans, and Raymond J. Grout. 1988. Alkaloids of Erythroxylum cuneatum, E. ecarinatum and E. australe. Phytochemistry 27 (7): 2181-84. Said, Mansour S. al-, William C. Evans, and Raymond J. Grout. 1989. Alkaloids of Erythroxylum hypericifolium stem bark. Phytochemistry 28 (2): 671-73. Sauerwein, M., F. Sporer, and M. Wink. 1993. Allelochemical properties of derivatives from tropane and ecgonine. Planta Medica 59 suppL: A662 Todd, G. Fred, F. R. Stermitz, P. Schultheiss, A. P. Traub-Dargatz, and J. Traub-Dargatz. 1995. Tropane alkaloids and toxicity of Convolvulus arvensis. Phytochemistry 39:301-3. Xiao, P., and 1. Y. He. 1983. Ethnopharmacologic investigation on tropane-containing drugs in Chinese Solanaceous plants. Journal of Ethnopharmacology 8: 1-18.