In Vitro Culture and the Production of Secondary Metabolites in Hyoscyamus reticulatus L.
Tropane alkaloids constitute one of the distinctive groups of secondary metabolites of the Solanaceae and many plants containing them have long been utilized for their medicinal, hallucinogenic, and poisonous properties (Evans 1979). Hyoscyamus plants are
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1 Introduction Tropane alkaloids constitute one of the distinctive groups of secondary metabolites of the Solanaceae and many plants containing them have long been utilized for their medicinal, hallucinogenic, and poisonous properties (Evans 1979). Hyoscyamus plants are a natural source for the isolation of hyoscyamine (atropine) and scopolamine, 6-7 epoxide of hyoscyamine. Both alkaloids are of medicinal importance because of their suppressive activity on the parasympathetic nervous system. In addition, scopolamine is also applied to suppress the central nervous system, whereas hyoscyamine excites it. Ratios of hyoscyamine content to scopolamine content vary markedly between plant species. These differences result in a higher commercial demand for scopolamine than for hyoscyamine (and its racemic form atropine). Both appear in the USA in the list of the ten most used compounds of plant origin (Straus 1989). Because many tropane alkaloid-producing species accumulate hyoscyamine as the major alkaloid and scopolamine in minor quantities, it is of commercial importance to increase scopolamine content in these species (Hashimoto and Yamada 1992). Moreover, these plants also synthesize the calystegines, a pseudotropine-derived group of alkaloids, found in considerable amounts in Atropa and Hyoscyamus species, exerting a strong inhibitory activity on ~-glycosidases, which can be of great importance for cell recognition (Portsteffen et al. 1994). The latter can possibly result in treatment of some types of cancers. This chapter mainly deals with H. reticulatus and describes the optimization of culture conditions for growth and productivity of tropane alkaloids from transformed H. reticulatus roots. Methodologies to enhance secondary metabolite levels are also discussed, together with a new technique of permeabilization of H. reticulatus-hairy roots for the release of stored tropane alkaloids. These recent developments are largely based on our published and unpublished experimental results.
IDepartment of Pharmacognosy, Faculty of Pharmacy, Medical University, Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria Biotechnology in Agriculture and Forestry, Vol. 51 Medicinal and Aromatic Plants XII (ed. by T. Nagata and Y. Ebizuka) © Springer-Verlag Berlin Heidelberg 2002
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I. Ionkova
1.1 Distribution and Importance of the Plant The four genera of subtribe Hyoscyaminae (Scopolia, Physochlaina, Prezewalskia, Hyoscyamus) produce hyoscyamine as the usual major alkaloid with some hyoscine, but some Hyoscyamus species may contain hyoscine as the principal alkaloid. Hyoscyamus plants are herbaceous, differing essentially from other solanaceous genera by having a fruit composed of a thornless seed capsule with a cover. The genus consists of 14 species: H. albus L. (including var. desertorum, var. canariensis), H. arenarius Dun., H. aureus L., H. ceratophyllus Fisch., H. eminens Kunce, H. Jalezlez Coss., H. grandifLorus Franch., H. muticus L., H. niger L. (including var. agrestis, var. bohemicus, var. pallidus), H. physaloides L., H. pseu
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