Levbid
The role and source of 5'-deoxyadenosyl radical in a carbon skeleton rearrangement catalyzed by a plant enzyme.

Ollagnier S, Kervio E, Retey J.

Lehrstuhl fur Biochemie, Institut fur Organische Chemie, Universitat Karlsruhe, Germany.

The last step in the biosynthesis of tropane alkaloids is the carbon skeleton rearrangement of littorine to hyoscyamine. The reaction is catalyzed by a cell-free extract prepared from cultured hairy roots of Datura stramonium. Adenosylmethionine stimulated the rearrangement 10-20-fold and showed saturation kinetics with an apparent Km of 25 microM. It is proposed that S-adenosylmethionine is the source of a 5'-deoxyadenosyl radical which initiates the rearrangement in a similar manner as it does in analogous rearrangements catalyzed by coenzyme B12-dependent enzymes. Possible roles of S-adenosylmethionine as a radical source in higher plants are discussed.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9824314&dopt=Abstract hyoscyamine Levbid SL



Levbid
Selectivity manipulation using nonaqueous capillary electrophoresis. Application to tropane alkaloids and amphetamine derivatives.

Cherkaoui S, Varesio E, Christen P, Veuthey JL.

University of Geneva, Laboratory of Pharmaceutical Analytical Chemistry, Switzerland.

Non-aqueous capillary electrophoresis was investigated for its potential in the analysis of pharmaceutical compounds, namely tropane alkaloids and amphetamine derivatives. The separation of these drugs was compared in aqueous and organic media such as methanol and/or acetonitrile. Selectivity, migration times and efficiency were critically affected by the composition of the methanol/acetonitrile mixture, as well as by the nature and the concentration of the electrolyte. In particular, the migration orders of two positional isomers, littorine and hyoscyamine, were inverted in the presence of trifluoroacetic acid in the nonaqueous medium. The same behavior was observed for amphetamine-methamphetamine and for two methylenedioxyamphetamine derivatives.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9870386&dopt=Abstract hyoscyamine Levbid SL



Levbid
Capillary electrophoresis for the analysis of tropane alkaloids: pharmaceutical and phytochemical applications.

Mateus L, Cherkaoui S, Christen P, Veuthey JL.

Laboratory of Pharmaceutical Analytical Chemistry, University of Geneva, Switzerland.

Three capillary electrophoresis methods, using UV detection, were developed for the simultaneous determination of several tropane alkaloids, including atropine, scopolamine and synthetic derivatives. After optimization, the validated capillary zone electrophoresis methods were applied to the determination of these compounds in various pharmaceutical forms, such as ophthalmic and injection solutions, tablets, suppositories and aerosols. Capillary electrophoresis in the micellar mode was found to be more appropriate for the analysis of hyoscyamine and scopolamine in plant material. These two compounds are generally found together with other tropane alkaloids which present similar structures and charge to mass ratio. Furthermore, the separation of positional isomers, such as hyoscyamine and littorine generally encountered in plant extracts, was also considered. The developed method was applied to the analysis of hairy root extracts of Datura candida x Datura aurea, Datura quercifolia and Hyoscyamus albus.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9919984&dopt=Abstract hyoscyamine Levbid SL