William J. Griffin

Chemotaxonomy and geographical distribution of tropane alkaloids.

This review illustrates the distribution of tropane alkaloids within the families Solanaceae, Erythroxylaceae, Proteaceae, Euphorbiaceae, Rhizophoraceae, Convolvulaceae and Cruciferae. Whereas tropane alkaloids are characteristic of the genera Datura, Brugmansia (tree datura) and Duboisia of the Solanaceae, the distribution is more widespread with novel tropane derivatives in families not traditionally associated with these bases. The chemical nature of more recently discovered water-soluble calystegines and the di- and trimeric forms from the Convolvulaceae (e.g. schizanthines from Schizanthus spp.), truxillines from Bolivian coca leaves and moonines of Erythroxylum moonii are highlighted. Where possible and appropriate, links between the phytochemistry and taxonomy are discussed.

Alkaloids of Duboisia hopwoodii

Leaf and root collections of Duboisia hopwoodii were made from Alice Springs in central and Western Australia. From D. hopwoodii collected at Alice Springs were isolated nornicotine, nicotine, myosmine and N-formylnornicotine; cotinine, N-acetylnornicotine, anabasine, anatabine, anatalline and bipyridyl were detected by GC/MS. Root material contained hyoscyamine, scopolamine, nicotine and nornicotine; N-formylnornicotine was detected by GC/MS. D. hopwoodii from Western Australia yielded nicotine, nornicotine, hyoscyamine and metanicotine. Root material contained nornicotine, hyoseyamine, myosmine and N-formylnornicotine, GC/MS detected cotinine and N-acetylnornicotine.

Alkaloids of the leaves of Erythrophleum chlorostachys

From the leaves of Erythrophleum chlorostachys (F. Muell.) Bail. growing at Mareeba, North Queensland, β-dimethylaminoethyl cinnamate (II), N-2-hydroxyethyl-N-methyl cinnamamide (III), N-2-hydroxyethyl-N-methyl-trans-p-hydroxycinnamamide (IV) and N-2-hydroxyethylcinnamamide (V) were isolated. The structures were confirmed by synthesis. The amides (III), (IV) and (V) may possibly be artefacts of isolation since, as free bases, the cinnamic esters isomeric with (III) and (V) rearrange to (III) and (V) respectively, with half-lives less than 3 days and 1 day, respectively. Leaves of E. chlorostachys growing at Cooktown, North Queensland, and at Darwin, N.T., did not contain these compounds but contained alkaloidal esters of diterpenoid acids as in other Erythrophleum species.

Scopolamine content of a Duboisia hybrid in callus cultures

Scopolamine levels in a Duboisia leichhardtii × D. myoporoides hybrid were determined by radioimmunoassay and gas liquid chromatography in explants, callus and at various stages of plant regeneration. Scopolamine could not be detected in undifferentiated callus or differentiated shoots. Scopolamine only occurred in cultures which had developed roots. After 16 weeks, regenerated plants contained scopolamine at a level comparable with that in seedlings of a similar age. The scopolamine content of regenerated field-grown plants had scopolamine levels similar to conventionally vegetatively-propagated hybrid plants, except that littorine was the second major alkaloid, rather than hyoscyamine.

Rubragenin, chenogenin and wallogenin, steroidal sapogenins from Cordyline rubra

Abstract Three new steroidal sapogenin triols have been isolated from the leaves of Cordyline rubra. NMR spectroscopic and mass spectrometric data prove the compounds to be (22S,25R)-5α-furostan-22,25-epoxy-1β,3α,26-triol (rubragenin), (22R,25R)-5α-furostan-22,25-epoxy-1β,3α,26-triol (wallogenin), and (22R,25R)-5α-spirostane-1β, 3α,25-triol (chenogenin). Wallogenin is epimeric at C-22 to all the previously reported ‘furanose’ F-ring sapogenins.

Crabbogenin, 1β-hydroxycrabbogenin, strictagenin and pompeygenin, four new steroidal sapogenins from cordyline stricta leaves

From the leaves of Cordyline stricia Endl. four new steroidal sapogenins crabbogenin {5α-spirost-25(27)-en-3α-ol}, 1β-hydroxycrabbogenin, strictagenin {(20S, 22S, 25S)-5α-furostan-22, 25-epoxy-1β, 3α, 26-triol} and pompeygenin {(25S)-5α-spirostane-1β, 3α-25-triol} have been isolated and their structures determined by chemical and spectroscopic methods.

Alkaloids and metabolism in a Duboisia hybrid

A Duboisia hybrid contained scopolamine, 6-hydroxyhyoscyamine and hyoscyamine as major alkaloids and similar minor alkaloids as the parent species, D. leichhardtii and D. myoporoides. Unlike D. myoporoides, there was almost complete absence of pyridine bases. Tritiated scopolamine was infiltrated into a 2-year-old, field grown tree via a wick method. The scopolamine administered was metabolised to aposcopolamine. Hyoscyamine, 6-hydroxy-hyoscyamine and other minor Duboisia alkaloids had specific activities that were too small for them to be direct metabolites of scopolamine. Activity was located in acidic fractions that were shown to contain aromatic protons and water soluble basic fractions and are presumed to be responsible for the activity of these other alkaloids. The metabolic process occurred within the bark; alkaloids already accumulated appeared to be removed from the metabolic process.

Alkaloid metabolism in callus and regenerating shoot cultures of a Duboisia hybrid

Undifferentiated callus and regenerating shoot callus on Murashige and Skoog (MS) medium was unable to metabolize scopolamine to hyoscyamine. Shoots on MS medium supplemented with hyoscyamine on extraction afforded unchanged hyoscyamine (44%). However, 16% was converted to 6-hydroxyhyoscyamine and 12% to scopolamine. Metabolism appeared unaffected by the number of shoots formed. Callus only gave very low yields of these two metabolities. Control callus and shoots on MS medium without alkaloid contained traces of valtropine and/or butropine. However, both callus and shoots on MS medium supplemented with either scopolamine or hyoscyamine showed enhanced levels of these minor alkaloids at times by a factor exceeding 500.

Two furostane sapogenins from Cordyline rubra

From the leaves of Cordyline rubra two new steroidal sapogenins have been isolated. NMR and IR spectroscopic and mass spectrometric data prove the compounds to be 1β,3α-dihydroxy-furost-5-ene and 1β,3α,26-trihydroxy-5α-furostane.

Steroidal sapogenins from Cordyline cannifolia leaves

From three separate collections of Cordyline cannifolia leaves, three main sapogenins were obtained and identified as cordylagenin (1β,3α-dihydroxy-5α,25β-spirostane), its 3β,25α-isomer, brisbagenin; and a new sapogenin, cannigenin, shown to be the 25α epimer of cordylagenin. In addition, small quantities were found of smilagenin and yamogenin and TLC indicated the presence of ruscogenin/neoruscogenin. The dihydroxy sapogenin content of C. cannifolia leaves was found to vary from 0.02% to 0.43% of the dry weight. In a cultivation trial, this content of the leaves fell markedly over a two year period.