Planta Med 2006; 72(2): 99-113
DOI: 10.1055/s-2005-916258
Review
© Georg Thieme Verlag KG Stuttgart · New York

Structural Relationships, Distribution and Biological Activities of Stemona Alkaloids

Harald Greger1
  • 1Comparative and Ecological Phytochemistry Section, Institute of Botany, University of Vienna, Austria
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Publikationsverlauf

Received: October 6, 2005

Accepted: December 1, 2005

Publikationsdatum:
11. Januar 2006 (online)

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Abstract

Stemona alkaloids represent a unique class of natural products exclusively isolated from the monocotyledonous family Stemonaceae comprising three genera mainly distributed in southeast Asia. Structurally the alkaloids are characterised by a pyrrolo[1,2-a]azepine nucleus usually linked with two carbon chains mostly forming terminal lactone rings. Based on biosynthetic considerations and their various distribution the present review describes 82 Stemona alkaloids grouped into three skeletal types. Due to different carbon chains attached to C-9 of the pyrroloazepine nucleus they were classified into stichoneurine-, protostemonine- and croomine-type alkaloids. The genera Croomia and Stichoneuron only accumulate croomine or stichoneurine derivatives, respectively, whereas the genus Stemona produces all three types of alkaloids. However, species-specific accumulation trends towards certain structural types represent valuable chemosystematic criteria. Bioassays with larvae of Spodoptera littoralis exhibited very high insect toxicity for the roots of Stemona species containing certain protostemonine derivatives, especially didehydrostemofoline, whereas those with dominating stichoneurine or croomine derivatives showed low toxicity but sometimes remarkable repellence due to an accumulation of tuberostemonine. Tuberostemonine also showed effects on the motility of helminth worms and reduced the excitatory transmission at the crayfish neuromuscular junction. Significant antitussive activity was shown for the stereoisomeric neotuberostemonine in guinea-pig after cough induction by citric acid aerosol stimulation. Studies on structure-activity relationship with seven related compounds revealed that the saturated tricyclic pyrrolobenzazepine nucleus of tuberostemonines is the prerequisite for antitussive activity.

References

Prof. Dr. Harald Greger

Comparative and Ecological Phytochemistry Section

Institute of Botany

University of Vienna

Rennweg 14

1030 Wien

Austria

Telefon: +43-1-4277-54070

Fax: +43-1-4277-9541

eMail: harald.greger@univie.ac.at