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[摘要]：The Kentucky coffeetree, Gymnocladus dioicus (L., K. Koch) is a leguminous tree reputed to be toxic to livestock and to contain the toxic nicotinic acetylcholine receptor agonist cytisine. Analysis of extracts of various tree parts by gas chromatography-mass spectrometry failed to reveal the presence of cytisine. Neither [H-3]-epibatidine binding in rat cerebral cortex nor functional fluorescence assays in cultured cells expressing nicotinic receptor subunits indicated significant activity. However, a novel purine alkaloid, 3-((E)-3-methylbuta-1,3-dienyl)-1,7-dimethylisoguanine, which we have named dioicine, was identified as the major lipophilic alkaloid in the methanolic extract from leaves and seeds. Dioicine and its hydrolysis products are likely to be responsible for the historical use of the tree's seeds as a coffee substitute. Herein we describe the isolation, structure elucidation and preliminary biological characterization of dioicine. |
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