page_title: Dioscorine
section_title: Biosynthesis
hierarchical_section_title: Dioscorine / Chemical Properties / Biosynthesis
caption_attribution_description: English: proposed biosynthetic pathway to dioscorine from trigonelline
context_page_description: Dioscorine is an alkaloid toxin isolated from the tubers of tropical yam on several continents. It has been used as a monkey poison in some African countries, and as an arrow poison to aid in hunting in several parts of Asia. It was first isolated from Dioscorea hirsute by Boorsma in 1894 and obtained in a crystalline form by Schutte in 1897, and has since been found in other Dioscorea species. Dioscorine is a neurotoxin that acts by blocking the nicotinic acetylcholine receptor. Dioscorine is generally isolated in tandem with other alkaloids such as dioscin but is usually the most potent toxin in the mixture. It is a convulsant, producing symptoms similar to picrotoxin, with which it shares a similar mechanism of action.
context_section_description: Dioscorine is one of few alkaloids to possess an isolated isoquinuclide nucleus that is not part of a condensed ring system, unlike catharanthine or other indole alkaloids.  Its biosynthesis starts with trigonelline (nicotinic acid methylated at the nitrogen). The pathway was anticipated by the known reactivity of trigonelline. The process yields dumetorine as a side product.  Dumetorine is an alkaloid that can be isolated from Dioscorea dumetorum.
caption: Biosynthesis of dioscorine (highlighted) and dumetorine from trigonelline in Dioscorea hispida.
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