Dioscorine  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" (synonymous with "Dioscorea hirsuta") 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. (Dioscorine is not to be confused with dioscorin, the yam storage protein.) Dioscorine was first isolated from the tubers of "Dioscorea hirsuta" by Boorsma in 1894, and the tubers of "Dioscorea hispida" by Levya and Gutierrez in 1937. It was obtained in a crystalline condition by Schutte. In tropical lands, tubers from varieties of these species are eaten, but the alkaloid-bearing species are of toxicological interest because of their poisoning abilities. Dioscorine produces insecticidal and antifeedant responses in various species of insects, but has more interesting historical applications. These are dependent on the geographical location of the specific tuber (Table 1). Poisoning from dioscorine first appeared from accidental food poisoning from the yam, especially during periods of severe drought in many parts of Africa. People then began making the distinction between edible and toxic plants, and put the toxins to use in hunting. Cases of poisoning have officially been reported since the 1930s but had been happening earlier. Dioscorine is an alkaloid with a 6-membered nitrogen-containing heterocycle. Pinder extensively discussed the method of extraction of and the chemical substitution of dioscorine (Figure 1). From his studies, Pinder also concluded that 2-oxotropane is a degradation product of dioscorine and described the formula of the alkaloid. Dioscorine derives its basic nature and nucleophilicity from the tertiary amine and carbonyl functional groups.