Glycosides from Lily of the Valley for Controlled Poisoning
Lily of the valley (Convallaria majalis) is one of the medicinal plants long known to contain cardioactive glycosides (primarily convallatoxin and convalloside). Glycoside bonds form similar to acetal bonds from a hemiacetal and an alcohol. Convallatoxin (pictured below) is formed from the hemiacetal rhamnopyranoside and a hydroxy group of the steroid strophanthidin.
Although the glycosides in lily of the valley are certainly effective, only up to 10 % are resorbed in the digestive tract, meaning that (according to Frohne and Pfänder ) severe intoxication is unlikely to occur following ingestion. Most cases of poisoning occur when lily of the valley is mistaken for bear’s garlic and eaten. Walter, given he was responsible for the poisoning, chose the glycoside from lily of the valley for his purposes cleverly. The symptoms are similar to those from ricin, but with a much lower risk of death.
 D. Frohne, H. J. Pfänder, Giftpflanzen, Wissenschaftliche Verlagsgesellschaft, Stuttgart, 2004.