Abstract:
Bufadienolide-type cardiac glycosides have a worldwide distribution and are mainly
synthesized by plants, but there are also animal sources. In South Africa, members of three genera
of the Crassulaceae (Cotyledon, Tylecodon and Kalanchoe) cause a unique chronic form of cardiac
glycoside poisoning, predominantly in small stock. This paretic/paralytic condition is referred to as
“krimpsiekte”, cotyledonosis or “nenta”. “Krimpsiekte” is a plant poisoning only reported from South
Africa and is regarded as the most important plant poisoning of small stock in the semi-arid Little
Karoo and southern fringes of the Great Karoo. The toxicosis is caused by cumulative bufadienolides
which have neurotoxic properties. Four types of cumulative neurotoxic bufadienolides, namely
cotyledoside, and the tyledosides, orbicusides and lanceotoxins, have been isolated. Based on
the structure activity relationships and certain toxicokinetic parameters possible reasons for their
accumulation are presented. Consumption of edible tissues from animals that have ingested these
plants poses a potential risk to humans.
