tutin

Tutin is a poisonous plant derivative found in New Zealand tutu plants (several species in the genus Coriaria). It acts as a potent antagonist of the glycine receptor, and has powerful convulsant effects. It is used in scientific research into the glycine receptor. It is sometimes associated with outbreaks of toxic honey poisoning when bees feed on honeydew exudate from the sap-sucking passion vine hopper (Scolypopa australis) insect, when the vine hoppers have been feeding on the sap of tutu bushes. Toxic honey is a rare event and is more likely to occur when comb honey is eaten directly from a hive that has been harvesting honeydew from passionvine hoppers feeding on tutu plants. History Tutin was first discovered as a honey contaminant in the late 19th century. Missionaries from overseas introduced the western honey bee (Apis mellifera) to New Zealand in 1839. A few decades later, people eating the local honey would suffer from symptoms like vomiting, headaches and confusion. At this point the neurotoxin was studied, and in the early 1900s its toxic effects were fully characterised. The toxin was known to come from the tutu plant. However, neither the nectar nor the pollen of the tutu plant contain this toxin, the two parts the honey bees ingest. Eventually it was found that the passion vine hopper (Scolypopa australis), a pest insect, extracts sap from young shoots of the tutu plant and releases secretions, honeydew, that contain the tutin toxin. Honeybees will consume honeydew as a supplementary food source, thereby contaminating the honey they produce with this toxin. Further outbreaks of tutin poisoning would periodically appear from that point onwards. As late as 2008 a family had to be hospitalized due to severe symptoms caused by homegrown honey with tutin contaminations. Structure and chemical properties Tutin is a polyoxygenanted polycyclic sesquiterpene from the picrotoxane family. Tutin is one of a series of chemically and pharmacologically similar compounds of which picrotoxinin and coriamyrtin have been mostly studied. Conroy proposed the structure for picrotoxinin, which was confirmed by X-ray crystallographic studies and also determined the absolute configuration of the molecule. Karyone and Okuda proposed the tutin structure based on the pictrotoxinin structure and chemical degradation studies.