Ledol
Ledol is a poisonous sesquiterpene that can cause cramps, paralysis, and delirium. Caucasian peasants used Rhododendron plants for these effects in shamanistic rituals. Ledol resides in the essential oils of certain plants and when crushed, these oils are released. One of the plants with the highest concentration of these essential oils is Rhododendron tomentosum.
The word "ledol" comes from the Greek word "ledos" meaning "robe". This likely comes from the "wooly" appearance of the plant, which has hair-like stalks stemming from the flower.
Historical and traditional uses
The earliest known written record of Rhododendron plant toxicity dates back to 401 B.C. in China. Despite their toxicity, Rhododendron species have been documented in traditional medicinal practices across various cultures, including Chinese, Ayurvedic, European, and North American practices.The accounts of Rhododendron from around the world describe numerous health benefits and treatments to various ailments.
R. tomentosum is highly recorded with various uses, like treating rheumatism, coughs, colds, and insect bites. Some common names it has are "wild rosemary", "marsh tea", and "marsh rosemary".
Scientists have studied R. tomentosums shoots, due to the shoots having the highest concentration of essential oils, for potential antidiabetic, antimicrobial, and antioxidant purposes.
Mechanism of action
Although the ledol mechanism of action is quite under-studied, ledol is a sesquiterpenoid and studies on similar sesquiterpenoids, such as picrotoxinin, have shown that these molecules often target GABA receptors. These sesquiterpenoids act as GABA antagonists on GABA post-synaptic receptors. GABA-A receptors, in particular, function as chloride channels that facilitate the flow of chloride ions across cell membranes.When GABA is deficient, symptoms can include respiratory difficulty, seizures, delirium, vomiting, nausea, gastrointestinal issues, headaches, increased blood pressure, and muscle cramps. This pattern reflects how known GABA-A receptor antagonists, such as picrotoxinin, affect the body. Ledol has similar—if not identical—effects in the body, albeit milder than those of known GABA-A antagonists, according to sources.
Another sesquiterpenoid, Nootkatone, was proven to exhibit similar effects in insects.