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Ledol

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Ledol
Names
IUPAC name
6β,11-Cyclo-1β,4α,5β-guaian-10α-ol
Systematic IUPAC name
(1aR,4R,4aS,7R,7aS,7bS)-1,1,4,7-Tetramethyldecahydro-1H-cyclopropa[e]azulen-4-ol
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/C15H26O/c1-9-5-6-10-12(9)13-11(14(13,2)3)7-8-15(10,4)16/h9-13,16H,5-8H2,1-4H3/t9-,10+,11-,12-,13-,15-/m1/s1
    Key: AYXPYQRXGNDJFU-AOWZIMASSA-N
  • InChI=1/C15H26O/c1-9-5-6-10-12(9)13-11(14(13,2)3)7-8-15(10,4)16/h9-13,16H,5-8H2,1-4H3/t9-,10+,11-,12-,13-,15-/m1/s1
    Key: AYXPYQRXGNDJFU-AOWZIMASBF
  • C[C@@H]1CC[C@H]2[C@@H]1[C@H]3[C@H](C3(C)C)CC[C@@]2(C)O
Properties
C15H26O
Molar mass 222.372 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Ledol is a poisonous sesquiterpene that can cause cramps, paralysis, and delirium.[citation needed] Caucasian peasants used Rhododendron plants for these effects in shamanistic rituals.[1] 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.[2]

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.[3]

Historical and Traditional Uses

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The earliest known written record of Rhododendron plant toxicity dates back to 401 B.C. in China.[4] 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. tomentosum's shoots, due to the shoots having the highest concentration of essential oils, for potential antidiabetic, antimicrobial, and antioxidant purposes.[5]

Mechanism of Action

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An image of Rhododendron tomentosum flowers, hair-like fibers stem from the flower, which inspired the name of the toxic molecule within its essential oils.

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.[6] 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.[7]

When GABA is deficient, symptoms can include respiratory difficulty, seizures, delirium, vomiting, nausea, gastrointestinal issues, headaches, increased blood pressure, and muscle cramps.[8] This pattern reflects how known GABA-A receptor antagonists, such as picrotoxinin, affect the body.[9] Ledol has similar—if not identical—effects in the body, albeit milder than those of known GABA-A antagonists, according to sources.[10]

Another sesquiterpenoid, Nootkatone, was proven to exhibit similar effects in insects.[11]

Metabolism

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Even though the metabolism of ledol has yet to be elucidated, a 2023 article involving sesquiterpene lactones, such as parthenolide, showed the sesquiterpenes reacting to human liver microsomes.[12] This demonstrates the reactivity with the liver’s CYP3A4 enzyme. Through relation, the metabolism is possibly facilitated through the liver if ingested.

Sources

[edit]

Ledol is found in labrador tea,[13] an herbal tea (not a true tea) made from three closely related species:

Ledol is also found in the essential oil of priprioca at a concentration of around 4%.[14]

Ledol is also found to varying concentrations in the following plants:[15]

References

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  1. ^ Andrews, Steve; Rindsberg, Katrina (April 2001). Herbs of the Northern Shaman: A Guide to Mind-Altering Plants of the Northern Hemisphere. Loompanics Unlimited. ISBN 1-55950-211-8. OCLC 780276732.
  2. ^ Dampc, Anna; Luczkiewicz, Maria (2015). "Labrador tea – the aromatic beverage and spice: a review of origin, processing and safety". Journal of the Science of Food and Agriculture. 95 (8): 1577–1583. Bibcode:2015JSFA...95.1577D. doi:10.1002/jsfa.6889. PMID 25156477.
  3. ^ Dampc, Anna; Luczkiewicz, Maria (1 March 2013). "Rhododendron tomentosum (Ledum palustre). A review of traditional use based on current research". Fitoterapia. 85: 130–143. doi:10.1016/j.fitote.2013.01.013. PMID 23352748.
  4. ^ Popescu, Ruxandra; Kopp, Brigitte (2 May 2013). "The genus Rhododendron: An ethnopharmacological and toxicological review". Journal of Ethnopharmacology. 147 (1): 42–62. doi:10.1016/j.jep.2013.02.022. PMID 23454683.
  5. ^ Dampc, Anna; Luczkiewicz, Maria (June 2015). "Labrador tea – the aromatic beverage and spice: a review of origin, processing and safety". Journal of the Science of Food and Agriculture. 95 (8): 1577–1583. Bibcode:2015JSFA...95.1577D. doi:10.1002/jsfa.6889. PMID 25156477.
  6. ^ Matsumura, F.; and Ghiasuddin, S. M. (1 January 1983). "Evidence for similarities between cyclodiene type insecticides and picrotoxinin in their action mechanisms". Journal of Environmental Science and Health, Part B. 18 (1): 1–14. Bibcode:1983JESHB..18....1M. doi:10.1080/03601238309372355. PMID 6187794.
  7. ^ Phulera, Swastik; Zhu, Hongtao; Yu, Jie; Claxton, Derek P.; Yoder, Nate; Yoshioka, Craig; Gouaux, Eric (25 July 2018). "Cryo-EM structure of the benzodiazepine-sensitive α1β1γ2S tri-heteromeric GABAA receptor in complex with GABA". eLife. 7: e39383. doi:10.7554/eLife.39383. ISSN 2050-084X. PMC 6086659. PMID 30044221.
  8. ^ Chen, Richard J.; Sharma, Sandeep (2025). "GABA Receptor". StatPearls. StatPearls Publishing.
  9. ^ "Picrotoxinin SDS" (PDF).
  10. ^ Dampc, Anna; Luczkiewicz, Maria (1 March 2013). "Rhododendron tomentosum (Ledum palustre). A review of traditional use based on current research". Fitoterapia. 85: 130–143. doi:10.1016/j.fitote.2013.01.013. PMID 23352748.
  11. ^ Norris, Edmund J.; Chen, Rui; Li, Zhilin; Geldenhuys, Werner; Bloomquist, Jeffrey R.; Swale, Daniel R. (1 May 2022). "Mode of action and toxicological effects of the sesquiterpenoid, nootkatone, in insects". Pesticide Biochemistry and Physiology. 183: 105085. Bibcode:2022PBioP.18305085N. doi:10.1016/j.pestbp.2022.105085. PMID 35430075.
  12. ^ Grafakou, Maria-Eleni; Barda, Christina; Skaltsa, Helen; Heilmann, Joerg (2 June 2024). "Study on the metabolism of natural sesquiterpene lactones in human liver microsomes using LC-Q-TOF-MS/MS". Natural Product Research. 38 (11): 1855–1863. doi:10.1080/14786419.2023.2226301. PMID 37354443.
  13. ^ Dampc, Anna; Luczkiewicz, Maria (2015). "Labrador tea – the aromatic beverage and spice: A review of origin, processing and safety". Journal of the Science of Food and Agriculture. 95 (8): 1577–1583. Bibcode:2015JSFA...95.1577D. doi:10.1002/jsfa.6889. PMID 25156477.
  14. ^ Azambuja, Wagner. "Priprioca Essential Oil - Óleos Essenciais O Guia do Brasil". Óleos Essenciais. Brazil. Archived from the original on 13 September 2017. Retrieved 12 September 2017.
  15. ^ Duke, James A. (1992). "Handbook of phytochemical constituents of GRAS herbs and other economic plants". Department of Agriculture, Agricultural Research Service. 1992-2016. Dr. Duke's Phytochemical and Ethnobotanical Databases. Boca Raton, FL: CRC Press. doi:10.15482/USDA.ADC/1239279. Archived from the original on 2021-09-30. Retrieved 2017-09-13.
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