Tropane alkaloid

Tropane alkaloids are a class of bicyclic [3.2.1] alkaloids and secondary metabolites that contain a tropane ring in their chemical structure.^[1] Tropane alkaloids occur naturally in many members of the plant family Solanaceae. Certain tropane alkaloids such as cocaine and scopolamine are notorious for their psychoactive effects, related usage and cultural associations.^{[2][3][4][5][6][7]} Particular tropane alkaloids such as these have pharmacological properties and can act as anticholinergics or stimulants.

Chemical structure of tropane which forms the core of tropane alkaloids

Chemical structure and phylogeny of tropane alkaloids. Displayed are 3 chemical compounds that occur as natural products in 5 plant species

Classification

Anticholinergics

Anticholinergic drugs^[8] and deliriants:^[9]

• Atropine, racemic hyoscyamine, from the deadly nightshade (Atropa belladonna)
• Hyoscyamine, the levo-isomer of atropine, from henbane (Hyoscyamus niger), mandrake (Mandragora officinarum) and the sorcerers' tree (Latua pubiflora).
• Scopolamine, from henbane and Datura species (Jimson weed)

All three acetylcholine-inhibiting chemicals can also be found in the leaves, stems, and flowers in varying, unknown amounts in Brugmansia (angel trumpets), a relative of Datura. The same is also true of many other plants belonging to subfamily Solanoideae of the Solanaceae, the alkaloids being concentrated particularly in the leaves and seeds. However, the concentration of alkaloids can vary greatly, even from leaf to leaf and seed to seed.^[10][11]

Stimulants

Stimulants and cocaine-related alkaloids:

• Cocaine, from coca plant (Erythroxylum coca)
• Ecgonine, a precursor and metabolite of cocaine
• Benzoylecgonine, a metabolite of cocaine
• Hydroxytropacocaine, from coca plant (Erythroxylum coca)
• Methylecgonine cinnamate, from coca plant (Erythroxylum coca)

Others

• Catuabines, found in catuaba, an infusion or dry extract made from Erythroxylum vaccinifolium
• Scopine

Synthetic analogs of tropane alkaloids also exist, such as the phenyltropanes. They are not considered to be alkaloids per definition.

Biosynthesis

The biosynthesis of the tropane alkaloids have attracted intense interest because of their high physiological activity as well as the presence of the bicyclic tropane core.^[12]

Final stages in the pathway for the biosynthesis of the tropane alkaloid cocaine.

References

1. O’Hagan, David (2000). "Pyrrole, pyrrolidine, pyridine, piperidine and tropane alkaloids (1998 to 1999)". Natural Product Reports. 17 (5): 435–446. doi:10.1039/a707613d. PMID 11072891.
2. Hesse M (2002). Alkaloids: Nature's Curse or Blessing?. Weinheim: Wiley-VCH. p. 304. ISBN 978-3-906390-24-6.
3. Ryzik M (10 June 2007). "Cocaine: Hidden in Plain Sight". The New York Times. Archived from the original on 11 August 2017. Retrieved 18 May 2017.
4. "The Buyers – A Social History of America's Most Popular Drugs". FRONTLINE. PBS. Archived from the original on 14 May 2017. Retrieved 18 May 2017.
5. Anderson L. "Devil's Breath: Urban Legend or the World's Most Scary Drug?". Drugs.com. Retrieved 9 July 2019.
6. Fatur, Karsten (June 2020). ""Hexing Herbs" in Ethnobotanical Perspective: A Historical Review of the Uses of Anticholinergic Solanaceae Plants in Europe". Economic Botany. 74 (2): 140–158. doi:10.1007/s12231-020-09498-w. ISSN 0013-0001. S2CID 220844064.
7. Rätsch, Christian, The Encyclopedia of Psychoactive Plants: Ethnopharmacology and Its Applications pub. Park Street Press 2005
8. Grynkiewicz, G; Gadzikowska, M (2008). "Tropane alkaloids as medicinally useful natural products and their synthetic derivatives as new drugs". Pharmacological Reports. 60 (4): 439–63. PMID 18799813.
9. Volgin, A. D.; Yakovlev, O. A.; Demin, K. A.; Alekseeva, P. A.; Kyzar, E. J.; Collins, C.; Nichols, D. E.; Kalueff, A. V. (16 October 2018). "Understanding Central Nervous System Effects of Deliriant Hallucinogenic Drugs through Experimental Animal Models". ACS Chemical Neuroscience. 10 (1): 143–154. doi:10.1021/acschemneuro.8b00433. PMID 30252437. S2CID 52824516. Retrieved 18 May 2021.
10. The Biology and Taxonomy of the Solanaceae edited by Hawkes, J.G., Lester, R.N. and Skelding, A.D. (Linnean Society Symposium Series Number 7) Published for the Linnean Society of London by Academic Press 1979 ISBN 0-12-333150-1
11. Eich, Prof. Dr. Eckhart, 2008, Solanaceae and Convolvulaceae: Secondary Metabolites - Biosynthesis, Chemotaxonomy, Biological and Economic Significance (A Handbook) pub. Springer-Verlag Berlin Heidelberg, ISBN 978-3-540-74541-9.
12. Leete, Edward (1990). "Recent Developments in the Biosynthesis of the Tropane Alkaloids1". Planta Medica. 56 (4): 339–352. doi:10.1055/s-2006-960979. PMID 2236285.