Tropane alkaloids are a class of alkaloids and secondary metabolites that contain a tropane ring in their chemical structure. The class consists of more than 200 compounds
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Tropane alkaloids naturally occur in plants of the families Erythroxylaceae (including coca) and Solanaceae (including mandrake, henbane, deadly nightshade, datura, potato, tomato). Important tropane alkaloids are atropine, hyoscyamine and scopolamine. Atropine is an racemic mix of the R- an L-enantiomer of hyoscyamine.
The L-hyoscyamine is the active form. These tropane alkaloids are known to prevent binding of acetylcholine to its receptor and as a result have effects on heart rate, respiration and functions in the central nervous system (anticholinergic poisoning). Scopolamine, acting as an antagonist at both
peripheral and central muscarinic receptors, is thought to be the primary compound responsible for the toxic effects of these plants.
Tropane alkaloids are found in all parts of the plants, with highest concentrations in roots and seeds
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The proportion of each alkaloid present varies among species, time of year, location, and part of plant. As little as one-half teaspoon of Datura seed, equivalent to 0.1 mg of atropine per seed, has caused death from cardiopulmonary arrest. The usual route of ingestion is as a tea, although ingesting seeds or other plant parts and smoking dried leaves also are common
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Scopolamine has three primary medical uses: treatment of nausea and motion sickness, treatment of intestinal cramping, and for ophthalmic (relating to eyes) purposes. Use as a general depressant and adjunct to narcotic painkillers is also common. The drug is less commonly used as a preanesthetic
agent and uncommonly for some forms of Parkinsonism. Scopolamine is also used as an adjunct to narcotic analgesia, such as the product Twilight Sleep which contains morphine and scopolamine, some of the original formulations of Percodan and some European brands of injectable methadone, as
well as use of tablets or patches to combat nausea as well as enhance the pain-killing ability of various opioids. Scopolamine can be used as an occasional sleep aid and was available in some over the counter products in the United States for this purpose until November 1990
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Relatively recent a novel group of tropane alkaloids was detected in deadly nightshade: calystegines. These alkaloids were also detected in extracts of the roots of Calystegia sepium (hedge bindweed) and Convolvulus arvensis (field bindweed), both in the family Convolvulaceae. Calystegines are formed
partially by the same biosynthetic steps as the well-known and medicinally significant tropane alkaloids.
Other tropane alkaloids are used as stimulants, such as cocaine and cocaine-related alkaloids:
cocaine, from Erythroxylum coca
ecgonine, a precursor and metabolite of cocaine
benzoylecgonine, a metabolite of cocaine
hydroxytropacocaine
methylecgonine cinnamate
catuabines, found in the drug catuaba, from Erythroxylum vacciniifolium
Exposure to tropane alkaloids
In an opinion of the Scientific Committee of the Panel on Contaminants in the Food Chain on Animal Nutrition on Undesirable Substances in Feed from the EFSA (2008) the exposure of animals to tropane alkaloids has been described extensively. Often tropane alkaloid poisoning in animals is the result of the consumption of Datura plants rather than contamination of feed materials with Datura seeds. The consumption of fresh Datura plants is unlikely because the plant has a very unpleasant taste and odour, but animals do not detect the impurities in dried material like hay. Tropane alkaloids are fairly stable during drying and heat treatment of feed materials. After baking bread from wheat flour contaminated with jimsonweed seeds (Datura stramonium) the baked bread still contained 72 - 100% of the tropane alkaloid content of the flour
Cases of Datura intoxication have been reported for many (farm) animals, but pigs are especially sensitive. Plant poisonings of humans can be aggregated into different categories: unintended ingestions (contamination, mistaken identity, carry-over), intended ingestions, and poisoning due to abuse of plant material (overdoses). Bulk commercial grain, such as soybeans and wheat, may be contaminated by nongrain impurities, including jimsonweed seeds, that coexist with the crop to be harvested
Unintended ingestions often occur in children or from a mix-up of plants and mushrooms in adults. Jimsonweed (or Jamestown weed) is named for a case of human poisoning in Jamestown, USA., when soldiers were poisoned by eating the plant in a salad and then suffered delirium and hallucinations.
RIKILT Report 2010.011 11Intended ingestions are common in homicides and suicides. Increasingly common is the abuse of plants for hallucinogenic reasons. The use of cocaine for this purpose is very well known, either ingestion through chewing of coca leaves or intake of more purified forms.
In a study using seeds of jimsonweed obtained from different locations in the USA an average concentration of 2.3 and 0.5 mg/g seeds of atropine and scopolamine, respectively, was detected
Other sources
indicate levels between 1 and 9 mg/g seeds. The estimated lethal dose of atropine in humans is 10 mg and 2–4 mg for scopolamine. Without treatment the intake of 2 to 5 berries of deadly nightshade in children and 10 to 20 berries in adults is considered lethal
Jimson weed toxicity usually occurs within 60 minutes after ingestion and clinical symptoms may persist for 24 to 48 hours
One jimsonweed seed weighs approximately 8 mg, which means that approximately 100 seeds are equivalent with 10 mg atropine.
Another source reports that for adults 100 mg atropine, 100 mg scopolamine or 10 mg hyoscyamine is considered a lethal dose, but for children only a few milligram is sufficient. The intake of 2 to 5 berries of Atropa belladonna in children and 10 tot 20 berries in adults is considered lethal.
http://www.rikilt.wur.nl/NR/rdonlyres/BDEEDD31-F58C-47EB-A0AA-23CB9956CE18/122855/R2010011.pdf