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Gastrointestinal Toxic Plants
TOXINS THAT LEAD TO GASTROINTESTINAL IRRITATION
Plants that cause gastrointestinal irritation are generally benign but some species can have significant systemic toxicity.
Calcium oxalate crystals are found in Dieffenbachia spp., Philodendron spp., Elephant’s ear (Xanthosoma violaceum), Arum lily (Zantedeschia aethopica) and similar plants. The insoluble salts are not systemically absorbed but cause irritation and swelling in the oropharynx and oesophagus.
Toxalbumins can cause significant systemic toxicity in addition to gastrointestinal irritation. The two important plants are the jequirity pea (Abrus precatorius ) and the castor bean (Ricinus communis) whose seeds contain the toxalbumins abrin and ricin, respectively. Toxalbumins enter cells and bind to the 60S ribosomal subunit, inhibiting protein synthesis. Ingestion of the seeds rarely results in toxicity as the toxins are only released by damaging the hard shells by chewing or digestion. If this occurs, severe gastroenteritis, CNS depression and cardiac arrhythmias may occur. Deaths from abrin ingestion have occurred but, because of its poor gastrointestinal absorption, have not been reported from ricin ingestion. A reputed case of ricin lethality was thought to occur in 1978 when a Bulgarian dissident was injected with a 1.5 mm hollow metal sphere from the tip of an umbrella whilst waiting for a bus in London. Over the next 3 days he developed severe gastroenteritis and died. Because of the small volume contained within the injected sphere and the subsequent symptoms, ricin was considered virtually the only possible toxin that could have been responsible.
Colchicine from the Autumn crocus (Colchicum autumnale) and gloriosine from the Glory lily (Gloriosa superba) inhibits intracellular microtubules, thus preventing cell division. Multi system failure may occur with death resulting from respiratory or cardiac failure.
Late complications include bone marrow suppression.
Unripe ackee fruit (Blighia sapida) contains hypoglycin which causes hypoglycaemia, hepatotoxicity, encephalopathy and seizures.
Amatoxin is found in the mushrooms Amanita phalloides and related species and Galerina spp. The resultant gastrointestinal toxicity is typically delayed for up to 12 hours post-ingestion. This is an important differential from other less toxic mushrooms which cause earlier gastrointestinal symptoms. Liver injury may occur 24 to 36 hours after ingestion and hepatic failure and subsequent multi-system failure may result.
Solanine alkaloids are found in the vines and suckers of tomato plants (Lycopersion esculentum) and in a wide variety of Solanum spp. including the common nightshade (S. nigrum americanum), green potatoes (S. tuberosum) and the Jerusalem cherry (S. pseudocapsicum). Gastroinestinal toxicity, delirium and coma may result from significant ingestions.
Poinsettia (Euphorbia spp.), Amaryllis spp., Holly (Ilex aquifolium), Daphne spp, Wisteria, Privet (Ligustrum spp.), and the Peppercorn tree (Schinus areira) cause gastrointestinal toxicity but minimal systemic toxicity.
Calcium oxalate crystals
- Arum family (Araceae )
- Elephant's ear (Cunjevoi )
- Monstera spp.
These are common but mostly cause only local irritation to mouth. Serious toxicity is rare.
These are very potent toxins which inhibit protein synthesis and cause a delayed and severe haemorrhagic gastroenteritis followed by multiorgan failure.
Colchicine & gloriosine
These have severe toxicity with similar symptoms to toxalbumins (see colchicine poisoning).
- Amanita phalloides and related species (Death Cap mushroom)
Usually taken accidentally when misidentified by people picking field mushrooms or looking for hallucinogenic mushrooms. These mushrooms are not common in Australia but have been found.
Toxicity has a delayed onset. Initially the patient is well. This is followed by a severe gastroenteritis at about 12 hours post ingestion. There may be a subsequent recovery followed by multiorgan failure at about 72 hours, predominantly hepatorenal. The ALT peak occurs at about 60 hours. The toxic component undergoes enterohepatic circulation so repeat dose activated charcoal may be helpful. Renal clearance is the major route of elimination and generous fluid replacement is indicated. Haemoperfusion may be beneficial though the majority of the toxin is excreted prior to the onset of clinical symptoms anyway.
Identification of amatoxin mushrooms
The presence of the following features may help aid identification though expert help should be sought if there is any doubt.
- Olive green cap (when mature)
- Ring (annulus)
- Cup (volva)
- White spores & gills
- Gills not attached to stalk
- Melzer's reagent reacts with spores to give a blue colour
- This is a simple test that can be performed in emergency departments on mushrooms or gastric contents
- Tomato leaves
- Green potatoes
- Jerusalem cherry
Serious poisoning is rare as the toxin is very bitter. Associated symptoms include fever, headache, delirium and hallucinations.
Other gastrointestinal irritants
- Amaryllis spp.
- Jonquil bulbs
- Peppercorn tree (Schinus areira)
None of these has been associated with fatal poisoning.