Toxic Effects of Plants

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Toxic Effects of Plants

• Robyn Fullerton
• ENVS531
• November 11, 2002

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Outline

• Background on plant poisoning
• Research on plants injurious to humans
• Systemic poisoning - vascular plants
• Systemic poisoning - mushrooms
• Skin injury

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Background on Plant Poisonings

• 10 of all calls to Poison Control
• Plant responsible for poisoning typically
  dependent on age of patient
• infants - houseplants
• pre-school - yard plants and berries
• adolescents and beyond - plants for
  hallucinogenic properties
• Affected by insecticides and fertilizers

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Research on Plants Injurious to Humans

• Recurring problems in research
• failure to document plant
• failure to use appropriate route of
  administration
• failure to use appropriate assay
• failure to provide standard medical care
• interpretation of literature

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Research on Plants Injurious to Humans

• Failure to document plant
• identified by trivial name only
• plants can share the same trivial name
• failure to retain plant specimens after research
  and publication

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Research on Plants Injurious to Humans

• Failure to use appropriate route of
  administration
• differing biologic activities depending on route
  of entry
• lectins
• cause erythrocyte agglutination
• not absorbed from the intestine
• do not affect target site unless administered via
  the intravenous route

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Research on Plants Injurious to Humans

• Failure to use appropriate assay
• testing limited
• material
• time
• money
• interest
• Eupatorium rugosum
• causes milksickness
• tested in fish

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Research on Plants Injurious to Humans

• Failure to provide standard medical care
• studies typically only measure lethality
• no supportive treatments studied
• rehydration
• respiratory support
• correction of electrolyte and glucose deficiencies

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Research on Plants Injurious to Humans

• Interpretation of the literature
• animal studies historically inappropriately
  applied to humans
• plant lore accepted as fact
• stinging nettles and ants
• assumed both contained formic acid
• assumptions accepted since 1900 with no
  experimental study

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Systemic Poisoning - Vascular Plants

• Treatment typically symptomatic
• Specific plant diagnosis difficult
• Toxicity varies with single species
• part of plant ingested
• maturity
• growing conditions
• genetic variations
• Exhibit wide range of toxic effects

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Systemic Poisoning - Vascular Plants

• Irritation of oral cavity
• dumbcane and members of family Araceae
• immediate pain/swelling of oral tissues
• caused by calcium oxalate crystals
• needle-shaped - mechanical injury
• pathway for pain-inducing protein material
• relieved with cool liquid or ice cream

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Systemic Poisioning - Vascular Plants

• Emesis not associated with Diarrhea
• bulbs of family Amaryllidaceae
• Narcissus and Amaryllis
• resemble onions
• characterized by heavy repeated vomiting
• caused by alkaloid lycorine
• acts on emetic receptors in CNS
• symptomatic treatment

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Systemic Poisoning - Vascular Plants

• Diarrhea associated with emesis
• saponins
• steroidal glycosides
• pokeweed
• root - mistaken for horseradish
• leaves - used in salads
• hydrolyzed to triterpene compounds
• severe gastritis with vomiting and diarrhea
• buttercups
• hydrolyzed to produce protanemonin

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Systemic Poisoning - Vascular Plants

• Gastroenteritis after latent period
• castor bean and rosary pea
• contain toxalbumins
• two linked polypeptide chains
• binds to intestinal wall
• inhibits ribosomal protein synthesis
• severe abdominal pain, diarrhea, bloody mucus and
  death are possible

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Systemic Poisoning - Vascular Plants

• Convulsants
• water hemlock
• mistaken for raw parsnip
• treatment supportive in nature
• management of airway
• respiratory support
• relief of convulsions
• acute renal failure rare secondary effect

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Systemic Poisoning - Vascular Plants

• Belladonna alkaloids
• all species of Datura
• entire plant is toxic
• seeds and leaves used for deliriant effect
• exhibits atropinic effects
• therapeutic intervention typically not necessary

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Systemic Poisoning - Vascular Plants

• Affect the cardiovascular system
• fox-glove, lily-of-the-valley, oleander
• caused by digitalislike glycosides
• serious, life-threatening effects
• conduction defects
• sinus bradycardia
• treatment
• ECG, serum potassium, atropine
• DigibindR

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Systemic Poisoning - Vascular Plants

• Affect skeletal muscle tone
• coyotillo (buckthorn)
• found in American Southwest
• contains toxic anthrecenones
• muscle weakness
• begins in lower extremities
• fatalities due to respiratory muscle failure
• causes loss of myelin and fragmentation of axons

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Systemic Poisoning - Mushrooms

• Identification of toxic mushrooms ingested
  difficult and impractical
• Specific classes of toxicity
• immediate/rapid onset
• latent period before onset

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Systemic Poisoning - Mushrooms

• Gastrointestinal discomfort
• rapid onset
• emesis or diarrhea typical effects
• can result in dehydration and hypovolemic shock
• treatment symptomatic in nature

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Systemic Poisoning - Mushrooms

• Evoke sweating
• rapid onset
• contain muscarine
• not affected by cooking
• most sensitive effect of ingestion
• higher doses - more severe effects
• treated symptomatically
• extreme cases - atropine administered

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Systemic Poisoning - Mushrooms

• Evoke inebriation or hallucinations
• rapid onset
• contain psilocybin
• effects dependent on various factors
• dose
• mood, sophistication, age and personality
• treatments vary
• adults - typically none
• children - external cooling, respiratory
  management

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Systemic Poisoning - Mushrooms

• Delirium with sleep or coma
• rapid onset
• Amanita muscaria, A. pantherina
• contain muscinol and ibotenic acid
• acts on post-synaptic receptors
• initial symptoms - drowsiness, dizziness, sleep
• elation, tremors, manic excitement follows
• rarely severe in adults

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Systemic Poisoning - Mushrooms

• Exhibit a disulfiramlike effect
• rapid onset
• Coprinus atramintarius
• toxic if alcohol consumed within 3 days of
  ingestion of mushroom
• caused by cyclopropanone hydrate
• metabolite of mushroom toxin coprine
• has alcohol-sensitizing action

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Systemic Poisoning - Mushrooms

• Induction of headache
• latent period
• Gyromitra exculenta
• mistaken for morel
• caused by monomethyl hydrazine
• symptoms arise 6-8 hours after ingestion
• headache, emesis, abdominal fullness
• rare effect is fatal hepatic necrosis
• typical recovery time of 2-6 days

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Systemic Poisoning - Mushrooms

• Emesis and Profuse Diarrhea
• latent period
• Amanita phalloides
• cause of almost all fatalities in N.A.
• one-half cap is typical human lethal dose
• caused by amatoxins
• bind to and inhibit RNA polymerase II
• disrupt maintenance of cell
• undergo extensive enterohepatic cycling

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Systemic Poisoning - Mushrooms

• Emesis and Profuse Diarrhea
• symptoms arise about 12 hours after ingestion
• nausea, vomiting, diarrhea, abdominal pain
• rapidly develop hepatic insufficiency
• decrease in blood glucose and clotting factors
• treatment with fluids and activated charcoal
• fatality rate of 10

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Systemic Poisoning - Mushrooms

• Polydipsia and polyuria
• latent period
• caused by toxin orellanine
• 3-17 days before symptom onset
• begins with polydipsia followed by polyuria
• progress to renal tubular necrosis
• treatment symptomatic
• treat for possible renal failure

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Plants Causing Skin Injury

• Problem of enormous magnitude
• Common plants such as poison ivy and poison oak
• poison oak
• responsible for one-half of all workers
  compensation claims in CA

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Plants Causing Skin Injury

• Mechanical injury
• produced by splinters, thorns, awns and leaf
  edges
• can introduce bacteria and fungi
• produces non-infectious skin lesions

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Plants Causing Skin Injury

• Delayed contact sensitivity
• aka allergic contact dermatitis
• standard chemistry for sensitizers
• low molecular weight (haptens)
• react with cutaneous proteins
• poison ivy and poison oak
• develops after one or more contacts
• subsequent exposure elicits response dependent on
  dose
• 3-5 weeks to develop skin reactivity

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Plants Causing Skin Injury

• Contact urticaria
• nettles
• hollow, stinging hairs inject chemical into skin
• mixture of acetylcholine, histamine, and
  serotonin
• causes local vasodilation, sweating and pain
• recovery in 3-5 days

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Plants Causing Skin Injury

• Phototoxicity
• parsnips, caraway, dill, parsley and citrus
• sensitize skin to long-wave UV light
• contain furocoumarins
• skin burns within 6-24 hours of contact
• range from mild irritation to severe blistering
• relieved with aspirin or corticosteroids

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Plants Causing Skin Injury

• Primary chemical irritation
• spurges, buttercups and wild pepper
• resembles contact with corrosive acid
• affected by dose, exposure time, genetics,
  temperature and humidity
• serious eye damage possible
• keratoconjunctivitis with transient blindness

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Conclusions

• Multitude of other toxic plants and toxic effects
• carcinogens, teratogens, steroids,
  thyroid-blockers
• Research/investigation still needed
• mechanisms of toxicity
• specific antidotes
• DONT EAT A PLANT IF YOU DONT KNOW WHAT IT IS!!!!

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References

• Amdur, M.O., J. Doull, and C.D. Klaassen (Eds),
  (1991). Casarett and Doulls Toxicology (4th
  Edn). McGraw-Hill, Inc., New York.

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Questions

• 1. Why are lectins typically not toxic when
  ingested or administered orally?
• 2. What are the two defining chemical
  characteristics of chemicals causing allergic
  contact dermatitis?