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Toxic Effects of Plants

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10% of all calls to Poison Control ... pre-school - yard plants and berries ... Belladonna alkaloids. all species of Datura. entire plant is toxic ... – PowerPoint PPT presentation

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Title: Toxic Effects of Plants


1
Toxic Effects of Plants
  • Robyn Fullerton
  • ENVS531
  • November 11, 2002

2
Outline
  • Background on plant poisoning
  • Research on plants injurious to humans
  • Systemic poisoning - vascular plants
  • Systemic poisoning - mushrooms
  • Skin injury

3
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

4
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

5
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

6
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

7
Research on Plants Injurious to Humans
  • Failure to use appropriate assay
  • testing limited
  • material
  • time
  • money
  • interest
  • Eupatorium rugosum
  • causes milksickness
  • tested in fish

8
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

9
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

10
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

11
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

12
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

13
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

14
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

15
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

16
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

17
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

18
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

19
Systemic Poisoning - Mushrooms
  • Identification of toxic mushrooms ingested
    difficult and impractical
  • Specific classes of toxicity
  • immediate/rapid onset
  • latent period before onset

20
Systemic Poisoning - Mushrooms
  • Gastrointestinal discomfort
  • rapid onset
  • emesis or diarrhea typical effects
  • can result in dehydration and hypovolemic shock
  • treatment symptomatic in nature

21
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

22
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

23
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

24
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

25
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

26
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

27
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

28
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

29
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

30
Plants Causing Skin Injury
  • Mechanical injury
  • produced by splinters, thorns, awns and leaf
    edges
  • can introduce bacteria and fungi
  • produces non-infectious skin lesions

31
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

32
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

33
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

34
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

35
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!!!!

36
References
  • Amdur, M.O., J. Doull, and C.D. Klaassen (Eds),
    (1991). Casarett and Doulls Toxicology (4th
    Edn). McGraw-Hill, Inc., New York.

37
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?
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