II. Poisonous Plants
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Acute vs. chronic toxicity
a) internal poisons
b) allergens
c) cell modifiers: mutagens, teratogens and
lectins
a. Internal Poisons
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Alkaloids
Glycosides
Oxalates
Resins
Alkaloids
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N-containing heterogenous group of
medicinal, toxic, and psychoactive
compounds
Found in high concentrations in the
Apocynaceae, Berberidaceae, Fabaceae,
Papaveracea, Ranunculaceae, Rubiaceae,
and Solanaceae
Not found in the Lamiaceae, Rosaceae, and
the Gymnosperms
Glycosides
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combination of sugar(s) or glycone and
another compound (aglycone)
glucose is the most common sugar
toxicity is associated with aglycone moiety
Cynogenic glycosides
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Hydrolized to HCN and sugar
Amygdalin is found in seeds of apples,
pears, apricot, bitter almonds, wild and
domestic cherries, peaches and plums.
HCN blocks the action of cytochrome
oxidase in respiration causing cellular
asphyxiation
Anthraquinone glycosides
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Hydrolysis of anthraquinones
Found in aloe and rhubarb
Cardioactive glycosides
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Aglycones are steroidal
Act on the heart (paralysis)
Found in Digitalis (foxglove) and
Antirrhinum (snapdragon)
Saponin glycosides
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Aglycone forms a steroid or triterpene that
form colloidal dispersions in water
Irritates mucous membranes and destroys
blood cells.
Found in yams, ginseng, licorice, beech,
poke, alfalfa, and english ivy
Coumarin glycosides
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Aglycone is a
benzopyranone
Causes internal
bleeding and
dermatitis
Not common
Found in Artemesia
species (sagebrush)
Oxalates
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organic acid that forms in crystals in
vacuole
Reach dangerous levels in oxalis, rhubarb,
dock and purslane
Resins
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Amorphous products of complex nature.
Insoluble in water and do not contain N
Mixture of oils, gums and sugars
Found in water hemlock, milkweed,
rhododendron and azaleas
Allergens
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Pollen can cause:
Anaphylatic shock
Allergenic rhinitis (hayfever)
Asthma
Dermatitis
Photodermatitis
Mutagens can cause:
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Replacement of nucleotide in DNA
Loss of addition of nucleotide causing more
serious mutagenesis
Nondisjunction of chromosomes (extra
chromosomes)
Polyploidy (extra set of chromosomes)
Teratogens
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Effects on somatic cells of growing
embryos usually resulting in malformed
organs
Lectins
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Can be highly toxic
Proteins with carbohydrate chains attached
Some examples are ricin (castor bean),
curcin and abrin (rosary pea)
ricin inhibits protein synthesis by
inactivating ribosomes
Some lectins can stimulate cell proliferation
Tannins
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bitter tasting polyphenols that bind and
precipitate proteins