II. Poisonous Plants

1
II. Poisonous Plants

• Acute vs. chronic toxicity
• a) internal poisons
• b) allergens
• c) cell modifiers mutagens, teratogens and
  lectins

2
a. Internal Poisons

• Alkaloids
• Glycosides
• Oxalates
• Resins

3
Alkaloids

• 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

4
Glycosides

• combination of sugar(s) or glycone and another
  compound (aglycone)
• glucose is the most common sugar
• toxicity is associated with aglycone moiety

5
Cynogenic glycosides

• 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

6
Anthraquinone glycosides

• Hydrolysis of anthraquinones
• Found in aloe and rhubarb

7
Cardioactive glycosides

• Aglycones are steroidal
• Act on the heart (paralysis)
• Found in Digitalis (foxglove) and Antirrhinum
  (snapdragon)

8
Saponin glycosides

• 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

9
Coumarin glycosides

• Aglycone is a benzopyranone
• Causes internal bleeding and dermatitis
• Not common
• Found in Artemesia species (sagebrush)

10
Oxalates

• organic acid that forms in crystals in vacuole
• Reach dangerous levels in oxalis, rhubarb, dock
  and purslane

11
Resins

• 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

12
Allergens

• Pollen can cause
• Anaphylatic shock
• Allergenic rhinitis (hayfever)
• Asthma
• Dermatitis
• Photodermatitis

13
Mutagens can cause

• Replacement of nucleotide in DNA
• Loss of addition of nucleotide causing more
  serious mutagenesis
• Nondisjunction of chromosomes (extra chromosomes)
• Polyploidy (extra set of chromosomes)

14
Teratogens

• Effects on somatic cells of growing embryos
  usually resulting in malformed organs

15
Lectins

• 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

16
Tannins

• bitter tasting polyphenols that bind and
  precipitate proteins