Thursday, August 18, 2011

Plant and Animal Toxins

Any substance poisonous to an organism; often restricted to poisons produced by living organisms. In addition to those from such microorganisms as bacteria (see bacterial diseases), dinoflagellates, and algae, there are toxins in fungi (mycotoxins; see aflatoxinmushroom poisoning), higher plants (phytotoxins), and animals (zootoxins, or venoms). The plants include nightshade (see nightshade family), poison hemlock,foxglovemistletoe, and poison ivy. Many plant toxins (e.g., pyrethrins, nicotine, rotenone) apparently protect their producers against certain animals (especially insects) or fungi. Similar defensive secretions in animals may be widely distributed or concentrated in certain tissues, often with some sort of delivery system (e.g., spines, fangs). Animals such as spiders and snakes use venoms to catch prey and often for defense. Many normally edible fishes and shellfishes become poisonous after feeding on toxic plants or algae.

Certain bacterial and plant toxins have the unusual ability to catalyze chemical reactions inside animal cells. Such toxins are always composed of two functionally distinct parts termed A and B, and they are often called A-B toxins. The B part binds to receptor molecules on the animal cell surface and positions the toxin upon the cell membrane. Subsequently, the enzymically active A portion of the toxin crosses the animal cell membrane and catalyzes some intracellular chemical reaction that disrupts the cell physiology or causes cell death. 

A large group of toxins breach the normal barrier to free movement of molecules across cell membranes. In sufficient concentration such cytolytic toxins cause cytolysis, a process by which soluble molecules leak out of cells, but in lower concentration they may cause less obvious damage to the cell's plasma membrane or to its internal membranes. 

Tetanus and botulinal neurotoxins block the transmission of nerve impulses across synapses. Tetanus toxin blockage results in spastic paralysis, in which opposing muscles contract simultaneously. The botulinal neurotoxins principally paralyze neuromuscular junctions and cause flaccid paralysis.
Gram-negative bacteria, such as Salmonella and Hemophilus, have a toxic component in their cell walls known as endotoxin or lipopolysaccharide. Among other detrimental effects, endotoxins cause white blood cells to produce interleukin-1, a hormone responsible for fever, malaise, headache, muscle aches, and other nonspecific consequences of infection. The exotoxins of toxic shock syndrome and of scarlet fever induce interleukin-1 and also tumor necrosis factor, which has similar effects. See also EndotoxinFeverScarlet feverToxic shock syndrome.
Toxoids are toxins that have been exposed to formaldehyde or other chemicals that destroy their toxicities without impairing immunogenicity. When injected into humans, toxoids elicit specific antibodies known as antitoxins that neutralize circulating toxins. Such immunization (vaccination) is very effective for systemic toxinoses, such as diphtheria and tetanus


toxin - a poisonous substance produced during the metabolism and growth of certain microorganisms and some higher plant and animal species
venom - toxin secreted by animals; secreted by certain snakes and poisonous insects (e.g., spiders and scorpions)
Cardiovascular Toxins
Avocado (leaves, seeds, stem, skin)*
Azalea (entire rhododendron family)
Autumn crocus (Colchicum autumnale)*
Bleeding heart*
Castor bean*
Foxglove (Digitalis)*
Mistletoe berries*
Mountain laurel
Oleander *
Rosary Pea*

Gastrointestinal Toxins
Amaryllis bulb*
Azalea (entire rhododendron family)
Autumn crocus (Colchicum autumnale)*
Bird of Paradise
Buttercup (Ranunculus)
Castor bean*
Chocolate *
Chrysanthemum (a natural source of pyrethrins)
Crocus bulb
Croton (Codiaeum sp.)
Cyclamen bulb
Dumb cane (Dieffenbachia)*
English ivy (All Hedera species of ivy)
Hyacinth bulbs
Holly berries
Iris corms
Lily (bulbs of most species)
Marijuana or hemp (Cannabis)*
Narcissus, daffodil (Narcissus)
Pencil cactus/plant*
Potato (leaves and stem)
Rosary Pea*
Spurge (Euphorbia sp.)
Tomatoes (leaves and stem)

Respiratory Toxin
Chinese sacred or heavenly bamboo*
Dumb cane (Dieffenbachia)*
Elderberry, unripe berries*
Jimson weed*

Neurological Toxins
Alcohol (all beverages, ethanol, methanol, isopropyl)
Amaryllis bulb*
Azalea (entire rhododendron family)
Bracken fern
Castor bean*
Choke cherry, unripe berries*
Chrysanthemum (natural source of pyrethrins)
Crocus bulb
Delphinium, larkspur, monkshood*
Lupine species
Marijuana or hemp (Cannabis)*
Mistletoe berries*
Morning glory*
Potato (leaves and stem)
Rosary Pea*
Tomatoes (leaves and stem)

Kidney/Organ Failure Toxins
Calla lily*
Rhubarb leaves*


nicotine - an alkaloid poison that occurs in tobacco; used in medicine and as an insecticide
strychnine - an alkaloid plant toxin extracted chiefly from nux vomica; formerly used as a stimulant
brucine - a bitter alkaloid poison resembling strychnine and extracted from nux vomica
hemlock - poisonous drug derived from an Eurasian plant of the genus Conium; "Socrates refused to flee and died by drinking hemlock"
toxin - a poisonous substance produced during the metabolism and growth of certain microorganisms and some higher plant and animal species
mycotoxin - a toxin produced by a fungus
curaretubocurarine - a toxic alkaloid found in certain tropical South American trees that is a powerful relaxant for striated muscles; "curare acts by blocking cholinergic transmission at the myoneural junction"

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