Poisonous Plants, Fungi, and Algae

1. Poisonous Plants, Fungi, and Algae IV - Poisonous Plants

2. Poisonous Plants • Early societies knew the dangers of poisonous plants and avoided eating them • Knowledge of these plants passed on • Poisonous plants also put to use • Used by many societies to capture prey • Possibly even to poison enemies • Many South American tribes still use blowguns with poisonous darts

3. Active Compounds • As with medicinal and psychoactive plants, the active compounds include terpenes, phenolics, alkaloids, and glycosides • Some plants have medicinal or psychoactive properties • Several well known poisonous plants that have some historical and or medical importance • digitalis • strychnine • poison hemlock

4. Poisonous Plants Today • In contemporary society the biggest danger is accidental poisonings by common house plants and yard plants • About 5% of all poisoning cases are caused by yard plants (not including mushrooms) • Young children are most likely to be poisoned by these plants

5. A few Poisonous Plants

6. Dumb cane

7. Dumb cane • The stem and leaves contain calcium oxalate crystals which can cause intense burning and irritating sensation to the mouth and tongue • Oral toxicity is well known with severe swelling of the lips, mouth and tongue which can lead to difficulty of swallowing and breathing. • Death can occur if base of the tongue swells enough to block the air passage • Also a problem with pets especially cats

8. Yew (Taxus spp)

9. Taxus species • In addition to anticancer compounds also contain toxic alkaloids - taxines • Occur in all parts of the plant except the aril • Causes sudden death often just a few hours after ingestion due to cardiac arrhythmia • Taxine inhibits sodium and calcium currents, blocking myocardial conduction • Animals found dead next to yew bushes

10. Pokeweed

11. Poke - Phytolaccaamericana • Roots and seeds especially toxic • Young stems and leaves often eaten as cooked greens - should be avoided? • Toxic compound - phytolaccigenin - triterpene saponins • Also contains toxic alkaloids and other glycosides

12. Oleander

13. Oleander - Nerium oleander • All parts of the plant are toxic • At least 50 toxic cmpds in the plant • Cardiac glycosides - oleandroside and nerioside are similar in action to digitalis • Toxins even found in smoke from burning leaves • Toxins absorbed by hotdogs cooked on a oleander branch

14. Castor bean - Riccinus communis

15. Ricinuscommunis - Castor bean • Seeds - primary source of toxin, but the rest of the plant considered slightly toxic as well • Symptoms - Stomach irritation, diarrhea, abdominal pain, severe dehydration, increased heart rate, profuse sweating, collapse, convulsions, death • Major toxin is ricin, a water soluble protein, which is concentrated in the seed

16. Ricin • One of the most potent natural toxins known • One seed can kill a child • Inhibit protein sythesis by specifically and irreversibly inactivating eukaryotic ribosomes • A single ricin molecule that enters the cytosol can inactivate over 1,500 ribosomes per minute and kill the cell • Lots of possible medical applications - could also be used in biological warfare - weapon of mass destruction • http://www.emedicine.com/emerg/topic889.htm

17. Cycads • Cycads are gymnosperms with a palm-like appearance • They are found in tropical and subtropical areas of the world • Large female cones with large seeds

18. Cycads • Cycads are rich in starch, which is found in the roots, stems, and seeds, and they have a long history as food as well as a medicinal plant • However they contain toxic compounds, which must be removed by processing the starch before the flour is used • Crushed seeds soaked in water which slowly dissolves the toxins out of the plant material over several days to weeks.

19. Cycad toxins • Cycasin and BMAA (beta-methylamino-alanine) • Cycasin is a carcinogenic and neurotoxic glycoside • BMAA is an unusual amino acid which is also neurotoxic and believed to act by mimicing glutamate and blocking glutamate receptors in the brain

20. Cycad toxins • Toxins cause gastrointestinal and liver problems • Toxins also occur in the leaves of many cycads, and have caused poisonings in cattle and sheep grazing on the leaves. • Also implicated in a number of neurological conditions including Guam Disease

21. Guam Disease • Following World War II, physicians found that ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig's disease), was about 100 times greater among the native population in Guam than the rest of the world • Later studies found that the incidence of Parkinson's disease and Alzheimer's-like dementia were also much higher among this population. • Although the causes of these conditions are unknown, many scientists believe the neurotoxins in cycads may be at least partly responsible.