My watch list
my.bionity.com  
Login  

Phototoxin



Part of a series on
Toxicology and poison
Toxicology (Forensic) - Toxinology
History of poison
(ICD-10 T36-T65, ICD-9 960-989)
Concepts
Poison - Venom - Toxicant - Antidote
Acceptable daily intake - Acute toxicity
Bioaccumulation - Biomagnification
Fixed Dose Procedure - LD50 - Lethal dose
Toxic capacity - Toxicity Class
Toxins and venoms
Neurotoxin - Necrotoxin - Hemotoxin
Mycotoxin - Aflatoxin - Phototoxin
List of fictional toxins
Incidents
Bradford - Minamata - Niigata
Alexander Litvinenko - Bhopal
2007 pet food recalls
List of poisonings
Poisoning types
Elements
Toxic metal (Lead - Mercury - Cadmium - Antimony - Arsenic - Beryllium - Iron - Thallium) - Fluoride - Oxygen
Seafood
Shellfish (Paralytic - Diarrheal - Neurologic
Amnesic)
- Ciguatera - Scombroid
Tetrodotoxin
Other substances
Pesticide - Organophosphate - Food
Nicotine - Theobromine - Carbon monoxide - Vitamin - Medicines
Living organisms
Mushrooms - Plants - Animals
Related topics
Hazard symbol - Carcinogen
Mutagen - List of Extremely Hazardous Substances - Biological warfare

Phototoxins are toxins that can cause allergic reactions in particularly susceptible individuals and which can cause dangerous photosensitivity in a much broader range of subjects.

Additional recommended knowledge

Phototoxins are common in:

  • a variety of plants (including food plants where they may be a biological defence):
    • many citruses contain essential oils that are photosensitisers;
    • some herbal remedies (notably St John's wort, though incident rates for this plant are reportedly low);
  • some prescribed medications (such as tetracycline antibiotics); and
  • many essential oils, perfumes and cosmetics.

Ingested medications may cause systemic photosensitivity and topically applied medications, cosmetics and essential oils may lead to local (or perhaps systemic) photosenstivity. Curiously and ironically, para-aminobenzoic acid (PABA) found in some sunscreens can also cause photosensitivity.

Upon exposure to light, notably light containing ultraviolet radiation, discolouration of the skin (whether as inflammation, lightening or darkening) or rashes may result. In extreme cases, blistering may also occur.

Uses

The marigold plant produces the phototoxin alpha-terthienyl, which functions as a nematicide. When exposed to near ultraviolet light, such as in sunlight, alpha-terthienyl generates the toxic singlet oxygen.[1] Alpha-terthienyl results in damage to the respiratory, digestive and nervous system of larvae, resulting in 100% death rates in concentrations of 33 ppb.[2] This makes it an interesting natural insecticide.

Rose bengal and other singlet oxygen generating phototoxins are also used in synthetic organic chemistry. They have also found use in photodynamic therapy, where the toxin is activated by intense light to destroy cancer cells.

References

  1. ^ J. Bakker, F. J. Gommers, I. Nieuwenhuis and H. Wynberg. Photoactivation of the nematicidal compound alpha-terthienyl from roots of marigolds (Tagetes species). A possible singlet oxygen role. JBC, Vol. 254, Issue 6, 1841-1844, Mar, 1979. http://www.jbc.org/cgi/content/abstract/254/6/1841
  2. ^ Manish Nivsarkar, Bapu Cherian and Harish Padh. Alpha-terthienyl: A plant-derived new generation insecticide. Current Science, Vol. 81, No. 6, 25 September 2001. http://www.ias.ac.in/currsci/sep252001/667.pdf

See also

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Phototoxin". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE