Hypoxanthine-3- N oxide

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Structural formula
Structure of hypoxanthine-3-N-oxide
Surname Hypoxanthine-3- N oxide
other names
  • Frightful
  • 1,7-dihydro-6 H -purine-6-one-3-oxide
Molecular formula C 5 H 4 N 4 O 2
External identifiers / databases
CAS number 19765-65-2
PubChem 192963
ChemSpider 10565250
Wikidata Q73260904
Molar mass 152.11 g · mol -1
safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Hypoxanthine-3- N oxide is oxidized xanthine - derivatives , which as alarm pheromone is because it of certain fish is released for injuries. Its discoverer, Karl von Frisch , called the secretion containing this substance a deterrent . This term can be found in current and even in English-language literature.


In 1936, Karl von Frisch discovered a substance in the skin of minnows which, when released (through injury), permanently scares away other individuals of this small schooling fish. As a result, fish avoid (through learning) a place where a conspecific was injured, often for days as a possible location for a predatory fish. The substance was later found in other carp fish as well .

Chemistry and physiology

Chemically it is hypoxanthine -3- N -oxide, biologically it is a pheromone that is produced and stored in special cells ('piston cells'). Since it can only be produced physiologically with great effort, there can be no doubt as to its usefulness. It probably originated as a protective substance for the skin against parasites and UV damage. In numerous experiments peculiarities of its effect were determined. In this way, other predators may also be attracted. In some species of fish, its formation in males is suppressed during reproduction.

Observations in a natural environment as well as considerations about the evolution of such an alarm pheromone, however, have cast doubts about the effect of the deterrent as an alarm pheromone.

Hypoxanthine-3- N -oxide characterizes the taxon Ostariophysi . But it is also found (as a pheromone) in other taxa, such as the Etheostomatinae ( jumping bass ). Substances with a similar effect have also been discovered in tadpoles, mussels, snails and allegedly (spread through the air) even in angiosperms .

Individual evidence

  1. This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  2. ^ Karl von Frisch (1941): About a frightful fish skin and its biological significance . In: Journal of Comparative Physiology . Vol. 29, pp. 46-145.
  3. a b Stephanie A. Kraft: Naive Prey versus Nonnative Predators: A Role for Behavior in Endangered Species Conservation . In: All Graduate Theses and Dissertations, Paper 442 . Utah State University, 2009 (English, full text ).
  4. ^ AE Magurran, PW Irving, PA Henderson: Is there a Fish Alarm Pheromone? A Wild Study and Critique. In: Proceedings of the Royal Society B: Biological Sciences. 263, 1996, pp. 1551-1556, doi: 10.1098 / rspb.1996.0227 .