Domoic acid has been responsible for several deaths and both permanent and transitory illness in over a hundred people. The toxin is produced by marine diatoms which are members of the genus Pseudo-nitzschia. Both shellfish and fish can accumulate this toxin without apparent ill effects; however, in humans the toxin crosses into the brain and interferes with nerve signal transmission. People poisoned with very high doses of the toxin can die, while lower doses can cause permanent brain damage (short term memory loss). When this toxin was discovered in certain West coast fish and shellfish, both recreational and commercial fisheries were briefly closed. This closure, though relatively short, had serious economic impacts on those communities dependent on these fisheries.
The first reported outbreak of domoic acid poisoning occurred in 1987 when shellfish from Prince Edward Island Canada were consumed. In that outbreak, 3 people died and over 100 people developed various toxic symptoms. Domoic acid was found to be produced by the diatom Pseudo-nitzschia multiseries. The most unusual, and most serious toxic symptom, was a loss of short term memory--hence the initial designation of the syndrome in humans as amnesiac shellfish poisoning (ASP). However, since the toxin has been found in fin-fish and the chemical structure of the toxin is now known, a more accurate term is Domoic Acid Poisoning. In 1991, along the beaches of Monterey Bay, CA, dead and dying seabirds were observed--many of the sick birds displayed unusual symptoms suggesting a neurological toxin. Examination of the contents of the dead bird's stomachs revealed high levels of domoic acid. Furthermore, the birds had been eating anchovies from the bay. In turn, examination of the anchovy gut contents showed that these fish had been consuming the diatom called
Pseudo-nitzschia australis. Quick action by state health departments along the west coast of the United States prevented human illnesses by closures of both recreational and commercial shellfisheries.
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Kainic Acid
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The early work on domoic acid is closely intertwined with a related compound, kainic acid and its use as a anthelminthic (a parasite remedy). These products were found in the Rhodophyta, or red algae, Chondria armata and Digenea simplex. Initial studies centered on Digenea, a red alga found in tropical and sub-tropical waters that has been used for centuries as an anthelminthic (Baslow, 1969; Scheuer, 1973; Scheuer, 1980). Murakami et al. (1953) isolated the active anthelmintic ingredient and named it digenic acid and then later renamed it kainic acid (Murakami et al., 1954) after the Japanese name for the alga--kaininso.
While domoic acid has recently, i.e., in 1987, been found to be toxic to humans, the compound itself was first isolated in 1959 by Daigo from Chondria armata and its final structure and stereochemistry determined in 1966 by Takemoto et al. Domoic acid has also been isolated from another red algae, Alsidium corallinum, by Impellizzeri et al. (1975). Dr. Steve Bates, Department of Fisheries and Oceans-Canada, has prepared an extensive bibliography on domoic acid.
For more detailed information about the fascinating history and chemistry of marine natural products, the volumes by Paul Scheuer in the references below are highly recommended--these books are part of a larger series by Dr. Scheuer. In addition, the title by Baslow is also highly recommended, the author updated his original 1969 book on Marine Pharmacology in 1977, unfortunately both books are out of print but probably available in university/college libraries.
References:
Baslow, M. H. 1969. "Marine Pharmacology", Williams & Wilkins Co. Baltimore, MD. pp 69-71.
Daigo, K. Yakugaku Zasshi 79: 350-368, (1959)- a series of four papers. Chem.Abstr. 53, 14218 (1959).
Impellizzeri, G., Mangiafico, S., Oriente, G., Piattelli,M., Sciuto, S., Fattorusso, C., Magno, S.,E., Santacroce, and Sica, D. 1975. Phytochemistry 14: 1549-1557.
Scheuer, P.J. 1973. "Chemistry of Marine Natural Products", Academic Press, New York. pp139-140.
Scheuer, P. J. 1980. "Marine Natural Products, Chemical and Biological Perspectives", Volume 3, Academic Press, New York. pp 100-106.
Takemoto, T. Daigo, K., Kondo, Y., and Kondo, K. Yakugaku Zasshi 86:874-877, (1966). Chem. Abstr. 66, 28604 (1967).
Overview
Phytoplankton
Marine Biotoxins
West Coast HABs