Domoic acid (MW=311; C15H21NO6) is a tricarboxylic acid similar to the glutamate receptor agonist kainic acid. It has an (intra-peritoneally) of 3.6 mg / kg. It is polar making it soluble in water and insoluble in organic solvents. The three carboxylic acids have pKa's of 2.1, 3.7 and 5.0 with the amino group in the pentameric ring having a pKa of 9.8. (2) Glutamic Acid is a neurotransmitter responsible for the release of Calcium ions into the cell. When Glutamate is present in high concentrations, an excess of Ca2+ ions will flood the cell. These will cause the cell to "fire" uncontrollably, causing the neuron to eventually swell and burst. As Domoic Acid is an analog to Glutamic Acid, when present in the body it will cause the same "exitotoxic" effect.
Source of Structure: http://www.transy.edu/homepages/chem4014/mathis/domoicacid/structure.htm
Domoic Acid is a poison, produced by the diatom Pseudo-nitzschia.
Picture of Psuedo-nitzschia diatom, responsible for producing Domoic acid, the sole agent involved in Amnesiac Shellfish Poisoning. Many members of the Pseudo-nitzschia family are found along the western coast of the United States, along the Gulf of Mexico and Canada. Domoic acid has been found in mussels, clams, scallops. Regulatory limits in shelfish have been established as 20ug/g, due to the huge heath concerns. Source: http://www.chbr.noaa.gov/CoastalResearch/Pictures/Algae/PseudoN.jpg The Pacific razor clam is being affected by the sudden increase of domoic acid. (3)
Links to Other Areas of Interest Related to Domoic Acid Poisoning
Signs and Symptoms of Domoic Acid Poisoning
Modes of Action of Domoic Acid
Treatment for Domoic Acid Poisoning
Interesting Links/StoriesBIOTOXIN IN HARMFUL ALGAL BLOOM RESPONSIBLE FOR THE DEATHS OF SEIZURING SEA LIONS OFF MONTEREY COAST
My Summary: The biotoxin, Domoic Acid has recently caused deaths in more than 50 seals along the central coast. Domoic Acid will cause seizures and vomiting, eventually leading to death of the marine mammals. High levels of domoic acid were later found in anchoives and sardines, delacies of Central Coast sea lions. When tissue samples were taken, scientists discovered microscopic lesions in certain sections of the brain which is consistent of Domoic acid seizures. Interestingly, when biotoxin assays were performed, only 4 sea lions tested positive for Domoic Acid. Domoic acid is quickly biotransformed and removed from the body, therefore the low amount of positive results, does not elliminate Domoic Acid poisoning as a suspect.