Domoic acid

Domoic acid (DA), was originally isolated from the macroscopic red alga Chondria armata, locally known in Japan as domoi, it being the antihelminthic agent in a long used traditional medicine. It was later identified as the cause of an unusual shellfish poisoning syndrome, amnesic shellfish poisoning, that first occurred on Prince Edward Island in Canada. The source of the toxin was the diatom Pseudo-nitzschia (previously Nitzschia) pungens forma multiseries. 

Other DA producing diatoms include Pseudo-nitzschia seriata, P.multiseries, P. australis, P. pseudodelicatissima, P.delicatissima, and P. turgidula.

 

Domoic acid (MW=311; C15H21NO6) is a tricarboxylic acid similar to the glutamate receptor agonist kainic acid, being cyclised analogues of L-glutamate. It is only mildly toxic to mammals, with an LD50 to mice (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.

Domoic acid

Amnesic shellfish poisoning

Domoic acid is a potent amino acid neuroexcitant that acts preferentially upon a sub-class of ionotropic glutamate receptors found in nervous tissue, particularly the brain. These glutamate receptors ligand gated ion channels, which respond to L-glutamate by opening and allowing the passage of cations. This action triggers many intracellular cascades either directly by their introduction of cations or indirectly by the second messengers produced by these cascades such as cyclic AMP, or reactive oxygen species. Induction of neuronal imbalance can cause the brain to malfunction and may lead to lesions in the brain that can cause permanent injury.

Quilliam MA & Wright JL (1989) The amnesic shellfish poisoning mystery. Anal Chem. 61, 1053A-106A.

Wright JL (1998) Domoic acid--ten years after. Nat Toxins 6, 91-92.

Wright JLC, Boyd RK, de Freitas ASW, Falk M, Foxall RA, Jamieson WD, Laycock MV, McCulloch AW, McInnes AG, Odense P, Pathak VP, Quilliam MA, Ragan MA, Sim PG, Thibault P, Walter JA, Gilgan M, Richard DJ & Dewar D (1989) Identification of domoic acid, a neuroexcitatory amino acid, in toxic mussels from eastern Prince Edward Island. Can J Chem 67, 481-489.

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Page last updated - December 18, 2008

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