Domoic Acid DOM

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Domoic Acid (DOM)

• By Cassandra Hamilton
• February 14, 2006

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Description

• Present in a variety of marine species and has
  been isolated in macro-and micro-algae
• A secondary amino acid and a member of the
  kainoid class of organic compounds
• Very water soluble

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Discovery

• Japanese researchers performed first isolation of
  DOM in red algae, Chondria armata
• Before discovery, Chondria armata was used as a
  deworming medicine for children

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Other Species

• Can be found in different plankton species
• -e.x. Pseudonitzschia pungens f.
  multiseries.
• Some plankton may be acquiring the ability to
  produce DOM through global warming and pollution
• Plankton are a main food source for numerous
  aquatic organisms
• -e.x. mussels, oysters, clams

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Toxicity Mechanisms

• DOM causes problems in the nervous system via
  neurons
• It stimulates non-NMDA receptors
• It is a more potent agonist at these receptors
  compared to glutamate.
• Through a variety of ways, DOM will either cause
  a direct or indirect over-stimulation of
  post-synaptic receptors leading to the influx of
  excessive amounts of Ca2, which causes cell
  damage

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Toxicity Profile

• Bivalves are not affected by massive doses of DOM
  (1000 ppm)
• In humans and monkeys
• -Low dose of DOM (1/20 to 1/10 of the
  LD50) causes nausea, vomiting, and diarrhea
• -An increased DOM dose (1/10 to 1/5 of the
  LD50) causes muscle fasciculations and
  intermittent forelimb rigidity
• -A higher DOM dose causes neurotoxic
  symptoms, such as headaches and confusion in
  humans.

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Toxicity Profile Contd

• Damage can take place once seizures begin
• - the hippocampus, entorhinal cortex,
  amygdala, lateral thalamus and hypothalamus may
  be affected
• If not treated, then the last step is death
• Also, DOM is known as amnesic shellfish
  poisoning
• - causes deficits in memory function

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Toxic Episodes

• Occurred in Canada - 1987
• - 250 people fell ill after consuming
  shellfish, but only 107 cases were confirmed as
  amnesic shellfish poisoning
• - 3 elderly patients between 71-84 yrs. died
• Monterey Bay, C.A. 1991
• death of numerous pelicans and comorants after
  consuming anchovies
• Today, DOM is constantly monitored worldwide to
  prevent anymore incidents

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Treatments/Antidotes

• DOM is eliminated through urinary excretion
• - useful to increase renal clearance
• To prevent long-term neurological damage
• - control seizures

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Problems

• Medical advice has remained largely unchanged
  since 1987
• Also, no new antidotes have been developed as of
  yet.