Okadaic acid

This toxin was first isolated from the sponge Halichondria okadai and is a complex lipophilic polyether readily soluble in many organic solvents, degrading in acid or base.

Figure: 1 Okadaic acid

Diarrhetic shellfish poisoning

Diarrhetic shellfish poisoning (DSP) was first reported from the Tohoku district in Japan. Since then, reports of DSP have emerged from every continent except Africa and Australia. DSP has never resulted in a human fatality. As well as diarrhoea, other gastrointestinal symptoms include vomiting, nausea and abdominal cramps, possibly becoming so severe that the patient is incapacitated. Treatment usually is to simply make the patient as comfortable as possible for the duration of the intoxication. Symptomatic treatment for severe diarrhoea such as fluid replacement should be employed. Common anti-diarrheals would provide little relief to DSP victims because much of the diarrhetic effect is caused by epithelial destruction.

Apart from this acute effect, chronic exposure may promote cancer as it enhances skin tumours on mice when applied after a known carcinogen. Okadaic acid potently inhibits serine/threonine phosphatases, enzymes which dephosphorylate serine and threonine residues of other enzymes receptors, switching them off or on as the case may be.

Microalgae that produce diarrhetic shellfish toxins

Diarrhetic shellfish toxins originate in dinoflagellates, specifically Prorocentrum lima, Prorocentrum elegans, Prorocentrum hoffmannianum and Prorocentrum concavum, Dinophysis acuminata, Dinophysis acuta, Dinophysis fortii, Dinophysis hastata, Dinophysis mitra, Dinophysis rotundata, Dinophysis norvegica and some strains of Dinophysis tripos.

Further Reading

Cohen P, Holmes CF & Tsukitani Y (1990) Okadaic acid: a new probe for the study of cellular regulation. Trends Biochem Sci 15, 98-102.

Ito E & K Terao (1994) Injury and recovery process of intestine caused by okadaic acid and related compounds. Nat Tox 2, 371-377.

Kumagai M, Yanagi T, Murata M, Yasumoto T, Kat M, Lassus P & Rodriguez-Vazquez JA (1986) Okadaic acid as the causative toxin of diarrhetic shellfish poisoning in Europe. Agric Biol Chem 50, 2853-2857.

Murata M, Shimitami M, Sugitani H, Oshima Y & Yasumoto T (1982) Isolation and structural elucidation of the causative toxin of the diarrhetic shellfish poisoning. Nippon Suisan Gakkaishi 48, 549-552.

Tachibana K, Scheuer P, Tsukitani Y, Kikuchi H, Enden V, Clardy J, Gopichand Y & Schmitz F (1981) Okadaic acid, a cytotoxic polyether from two marine sponges of the genus Halichondria. J Am Chem Soc 103, 2469-2471.

Yasumoto T, Oshima Y & Yamaguchi M (1978) Occurrence of a new type of shellfish poisoning in the Tohoku district. Nippon Suisan Gakkaishi 44, 1249-1255.

Yasumoto T, Murata M, Oshima Y, Sano M, Matsumoto GK & Clardy J (1985) Diarrhetic shellfish toxins. Tetrahedron 41, 1019-1025.

e-mail: web@aims.gov.au
Page last updated - December 18, 2008

©2000-2005 Australian Research Network for Algal Toxins

URL http://www.aims.gov.au/arnat

[ About AIMS ] [ AIMS research ] [ AIMS facilities ] [ AIMS news ] [ AIMS search ]
[ AIMS publications ] [ Doing business with AIMS ] [ What's new ]
[ Site index ] [ Navigating this site ] [ Privacy policy ] [ Links ]