Identification of okadaic acid from a Caribbean dinoflagellate, Prorocentrum concavum

Lipid-soluble toxins were isolated from a Caribbean strain of the epiphytic dinoflagellate Prorocentrum concavum Fukuyo. The major lipid-soluble toxin (LD50 = 210 +/- 15 micrograms/kg i.p. in mice) was purified by normal and reversed-phase column chromatography and characterized by 1H NMR and mass spectrometry. The toxin was identified as okadaic acid by interpretation of the spectral data. Okadaic acid was previously identified as a toxic component of the related species P. lima (Ehrenberg) Dodge. The finding of okadaic acid production in P. concavum and P. lima, abundant primary producers in the ciguatera-endemic Caribbean, suggests that the role of this toxin in the etiology of ciguatera may be more significant than previously thought.