[1] One of the primary causes of diarrhetic shellfish poisoning, okadaic acid is a potent inhibitor of specific protein phosphatases, and has a variety of negative effects on cells.

Attempts were made to determine the source of the symptoms; however, they failed to elucidate the true culprit, instead implicating a species of microplanctonic dinoflagellates.

Studies following this outbreak showed that toxicity of these mussels and scallops appeared and increased during the months of June and July, and all but disappeared between August and October.

[7][8] Elsewhere in Japan, in 1975 Fujisawa pharmaceutical company observed that the extract of a black sponge, Halichondria okadai, was a potent cytotoxin; this was dubbed Halichondrine-A.

[3][11] Okadaic acid (OA) and its derivatives, the dinophysistoxins (DTX), are members of a group of molecules called polyketides.

Okadaic acid and its derivatives are some of the most well studied of these polyketides, and research on these molecules via isotopic labeling has helped to elucidate some of those modifications.

Failure to perform one of more of these three steps, combined with several unusual reactions is what allows for the formation of the functionality of okadaic acid.

Carbon deletion and addition at the alpha and beta position comprise the other transformations present in the okadaic acid biosynthesis.

To do this, Forsyth et al. designed the synthesis to allow for structural changes and installation of important functional groups before large pieces were joined.

However, designed to display new techniques developed in their group, Ley's synthesis included forming the spiroketals using (diphenylphosphineoxide)-tetrahydrofuran and (phenylsulfonyl)-tetrahydropyrans, allowing for more mild conditions.

Similar to those above, a portion of the stereochemistry in the molecule was set by starting materials obtained from the chiral pool, in this case mannose.

[3] Because of its inhibitory effects in phosphatases, okadaic acid has shown promise in the world of medicine for numerous potential uses.