Abstract
Dinophysistoxin-3 (DTX3, 3), the principal toxin of scallops implicated in diarrhetic shellfish poisoning, is a mixture of 7-0-acyl esters of 35-methylokadaic acid. To investigate the effects of unsaturation in the acyl moieties on biological activities, three demethyl analogs of DTX3, 7-O-palmitoyl, 7-O-linoleoyl, and 7-O-docosahexaenoyl okadaic acid, were prepared and tested for mouse lethality, cytotoxicity, and diarrheagenicity. The activities of okadaic acid were generally decreased by acylation of 7-OH. The decrease was most significant in the mouse lethality, moderate in cytotoxicity, and only slight in the fluid accumulating potency in mouse intestinal loops. Diarrheagenicity measured by suckling mouse assays was affected little by the acylation. Potency of analogs genellaly increased in parallel with the unsaturation in the acyls.
