Spiroimine shellfish poisoning (SSP) and the spirolide family of shellfish toxins: Isolation, structure, biological activity and synthesis

Spirolides are metabolites of the dinoflagellates Alexandrium ostenfeldii and Alexandrium peruvianum. Spirolides (A-D) were isolated from the digestive glands of contaminated mussels ( Mytilus edulis), scallops (Placopecten magellanicus) and toxic plankton from the east coast of Nova Scotia in Canada. Fourteen members of the spirolide family of marine biotoxins have since been identified from around the world. The relative stereochemistry of these compounds was established via molecular modelling and NMR studies. Related marine toxins containing a spiroimine unit have been classified as fast-acting toxins and the spirolides also target muscarinic and nicotinic acetylcholine receptors and are weak activators of L-type transmembrane Ca2+ channels. The spirolides are macrocycles that are comprised of two parts: a bis-spiroacetal moiety and an unusual 6,7-bicyclic spiroimine.