Partial structures and binding studies of maitotoxin, the most potent marine toxin

Partial structures of maitotoxin (MTX) were deduced by extensive two-dimensional NMR measurements, showing that the toxin had carbon-carbon double bonds in both termini of the molecule, and a primary alcohol group at the end. These functionalities were used for preparation of a radioligand of MTX; [3H]H-MTX and [3H]benzoyl-MTX. Both radioligands had high levels of non-specific binding to tissues. The binding of [3H]MTX to rat glioma C6 cells was inhibited by a didesulfo-MTX, suggesting the presence of the specific site for MTX-binding on the external surface of the cell membrane.