Tetrodotoxin derivatives: chemical structure and blockage of nerve membrane conductance

The nerve-impuilse-blocking actions of derivatives of tetrodotoxin have been tested on lobster and squid axons. The block produced by deoxytetrodotoxin was similar to that produced by tetrodotoxin and was probably caused by tetrodotoxin contamination. Tetrodaminotoxin and anhydrotetrodotoxin also produced a similar block but at such high concentrations that tetrodotoxin contamination cannot be ruled out. The hydroxyl group of C(4) and the hemilactal oxygen links play an important role for the nerve-blocking action.