A new procedure of extraction of tetrodotoxin (I) is described. The structures of three quinazoline derivatives, tetrodoic acid (VIII) and anhydrotetrodoic acid (XII) obtained from I have been elucidated. Based on these structures, the structure and the absolute configuration of the toxin (I) are assigned as Ib. It is also demonstrated that I is a C11- compound and not a dimeric C22-form. The toxin (I) and anhydroepitetrodotoxin (II) are ...
