Tetrodotoxin (CAS number 4368-28-9)
IUPAC Name: Octahydro-12-(hydroxymethyl)-2-imino-5,9:7,10a-dimethano-10aH-[1,3]dioxocino[6,5-d]pyrimidine-4,7,10,11,12-pentol
Molecular weight: 319.2706 g
Formula: C11H17N3O8
Structure: The molecule is made up of a positively charged Guanidinium group which consists of a resonance stabilized cation, and an imidazole ring. In addition to these are the five fused ring systems containing hydroxyl groups, which aid stabilization of the TTX-sodium channel binding complex.
Tetrodotoxin is a white crystalline solid, darkens above 220 Celsius without melting, and exhibits no UV absorption. As it is completely insoluble in all solvents except acids, it apparently a weak base (pKa'8.76), and forms a crystalline hydrobromide soluble in water, from which the toxin is recovered by treatment with ammonia.
All of the observed toxicity is secondary to the action potential blockade. Tetrodotoxin acts on the central and the peripheral nervous systems (i.e. autonomic, motor, sensory nerves).
Tetrodotoxin also stimulates the chemoreceptor trigger zone in the medulla oblongata and depresses the respiratory and vasomotor centers in that area.
The TTX is concentrated in liver, skin and gonads. The level of toxicity is seasonal, and in Japan, fugu is only served from October to March.
Click here for IR spectrum
Click here for HNMR generated from the gNMR program
Click here for Crystal structures