- Chemical Properties -

New Scientist January 20, 2001
" [Tetrodotoxin] is not an alkaloid, steroid or carbohydrate and it is not
like any conventional amino acid. It's a low molecular weight, small molecule
with a unique cage structure. "
-- as described by Harry Mosher (Stanford University) who isolated the
toxin in the 1960s.

Name (IUPAC): Octahydro-12-(hydroxymethyl)-2-imino-5, 9:7, 10a-dimethano-10aH-[1,3]
dioxocino[6,5-d]pyrimidine-4,7,10,11,12-pentol

CAS number: 4368-28-9

Molecular Formula: C₁₁H₁₇N₃O₈

Molecular Weight: 319.2706

-white crystalline solid

- water soluble non-protein

-Heat stable (except in allkaline environment)

-darkens above 220°C without melting

- weak base pKa 8.7

-odourless

Tetrodotoxin exists in an equilibrium mixture of its ortho ester, anhydride and lactone forms

"Equilibrium mixture"
-http://www.scripps.edu/chem/baran/images/grpmtgpdf/Vasan.pdf

"Various representations of Tetrodotoxin"
- http://www.life.umd.edu/grad/mlfsc/zctsim/Tetrodo.html

IR, NMR and Mass spectrum can be viewed here

The molecule consists of

- a positively charged Guanidinium group (3 Nitrogen atoms)
The resultant cation is stablised by resonance effect.

Guanidinium group

- Pyrimidine ring fused with other ring systems.
Of the additional ring systems, 5 of the rings contain the -OH group, which increases
the stability and ability of the toxin to bind to the aqueous interfaces in the cell.

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