Zetekitoxin AB

Zetekitoxin AB (ZTX) is a guanidine alkaloid found in the Panamanian golden frog "Atelopus zeteki". It is an extremely potent neurotoxin.
Structure.
ZTX is a guanidine alkaloid. It's structurally related to saxitoxin, but with some differences. ZTX has a guanidine core similar to saxitoxin. It contains an isoxazolidine ring, a sulfonate group and a N-hydroxycarbamate group.
Mechanism of action.
ZTX is an extremely potent sodium channel blocker. It has been shown to block the voltage-gated sodium channels at picomolar concentrations. It is about 580 times more potent than saxitoxin.
Toxicity.
ZTX is an extremely potent neurotoxin. The of ZTX in mice is 11 μg/kg.