Huwentoxin-I

Huwentoxin-I (HwTx-I) is a neurotoxin that was originally isolated from the venom of the Chinese bird spider Ornithoctonus huwena. Huwentoxin-I is known to be an inhibitor of tetrodotoxin-sensitive voltage-gated sodium channels (TTX-S) (IC50 ~ 50 nM) and N-type voltage-sensitive calcium channels (IC50 ~ 100 nM) in mammalian DRG, hippocampus and insect’s DUM neurons. It has only a very weak effect on L-type calcium channels, no effect on TTX-R channels and has virtually no effect on muscle sodium channels. The selectivity of Huwentoxin-I for calcium channels appears to be higher than ω-conotoxin MVIIA and equivalent to ω-conotoxin GVIA. Huwentoxin-I demonstrated an antinociceptive effect in the rat model of the formalin test when administrated intrathecally (ED50 ~ 0.28 µg/kg), without side effects of the ones led by ω-conotoxin MVIIA.