 The intraperitoneal LD50 value of HNTX-IV in mice is 0.2 mg/kg.HNTX-III is 40 times more potent that HNTX-IV.HNTX-III and HNTX-IV have an antagonistic effect on the toxin BMK-I, a toxic protein in the venom of the scorpion Buthus martensii.