Isolation of neurotoxic peptides from the venom of the 'armed' spider Phoneutria nigriventer.

Three neurotoxic fractions, lethal to mice, were isolated from the venom of the spider Phoneutria nigriventer, by gel filtration and reverse phase chromatography (Phoneutria toxins 1, 2 and 3). These toxins have mol. wts in the range 6000-9000, and have different amino acid compositions and N-terminal amino acid sequences. The toxins also differ in the lethality and signs they cause in mice after intracerebro-ventricular injection. The median LD50 being respectively for the whole venom, toxins 1, 2 and 3, 47 +/- 5 micrograms, 45 +/- 4 micrograms, 1.7 +/- 0.7 micrograms and 137 +/- 10 micrograms/kg mouse. Toxins 1 and 2 induce excitatory symptoms in mice and toxin 3 a flaccid paralysis with an ED50 of 40 +/- 5 micrograms/kg mouse as measured also by intracerebro-ventricular injection. The presence in the venom of a non-neurotoxic, smooth muscle active peptide is also described.