Background. Numerous studies report procedures to isolate jellyfish venom, a complex mixture of polypeptides and enzymes. In the present study the dermotoxicity of two different purified preparations of nematocysts of Olindias Sambaquiensis, a hydromedusa endemic at the Blanca Bay (Argentina), has been evaluated by means of prick, patch and scratch-patch tests. Methods. Two preparations called A and B have been used. Preparation A: in order to detach the nematocysts from the surrounding tissue, the tentacles of Olindias Sambaquiensis were soaked in distilled water, mechanically broken up, filtrated through a plankton net and centrifuged. Preparation B: the suspension containing the purified nematocysts was centrifuged and the pellet was sonicated and then centrifuged again in order to separate the venom from the fragments of the nematocysts wall. The two preparations were tested on 20 males volunteers by prick, patch and scratch tests. Results. All prick and patch tests resulted negative. An erythema was observed after 48 hours in 6 subjects tested with preparation A and in 8 subjects tested with preparation B by scratch-patch test. After 96 hours none of the patients showed erythema. Conclusions. The procedure of separation of nematocysts used in the present study confirmed that Olindias Sambaquiensis venom is dermotoxic. The scratch- patch test is the most useful method to evaluate the dermotoxicity of purified nematocysts. The dermatoxic activity was maintained by both preparations, in particular B. This is the first demonstration that the toxic activity of a jellyfish venom is not influenced by nematocysts walls.
