Aim: 

Nematocysts, organoids specialized for both aggression and predation strategies in Cnidarians, contain a crude venom with biologically active substances. Crude venom extracted from isolated nematocysts of the Scyphozoan Pelagianoctiluca is haemolytically active towards human erythrocytes. The aim of the present work is to verify the inhibitory effect of different carbohydrates as osmotic protectants upon crude venom-induced haemolysis.

Methods: 

Crude venom was extracted by sonication of nematocysts isolated from oral arms of Pelagia noctiluca. Haemolytic test was then performed upon human 0.05% erythrocytes suspension by treatment with different aliquots of crude venom (5%, 10%, 20% v/v respectively) with or without alternatively glucose, trehalose, lactose, N-acetyl D-galattosamine, N-metylmannopyranose, Polyethylenglycole at different MW (25 mM final concentration).

Results: 

Crude venom from Pelagia noctiluca nematocysts was haemolytically active upon human erythrocytes with a dose-dependent response. Haemolysis due to the crude venom was totally blocked by PEG with MW > 3400, while no inhibitory effect was seen after treatment with the other carbohydrates.

Conclusion: 

Crude venom-induced haemolysis upon human erythrocytes was impaired by osmotic protectants with high MW. In particular such result may account for a pore forming mechanism of Pelagianoctiluca toxins on cell membrane. Since the employed small osmoticants did not impair haemolysis, lesions with diameter comparable to that of PEG 6000 could be formed.