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The sea anemone Anemonia sulcata is a well-known natural source of supply of biologically active polypeptides. So far, five toxins, ATX I, II, III, IV and AS V, several polyvalent protease inhibitors, an elastase inhibitor, two blood pressure-depressive polypeptides and very recently peptides that inhibit competitively the binding of 125I-dendrotoxin to rat brain membranes and block the voltage-sensitive K+ channels, have been isolated from it. The sea anemone toxins (especially toxin II of A. sulcata, ATX II) are very important tools in neurophysiological and pharmacological research, and their structure-function relationship has been investigated. Because of the great scientific value of the sea anemone toxins a simplification of their purification procedure was elaborated.

The lethal potency of 29 toxins from scorpion, sea anemone, snake and bee venoms was studied. Lethality following intracisternal injection of these toxins is considerably higher than following i.p. injection (except for the snake neurotoxins). This is of practical interest in the determination of the concentration of active toxins in a solution when only small amounts are available, as in the case of radiolabelled toxins.

A simple and rapid method is described for the isolation from the sea anemone Anemonia sulcata of four protein fractions of low molecular weight which have lethal activity against crabs. These proteins have been partially purified on ion exchange resins Dowex 50 W and CM cellulose and have been examined by zonal electrophoresis and micro isoelectric focusing. The stability of the fractions was determined under various experimental conditions. The fractions have strong paralytic action on Carcinus maenas . The toxic activity, however, greatly differs from one fraction to another.

A toxin of low molecular weight was isolated from tentacles of the sea anemone Anemonia sulcata P. Partially purified toxin was obtained by precipitation with ammonium sulphate, ion exchange chromatography on DEAE cellulose and chromatography on Sephadex G-50. The molecular weight of a partially purified toxin, probably a basic protein was approximately 6000 as determined by gel filtration. Disc electrophoresis of the partially purified toxin revealed four proteins. Heating for 15 min at 90°C inactivated the toxin. The toxic activity remained unchanged over 12 months when stored in frozen solution at −26°C. The ld 100 is 6 mg of the toxin per kg (rat) by i.v. injection. The toxin showed a cardiotropic action on the rat heart. When injected i.v. the toxin caused cardiac arrhythmia and fall of the arterial blood pressure.