Cytotoxic activity of a methanol extract of Phallusia nigra (Tunicata, Ascidiacea)

Tunicates have been reported to be a rich source of biologically active compounds. In this study, we demonstrate the presence of cytotoxic substances in Phallusia nigra, a common tunicate from Brazilian coastal waters. An extract of tunicate tissue was obtained by homogenizing the visceral organs from 50 specimens in methanol, followed by filtration and concentration in a rotary vacuum evaporator. Finally, the concentrate was partitioned with chloroform to remove lipids. The resulting extract possessed antimitotic and hemolytic activity. The former was demonstrated as a delay in the development of sea urchin eggs by partially inhibiting the process of cleavage (first cleavage, EC50 ñ SEM = 3.44 ñ 0.84 mg/ml). The <500 molecular fraction of the extract obtained by ultrafiltration also inhibited cell proliferation (the number of viable cells was decreased by 68 per cent with 500 mug/ml) and DNA synthesis of T47D cells derived from human breast carcinoma as measured by [3H]-thymidine incorporation (66 per cent of the control value after 24-h incubation with 100 mug/ml). Dose-dependent hemolysis obtained with P. nigra extract on mouse erythrocytes had an EC50 ñ SEM = 1.12 ñ 0.02 mglml for a 0.5 per cent erythrocyte suspension. Hemolysis could be reduced by pre-incubating the cells with choline-containing phospholipid. Sphingomyelin (40 mug/ml) increased the EC50 by twofold to 2.86 ñ 0.04 mg/ml, but phosphatidylcholine (80 mug/ml) did not modify hemolysis.

Hemolytic activity of the nematocyst venom from the sea anemone Bundodosoma Caissarum

The nematocyst venom of the sea anemone Bunodosoma caisarum obtained by electric stimulation of the animals has hemolytic activity on fish, toad, snake, mice and rat erythrocytes. The hemolytic action was dose-dependent and the ED50 varied between 2.9 and 7.6*g venom/ml erythrocyte suspension (0.5%, v/v). Toad erythrocytes were the most sensitive while rat erythrocytes were the most resistant to the sea anemone venom. The hemolytic activity of venom in mice was partially inhibited by preincubation of the venom with sphingomyelin for 1h. The ED50 was increased 3.8-fold when 10.0* sphingomyelin per ml erythrocyte suspension produced approximately 95% hemolysis and were inhibited only by 40.0*g sphingomyelin. The hemolysin activity was inhibited by heating to 90-C but not to 70-C

Antimitotic effect of an extract of the sea anemone bunodosoma caissarum on sea urchin EGG development

A methanolic extract of the sea anemone Bunodosoma caissarum has an antimiototic effect on sea urchin egg development. The extract produces a dose-dependent inhibition of cell cleavage. When the extract is alded together with sperm to unfertilized sea urchin eggs, the ED50 is 0.60 ñ 0.03 mg/ml (x ñ SEM). When added shortly after fertilization, the extract produces the same kind of progressive inhibition but with an ED50 of 0.98 ñ 0.16 mg/ml. In the first case, detachment of the vitelline layer is inhibited whereas in the second case the extract inhibits cleavage even when the membrane is present