title: Cytotoxic activity of a methanol extract of Phallusia nigra (Tunicata, Ascidiacea).
abstract: 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 +/- SEM = 3.44 +/- 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% with 500 micrograms/ml) and DNA synthesis of T47D cells derived from human breast carcinoma as measured by [3H]-thymidine incorporation (66% of the control value after 24-h incubation with 100 micrograms/ml). Dose-dependent hemolysis obtained with P. nigra extract on mouse erythrocytes had an EC50 +/- SEM = 1.12 +/- 0.02 mg/ml for a 0.5% erythrocyte suspension. Hemolysis could be reduced by pre-incubating the cells with choline-containing phospholipid. Sphingomyelin (40 micrograms/ml) increased the EC50 by two-fold to 2.86 +/- 0.04 mg/ml, but phosphatidylcholine (80 micrograms/ml) did not modify hemolysis.
authors: Departamento de Fisiologia, Universidade de São Paulo, Brasil.
authors: L V
authors: LV
authors: Costa
authors: E L
authors: EL
authors: Malpezzi
authors: D H
authors: DH
authors: Matsui
authors: G M
authors: GM
authors: Machado-Santelli
authors: J C
authors: JC
authors: Freitas
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D001938:Brazil; D006461:Hemolysis / Q000187:drug effects; D000432:Methanol / Q000378:metabolism / Q000633:toxicity*; D051379:Mice; D010741:Phospholipases A / Q000378:metabolism; D012617:Sea Urchins / Q000187:drug effects; D014561:Urochordata / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D010741:Phospholipases A; D000432:Methanol