Biological activity in extracts of ascidians (Tunicata, Ascidiacea) from the northeastern Brazilian coast

Ascidians are marine animals with a great ability to synthesize bioactive substances, This study examined the cytotoxic potential of 10 ascidians found in the coastal waters of Northeast Brazil. Samples of the species Eudistoma vannamei Millar, 1977, Eudistonza sp., Didemnum ligulum Monniot F., 1983, Didemnum psammatodes (Sluiter, 1895), Didemnum sp., Polysyncraton sp., Trididemium sp., Cystodytes dellechiajei (Della Valle, 1877), Euherdmania sp., and an unidentified species belonging to the Holozoidae family were extracted in methanol 5:1 (v/w). The extracts were tested for cytotoxicity using the brine shrimp lethality assay, sea urchin egg development assay, hemolysis assay, and MTT assay using tumor cell lines. The extract of E. vannamei showed the highest toxicity in brine shrimp (LD50 = 34.7 mug/ml) and in all tumor cell lines tested, with an IC50 of <2 mug/ml for CEM, 11.2 mug/ml for HL-60, 23.8 mug/ml for B16, and 14.3 mug/ml for HCT-8. In sea urchin eggs, it inhibited the cell cycle progression mainly at the blastula stage (IC50 = 74.8 mug/ml). The extract of Euherdmania sp. also exhibited some toxicity in these assays, but at a lower potency than that of E. vannamei. The extracts of D. psammatodes and Polysyncraton sp. showed a strong inhibition of the sea urchin egg cell cycle during both phases examined, first cleavage and blastula, with a possible action on the cell microfilament apparatus. The extract of D. ligulum showed selective toxicity toward HCT-8 cells (IC50=35.3 mug/ml). The extract from the Holozoidae was the only one that possessed a hemolytic effect, with an IC50 of 175.2 mug/ml. Further studies are necessary for a better characterization of the active principles of these extracts and a Possible elucidation of the mechanisms of action. (C) 2002 Elsevier Science B.V. All rights reserved.