Poster 212 - Preliminary studies with extracts of Astropecten marginatus collected from Caraguatatuba

Poster 212. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.571.

Preliminary studies with extracts of Astropecten marginatus collected from CaraguatatubaBay, São Paulo, Brazil.

¹Naves, J.L.; ²Dias, G. M.; ³Delboni, C. G. M.; ²Majer, A. P.; ¹Freitas, J.C.

1 Dpto. Fisiologia, IB, USP; 2 Dpto. Zoologia, IB, UNICAMP; 3 Dpto. Zoologia, IB, USP, Brasil.

Introduction: Echinoderms are susceptible to predation, its abundance suggest that they are able to resist predators through effective defense mechanisms. Previous studies have focused on the secondary metabolite chemistry of echinoderm tissues, and revealed saponin compounds in asteroids. Saponins have been shown to elicit detergent-like effects on cell membranes causing cell lysis. At Caraguatatuba Bay, Astropecten marginatus is na abundant starfish species, feeding upon the clam Tivela mactroides, which is commercially explored as food by local people. The present study examines pharmacological activity of tissues isolated of A. marginatus and possible relationship with their food.

Materials and Methods: Fresh specimens of A. marginatus were collected at Caraguatatuba Bay, in the coast of São Paulo States, Brazil. The animals were measured, weighed, dissected and frozen. The caecum and gonads were weighed and analyzed separately. After homogenization in MeOH and filtration, the extracts were dried out on a rotary vacuum-evaporator (50 ºC), dissolved in Krebs physiological solution and tested in the hemolytic assays using mice erytrocytes.

Results and discussion: The A. marginatus extracts induced hemolysis (CE₅₀ 187,7 ug/mL, IC 93,75 to 375,8 ug/mL). Previous studies with A. irregularis aqueous extracts by others authors were found to produce muscle contractions in its prey gastropod Buccinum undatum and sulfated mucopolysaccharide was found in the starfish tube feet aqueous extracts and may be responsible for the clam Pecten maximus escape response. T. mactroides is not able to exhibit escape responses and it may explain why this prey is easily caught by A. marginatus. It is well known that starfishes possess water soluble heat-stable toxic saponin substances (known as asterosaponins) and its hemolytic activity was studied in rabbit erythrocytes and it was also found to be lethal for fishes (Fundulus heteroclitus). Fishes may die because of gill epithelia damage induced by the saponin cytolytic effects. A. marginatus saponins may protect itself from fish predation. These data are the first toxinologycal studies with A. marginatus from the brazilian coast.