Atividade Anticoagulante de Galactanas Sulfatadas de Algas Marinhas Vermelhas do Gênero Halymenia C. Agardh (Gigartinales, Rhodophyta) e seu Efeito Imunoestimulante no Camarão Marinho Litopenaeus vannamei (Boone, 1931)

Abstract

Many substances have been shown to possess anticoagulant and immunostimulant activities, including sulfated polysaccharides (SP) of marine algae. They also exhibit antithrombotic and antiviral activities. It is important to describe new substances capable of preventing known adverse effects of heparin such as hemorrhages and thrombocytopenia. Moreover, the use of immunostimulants can also lessen cultivated aquatic organism stress. The aim of this work was to evaluate both the anticoagulant activity of sulfated galactans present in two species of red marine seaweed belonging to genus Halymenia and their immunostimulant effects on white Pacific shrimp Litopenaeus vannamei. SP were extracted from marine seaweed collected in Praia de Fleixeiras-CE. Following the extraction, crude extracts were fractioned in DEAEcellulose column and fractions were eluted with different concentrations of NaCl solution. Fraction purification grade was evaluated by electrophoresis. Anticoagulant activity was analyzed by aPTT’s test using rabbit plasma and the clotting time was measured in a coagulometer. Three different amount of SP (0.5 and 1.5 μg.L-1 and 1.0 mg.L-1) were used twice a day (9 and 17h) to evaluate immunostimulant activity on L. vannamei through immersion baths, after changing tank water and before feeding the animals. The control group was maintained without SP addition. The experiment lasted 20 days. Shrimps were treated by immersion in SP for the first 15 days, and in the last 5 days they were submitted to stress when no water was renewed. There was no significant difference on mortality among the treatments. After the stress, the mortality of shrimps treated with 1.0 mg.L-1 was lower than the others (control group, 0.5 and 1.5 μg.L-1). Anticoagulant activity was detected in fractions obtained from H. pseudofloresia, the highest being in that eluted with 1.25 M NaCl from the first extraction procedure. Thus, it was possible to obtain SP from red marine seaweed H. pseudofloresia which showed higher anticoagulant activity than heparin and was capable of lowering mortality of L. vannamei under stress conditions.