AvaliaÃÃo do efeito da α-d-glucana sulfatada do lÃquen Ramalina celastri livre e encapsulada em lipossomas frente à infecÃÃo experimental por Schistosoma mansoni

AUTOR(ES)

Rosangela Vidal De Souza AraÃjo

DATA DE PUBLICAÇÃO

2004

RESUMO

Liposomes have been considered successful drug carriers in vivo. A variety of polysaccharide act as biological response modifiers (BRM). The antischistosomal activity of the polysaccharide α-glucana-SO4, extracted from Ramalina celastri, was examined. Both free and liposome-encapsulated forms of α-glucana-SO4 were considered. Liposomes were obtained according to the lipid thin film method. The effect of the treatment with unloaded and α-glucana-SO4-loaded liposomes on egg excretion, worm burden, hepatic and intestine granuloma formation was assessed on infected Swiss albino mice. Furthermore, histochemical analyses of liver and intestine were carried out using peroxidase-conjugated lectins (WGA and Con A). Swiss albino female mice (four groups, n=10 animals/group) were infected with about 150 cercariae of Schistosoma mansoni, and treated with i.p. single dose (10 mg/kg) 24 h after infection. Fifty-six days after infection, animals were sacrificed, and submitted to perfusion. Their liver and intestine were colected and submitted to histological routines. Liposomes containing 2 mg/ml α-glucana-SO4 were manufactured with an encapsulation ratio of 50%. Parasitological analysis (eggs excretion and worms recovered) revealed that the treatment with free α-glucana-SO4 was as efficient as its encapsulated form; nevertheless, the control group of empty-liposomes exhibited an unexpected parasitological effect. Concerning the hepatic granuloma formation, only the treatment with free and encapsulated α-glucana-SO4 (62% and 63%, respectively), when compared to the control groups. However, a few intestine granulomas were detected. The histochemical profile of egg-granuloma system showed that Con A promoted an intense staining in hepatic cells of animals treated with free and encapsulated α-glucana-SO4, whereas the egg-granuloma system of the control groups 150 mM NaCl and empty liposomes was not at all reconized by this lectin. . The WGA lectin, was intensely bounded with cells in egg-granuloma system for all groups. In conclusion the antischistosomal effect of the polysaccharide was characterized

ASSUNTO(S)

ramalina celastri schistosoma mansoni lipossomas bioquimica

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