RESUMO
Four polysaccharides Pc-1, Pc-2, Pc-3 and Pc-4 were isolated from water and alkali extracts of the lichen Peltigera canina using ethanol fractionation, gel filtration and preparative HP-GPC. The monosaccharide composition was determined by methanolysis and GC and showed mannose and galactose as the predominating structural units. The mean M(r) was determined by HP-GPC. The heteroglycans were tested for in vitro immunomodulating activities and showed mitogenic activity in rat spleen cell proliferation assay and stimulated IL-10 secretion. In rat peritoneal macrophages, the heteroglycans stimulated TNF-alpha secretion, but not IL-10 secretion. These results indicate that the polysaccharides influence cells of the immune system both from the innate and the adaptive systems.
Assuntos
Fatores Imunológicos/farmacologia , Líquens , Fitoterapia , Extratos Vegetais/farmacologia , Baço/efeitos dos fármacos , Fator de Necrose Tumoral alfa/efeitos dos fármacos , Animais , Proliferação de Células/efeitos dos fármacos , Feminino , Fatores Imunológicos/administração & dosagem , Fatores Imunológicos/uso terapêutico , Interleucina-10/biossíntese , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Ratos , Ratos Endogâmicos Lew , Baço/citologia , Baço/metabolismo , Fator de Necrose Tumoral alfa/biossínteseRESUMO
A lentinan-type gel-forming beta-glucan, Ths-2, has been isolated in about 1.5% yield from the alkali extract of the lichen Thamnolia vermicularis var. subuliformis, using ethanol fractionation, dialysis and gel filtration. The mean Mr of Ths-2 was determined by GP-HPLC to be 67 kD, and the optical rotation was measured to be -14 degrees. The structure of Ths-2 was further elucidated by methylation analysis by GC-MS, 1H- and 13C-NMR spectroscopy and selective enzymatic hydrolysis with exo-(1 --> 3)-beta-D-glucanase followed by analysis of oligosaccharides by HPAEC-PAD. Ths-2 was found to be consisting of a (1 --> 3)-beta-D-glucopyranosyl main chain with branches of a (1 --> 6) linked glucopyranosyl unit on every third unit of the main chain. Similar polysaccharide structures have been described from fungi, but this is the first report of a lentinan-type (1 --> 3)-beta-D-glucan from a lichen species. The immunomodulating activity of Ths-2 was tested in an in vitro anti-complementary assay, and proved to be strongly active.
