Chemical composition and antitumor activity of polysaccharide from Inonotus obliquus

Abstract

The alkaline soluble polysacchride AIOPA isolated and purii¬ed from Inonotus obliquususing gel i¬ltration was subjected to composition analysis and determined for the antitumor and immunomodulatory activitives. Based on the results of high performance size-exclusion chromatography (HPSEC), gas chromatography (GC) and infra-red (IR) spectrum, AIOPA consisted of rhamnose, xylose, manose, galactose, glucose and galacturonic acid in a molar ratio of 3.09:1.61:2.06:4.45:19.7:1 with a molecular weight of 6.3 kDa. In the present study, it was found that AIOPA remarkably enhanced spleen and thymus index in mice bearing S180 sarcoma, and also stimulated LPS-induced splenocyte proliferation. Immunomodulatory activity assay in vitro indicated AIOPA could signii¬cantly enhance cellular lysosomal enzyme activity, nitric oxide (NO) formation and tumor necrosis factor-a (TNF-α) secretion in macrophages. Furthermore, AIOPA dose-dependently stimulated macrophages to produce NO through the up-regulation of inducible NO synthase (iNOS) activity and the maximal effect occurred at a concentration of 300 ug/ml by AIOPA.These data suggest that the antitumor activity of AIOPA may be associated with its potent immunostimulating effect. Key words: Inonotus obliquus, polysaccharide, immunomodulatory, antitumor.