A Water-Soluble Polysaccharide from the Fruit Bodies ofBulgaria inquinans(Fries) and Its Anti-Malarial Activity

Abstract

A water-soluble polysaccharide (BIWS-4b) was purified from the fruit bodies ofBulgaria inquinans(Fries). It is composed of mannose (27.2%), glucose (15.5%) and galactose (57.3%). Its molecular weight was estimated to be 7.4 kDa (polydispersity index, Mw/Mn: 1.35). Structural analyses indicated that BIWS-4b mainly contains (1→6)-linked, (1→5)-linked and (1→5,6)-linkedβ-Galfunits; (1→4)-linked and non-reducing terminalβ-Glcpunits; and (1→2)-linked, (1→6)-linked, (1→2,6)-linked and non-reducing terminalα-Manpunits. When examined by the 4-day method and in a prophylactic assay in mice, BIWS-4b exhibited markedly suppressive activity against malaria while enhancing the activity of artesunate. Immunological tests indicated that BIWS-4b significantly enhanced macrophage phagocytosis and splenic lymphocyte proliferation in malaria-bearing mice and normal mice. The anti-malarial activity of BIWS-4b might be intermediated by enhancing immune competence and restoring artesunate-suppressed immune function. Thus, BIWS-4b is a potential adjuvant of anti-malaria drugs.