The bark of Parkia biglobosa is used in traditional medicine to cure a wide range of illnesses. Polysaccharides were extracted from the bark with 50% ethanol-water, 50°C and 100°C water, and seven active fractions obtained by anion exchange chromatography and gel filtration. The complement fixation and macrophage stimulating activities of the different fractions were determined. The acidic fractions PBEII-I and PBEII-IV were the most active in the complement fixation assay, but the other fractions were also potent compared to the positive control BPII from Biophytum petersianum. Fractions PBEII-I and PBEII-IV were also the most potent fractions in stimulating macrophages to release nitric oxide. Structural studies showed that PBEII-I and PBEII-IV were pectic type polysaccharides, containing arabinogalactan type II structures. The observed differences in biological activities among the seven purified polysaccharide sub-fractions are probably due to differences in monosaccharide compositions, linkage types and molecular sizes.
Keywords: 4-O-methyl-glucuronic acid; 4-OMe-GlcA; AG-I; AG-II; Ara; Complement system; GC–MS; Gal; GalA; Glc; GlcA; Immunomodulation; LPS; Macrophage stimulation; Man; NO; Parkia biglobosa; Pectic polysaccharides; RG-I; RG-II; Rha; Xyl; arabinogalactan type I; arabinogalactan type II; arabinose; galactose; galacturonic acid; gas chromatography–mass spectrometry; glucose; glucuronic acid; lipopolysaccharide; mannose; nitric oxide; rhamnogalacturonan type I; rhamnogalacturonan type II; rhamnose; xylose.
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