Isolation, Structural Characterization, and Biological Activity of the Two Acidic Polysaccharides from the Fruits of the Elaeagnus angustifolia Linnaeus.

Elaeagnus angustifolia Linnaeus is a medicinal plant and its fruit has pharmacological activity such as antiinflammatory, antiedema, antinociceptive, and muscle relaxant functions, etc. Two acidic homogeneous polysaccharides (EAP-H-a1 and EAP-H-a2) were isolated from the fruits of Elaeagnus angustifolia L. through DEAE-52 and Sephadex G-75 column chromatography, and the physicochemical, structural properties, and biological activities of the polysaccharides were investigated. Both EAP-H-a1 and EAP-H-a2 were composed of Rha, Ara, Xyl, Glc, and Gal with the molar ratios of 13.7:20.5:23.3:8.8:33.4 and 24.8:19.7:8.2:8.4:38.6, respectively, and with the molecular weights of 705.796 kDa and 439.852 kDa, respectively. The results obtained from Fourier transform infrared spectroscopy (FTIR) confirmed the polysaccharide nature of the isolated substances. Congo red assay confirmed the existence of a triple-helix structure. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis revealed that EAP-H-a1 and EAP-H-a2 had irregular fibrous, filament-like surfaces; and both had crystalline and amorphous structures. Bioactivity analysis showed that the crude polysaccharide, EAP-H-a1, and EAP-H-a2 had clear DPPH and ABTS free radical scavenging activity, and could promote the secretion of NO and the phagocytic activities of RAW 264.7 and THP cells, which showed clear antioxidant and immuno-regulatory activity. These results indicated that Elaeagnus angustifolia L fruit acidic polysaccharides may have potential value in the pharmaceutical and functional food industries.

Structural characterization and antioxidant activities of a water soluble polysaccharide isolated from Glycyrrhiza glabra.

A water-soluble polysaccharide, named GPN, with molecular mass 38.7 kDa was isolated from Glycyrrhiza glabra with hot water extraction, ethanol precipitation, and purified by column chromatography. Monosaccharide composition analysis confirmed the presence of predominant glucose (98.03%) and trace amount of mannose, arabinose, and galactose. Methylation and GC-MS analysis revealed that the main glycosidic bonds in GPN comprised 1,4-linked Glcp, T-linked Glcp, 1,4,6-linked Glcp, and 1,6-linked Glcp. Based on these results and 1D/2D NMR spectroscopy, GPN has a linear backbone of 1,4-linked α-D-Glcp and 1,6-linked α-D-Glcp which substituted at C-4 of glucose. The side chain probably composed from 1,4-linked to main side α-D-Glcp and terminal 1-linked ß-D-Glcp to the C-3 of D residue. Congo red assay confirmed the existence of triple helix structure. Moreover, SEM and XRD analysis revealed that the GPN had irregular fibrous, filaments like surface; and both crystalline and amorphous structure. GPN also displayed favorable thermal stability. Moreover, G.glabra polysaccharide showed good antioxidant activity.