No abstract

In this study, the edible mycelia of Cordyceps sinensis (Berk.) Sacc. were sequentially extracted by petroleum ether, ethyl acetate, ethanol and ultrasonic water-bath (75 degrees C), and the water extract was further isolated by Sephadex G-100 to afford a petroleum ether extract (PE), ethyl acetate extract (EAE), ethanol extract (EE), glycoprotein (GP) and a purified polysaccharide (PS). In combination with component analysis, the isolated PS showed d-Glc, d-Man, l-Ara and d-Gal in a molar ratio of 8:90:1:1. The average molecular weight of PS was determined as approximately 8.3 x 10(4). The immunomodulatory potentials of these samples (PE, EAE, EE, GP and PS) at three dose levels on the cellular and humoral immune responses of ICR mice against ovalbumin (OVA) were studied. ICR mice were immunized subcutaneously with 100 microg OVA alone or with 100 microg OVA dissolved in saline containing these samples (100, 200 or 400 microg) on days 1 and 15. Two weeks later (day 28), concanavalin A (Con A)- and OVA-stimulated splenocyte proliferation and OVA-specific antibody in serum were investigated. These samples, except for PS, significantly enhanced the Con A- and OVA-induced splenocyte proliferation in OVA-immunized mice at a suitable dose (p < 0.05 or p < 0.01). OVA-specific IgG, IgG1 and IgG2b antibody levels in serum were significantly enhanced by these extracts and PS compared with the OVA control group (p < 0.05, p < 0.01 or p < 0.001).

A technique of high-performance gel permeation chromatography (HPGPC)-evaporative light-scattering detection and circular dichroism (CD) was developed for the measurement of thermal effects on the homogeneity and conformation of polymeric carbohydrate conjugates and was applied to an acid polysaccharide conjugate (GTa) isolated from the composite enzyme extract of green tea. Incubations in water at 40 and 70 degrees C for 1.0, 2.5, and 5.0 h have no effects on GTa. In contrast, when incubated in water for 1.0, 2.5, and 5.0 h at 98 degrees C, a single symmetrical peak corresponding to GTa in HPGPC was split into two adjacent peaks representing two different components formed, and CD spectra revealed an additional positive Cotton effect at 216 nm. To contribute toward our understanding of thermal effects of this polymeric carbohydrate conjugate on antioxidant activity, GTa and related heat-treated samples (GTa-HTI, GTa-HTII, and GTa-HTIII), the latter being obtained from 1.0, 2.5, and 5.0 h incubations at 98 degrees C, respectively, were subjected to the self-oxidation of 1,2,3-phentriol assay and found to have respective scavenging activities in a concentration-dependent manner. In comparison with GTa, the scavenging potency of heat-treated samples was similar at the dosage range of 50-300 microg/mL but became stronger with continually increasing concentration. Moreover, the present study also provides further insights into the optimal preparation of tea polysaccharide conjugates.

Abstract:In order to investigate the antioxidant properties of the polysaccharides from the brown alga Sargassum fusiforme, the crude polysaccharides from S. fusiforme (SFPS) were extracted in hot water, and the lipid peroxidation inhibition assay exhibited that SFPS possessed a potential antioxidant activity. Hence, two purely polymeric fractions, SFPS-1 and SFPS-2 were isolated by the column of DEAE (2-diethylaminoethanol)-Sepharose Fast Flow, with their molecular weights of 51.4 and 30.3 kDa determined by high performance gel permeation chromatography (HPGPC). They were preliminarily characterized using chemical analysis in combination of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and found to contain large amounts of uronic acids and β-glycosidical linkages. The antioxidant activities of these two SFPS fractions were evaluated using superoxide and hydroxyl radical-scavenging assays. The results show that the antioxidant ability of SFPS-2 was higher than that of SFPS-1, probably correlating with the molecular weight and uronic acid content.

A water-soluble glycopeptide (PGY), fractionated and purified from the aqueous extract of the fruiting bodies of Ganoderma lucidum via two-step dialysis, anion-exchange and gel permeation chromatography, was constituted of two moieties of carbohydrate and peptide. Carbohydrate characterization with component analysis, methylation analysis, periodate oxidation, Smith degradation, enzymic hydrolysis, and IR and NMR experiments demonstrated that the carbohydrate moiety possessed a backbone of approximately thirty-three (1 → 3)-linked β-D-glucopyranosyl residues, and side chains, at positions 6, of single α-L-arabinofuranosyl residues for every three Glcp residues in the main chain. On the basis of the results of amino acid composition and trypsin digestion, the peptide moiety shown to consist of Arg, Ser, Ala, and Gly in a ratio of 1:1:2:2, exhibited the sequence of Ser-Arg-[(Ala)2(Gly)2], and was O-attached to the carbohydrate moiety via Ser. To contribute toward our understanding of structure-activity relationship, a series of expected derivatives generated from PGY by trypsin digestion, debranching, and NaIO4-oxidation following reduction experiments, including PTC, DB-PGY, and PPP, were obtained. All of them, as well as PGY and reference compound (BHT), were evaluated with two conventional antioxidant testing systems of DPPH and superoxide radicals scavenging, and found to have their respective antioxidant activities in a concentration-dependent manner. Comparable radical scavenging activities observed between PTC and PGY demonstrated that the removal of Ala and Gly in peptide moiety did not result in the variation of biological functions of PGY. However, it was very interesting to note that the scavenging activity of PPP was higher for DPPH radicals with an SC50 value of 116.4 ± 5.1 μg/mL, and lower for superoxide radicals with an SC50 value of 205.2 ± 14.4 μg/mL than that of PGY with corresponding SC50 values of 133.5 ± 5.5 and 140.5 ± 7.7 μg/mL, and moreover, DB-PGY displayed the weakest scavenging potency in the tested samples, indicating that the carbohydrate moiety, in particular the side chain of nonreducing end-units of Araf residues as the functional region played a vital role in the structure and antioxidant activity. In addition, compared with the SC50 value of BHT, PGY showed lower DPPH radical scavenging activity, but possessed higher superoxide radical quenching potency, suggesting that it could be presented as a possible new source of natural antioxidants.