Xue-Qiang Zha

Comparison of hypoglycemic and antioxidative effects of polysaccharides from four different Dendrobium species

Four polysaccharides from Dendrobium huoshanense (DHP), D. officinale (DOP), D. nobile (DNP) and D. chrysotoxum (DCP), which had obvious differences in intrinsic viscosities and monosaccharide compositions, were extracted to compare their hypoglycemic and antioxidative activities in alloxan-induced diabetic mice by oral administration. The analysis of fasting blood glucose, glycosylated serum protein and serum insulin levels showed that DHP, DOP and DNP, but not DCP, possessed significant hypoglycemic effect with the decreasing order of DHP>DNP>DOP. Histopathological observation confirmed the capability of DHP, DOP and DNP to intervene the damage in pancreas tissues. The determination of superoxide dismutase, catalase, malonaldehyde and L-glutathione levels in the liver and kidney displayed that DHP, DOP and DNP had protective effects against alloxan-induced oxidative damage and the effect of DHP ranked first. These results suggested that there were significant differences in hypoglycemic and antioxidative activities between four Dendrobium polysaccharides, which may be contributed to their physicochemical properties.

Structural characterisation, physicochemical properties and antioxidant activity of polysaccharide from Lilium lancifolium Thunb.

A novel polysaccharide fraction (LP2-1) was isolated and purified from the edible bulbs of Lilium lancifolium Thunb. by DEAE cellulose chromatography and Sephacryl S-400 size-exclusion chromatography. The structural characterisation, physicochemical properties and antioxidant activity of LP2-1 were investigated. The results showed that LP2-1 had an average molecular weight of approximately 8.52×10(3)kDa and was mainly composed of l-rhamnopyranose, d-arabinofuranose, d-glucopyranose and d-galactopyranose in the molar ratio of 1.88:2.13:1.00:2.50, and major functional groups of LP2-1 were COO and OH. The viscoelastic properties of LP2-1 systems exhibited a gel-like behaviour, with storage modulus higher than loss modulus, and both moduli increased with increasing Ca(2+) concentration. In addition, LP2-1 had DPPH and hydroxyl radicals scavenging activities, and also had the strong reducing power and chelating activity on ferrous ion. These results suggest that LP2-1 has good antioxidant activity and can be used in food industry.

Structural analysis and antioxidant activities of polysaccharide isolated from Jinqian mushroom.

Jinqian mushroom is a precious edible mushroom with delicious taste and high nutritional value. In this paper, a polysaccharide fraction JQPs was isolated and purified from the fruiting body of Jinqian mushroom. The chemical structure, chain conformation and antioxidant activities of JQPs were investigated. The results indicated that JQPs was mainly composed of glucose with trace amounts of xylose. The backbone of JQPs consisted of β-(1 → 3)-D-glucan with β-(1 → 6)-glucosyl side chain. The chain conformation analysis showed that JQPs was a triple helical polysaccharide. The antioxidant activity tests in vitro revealed that JQPs exhibited high DPPH radical and ABTS radical scavenging activities, moderate superoxide radical and hydroxyl radical scavenging activities, low reducing power and Fe(2+) chelating activities. The results suggested that JQPs could be used as a potential natural antioxidant.

Advances on Bioactive Polysaccharides from Medicinal Plants

In recent decades, the polysaccharides from the medicinal plants have attracted a lot of attention due to their significant bioactivities, such as anti-tumor activity, antioxidant activity, anticoagulant activity, antidiabetic activity, radioprotection effect, anti-viral activity, hypolipidemic and immunomodulatory activities, which make them suitable for medicinal applications. Previous studies have also shown that medicinal plant polysaccharides are non-toxic and show no side effects. Based on these encouraging observations, most researches have been focusing on the isolation and identification of polysaccharides, as well as their bioactivities. A large number of bioactive polysaccharides with different structural features and biological effects from medicinal plants have been purified and characterized. This review provides a comprehensive summary of the most recent developments in physiochemical, structural features and biological activities of bioactive polysaccharides from a number of important medicinal plants, such as polysaccharides from Astragalus membranaceus, Dendrobium plants, Bupleurum, Cactus fruits, Acanthopanax senticosus, Angelica sinensis (Oliv.) Diels, Aloe barbadensis Miller, and Dimocarpus longan Lour. Moreover, the paper has also been focused on the applications of bioactive polysaccharides for medicinal applications. Recent studies have provided evidence that polysaccharides from medicinal plants can play a vital role in bioactivities. The contents and data will serve as a useful reference material for further investigation, production, and application of these polysaccharides in functional foods and therapeutic agents.

Polysaccharide of Dendrobium huoshanense activates macrophages via toll-like receptor 4-mediated signaling pathways

The present work aimed at investigating the pattern recognition receptor (PRR) and immunostimulatory mechanism of a purified Dendrobium huoshanense polysaccharide (DHP). We found that DHP could bind to the surface of macrophages and stimulate macrophages to secrete NO, TNF-α and IL-1β. To unravel the mechanism for the binding of DHP to macrophages, flow cytometry, confocal laser-scanning microscopy, affinity electrophoresis, SDS-PAGE and western blotting were employed to verify the type of PRR responsible for the recognition of DHP by RAW264.7 macrophages and peritoneal macrophages of C3H/HeN and C3H/HeJ macrophages. Results showed that toll-like receptor 4 (TLR4) was an essential receptor for macrophages to directly bind DHP. Further, the phosphorylation of ERK, JNK, Akt and p38 were observed to be time-dependently promoted by DHP, as well as the nuclear translocation of NF-κB p65. These results suggest that DHP activates macrophages via its direct binding to TLR4 to trigger TLR4 signaling pathways.

Immunomodulatory activity on macrophage of a purified polysaccharide extracted from Laminaria japonica.

In this work, a novel water-soluble homogeneous polysaccharide (LJP-31) with a molecular mass of 2.24 × 10(6) Da was isolated and purified from Laminaria japonica using DEAE-cellulose and Sephacryl S500 chromatography. Results showed that LJP-31 mainly consists of arabinose, mannose, glucose and galactose in a molar ratio of 1.0:7.8:6.6:0.8. LJP-31 exhibited significant stimulation on macrophages and enhanced the production of NO, TNF-α, IL-1β, IL-6 and IL-10 as well as the up-regulation of their gene expressions. Western blot analysis suggested that LJP-31 has the positive effects on the translocation of NF-κB p65 from cytoplasm to nucleus and the phosphorylation of IκBα, ERK1/2, JNK1/2 and P38 in macrophages. Flow cytometric and confocal laser-scanning microscopy analysis indicated that toll-like receptor 4 (TLR4) was at least one of the recognition receptors of LJP-31 on the plasma membrane of macrophages. Taken together, LJP-31 may exert its immunostimulating potency via TLR4 activation of MAPK and NF-κB signaling pathways.

Structural identification and sulfated modification of an antiglycation Dendrobium huoshanense polysaccharide

Dendrobium huoshanense, an important food material, has been used to make teas and soups in the folk of China for centuries. In the present study, an antiglycation polysaccharide DHPD2 with molecular weight of 8.09 × 10(6)Da was extracted from the protocorm-like bodies of D. huoshanense. The backbone of DHPD2 contained (1→5)-linked α-l-Araf, (1→6)-linked α-d-Glcp, (1→6)-linked β-d-Glcp, (1→4)-linked β-d-Glcp, (1→3,6)-linked β-d-Galp and (1→6)-linked β-d-Galp, with the branches of terminal α-d-Xlyp and β-d-Manp. DHPD2 was further modified using chlorosulfonic acid-pyridine method, giving two sulfated derivatives with the substitution degree of 0.475 and 0.940. The appearance of two new characteristic absorption bands at near 1250 and 822cm(-1) in FT-IR spectra revealed the success of sulfation occurred to DHPD2. Moreover, the sulfated derivatives exhibited stronger inhibitory abilities on protein glycation than those of DHPD2. NMR analysis disclosed that the sulfation on C2 and C6 of sugar residues was beneficial to enhance this activity.

Physicochemical properties and antioxidant activities of polysaccharide from floral mushroom cultivated in Huangshan Mountain.

In this paper, a polysaccharide fraction (FMPS) was purified from the floral mushroom cultivated in Huangshan Mountain for the first time. Physicochemical properties and antioxidant activities of FMPS were investigated. FMPS had an average molecular weight of 7.2×10(5)Da and was composed of glucose. On the basis of FT-IR, NMR and methylation analysis, the repeating unit of FMPS was established as (1→3)-linked β-d-glucopyranosyl backbone with 1-linked β-d-glucopyranosyl branches substituted at O-6 position of (1→3)-linked β-d-glucopyranosyl residues. The advanced structure studies indicated that FMPS was a triple-helical polysaccharide. The main hydrodynamic radius (Rh) of FMPS was 23.4nm and it could form a stable system with water in 1.2×10(-2)g/mL solutions. In addition, FMPS exhibited high DPPH radical scavenging activities (79.46% at 5mg/mL) and hydroxyl radical scavenging activities (74.18% at 5mg/mL), as well as Fe(2+)chelating activities and ABTS radical scavenging activities to some extent.

An acetylated galactomannoglucan from the stems of Dendrobium nobile Lindl

A water-soluble polysaccharide DNP-W2 composed of glucose, mannose, and galactose in the molar ratio of 6.1:2.9:2.0 had been isolated from the stems of Dendrobium nobile. Its molecular weight was 1.8 x 10(4) Da determined by HPGPC. Structural features of DNP-W2 were investigated by a combination of chemical and instrumental analysis, including FTIR, GC, GC-MS, periodate oxidation-Smith degradation, methylation analysis, partial acid hydrolysis, and NMR spectroscopy. The results showed that DNP-W2 is a 2-O-acetylgalactomannoglucan and has a backbone consisting of (1-->4)-linked beta-D-Glcp, (1-->6)-linked beta-D-Glcp, and (1-->4)-linked beta-D-Manp, with branches at O-6 of (1-->4)-linked beta-D-Glcp and beta-D-Manp. The branches are composed of alpha-D-Galp. The acetyl groups are substituted at O-2 of (1-->4)-linked Manp. Preliminary tests in vitro reveals that DNP-W2 can stimulate ConA- and LPS-induced T and B lymphocyte proliferation.

Protective effect of polysaccharides from Opuntia dillenii Haw. fruits on streptozotocin-induced diabetic rats.

In this study, a novel water-soluble polysaccharide fraction with molecular weight of 6479.1kDa was isolated from the fruits of Opuntia dillenii Haw., which consisted of rhamnose, xylose, mannose and glucose in the molar ratio of 14.99:1.14:1.00:6.47. The protective effect of O. dillenii Haw. fruits polysaccharide (ODFP) against oxidative damage in streptozotocin (STZ)-induced diabetic rats was investigated. The results showed that oral administration of ODFP significantly decreased food intake, water intake, urine production, organ weights and blood glucose level, and increased body weight in STZ-induced diabetic rats. ODFP also significantly increased the activities of SOD, GPx and CAT, and decreased malondialdehyde level in serum, liver, kidney, and pancreas in STZ-induced diabetic rats. Moreover, histopathological examination showed that ODFP could markedly improve the structure integrity of pancreatic islet tissue in STZ-induced diabetic rats. These results suggest that ODFP have hypoglycemic and antioxidant properties and can protect rats from STZ-induced oxidative damage.