Li-Hua Pan

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.

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.

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.

Structural characterization and antioxidant activity of a low-molecular polysaccharide from Dendrobium huoshanense.

The present study aimed at investigating the structural features and antioxidant activities of a polysaccharide fraction (DHP1A) obtained from Dendrobium huoshanense, a precious herb medicine in China. DHP1A mainly consisted of mannose (Man), glucose (Glc) and a trace of galactose (Gal), with a molecular weight of 6700Da. Its backbone contained (1→4)-linked α-D-Glcp, (1→6)-linked α-D-Glcp and (1→4)-linked β-D-Manp, with a branch of terminal β-D-Galp. The in vitro antioxidant evaluation revealed that DHP1A had a remarkable inhibition effect on the FeCl2-induced lipid peroxidation. Furthermore, DHP1A pretreatment decreased the production of malondialdehyde (MDA), and restored the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the level of glutathione (GSH) in the livers of CCl4-treated mice. These results suggested that DHP1A was a potential antioxidant component in D. huoshanense.

Preventive effect of a galactoglucomannan (GGM) from Dendrobium huoshanense on selenium-induced liver injury and fibrosis in rats

This study was carried out to investigate the preventive effects of galactoglucomannan (GGM), a homogeneous polysaccharide from Dendrobium huoshanense, on liver injury and fibrosis induced by sodium selenite. Sprague-Dawley rats injected subcutaneously with sodium selenite at the dosage of 3.28 mgkg(-1) b.wt. were set as the model groups. Rats treated with sodium selenite at the dosage of 3.28 mgkg(-1) b.wt. and GGM at 50-200 mgkg(-1) b.wt. were set as the prevention groups. Biochemical and histological analysis showed that GGM significantly ameliorated selenite-induced liver injury and fibrosis in rats. Oral administration of GGM effectively attenuated the toxicity of selenite to liver tissue, which was judged both by the decreased activities of serum hepatic enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), and by liver histopathological examination. Meanwhile, GGM also reduced the levels of H(2)O(2) and malondialdehyde (MDA), elevated the levels of GSH, restored the fluidity of hepatic plasma membrane, and retained the activities of endogenous enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). The prevention of selenite-induced liver injury and fibrosis by GGM was further supported by the reduced expression of transforming growth factor-β1 (TGF-β1) and type I collagen. These results suggested that GGM may be developed into a novel antifibrotic agent for the prevention of liver injury and fibrosis.

Structure and bioactivity of a polysaccharide extracted from protocorm-like bodies of Dendrobium huoshanense

The crude polysaccharides of Dendrobium huoshanense were fractionated by anion-exchange chromatography and gel permeation chromatography, giving one homogeneous fraction DHP-4A with molecular weight of 2.32 × 10(5)Da. UV spectrum indicated that there was no existence of proteins and nucleic acids in DHP-4A. Monosaccharide analysis revealed that DHP-4A was made up of glucose, arabinose, mannose and rhamnose with a molar ratio of 13.8:3.0:6.1:2.1. The backbone of DHP-4A consisted of (1 → 6)-linked glucose, (1 → 6)-linked mannose and (1 → 3,6)-linked mannose. The βL-Rhap-(1 → 2)-β-L-Rhap-(1 → 4)-β-D-Manp-(1 → and α-L-Araf-(1 → 3)- α-L-Araf -(1 → 3)-α-L-Araf-(1 → were regarded as the branches attached to the C-3 position of (1 → 6)-linked mannose in the backbone. The sugar residue sequence was further determined by NMR spectra including (1)H NMR, (13)C NMR, HSQC and HMBC. Pharmacological tests showed that DHP-4A can significantly stimulate RAW 264.7 macrophage cells to secrete NO, TNF-α, IL-6 and IL-10 via activation of p38, ERK, JNK and translocation of nuclear NF-κB, indicating this polysaccharide possesses good immunoregulatory activity.

Immunoregulatory activities of Dendrobium huoshanense polysaccharides in mouse intestine, spleen and liver.

To evaluate the immunomodulating responses in intestine, spleen and liver, 50-200mg/kg of DHP was orally administrated to mice without or with methotrexate. The proliferation of marrow cells, which was performed with the addition of the supernatant of small intestinal lymphocytes isolated from the mice administrated orally with DHP, showed that the intestinal immune response was significantly enhanced in all DHP-treated groups. For the immune response in spleen, all tested doses of DHP remarkably promoted the proliferation of splenic cells and increased the secretion of interferon-γ (IFN-γ). For the immune responses in liver, DHP not only significantly stimulated the proliferation of hepatic cells and the secretion of IFN-γ at all tested doses of DHP, but also significantly elevated the secretion interleukin-4 (IL-4) at the doses of 100 and 200mg/kg. Moreover, DHP could recover methotrexate-injured small intestinal immune function (100 and 200mg/kg) and promoted cell proliferation and IFN-γ production (200mg/kg) in spleen and liver of methotrexate-treated mice. These results suggested that DHP after oral administration possessed immunomodulating effects both in small intestine immune system and in systemic immune system, which were further proved by the mRNA expression of IFN-γ and IL-4.

Dendrobium huoshanense polysaccharide prevents ethanol-induced liver injury in mice by metabolomic analysis.

The prevalence of alcohol consumption has increased in modern dietary life and alcoholic liver injury can follow. Dendrobium huoshanense polysaccharide (DHP) is a homogeneous polysaccharide isolated from Dendrobium huoshanense, which possesses hepatoprotection function. In this study, we investigated the metabolic profiles of serum and liver tissues extracts from control, ethanol-treated and DHP\ethanol-treated mice using a UHPLC/LTQ Orbitrap XL MS-based metabolomics approach. Our results indicated that DHP alleviated early steatosis and inflammation in liver histology and the metabolomic analysis of serum and hepatic tissue revealed that first, ethanol treatment mainly altered phosphatidylcholines (PCs) including PC (13:0) and phosphocholine, arachidonic acid metabolites including 20-ethyl PGF2α and amino acids including L-Proline; Second, DHP supplementation ameliorated the altered metabolic levels particularly involved in phosphocholine and L-Proline. These data suggested that DHP might restore the perturbed metabolism pathways by ethanol exposure to prevent the progression of alcoholic liver injury.

Structural identification and immunostimulating activity of a Laminaria japonica polysaccharide

In the present study, a new water-soluble polysaccharide (LJP-11) was obtained from Laminaria japonica by anion exchange DEAE-cellulose chromatography and Sephacryl S-500 chromatography. The average molecular weight of this polysaccharide was estimated to be about 2.89×10(6) Da by high performance liquid chromatography system. Gas chromatography showed that LJP-11 was composed of arabinose, mannose and glucose in a molar ratio of 1.0:1.16:6.33. LJP-11 contains a long backbone consisting of (1→4)-β-D-GlcpAc, (1→4)-α-D-Glcp, (1→6)-β-D-Glcp and (1→3,6)-α-D-Manp. The 1-linked β-L-Araf was linked to the C-6 of (1→3)-α-D-Manp and the sulfate group was attached to the C-4 of (1→6)-β-D-Glcp. Pharmacological tests displayed that LJP-11 can stimulate macrophages to release NO, IL-6, TNF-α and IL-10 as well as the up-regulation of their gene expressions, indicating LJP-11 has beneficial effects on immunostimulation. Moreover, LJP-11 exhibited 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. These results suggested that the activation of MAPK and NF-κB signaling pathways is one of the mechanisms responsible for the immunostimulating activity of LJP-11.

Enzymatic fingerprints of polysaccharides of Dendrobium officinale and their application in identification of Dendrobium species

Enzymatic fingerprinting of polysaccharides from Dendrobium officinale was studied and applied to authenticate Dendrobium species. Results showed that Dendrobium officinale species from Anhui province, Fujian province, Yunnan province, Guangdong province and Guangxi province of China, could be identified by polysaccharide analysis using carbohydrate gel electrophoresis (PACE). However, the fingerprints of Dendrobium officinale from Jiangxi province, Hu’nan province and Wenzhou, Yandangshan and Fuyang in Zhejiang province were very similar. As far as the fingerprints of different Dendrobium species were concerned, the differences between Dendrobium officinale, Dendrobium huoshanense, Dendrobium moniliforme, Dendrobium devonianum, Dendrobium aphyllum, Dendrobium wilsonii and Dendrobium crystallinum were obvious. Moreover, the genetic relationships between different samples were analyzed by using principal component analysis and unweighted pair group method with arithmetic mean cluster analysis. Results suggested that polysaccharide fingerprint analysis by PACE has the potential to become a valuable new method for the identification and control of quality of herbal medicines in future.