Yifa Zhou

Anti-fatigue activity of the water-soluble polysaccharides isolated from Panax ginseng C. A. Meyer

AIM OF THE STUDY Panax ginseng C. A. Meyer (ginseng) is a well-known Chinese herb often used in Asian countries for physical strength development. Ginseng polysaccharides are its active component and have a lot of pharmaceutical activities. However, anti-fatigue activity of ginseng polysaccharides has not yet been tested. The current study was designed to evaluate the anti-fatigue activity of ginseng polysaccharides (WGP) in an animal test for fatigue and compare the activities between the neutral (WGPN) and acidic (WGPA) portion in an attempt to determine whether the medicinal uses are supported by pharmacological effects. MATERIALS AND METHODS WGP, WGPN and WGPA were orally administrated to mice once daily for 15 days. Anti-fatigue activity was assessed using the forced swim test (FST) and serum biochemical parameters were determined by autoanalyzer and commercially available kits. RESULTS While all compounds were found to reduce immobility in the FST, the effect of WGPA was demonstrated in lower doses compared with WGP and WGPN. Moreover, the FST-induced reduction in glucose (GLU) and glutathione peroxidase (GPx) and increase in creatine phosphokinase (CK), lactic dehydrogenase (LDH) and malondialdehyde (MDA) levels, all indicators of fatigue, were inhibited by the corresponding doses of WGP, WGPN and WGPA. CONCLUSIONS Ginseng polysaccharides have anti-fatigue activity, also reflected in the effects on the physiological markers for fatigue. The acidic polysaccharide is more potent than the neutral polysaccharide.

Antitumor Activities and Immunomodulatory Effects of Ginseng Neutral Polysaccharides in Combination with 5-Fluorouracil

A neutral polysaccharide fraction (WGPN) prepared from Panax ginseng C.A. Meyer by hot water extraction and DEAE-cellulose chromatography was tested for its anticancer activity alone and in combination with 5-fluorouracil (5-FU) in Sarcoma-180 (S180) tumor-bearing mice by intragastric administration. WGPN alone inhibited S180 tumor growth in a bell-shaped dose-response curve, and the combination with 5-FU showed a synergistic effect. Studies of various immunological activities in S180-bearing mice revealed that WGPN stimulated the proliferation of lymphocytes, increased natural killer cell cytotoxicity, enhanced the phagocytosis and nitric oxide production by macrophages, and increased the level of tumor necrosis factor-alpha in serum. In combination with 5-FU, WGPN mitigated damage to the immune system caused by 5-FU in S180-bearing mice. These results suggest that WGPN might be a potential adjuvant for chemotherapeutic drugs.

Comparative studies of the antiproliferative effects of ginseng polysaccharides on HT-29 human colon cancer cells

Ginseng polysaccharide has anticancer activity. However, the structure–activity relationship and the activity mechanism are still unclear. Therefore, it is necessary to study the anticancer activity of structurally different ginseng polysaccharide fractions and their potential mechanisms. Ginseng polysaccharide fractions and their temperature-modified products were assayed for their effects on HT-29 cell proliferation by MTT assay, on cell cycle progression by flow cytometry, and on caspase-3 activation by western blot analysis. The HG-rich ginseng pectin inhibited cell proliferation and induced cell cycle arrest in the G2/M phase. The temperature-modified HG-rich pectin had dramatically increased antiproliferative effect and induced apoptosis accompanied by the activation of caspase-3. Starch-like glucan and arabinogalactan of ginseng exhibited no antiproliferative effects. Even after temperature modification, their inhibitory effects either remained unchanged or increased slightly. The HG-rich pectin exerts its antiproliferative effect via cell cycle arrest and the temperature modification markedly increased the antiproliferative effect.

Purification and in vitro anti-proliferative effect of novel neutral polysaccharides from Lentinus edodes.

A (1→6)-β-D-glucan (WPLE-N-1) and two mannogalactoglucans (WPLE-N-2 and WPLE-N-3) were isolated from the basidiocarps of Lentinus edodes by hot water extraction, ethanol precipitation, anion exchange chromatography, and further purified by gel-permeation chromatography (GPC). Their structural features were investigated by high performance liquid chromatography (HPLC), high performance gel-permeation chromatography (HPGPC), methylation analysis, periodate oxidation-Smith degradation, Fourier transform-infrared (FT-IR) and NMR spectroscopy, including two-dimensional (2D) NMR. HPLC analysis revealed that WPLE-N-1 was mainly composed of glucose (92%) with small amount of galactose (3.9%) and mannose (4.1%), WPLE-N-2 and WPLE-N-3 contained mannose-galactose-glucose in the molar ratio of 10:27:63 and 5:12:83, respectively. GPC and HPGPC showed that WPLE-N-1, WPLE-N-2 and WPLE-N-3 are homogeneous fractions and their molecular weights were estimated to be 757.5 kDa, 20.9 kDa and 4.7 kDa, respectively. Chemical and spectroscopic studies indicated that WPLE-N-1 consisted of (1→6)-β-D-glucopyranosyl residues; while WPLE-N-2 and WPLE-N-3 were found to contain (1→6)-, (1→4)- and (1→3)-α-D-glucopyranosyl residues, (1→6)-α-D-galactopyranosyl residues, (1→3,6)- and (1→2,4)-α-D-mannopyranosyl residues and terminal residues of D-glucopyranosyl residues. On a preliminary bioactivity test, these three polysaccharides exhibited antitumor activity against Sarcoma S-180, Carcinoma HCT-116 and HT-29 in vitro. This finding suggests that mannogalactoglucan should be explored as potential antitumor agents and utilized as tumor cell growth inhibitors for food and pharmaceutical industries.

The inhibitory effects of a rhamnogalacturonan I (RG-I) domain from ginseng pectin on galectin-3 and its structure-activity relationship.

Background: Structural elements in pectin that inhibit galectin-3, a β-galactoside-binding protein associated with cancer progression, are poorly defined. Results: Both backbone and side chains of pectin RG-I-4 were important for its anti-galectin-3 activity. Conclusion: High activity of RG-I-4 was due to cooperation between short β1,4-galactan side chains. Significance: The results are valuable for producing highly active pectin-based galectin-3 inhibitors. Pectin has been shown to inhibit the actions of galectin-3, a β-galactoside-binding protein associated with cancer progression. The structural features of pectin involved in this activity remain unclear. We investigated the effects of different ginseng pectins on galectin-3 action. The rhamnogalacturonan I-rich pectin fragment, RG-I-4, potently inhibited galectin-3-mediated hemagglutination, cancer cell adhesion and homotypic aggregation, and binding of galectin-3 to T-cells. RG-I-4 specifically bound to the carbohydrate recognition domain of galectin-3 with a dissociation constant of 22.2 nm, which was determined by surface plasmon resonance analysis. The structure-activity relationship of RG-I-4 was investigated by modifying the structure through various enzymatic and chemical methods followed by activity tests. The results showed that (a) galactan side chains were essential to the activity of RG-I-4, whereas arabinan side chains positively or negatively regulated the activity depending on their location within the RG-I-4 molecule. (b) The activity of galactan chain was proportional to its length up to 4 Gal residues and largely unchanged thereafter. (c) The majority of galactan side chains in RG-I-4 were short with low activities. (d) The high activity of RG-I-4 resulted from the cooperative action of these side chains. (e) The backbone of the molecule was very important to RG-I-4 activity, possibly by maintaining a structural conformation of the whole molecule. (f) The isolated backbone could bind galectin-3, which was insensitive to lactose treatment. The novel discovery that the side chains and backbone play distinct roles in regulating RG-I-4 activity is valuable for producing highly active pectin-based galectin-3 inhibitors.

Preparation of a glucan from the roots of Rubus crataegifolius Bge. and its immunological activity.

A water-soluble glucan (RCP-1) was prepared from the roots of Rubus crataegifolius Bge. by extraction with hot-water, deproteination by Sevag reagent, alpha-amylase treatment and ultrafiltration. RCP-1 consisted of only glucose, and its molecular weight was determined to be approximately 7KD by high performance gel permeation chromatography (HPGPC). Fourier transform infra-red spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), methylation and periodate oxidation analyses indicated that RCP-1 was an alpha-d-glucan. Its main chains were composed of (1-->4)- and (1-->6)-linked alpha-glucopyranosyls, and side chains were single alpha-glucopyranosyl residues attached to the O-6 of glucosyls in the main chains. RCP-1 could increase both cytotoxic activity against B16 melanoma cells and the production of nitric oxide (NO) of macrophages in vitro. Furthermore, in vivo bioassay tests indicated that RCP-1 could remarkably enhance T and B lymphocyte proliferations, augment the phagocytosis of macrophages and increase the tumour necrosis factor-alpha (TNF-alpha) levels in serum.

Structural elucidation and antioxidant activity of a water-soluble polysaccharide from the fruit bodies of Bulgaria inquinans (Fries)

The non-lichenized ascomycete Bulgaria inquinans (Fries), growing in the Changbai Mountain of China, has been used as medicinal diet for many years. In a previous study, we have reported that a heteropolysaccharide BIWS-4b from the fruit bodies of B. inquinans (Fries) exhibited markedly antimalarial and immunostimulating activities. In this paper, the structural features and antioxidant activity of BIWS-4b were investigated. The results showed that BIWS-4b contains an α-(1→2), (1→6)-mannan core to which the glucogalactan chains are attached. The glucogalactan chains were composed of (1→6)-, (1→5)- and (1→5,6)-linked β-Galf, (1→4)-linked and non-reducing terminal β-Glcp units, and might be attached to the mannan core at the O-2 positions of α-Manp units. The antioxidant assays showed that BIWS-4b exhibited good activities, including free radicals scavenging effects, ferrous ion-chelating ability and reducing power. Thus, BIWS-4b could be used as a natural antioxidant agent for food and pharmaceutical industries.

The Two Endocytic Pathways Mediated by the Carbohydrate Recognition Domain and Regulated by the Collagen-like Domain of Galectin-3 in Vascular Endothelial Cells

Galectin-3 plays an important role in endothelial morphogenesis and angiogenesis. We investigated the endocytosis of galectin-3 in human vascular endothelial cells and showed that galectin-3 could associate with and internalized into the cells in a carbohydrate-dependent manner. Our work also revealed that galectin-3 was transported to the early/recycling endosomes and then partitioned into two routes – recycling back to the plasma membrane or targeting to the late endosomes/lysosomes. Various N- and C-terminal truncated forms of galectin-3 were constructed and compared with the full-length protein. These comparisons showed that the carbohydrate-recognition domain of galectin-3 was required for galectin-3 binding and endocytosis. The N-terminal half of the protein, which comprises the N-terminal leader domain and the collagen-like internal repeating domain, could not mediate binding and endocytosis alone. The collagen-like domain, although it was largely irrelevant to galectin-3 trafficking to the early/recycling endosomes, was required for targeting galectin-3 to the late endosomes/lysosomes. In contrast, the leader domain was irrelevant to both binding and intracellular trafficking. The data presented in this study correlate well with different cellular behaviors induced by the full-length and the truncated galectin-3 and provide an alternative way of understanding its angiogenic mechanisms.

The inhibitory effects and mechanisms of rhamnogalacturonan I pectin from potato on HT-29 colon cancer cell proliferation and cell cycle progression

Pectin is an important dietary component of all fruits and vegetables. Some pectins have been shown to inhibit cancer cell growth, but the effective structures and mechanisms have remained unclear. In this study, we investigated the effects of four structurally distinct pectins on human colon cancer HT-29 cells and the possible mechanisms accounting for the actions. The proliferation inhibitory effect was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Flow cytometry was used to visualize the cell cycle distribution. An reverse transcription polymerase chain reaction (RT-PCR)-based assay was utilized to detect mRNA levels of the proteins related to cell cycle arrest. The data showed that the rhamnogalacturonan I domain-rich pectin from potato inhibited the proliferation of HT-29 cells and induced significant G2/M cell cycle arrest. This inhibitory effect was due to the down-regulation of cyclin B1 and cyclin-dependent kinase 1 expression, but not p21WAF1/CIP1 expression. The results suggested that the rhamnogalacturonan I domain might relate to the anticancer activity of pectin.

In vivo antimalarial activities of glycoalkaloids isolated from Solanaceae plants

Context: Malaria is one of the most common and serious protozoan tropical diseases. Multi-drug resistance remains pervasive, necessitating the continuous development of new antimalarial agents. Objective: Many glycosides, such as triterpenoid saponins, were shown to have antimalarial activity against Plasmodium falciparum in vitro. This study was to elucidate the ability of five glycoalkaloids against Plasmodium yoelii and develop new antimalarial lead compounds. Materials and methods: Glycoalkaloids were isolated from three kinds of Solanaceae plants: chaconine and solanine were isolated from Solanum tuberosum L. sprouts, solamargine and solasonine from Solanum nigrum L. fruit, tomatine from Lycopersicon esculentum Mill. fruit. The five isolated glycoalkaloids were evaluated against Plasmodium yoelii 17XL in mice with 4-day parasitemia suppression test in different concentrations. Results: Chaconine showed a dose-dependent suppression of malaria infection, ED50, 4.49 mg/kg; therapeutic index (TI), ≈9. At a dose of 7.50 mg/kg, the parasitemia suppressions of chaconine, tomatine, solamargine, solasonine and solanine were 71.38, 65.25, 64.89, 57.47 and 41.30%, respectively. At 3.75 mg/kg, the parasitemia suppression of chaconine was 42.66%, but the derivative, chaconine-6-O-sulfate, appeared to show no antimalarial activity. Simultaneous administration of chaconine and solanine in 1:1 did not show any synergistic effects. Discussion and conclusion: The results showed that the glycoalkaloids with chacotriose (chaconine and solamargine) were more active than those with solatriose (solanine and solasonine). Chaconine was the most active among the five glycoalkaloids. We propose that the activity is dependent upon non-specific carbohydrate interactions. The 6-OH of chaconine is important for antimalarial activity.