Structural characterization and immunostimulatory activity of a novel linear α-(1 → 6)-D-glucan isolated from Panax ginseng C. A. Meyer

Structural characterization of the glucan from Gastrodia elata Blume and its ameliorative effect on DSS-induced colitis in mice

The polysaccharide glucan was extracted from Gastrodia elata Blume, and its structural characterizations and beneficial effects against acute dextran sulfate sodium (DSS)-induced ulcerative colitis were investigated. The results showed that a polysaccharide GP with a molecular weight of 811.0 kDa was isolated from G. elata Blume. It had a backbone of α-D-1,4-linked glucan with branches of α-d-glucose linked to the C-6 position. GP exhibited protective effects against DSS-induced ulcerative colitis, and reflected in ameliorating weight loss and pathological damages in mice, increasing colon length, inhibiting the expression of inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), decreasing the levels of inflammatory related proteins NLRP3 and ASC, and elevating the anti-inflammatory cytokine interleukin-10 (IL-10) level in mouse colon tissues. GP supplementation also reinforced the intestinal barrier by promoting the expression of ZO-1, Occludin, and MUC2 of colon tissues, and positively regulated intestinal microbiota. Thus, GP treatment possessed a significant improvement in ulcerative colitis in mice, and it was expected to be developed as a functional food.

Breaking barriers: How modified citrus pectin inhibits galectin-8

Inhibition of galectin-3-mediated interactions by modified citrus pectin (MCP) could affect several rate-limiting steps in cancer metastasis, but the ability of MCP to antagonize galectin-8 function remains unknown. We hypothesized that MCP could bind to galectin-8 in addition to galectin-3. In this study, a combination of gradual ethanol precipitation and DEAE-Sepharose Fast Flow chromatography was used to isolate several fractions from MCP. The ability of these fractions to antagonize galectin-8 function was studied as well as the primary structure and initial structure-function relationship of the major active component MCP-30-3. The results showed that MCP-30-3 (168 kDa) was composed of Gal (13.8%), GalA (63.1%), GlcA (13.0%), and Glc (10.1%). MCP-30-3 could specifically bind to galectin-8, with an MIC value of 0.04 mg mL-1. After MCP-30-3 was hydrolyzed by β-galactosidase or pectinase, its binding activity was significantly reduced. These results provide new insights into the interaction between MCP structure and galectin function, as well as the potential utility in the development of functional foods.

The ameliorative effect on chemotherapy-induced injury and tumor immunosuppressive microenvironment of the polysaccharide from the rhizome of Menispermum dauricum DC

Combined medication has attracted increasing attention as an important treatment option for tumors due to the serious adverse effects of chemotherapy. In this study, as a new therapy strategy, a combination treatment of MDP (a polysaccharide from the rhizome of Menispermum dauricum DC.) with cyclophosphamide (CTX) was investigated. The results showed that combination treatment with MDP and CTX exerted a significantly synergistic anti-tumor effect in Lewis tumor-bearing mice, improved CTX-induced emaciation and hair loss, as well as increased the number of leukocytes, erythrocytes, hemoglobin, and platelets in the peripheral blood. In addition, compared with CTX alone, the thymus index and spleen index of the MDP + CTX group were increased, the number of CD3 + T cells, CD8 + T cells, white blood cells and B cells in spleen also increased significantly. MDP could also ameliorate the increase in liver and kidney index caused by CTX. In the Lewis lung cancer model, MDP showed a certain degree of anti-tumor effects, which may be related to its promotion of tumor-associated macrophages (TAMs) to M1 phenotype polarisation, enhancement of the number of T cells in tumor tissues and promotion of Th cells in tumor tissues to Th1 phenotype polarisation, thus alleviating the immunosuppressive microenvironment in tumor tissues. This study laid the foundation for the development of MDP as a polysaccharide drug for the treatment or adjuvant therapy of tumors and has important significance for the further clinical application of polysaccharides.

Structural Characteristics and Immunomodulatory Effects of Melanoidins from Black Garlic

Melanoidins are considered to have several biological activities. In this study, black garlic melanoidins (MLDs) were collected using ethanol solution extraction; 0%, 20%, and 40% ethanol solutions were used for chromatography. Three kinds of melanoidins were produced by macroporous resin, named MLD-0, MLD-20, and MLD-40. The molecular weight was determined, and the infrared and microscopic structures were studied. In addition, Balb/c mice were induced with cyclophosphamide (CTX) to establish an immune deficiency model to evaluate the immune efficacy of black garlic melanoidins (MLDs). The results showed that MLDs restored the proliferation and phagocytosis ability of macrophages, and the proliferation activity of B lymphocytes in the MD group was 63.32% (♀) and 58.11% (♂) higher than that in the CTX group, respectively. In addition, MLDs alleviated the abnormal expression of serum factors such as IFN-γ, IL-10, and TNF-α. 16SrDNA sequencing of intestinal fecal samples of mice showed that MLDs changed the structure and quantity of intestinal flora, and especially that the relative abundance of Bacteroidaceae was significantly increased. The relative abundance of Staphylococcaceae was significantly reduced. These results showed that MLDs improved the diversity of intestinal flora in mice, and improved the adverse state of immune organs and immune cells. The experiments confirm that black garlic melanoidins have potential value in immune activity, which provides an important basis for the development and utilization of melioidosis.

A Review of Antidepressant Effects and Mechanisms of Three Common Herbal Medicines: Panax ginseng, Bupleurum chinense, and Gastrodia elata

OBJECTIVES

Major depressive disorder (MDD) has been reported to affect an increasing number of individuals due to the modern lifestyle. Because of its complicated mechanisms and recurrent attacks, MDD is considered a refractory chronic disease. Although the mainstream therapy for MDD is chemical drugs, they are not a panacea for MDD because of their expensiveness, associated serious adverse reactions, and endless treatment courses. Hence, we studied three kinds of herbal medicines, namely, Panax ginseng C. A. Mey (PGM), Bupleurum chinense DC (BCD), and Gastrodia elata Blume (GEB), and reviewed the mechanisms underlying their antidepressant properties to provide a reference for the development of antidepressants and clinical medications.

METHODS

An extensive range of medicinal, clinical, and chemistry databases and search engines were used for our literature search. We searched the literature using certain web literature search engines, including Google Scholar, PubMed, Science Direct, CNKI (China National Knowledge Infrastructure), and Web of Science.

RESULTS

Experimental research found that active compounds of these three medicines exhibited good antidepressant effects in vivo and in vitro. Clinical investigations revealed that single or combined treatment of these medicines improved certain depressive symptoms. Antidepressant mechanisms are summarized based on this research.

CONCLUSION

The antidepressant mechanism of these three medicines includes but is not limited to ameliorating inflammation within the brain, reversing the hypothalamic-pituitary adrenal axis (HPA) system hyperfunction, inhibiting monoamine neurotransmitters reuptake, anti-neuron apoptosis and preventing neurotoxicity, and regulating depressive-related pathways such as the BDNF pathway and the PI3K/Akt/mTOR pathway.

A review of the immunomodulatory activities of polysaccharides isolated from Panax species

Panax polysaccharides are biopolymers that are isolated and purified from the roots, stems, leaves, flowers, and fruits of Panax L. plants, which have attracted considerable attention because of their immunomodulatory activities. In this paper, the composition and structural characteristics of purified polysaccharides are reviewed. Moreover, the immunomodulatory activities of polysaccharides are described both in vivo and in vitro. In vitro, Panax polysaccharides exert immunomodulatory functions mainly by activating macrophages, dendritic cells, and the complement system. In vivo, Panax polysaccharides can increase the immune organ indices and stimulate lymphocytes. In addition, this paper also discusses the membrane receptors and various signalling pathways of immune cells. Panax polysaccharides have many beneficial therapeutic effects, including enhancing or activating the immune response, and may be helpful in treating cancer, sepsis, osteoporosis, and other conditions. Panax polysaccharides have the potential for use in the development of novel therapeutic agents or adjuvants with beneficial immunomodulatory properties.

Comparisons of Isolation Methods, Structural Features, and Bioactivities of the Polysaccharides from Three Common Panax Species: A Review of Recent Progress

Panax spp. (Araliaceae family) are widely used medicinal plants and they mainly include Panax ginseng C.A. Meyer, Panax quinquefolium L. (American ginseng), and Panax notoginseng (notoginseng). Polysaccharides are the main active ingredients in these plants and have demonstrated diverse pharmacological functions, but comparisons of isolation methods, structural features, and bioactivities of these polysaccharides have not yet been reported. This review summarizes recent advances associated with 112 polysaccharides from ginseng, 25 polysaccharides from American ginseng, and 36 polysaccharides from notoginseng and it compares the differences in extraction, purification, structural features, and bioactivities. Most studies focus on ginseng polysaccharides and comparisons are typically made with the polysaccharides from American ginseng and notoginseng. For the extraction, purification, and structural analysis, the processes are similar for the polysaccharides from the three Panax species. Previous studies determined that 55 polysaccharides from ginseng, 18 polysaccharides from American ginseng, and 9 polysaccharides from notoginseng exhibited anti-tumor activity, immunoregulatory effects, anti-oxidant activity, and other pharmacological functions, which are mediated by multiple signaling pathways, including mitogen-activated protein kinase, nuclear factor kappa B, or redox balance pathways. This review can provide new insights into the similarities and differences among the polysaccharides from the three Panax species, which can facilitate and guide further studies to explore the medicinal properties of the Araliaceae family used in traditional Chinese medicine.

In vitro immunomodulatory activity of water-soluble glucans from fresh and dried Longan (Dimocarpus longan Lour.)

Longan (Dimocarpus longan Lour.) is a seasonal tropical fruit used by Chinese medicine in both fresh and dried pulp forms. Their polysaccharides have been reported to have biological activity. However, their composition and immune activity have not yet been disclosed. To fulfil this aim, hot water-soluble polysaccharides of fresh and dried longan pulp were fractionated according to their molecular weight by ultrafiltration (10, 50, 100 kDa cut off). The main polysaccharides recovered were 1,6-linked glucans branched at O-3 (4-8%), O-2 (1%), O-2,4 (0.1%), and O-3,4 (0.1%). The drying process promotes the solubility of the polysaccharides. These glucans from fresh and dried longan pulp have immunomodulatory activity, shown by in vitro phagocytosis, NO, TNF-α, and IL-6 macrophages production assays. They showed also to inhibit the inflammatory response induced by LPS. The immunological activity of these glucans seems to have different responses dependent on their molecular weight, related to the immune regulatory pathways.

Selenium-Containing Polysaccharides—Structural Diversity, Biosynthesis, Chemical Modifications and Biological Activity

Selenosugars are a group of sugar derivatives of great structural diversity (e.g., molar masses, selenium oxidation state, and selenium binding), obtained as a result of biosynthesis, chemical modification of natural compounds, or chemical synthesis. Seleno-monosaccharides and disaccharides are known to be non-toxic products of the natural metabolism of selenium compounds in mammals. In the case of the selenium-containing polysaccharides of natural origin, their formation is also postulated as a form of detoxification of excess selenium in microorganisms, mushroom, and plants. The valency of selenium in selenium-containing polysaccharides can be: 0 (encapsulated nano-selenium), IV (selenites of polysaccharides), or II (selenoglycosides or selenium built into the sugar ring to replace oxygen). The great interest in Se-polysaccharides results from the expected synergy between selenium and polysaccharides. Several plant- and mushroom-derived polysaccharides are potent macromolecules with antitumor, immunomodulatory, antioxidant, and other biological properties. Selenium, a trace element of fundamental importance to human health, has been shown to possess several analogous functions. The mechanism by which selenium exerts anticancer and immunomodulatory activity differs from that of polysaccharide fractions, but a similar pharmacological effect suggests a possible synergy of these two agents. Various functions of Se-polysaccharides have been explored, including antitumor, immune-enhancement, antioxidant, antidiabetic, anti-inflammatory, hepatoprotective, and neuroprotective activities. Due to being non-toxic or much less toxic than inorganic selenium compounds, Se-polysaccharides are potential dietary supplements that could be used, e.g., in chemoprevention.

Structural characterization and immunomodulatory activity of a heterogalactan from Panax ginseng flowers

A neutral polysaccharide fraction (WGFPN) was isolated from Panax ginseng flowers. Monosaccharide composition and HPSEC-MALLS-RI (high-performance size exclusion chromatography coupled with multi-angle laser light scattering detector and refractive index detector) analyses showed WGFPN was a heterogalactan with a molecular weight of 11.0 kDa. Methylation, 1D/2D NMR (nuclear magnetic resonance) spectra and enzymatic hydrolysis methods were used to characterize the structure of WGFPN. It possessed a less branched (1 → 4)-β-D-galactan and a significantly branched (1 → 6)-β-D-galactan. The side chains of (1 → 6)-β-D-galactan were branched with α-L-1,5-Araf and t-α-L-Araf residues at O-3. Trace amount of 1,4-linked Glcp, terminal Galp, terminal Glcp and terminal Manp residues might attached to the 1,6-linked galactan through O-3 or 1,4-linked galactan through O-6 as side chains. WGFPN could activate RAW264.7 macrophages through increasing macrophage phagocytosis, releasing NO and secreting TNF-α, IL-6, IFN-γ and IL-1β in vitro. Moreover, WGFPN could enhance the immunity of cyclophosphamide (CTX)-induced immunosuppressed mice in vivo. Hence, WGFPN might be a potential natural immunomodulatory agent.

Recent progress in polysaccharides from Panax ginseng C. A. Meyer

Panax ginseng C. A. Meyer (P. ginseng) has a long history of medicinal use and can treat a variety of diseases. P. ginseng contains a variety of active ingredients, such as saponins, polypeptides, volatile oils, and polysaccharides. Among them, saponins have always been considered as the main components responsible for its pharmacological activities. However, more and more studies have shown that polysaccharides play an indispensable role in the medicinal value of ginseng. Modern biological and medical studies have found that ginseng polysaccharides have complex structural characteristics and diverse biological activities, such as immune regulation, anti-tumor, antioxidant, hypoglycemic, and anti-radiation functions, among others. Additionally, the structural characteristics of ginseng polysaccharides are closely related to their activity. In this review, the research background, extraction, purification, structural characteristics, and biological activities of ginseng polysaccharides from different parts of P. ginseng (roots, flowers stems and leaves, and berries) under different growth conditions (artificially cultivated ginseng, mountain ginseng, and wild ginseng) are summarized. The structural characteristics of purified polysaccharides were reviewed. Meanwhile, their biological activities were introduced, and some possible mechanisms were listed. Furthermore, the structure-activity relationship of polysaccharides was discussed. Some research perspectives for the study of ginseng polysaccharides were also provided.

Plant-Derived Nutraceuticals and Immune System Modulation: An Evidence-Based Overview

Immunomodulators are agents able to affect the immune system, by boosting the immune defences to improve the body reaction against infectious or exogenous injuries, or suppressing the abnormal immune response occurring in immune disorders. Moreover, immunoadjuvants can support immune system acting on nonimmune targets, thus improving the immune response. The modulation of inflammatory pathways and microbiome can also contribute to control the immune function. Some plant-based nutraceuticals have been studied as possible immunomodulating agents due to their multiple and pleiotropic effects. Being usually more tolerable than pharmacological treatments, their adjuvant contribution is approached as a desirable nutraceutical strategy. In the present review, the up to date knowledge about the immunomodulating properties of polysaccharides, fatty acids and labdane diterpenes have been analyzed, in order to give scientific basic and clinical evidence to support their practical use. Since promising evidence in preclinical studies, limited and sometimes confusing results have been highlighted in clinical trials, likely due to low methodological quality and lacking standardization. More investigations of high quality and specificity are required to describe in depth the usefulness of these plant-derived nutraceuticals in the immune system modulation, for health promoting and disease preventing purposes.

Stereoselective synthesis of a branched α-decaglucan

The first and convergent synthesis of a branched Arca subcrenata Lischke α-decaglucan containing all of the α-(1 → 3), α-(1 → 4), and α-(1 → 6) glycosyl linkages was efficiently achieved. The tri- and tetrasaccharide fragments and fully protected decasaccharide were assembled in a one-pot manner with excellent α-stereoselectivity, which was secured by the synergistic α-directing effects of the TolSCl/AgOTf catalysis system and the remote participation effect or steric β-shielding of functionalized groups at the donor 6-O-position. Low substrate concentration was revealed to favor the α-stereochemical outcome of glycosylations between bulkier building blocks. The synthetic approach established here would be very useful for the preparation of more complex α-glucans containing different types of glycosidic linkages and branched architectures.

Structural characterization and immunostimulatory activity of a novel polysaccharide isolated with subcritical water from Sagittaria sagittifolia L

In the present study, we obtained polysaccharides from Sagittaria sagittifolia L. (SSP) with subcritical water extraction (SWE). Two water-soluble polysaccharides (SSP-W1 and SSP-S1) from the acquired SSP were isolated with DEAE-52 and Sephadex G-100. Besides, the structural characteristics and immunostimulatory activity were also investigated. The results showed that both SSP-W1 and SSP-S1 were homogeneous polysaccharides and the molecular weight was 62.03 KDa and 15.2 KDa, respectively. In addition, both SSP-W1 and SSP-S1 are heteropolysaccharides. Moreover, FT-IR analysis showed that SSP-W1 was α-pyranose polysaccharide, while SSP-S1 was a typical β-pyranose polysaccharide. Congo red staining showed that there was no triple helix structure in both SSP-W1 and SSP-S1. Furthermore, both SSP-W1 and SSP-S1 could promote the proliferation, production of NO, and secretion of TNF-α and IL-10 of macrophages RAW 264.7, significantly. Therefore, the polysaccharides extracted from Sagittaria sagittifolia L. with SWE have the potential to be used as immunoreactive agent in medicine and functional foods.

A new method for α-specific glucosylation and its application to the one-pot synthesis of a branched α-glucan

We have developed a new and highly efficient α-specific glucosylation method based on the synergistic α-directing effects of a TolSCl/AgOTf promoter system and the steric β-shielding or the remote participation of protecting groups at the donor 6-O-position.

Antitumor activity of orally administered maitake α-glucan by stimulating antitumor immune response in murine tumor

Maitake α-glucan, YM-2A, isolated from Grifola frondosa, has been characterized as a highly α-1,6-branched α-1,4 glucan. YM-2A has been shown to possess an anti-virus effect in mice; however, it does not directly inhibit growth of the virus in vitro, indicating that the anti-virus effect of YM-2A might be associated with modulation of the host immune system. In this study, we found that oral administration of YM-2A could inhibit tumor growth and improve survival rate in two distinct mouse models of colon-26 carcinoma and B16 melanoma. Orally administered YM-2A enhanced antitumor immune response by increasing INF-γ-expressing CD4⁺ and CD8⁺ cells in the spleen and INF-γ-expressing CD8⁺ cells in tumor-draining lymph nodes. In vitro study showed that YM-2A directly activated splenic CD11b⁺ myeloid cells, peritoneal macrophages and bone marrow-derived dendritic cells, but did not affect splenic CD11b^- lymphocytes or colon-26 tumor cells. YM-2A is more slowly digested by pancreatic α-amylase than are amylopectin and rabbit liver glycogen, and orally administered YM-2A enhanced the expression of MHC class II and CD86 on dendritic cells and the expression of MHC class II on macrophages in Peyer’s patches. Furthermore, in vitro stimulation of YM-2A increased the expression of pro-inflammatory cytokines in Peyer’s patch CD11c⁺ cells. These results suggest that orally administered YM-2A can activate dendritic cells and macrophages in Peyer’s patches, inducing systemic antitumor T-cell response. Thus, YM-2A might be a candidate for an oral therapeutic agent in cancer immunotherapy.

Isolation, purification, characterization and immunostimulatory activity of polysaccharides derived from American ginseng

In this study, crude American ginseng polysaccharide (AGPS) was extracted with hot water and preliminarily purified by using resin S-8 and Polyamide columns. Then, it was further purified and separated by DEAE-Sepharose CL-6B and Sepharose CL-6B chromatography, respectively. Five main fractions were obtained, named WPS-1, WPS-2, SPS-1, SPS-2 and SPS-3. Their homogeneities and structural characteristics were elucidated based on UV-vis spectroscopy, High Performance Gel Filtration Chromatography (HPGFC), Gas Chromatography (GC), Scanning Electron Microscopy (SEM), Infrared Spectrum (IR), and NMR Spectroscopy methods. Furthermore, the immunostimulatory effects of these fractions upon splenic lymphocyte proliferation, macrophage phagocytosis and nitric oxide (NO) production, were investigated in vitro. The results indicated that their stimulations could be ordered as SPS-3>SPS-1>CPS (crude polysaccharides)>WPS-1>WPS-2>SPS-2. Among them, SPS-3 showed more potent immunomodulatory activity and could be explored as a potential immunopotentiating agent for use in functional food or medicine.

Structure-function relationships of immunostimulatory polysaccharides: A review

Immunostimulatory polysaccharides are compounds capable of interacting with the immune system and enhance specific mechanisms of the host response. Glucans, mannans, pectic polysaccharides, arabinogalactans, fucoidans, galactans, hyaluronans, fructans, and xylans are polysaccharides with reported immunostimulatory activity. The structural features that have been related with such activity are the monosaccharide and glycosidic-linkage composition, conformation, molecular weight, functional groups, and branching characteristics. However, the establishment of structure-function relationships is possible only if purified and characterized polysaccharides are used and selective structural modifications performed. Aiming at contributing to the definition of the structure-function relationships necessary to design immunostimulatory polysaccharides with potential for preventive or therapeutical purposes or to be recognized as health-improving ingredients in functional foods, this review introduces basic immunological concepts required to understand the mechanisms that rule the potential claimed immunostimulatory activity of polysaccharides and critically presents a literature survey on the structural features of the polysaccharides and reported immunostimulatory activity.

Structural characterization of two water-soluble polysaccharides from black soybean (Glycine max (L.) Merr.)

Black soybeans (Glycine max (L.) Merr.) have been widely used as a health food and medicinal herb in oriental medicine. In the present study, the chemical structures of two water-soluble polysaccharides (black soybean polysaccharide 1 (BSPS-1) and black soybean polysaccharide 3 (BSPS-3)) isolated from black soybeans were characterized by high performance size-exclusion chromatography (HPSEC), methylation analysis, and 1D (1H, 13C) and 2D (COSY, TOCSY, HSQC, NOESY, and HMBC) NMR spectra. The molecular weights of BSPS-1 and BSPS-3 were 1.95 × 105 and 1.88 × 105 Da, respectively. Methylation analysis and NMR spectra indicate that BSPS-1 is composed of 1,6-α-d-glucopyranosyl residues. By contrast, BSPS-3 is mainly composed of a 1,3-β-d-galactopyranosyl residue backbone with side chains substituted at the O-6 position consisting of large content of T-α-l-Araf-(1→ residues, and small contents of →5)-α-l-Araf-(1→, →2)-α-l-Rhap-(1→, and 4-O-Me-β-d-GlcAp-(1→ residues. Our results suggest that BSPS-1 is a linear (1→6)-α-d-glucan, whereas BSPS-3 is a type II arabinogalactan. The unique structures of BSPS-1 and BSPS-3 indicate that they might have wide applications in food and pharmaceutical industries.

Phenotypic and functional analysis of the modification of murine bone marrow dendritic cells (BMDCs) induced by neutral Ginseng polysaccharides (NGP)

In this study, we reveal that a neutral polysaccharide isolated from a Chinese medicinal herb, named Ginseng (Panaxgiseng C.A. Meyer), promotes maturation of BMDCs via inducing changes both inside and outside BMDCs, as well as changes of functions. These affects of NGP on BMDCs were evaluated with use of conventional scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) for morphology of BMDCs, flow cytometry (FCM) for key surface markers of BMDCs, cytochemistry assay, FITC-dextran, bio-assay for their phagocytosis and enzyme linked immunosorbent assay (ELISA) for cytokine production by BMDCs. Our results proved that NGP induced maturation of BMDCs as reflected by the downregulation of acid phosphatase (ACP) activity inside the BMDCs, which occurs when phagocytosis of BMDCs decreased, while antigen presentation increased upon maturation. These data also revealed higher expression of MHC II, CD80, CD86, CD83, CD40 and secretion of higher level of IL-12 and low level of TNF-α. Our approach suggests that NGP could therefore stimulate the maturation of murine BMDCs through a series of regulation to the BMDCs.