Molecular mechanisms of immunomodulatory activity by polysaccharide isolated from the peels of Citrus unshiu

Construction and performance evaluation of polyguluronic acid polysaccharides-based drug delivery systems

Polysaccharides have garnered significant attention as potential nanoparticle carriers for targeted tumor therapy due to their excellent biodegradability and biocompatibility. Polyguluronic acid (PG) is a homogeneous acidic polysaccharide fragment derived from alginate, which is found in brown algae, possesses excellent bioactivities, unique properties. This study explored the immunomodulatory activity of PG and developed PG-based nanogels through modified disulfide bonds and Ca2+ dual crosslinking. We characterized their structure, assessed their drug-loading and release properties, and ultimately validated both the safety of the nanocarrier and the in vitro anti-tumor efficacy of the encapsulated drug. Results indicated that PG significantly enhanced the proliferative activity and phagocytosis of RAW264.7 cells while promoting reactive oxygen species (ROS) production and cytokine secretion. The study identified TLR4 as the primary receptor for PG recognition in RAW264.7 cells. Furthermore, PG-based drug-carrying nanogels were prepared, exhibiting uniform sizes of about 184 nm and demonstrating exceptional encapsulation efficiency (82.15 ± 0.82 %) and drug loading capacity (8.12 ± 0.08 %). In vitro release experiments showed that these nanogels could responsively release drugs under conditions of high glutathione (GSH) reduction, facilitating drug accumulation at tumor sites and enhancing therapeutic efficacy. This research not only expands the application of PG in drug delivery systems but also provides valuable insights into leveraging natural immunomodulatory polysaccharides as carriers for targeted drug delivery.

Polysaccharides in fruits: Biological activities, structures, and structure-activity relationships and influencing factors-A review

Fruits are a rich source of polysaccharides, and an increasing number of studies have shown that polysaccharides from fruits have a wide range of biological functions. Here, we thoroughly review recent advances in the study of the bioactivities, structures, and structure-activity relationships of fruit polysaccharides, especially highlighting the structure-activity influencing factors such as extraction methods and chemical modifications. Different extraction methods cause differences in the primary structures of polysaccharides, which in turn lead to different polysaccharide biological activities. Differences in the degree of modification, molecular weight, substitution position, and chain conformation caused by chemical modification can all affect the biological activities of fruit polysaccharides. Furthermore, we summarize the applications of fruit polysaccharides in the fields of pharmacy and medicine, foods, cosmetics, and materials. The challenges and perspectives for fruit polysaccharide research are also discussed.

Effect of the immunoregulation activity of a pectin polysaccharide from Saussurea laniceps petals on macrophage polarization

Saussurea laniceps is a traditional medicinal herb. In our previous study, a pectin polysaccharide, SLP-4, was isolated from the petals of S. laniceps. In this study, the immunomodulatory activity of SLP-4 was studied by analyzing its effects on macrophage (RAW 264.7 cells) polarization. The immunomodulatory activity assays indicated that SLP-4 could significantly enhance the pinocytic and phagocytic capacity and promote the expression and secretion of cytotoxic molecules (nitric oxide, increased by 6.4 times when the SLP-4 concentration was 800 μg/mL) and cytokines (tumor necrosis factor-α and interleukin-6 increased by 7.7 and 11.9 times, respectively) in original macrophage. The possible mechanism could be attributed to the activation of the mitogen-activated protein kinase and nuclear factor-κB signaling pathways through Toll-like receptors 2 and 4. Moreover, SLP-4 significantly induced M1 polarization of original macrophages and transferred macrophages from M2 to M1, but had little effect on the conversion of M1 macrophages into M2 phenotype. Overall, these results demonstrate the potential of SLP-4 as an attractive immunomodulating functional supplement.

Hawthorn Fruit (Crataegus spp.) Polysaccharides Exhibit Immunomodulatory Activity on Macrophages via TLR4/NF-κB Signaling Activation

The immunostimulatory effects and the involved molecular mechanisms of polysaccharides from hawthorn fruit (Crataegus spp.) have not been well understood. In this study, the chemical composition, monosaccharide composition, uronic acid content, and structural features of hawthorn fruit polysaccharides (HFP) and the two collected fractions were analyzed. Both AF1-2 and AF2 have pectic-like structural features rich in galacturonic acid. AF2 showed superior proinflammatory effects on macrophages which significantly increased the secretion of pro-inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α, but not AF1-2. AF2 was found to activate the nuclear factor-κB signaling pathway with suppressed expression of IκBα but up-regulated expression of p-IκBα and nuclear factor-κB P65. The surface binding site of AF2 on macrophage cells was characterized and toll like receptor-4 was responsible for AF2 induced activation of down-stream nuclear factor-κB signaling pathways. AF2 from hawthorn fruit could be potentially used as a natural source of immunomodulator in functional foods.

Analyzing the structure-activity relationship of raspberry polysaccharides using interpretable artificial neural network model

The structure-activity relationship has been a hot topic in the field of polysaccharide research. Six polysaccharides and three polysaccharide fragments were obtained from raspberry pulp. Based on their structural information and immune-enhancing activity data, an artificial neural network (ANN) model was used for prediction, and Gradient-weighted class activation mapping (Grad-CAM) algorithm was exploited for explanation structure-activity relationship of these raspberry polysaccharides in the present study. The structural information and immune activity data of raspberry polysaccharides were respectively used as input and output in the ANN model. The training and testing losses of ANN model was no longer decreased after trained for 200 epochs. The mean-square error (MSE) of training set and test set stabilized around 0.003 and 0.013, and the mean absolute percentage error (MAPE) of training set and test set were 0.21 % and 0.98 %, indicating the trained ANN model converged well and exhibited strong robustness. The interpretability analysis showed that molecular weight, content of arabinose, galactose or galacturonic acid, and glycosyl linkage patterns of →3)-Arap-(1→, Araf-(1→, →4)-Galp-(1 → were the main structural factors greatly affecting the immune-enhancing activity of raspberry polysaccharides. This work may provide a new perspective for the study of structure-activity relationship of polysaccharides.

Molecular Insights into the Macrophage Immunomodulatory Effects of Scrophulariae Radix Polysaccharides

Scrophulariae Radix (SR) has been widely used in Chinese herbal compound prescriptions, health care products and functional foods. The present study aimed to investigate the immunomodulatory activity of polysaccharides from SR (SRPs) in macrophages and explore the potential mechanisms. The results showed that four SRPs fractions (SRPs40, SRPs60, SRPs80 and SRPs100) had similar absorption peaks and monosaccharide compositions, but the intensities of absorption peaks and monosaccharide contents were distinguished. All SRPs fractions significantly enhanced the pinocytic activity, promoted the production of NO and TNF-α, increased the mRNA expressions of inflammatory factors (IL-1β, IL-6, TNF-α and PTGS2) and TLR2, and elevated the phosphorylation levels of p38, ERK, JNK, p65 and IκB. Moreover, the production of NO and TNF-α stimulated by SRPs was dramatically suppressed by anti-TLR2 antibody. These results indicated that SRPs activated macrophages through MAPK and NF-κB signaling pathways via recognition of TLR2.

Citri Reticulatae Pericarpium Limits TLR-4-Triggered Inflammatory Response in Raw264.7 Macrophages by Activating RasGRP3

Inflammation is an important immune response to pathogen invasion, but excessive inflammation leads to tissue injury and even cytokine storm. Therefore, proper response is needed depending on the intensity of the infection. Ras guanine nucleotide releasing protein 3 (RasGRP3) is a regulator of the TLR-mediated response. In low-intensity inflammation, it negatively regulates production of pro-inflammatory cytokines, especially IL-6. Citri Reticulatae Pericarpium, the peel of Citrus reticulata Blanco, is a major medicinal herb in Korean medicine. The present study aims to investigate whether the Citri Reticulatae Pericarpium extract (CRE) has immunomodulatory activity using the Raw264.7 macrophage. Also, we investigated the effect of CRE on RasGRP3 expression. In the present study, CRE reduced IL-6 production in the low-LPS environment (1 ng/mL) and did not in the high-LPS environment (100 ng/mL). The suppression of IL-6 production in the low-LPS environment (1 ng/mL) was abolished after the pretreatment of RasGRP3 siRNA. The reduced RasGRP3 protein content by 100 ng/mL LPS treatment was increased by CRE treatment. Additionally, nobiletin, a major component of CRE showed a suppressive effect on IL-6 production in the low-LPS environment (1 ng/mL). The present results suggest that CRE alleviates inflammatory response via activating RasGRP3 expression in low-intensity inflammation.

The Large Molecular Weight Polysaccharide from Wild Cordyceps and Its Antitumor Activity on H22 Tumor-Bearing Mice

Cordyceps has anti-cancer effects; however, the bioactive substance and its effect are still unclear. Polysaccharides extracted from Cordyceps sinensis, the fugus of Cordyceps, have been reported to have anti-cancer properties. Thus, we speculated that polysaccharides might be the key anti-tumor active ingredients of Cordyceps because of their larger molecular weight than that of polysaccharides in Cordyceps sinensis. In this study, we aimed to investigate the effects of wild Cordyceps polysaccharides on H22 liver cancer and the underlying mechanism. The structural characteristics of the polysaccharides of WCP were analyzed by high-performance liquid chromatography, high-performance gel-permeation chromatography, Fourier transform infrared spectrophotometry, and scanning electron microscopy. Additionally, H22 tumor-bearing BALB/c mice were used to explore the anti-tumor effect of WCP (100 and 300 mg/kg/d). The mechanism by WCP inhibited H22 tumors was uncovered by the TUNEL assay, flow cytometry, hematoxylin-eosin staining, quantitative reverse transcription-polymerase chain reaction, and Western blotting. Here, our results showed that WCP presented high purity with an average molecular weight of 2.1 × 10⁶ Da and 2.19 × 10⁴ Da. WCP was determined to be composed of mannose, glucose, and galactose. Notably, WCP could inhibit the proliferation of H22 tumors not only by improving immune function, but also by promoting the apoptosis of tumor cells, likely through the IL-10/STAT3/Bcl2 and Cyto-c/Caspase8/3 signaling pathways, in H22 tumor-bearing mice. Particularly, WCP had essentially no side effects compared to 5-FU, a common drug used in the treatment of liver cancer. In conclusion, WCP could be a potential anti-tumor product with strong regulatory effects in H22 liver cancer.

Characterization of macrophage activation after treatment with polysaccharides from ginseng according to heat processing

The worldwide persistence of infectious diseases is a significant public health issue. Consequently, studying immunomodulatory ingredients present in natural products, such as ginseng, is important for developing new treatment options. Here, we extracted three different types of polysaccharides from white (P-WG), red (P-RG), and heat-processed (P-HPG) ginseng and analyzed their chemical properties and immunostimulatory activity against RAW 264.7 murine macrophages. Carbohydrates were the main components of all three polysaccharide types, while uronic acid and protein levels were relatively low. Chemical analysis indicated that the content of carbohydrates (total sugar) increased with processing temperature, while that of uronic acid decreased. Treatment with P-WG, P-RG or P-HPG stimulated nitric oxide (NO) production and increased tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 levels in RAW 264.7 macrophages, with P-WG showing the highest activity among the three polysaccharides. The expression of inducible NO synthase, which affects NO secretion, was highest in the macrophages treated with P-WG. Analysis of intracellular signaling pathways showed that mitogen-activated protein kinases (ERK, JNK, and p38) and NF-kB p65 were strongly phosphorylated by P-WG in macrophages but were only moderately phosphorylated by P-RG and P-HPG. Collectively, these results suggest that the polysaccharides isolated from ginseng undergo different changes in response to heat processing and display different chemical compositions and immune-enhancing activities.

Characterization of effects of chitooligosaccharide monomer addition on immunomodulatory activity in macrophages

The present study aimed to investigate the effects of five chitooligosaccharide monomers of different molecular weights on immunomodulatory activity in macrophage-like RAW264.7 cells. The incubation of various chitooligosaccharide monomers enhanced phagocytosis and pinocytosis activity toward Staphylococcus aureus and Escherichia coli in RAW264.7 cells. The incorporation of chitooligosaccharide monomers significantly boosted the generation of reactive oxygen species and reactive nitrogen species, as well as the release of inflammatory cytokines. To further explore the mechanism of inflammation regulated by chitooligosaccharide, the activation inhibitors of NF-кB (CAPE) and TLR-4 (TAK-242) were utilized, the determination data demonstrated that chitobiose suppressed the expression of inflammatory cytokines and NF-кB p65. In addition, the investigation results revealed that the presence of the mannose receptor inhibitor (mannan) suppressed chitohexaose-induced phagocytic activity and inflammatory cytokines. These results suggested that the five distinct chitooligosaccharide monomers had inconsistent effects, the chitobiose and chitohexaose exhibiting the best biological activity in activating RAW264.7 cells, promoting cell proliferation, and increasing non-specific immunity.

Immunomodulatory Effects of an Aqueous Extract of Black Radish on Mouse Macrophages via the TLR2/4-Mediated Signaling Pathway

Here, we determined the immunostimulatory effects of black radish (Raphanus sativus ver niger) hot water extract (BRHE) on a mouse macrophage cell line (RAW 264.7) and mouse peritoneal macrophages. We found that BRHE treatment increased cell proliferation, phagocytic activity, nitric oxide (NO) levels, cytokine production, and reactive oxygen species synthesis. Moreover, BRHE increased the expression of the following immunomodulators in RAW 264.7 cells and peritoneal macrophages: pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), iNOS, and COX-2. BRHE treatment significantly up-regulated the phosphorylation of components of the mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), Akt, and STAT3 signaling pathways. Further, the effects of BRHE on macrophages were significantly diminished after the cells were treated with the TLR2 antagonist C29 or the TLR4 antagonist TAK-242. Therefore, BRHE-induced immunostimulatory phenotypes in mouse macrophages were reversed by multiple inhibitors, such as TLR antagonist, MAPK inhibitor, and Akt inhibitor indicating that BRHE induced macrophage activation through the TLR2/4-MAPK-NFκB-Akt-STAT3 signaling pathway. These results indicate that BRHE may serve as a potential immunomodulatory factor or functional food and provide the scientific basis for the comprehensive utilization and evaluation of black radish in future applications.

Extraction, characterization, antioxidant and anti-tumor activities of polysaccharides from Camellia fascicularis leaves

The ultrasonic-assisted extraction of polysaccharides from Camellia fascicularis (PCF) was optimized using response surface methodology. After separation and purification with DEAE-52 cellulose and Sephadex G-200 glucan gel columns, the purified polysaccharide components of PCFa-1 and PCFc-1 were analyzed for their structural characterization, antioxidant and anti-tumor activities in vitro. The results indicated that liquid to material ratio of 42 mL/g, ultrasonic time of 53 min, ultrasonic temperature of 73 °C, and ultrasonic power of 215 W were the optimum extraction conditions for PCF with maximum yields (4.05 %). PCFa-1 and PCFc-1 contained 5.88 % and 9.58 % uronic acid content, with 7.53 and 108.91 kDa of average molecular weights, respectively. The PCFa-1 was mainly constituted of galactose, arabinose, and glucose, while PCFc-1 was primarily composed of arabinose, glucose, galacturonic acid, and rhamnose. Fourier transform infrared spectra revealed that PCFa-1 and PCFc-1 contained typical polysaccharide bands. Scanning electron microscopy showed that the surface of PCFa-1 and PCFc-1 were irregular and clumpy structures. Nuclear magnetic resonance showed that PCFa-1 and PCFc-1 were mainly α-glycosidic bond conformation. Furthermore, the PCFc-1 showed better antioxidant capacities than PCFa-1 against hydroxyl, DPPH, and ABTS radicals and exhibited more potent toxicity on A549 and HepG2 cells. These research results suggested that PCF, especially PCFc-1, possesses great potential as natural antioxidants and anti-tumor drugs.

Regulation of innate and adaptive immunity using herbal medicine: benefits for the COVID-19 vaccination

Vaccination is a major achievement that has become an effective prevention strategy against infectious diseases and active control of emerging pathogens worldwide. In response to the coronavirus disease 2019 (COVID-19) pandemic, several diverse vaccines against severe acute respiratory syndrome coronavirus 2 have been developed and deployed for use in a large number of individuals, and have been reported to protect against symptomatic COVID-19 cases and deaths. However, the application of vaccines has a series of limitations, including protective failure for variants of concern, unavailability of individuals due to immune deficiency, and the disappearance of immune protection for increasing infections in vaccinated individuals. These aspects raise the question of how to modulate the immune system that contributes to the COVID-19 vaccine protective effects. Herbal medicines are widely used for their immune regulatory abilities in clinics. More attractively, herbal medicines have been well accepted for their positive role in the COVID-19 prevention and suppression through regulation of the immune system. This review presents a brief overview of the strategy of COVID-19 vaccination and the response of the immune system to vaccines, the regulatory effects and mechanisms of herbal medicine in immune-related macrophages, natural killer cells, dendritic cells, and lymphocytes T and B cells, and how they help vaccines work. Later in the article, the potential role and application of herbal medicines in the most recent COVID-19 vaccination are discussed. This article provides new insights into herbal medicines as promising alternative supplements that may benefit from COVID-19 vaccination.

Graphical abstract

http://links.lww.com/AHM/A31.

Characterization and macrophages immunomodulatory activity of two water-soluble polysaccharides from Abrus cantoniensis

The study aims to elucidate the physicochemical properties and immunomodulatory activity of two polysaccharides (ACP_t0 and ACP_t2) from Abrus cantoniensis. Results revealed that ACP_t0 with a molecular weight of 26.0 kDa, was mainly composed of glucose (83.1%) and galactose (6.1%), and that ACP_t2 with a molecular weight of 145.6/8.9 kDa, consisted of galactose (25.6%), galacturonic acid (22.2%), arabinos (16.6%) and galactose (11.0%) respectively. AFM and Congo red experiments suggested that ACP_t0 and ACP_t2 might be spherical particles with triple-helix conformation in aqueous solution. ACP_t0 and ACP_t2 exhibited immunomodulatory activity by promoting the proliferation, augmenting pinocytic and phagocytic capacities, releasing immunoactive molecules such as ROS, NO, iNOS, TNF-α, IL-6 and IL-1β, upregulation of the mRNA levels of corresponding cytokines in macrophages. Moreover, ACP_t0 and ACP_t2 were recognized by toll-like receptor 4 (TLR4) and exerted immunomodulatory effects via activating Myeloid differentiation factor 88 (MyD88), mitogen-activated protein kinases (MAPKs) and serine/threonine kinase (Akt) signaling pathways in macrophages. Notably, ACP_t2 had higher immunomodulatory activity than ACP_t0. Based on the present findings, ACP_t0 and ACP_t2 could be explored as an active component of immunomodulators in the food and pharmaceutical fields.

Immunostimulating and intracellular signaling pathways mechanism on macrophage of rhamnogalacturonan-I type polysaccharide purified from radish leaves

In this study, the intracellular signaling pathways involved in macrophage activation through the RG-I-type polysaccharide (REP-I) purified from radish leaves were elucidated. The gene expression and secretion of immune-related factors such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and nitrogen oxide (NO) from macrophages were enhanced by the addition of REP-I. Moreover, immunoblotting and immunocytochemistry analyses indicated that REP-I dose-dependently phosphorylated the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways. An investigation using different inhibitors revealed that the effect of REP-I on NO secretion was mostly promoted by c-Jun N-terminal kinase (JNK) and NF-κB. Furthermore, the secretion of IL-6 was mostly induced via extracellular-signal-regulated kinase (ERK), JNK, and NF-κB. TNF-α secretion was mostly induced via NF-κB. In contrast, an investigation using anti-pattern recognition receptor (PRR) antibodies revealed that the effect of REP-I on the secretion of NO was mostly related with dectin-1, scavenger receptor (SR), toll-like receptor (TLR)2, TLR4, CD14, and CD11b. Furthermore, the secretion of IL-6 was mostly involved with SR, and the secretion of TNF-α was mostly relevance to TLR2. In conclusion, it is affirmed that immunostimulatory activation of macrophage of REP-I purified from radish leaves was deeply associated with several PRR and phosphorylating MAPK and NF-κB.

Ultrasonication, immune activity, and photocrosslinked microgel formation of pectic polysaccharide isolated from root bark of Ulmus davidiana var. japonica (Rehder) Nakai

The root bark of Ulmus davidiana var. japonica (Rehder) Nakai (Japanese elm) has been used for inflammatory disease treatments. In this work, we isolated pectic polysaccharides from the root bark of U. davidiana (UDP) and explored the immune activities of intact and ultrasonicated UDP on human macrophages. The UDP-treated macrophages showed a proinflammatory response, indicating classical activation via Toll-like receptor-mediated recognition. For hydrogel formation, the ultrasonicated UDP was modified with methacrylate groups, then subjected to photocrosslinking. The formed bulk hydrogel was pulverized into microgels by homogenization, and the microgel size was modulated for macrophage phagocytosis. The UDP microgel-treated macrophages displayed microgel internalization and classical activation that involved upregulation of M1 polarization markers (IL6, TNF-α, and CCR7), indicating that the microgel can be used as a carrier for macrophage-targeted drug delivery.

The anti-atherosclerotic effects of natural polysaccharides: from phenomena to the main mechanisms of action

Polysaccharides (PSs) of plant origin have a variety of biological activities, anti-atherosclerotic including, but their use in atherosclerosis therapy is hindered by insufficient knowledge on the cellular and molecular mechanisms of action. In this review, the influence of several natural PSs on the function of macrophages, viral activity, and macrophage cholesterol metabolism has been discussed considering the tight interplay between these aspects in the pathogenesis of atherosclerosis. The anti-atherosclerotic activities of natural PSs related to other mechanisms have been also explored. Directions for further research of anti-atherosclerotic effects of natural PSs have been outlined, the most promising of which can be nutrigenomic studies.

Structural features and anticancer mechanisms of pectic polysaccharides: A review

The anticancer activity of pectic polysaccharides (PPs) was proved by numerous studies, and which also indicated that the bioactivity of PPs was closely related to its complicated structures. Based on the summary and analysis about structure characteristics and corresponding enzymatic process of the reported PPs, the anticancer mechanism and related structural features were systematically clarified. It was found that not only the direct effects on the cancer cells by proliferation inhibition or apoptosis, but also the regulation of immune system, gut microbiota and gut metabolism as indirect effects, jointly played important roles in the anticancer of PPs. Nevertheless, during the study of PPs as promising anticancer components, the exact structure-function relationship, digestion process in vivo, and comprehensive action mechanism are still not well understanding. With the unveiling of the proposed issues, it is believed that PPs are promising to be exploited as effective cancer therapy/adjunctive therapy drugs or functional foods.

Structures and immunomodulatory activity of one galactose- and arabinose-rich polysaccharide from Sambucus adnata

One galactose- and arabinose-rich polysaccharide isolated from Sambucus adnata was named SPS-1, which had an average molecular weight 138.52 kDa, and was composed of L-rhamnose, D-glucuronic acid, D-galacturonic acid, D-galactose, and L-arabinose in a molar ratio of 0.6:0.4:0.1:4.9:4.0. The primary structure of SPS-1 was further analyzed through methylation and NMR spectroscopy. The results showed that SPS-1 had the structural characteristics of AG-II pectin. The immunoactivity test showed that SPS-1 activated the phosphorylation of MAPKs-related proteins and further elevated the expression levels of related nuclear transcription factors (IκBα and NF-κB p65) in the cells through the TLR2 and MyD88/TRAF6-dependent pathway, thereby significantly enhancing the phagocytosis of macrophages and stimulating the secretion of NO, IL-1β, IL-6, and TNF-α, which activated the RAW264.7 cells. Therefore, SPS-1, acting as an immunomodulator, is a potential drug for immunological diseases.

Chemical elucidation and rheological properties of a pectic polysaccharide extracted from Citrus medica L. fruit residues by gradient ethanol precipitation

Citron (Citrus. medica L.) fruits are commonly utilized in the production of essential oil, therefore, the fruits residues turn out to be industrial byproducts. In the present study, a crude polysaccharide was extracted from citron fruit residues by hot water extraction and precipitation of ethanol (95%), after deproteinization, a major polysaccharide component (CMLP-2) was obtained by gradient ethanol precipitation (20%-80%). The physicochemical properties of CMLP-2 such as surface morphology, functional groups, and thermostability were examined by FT-IR spectroscopy, SEM, and thermogravimetric analysis. Moreover, the chemical structure of CMLP-2 was elucidated that CMLP-2 is an acidic pectic polysaccharide consisting of arabinose (Ara), galacturonic acid (GalA), and rhamnose (Rha) in a molar ratio of 4:2:1 with a molecular weight of 202.18 kDa. CMLP-2 is a novel pectic polysaccharide rich in rhamnogalacturonan I (RG-I). Moreover, rheological tests revealed that CMLP-2 solution is pseudoplastic and temperature resistant. The result could be a good basis for the utilization of Citrus medica L. fruits residues as plant-derived food additive.

Immunoenhancement and antioxidative damage effects of Polygonum Cillinerve polysaccharide on RAW264.7 cells

OBJECTIVES

The effects of Polygonum Cillinerve polysaccharide (PCP) on the immune and antioxidant activity were studied.

METHODS

The effects of PCP on cell proliferation, phagocytic activity, cell uptake, the secretion of NO, iNOS, IL-6, IL-12, CAT and POD, intracellular ROS, cell apoptosis and antioxidative mechanism were measured by MTT, ELISA, fluorescence staining, flow cytometry and western blot.

KEY FINDINGS

The results showed that PCP had no toxic effect at 31.25-1.95 µg/ml, could improve the uptake of neutral red and fluorescein isothiocyanate-labelled ovalbumin and promote the release of nitric oxide and nitric oxide synthase. Moreover, PCP also could promote the secretion of IL-6 and IL-12. The damage of RAW264.7 cells induced by hydrogen peroxide was significantly alleviated by PCP at 15.63-0.975 µg/ml. The mechanism of antioxidative damage might be that PCP inhibited the upstream p38 and the phosphorylation of JNK and ERK proteins, and down-regulated caspase 3 and up-regulated the protein expressions of cytochrome C and Bcl-2, finally PCP improved the antioxidative capacity and protected the oxidative damage of cells.

CONCLUSIONS

These results indicated that PCP had the better immunopotentiation and antioxidative damage activity.

Aqueous Extract from Leaves of Citrus unshiu Attenuates Lipopolysaccharide-Induced Inflammatory Responses in a Mouse Model of Systemic Inflammation

Inflammation is related to various life-threatening diseases including cancer, neurodegenerative diseases, and metabolic syndrome. Because macrophages are prominent inflammatory cells, regulation of macrophage activation is a key issue to control the onset of inflammation-associated diseases. In this study, we aimed to evaluate the potential anti-inflammatory activity of Citrus unshiu leaf extract (CLE) and to elucidate the mechanism underlying its anti-inflammatory effect. We found the inhibitory activity of CLE on the secretion of proinflammatory cytokines and a chemokine from mouse macrophage-like RAW 264.7 cells and mouse peritoneal macrophages. The inhibitory activity of CLE was attributed to downregulated JNK, p38 MAPK, and NF-κB signaling pathways, leading to suppressed gene expression of inflammation-associated proteins. Oral administration of CLE significantly decreased the serum level of proinflammatory cytokines IL-6 and TNFα and increased that of anti-inflammatory cytokine IL-10 in lipopolysaccharide-induced systemic inflammation mice. In addition, oral administration of CLE decreased secretion and gene expression of several proinflammatory proteins in the liver and spleen of the model mice. Overall results revealed that C. unshiu leaf is effective to attenuate inflammatory responses in vitro and in vivo.

Citrus peel flavonoid nobiletin alleviates lipopolysaccharide-induced inflammation by activating IL-6/STAT3/FOXO3a-mediated autophagy

Nobiletin, a polymethoxyflavone widely present in the peel of citrus fruits, has significant anti-inflammatory activity. Autophagy plays a critical role in maintaining cell homeostasis by promoting the degradation of intracellular structures in response to various stress. Recent research suggests the involvement of autophagy in the inflammatory process and therefore some inflammation-related diseases. However, the "cross-talk" between autophagy and nobiletin's anti-inflammation response remains not well elucidated. Therefore, this study was initiated with the aim of investigating the role of autophagy in nobiletin's protective effect against inflammation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Results showed that nobiletin significantly (P < 0.05) inhibited the release of nitric oxide (NO) and decreased the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner. Moreover, nobiletin significantly (P < 0.05) promoted autophagy as evidenced by the appearance of more autophagosomes, up-regulated LC3II protein, low-regulated p62 protein, and increased autophagy-related (Atg) genes' expression compared with the control treated with LPS alone. Addition of chloroquine, an autophagy inhibitor, alleviated nobiletin's anti-inflammatory effect, further supporting the requirement of an active autophagy process for the citrus peel flavonoid's biological activity. Mechanistically, we found that nobiletin treatment leads to activation of the IL-6/STAT3/FOXO3a signal pathway through the down-regulation of IL-6 and STAT3 phosphorylation and the upregulation of FOXO3a phosphorylation in the cell nucleus, which is responsible for induction of macrophage autophagy. Taken together, our study provides evidence that nobiletin suppresses inflammatory response through enhancing autophagy through activating the IL-6/STAT3/FOXO3a pathway in macrophage cells.

Structural characterization and immunomodulatory mechanisms of two novel glucans from Morchella importuna fruiting bodies

Two novel glucans named MIPB50-W and MIPB50-S-1 were obtained from edible Morchella importuna with molecular weights (M_w) of 939.2 kDa and 444.5 kDa, respectively. MIPB50-W has a backbone of α-(1 → 4)-d-glucan, which was substituted at O-6 position by α-d-Glcp-(1→. Moreover, MIPB50-S-1 has a backbone of α-(1 → 4)-d-glucan, which was substituted at O-6 position by α-d-Glcp-(1 → 6)-α-d-Glcp-(1→. This is the first report about glucan found in Morchella mushrooms. Furthermore, MIPB50-W and MIPB50-S-1 strengthened the phagocytosis function and the promoted secretion of interleukins (IL)-6/tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO), which induced the activation of Toll-like receptor 2 (TLR2), TLR4 as well as mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways. Interestingly, MIPB50-S-1 performed the better immunomodulatory activity than that of MIPB50-W in almost all tests. Therefore, MIPB50-W and MIPB50-S-1 are potential immune-enhancing components of functional foods.

Structural characterization of a novel polysaccharide from Pleurotus citrinopileatus and its antitumor activity on H22 tumor-bearing mice

In this research, a novel polysaccharide (PCP) was extracted from Pleurotus citrinopileatus and purified by Sephadex G-150 gel column, and its antitumor activity was investigated using the model H22 tumor-bearing mice. PCP was found to be composed of arabinose, galactose, glucose, xylose, mannose and glucuronic acid in a proportion of 0.66: 14.59: 10.77: 1: 0.69: 0.23 with average molecular weight of 7.30 × 10⁵ Da. Further analysis suggested that PCP was a pyranose with α-type and β-type glycosidic residues. The antitumor assays in vivo indicated that PCP could effectively suppress H22 solid tumor growth, protect immune organs and improve inflammation and anemia. Besides, Annexin V-FITC/PI double staining and JC-1 staining demonstrated that PCP could induce apoptosis of H22 hepatoma cells. The PI staining assay revealed that PCP induced H22 hepatoma cells apoptosis by arresting cell cycle in S phase. These results suggest that the polysaccharide from Pleurotus citrinopileatus possesses potential value in the treatment of liver cancer.

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.

Trends in the extraction, purification, characterisation and biological activities of polysaccharides from tropical and sub-tropical fruits - A comprehensive review

Tropical and sub-tropical fruits are tremendous sources of polysaccharides (PSs), which are of great interest in the human welfare system as natural medicines, food and cosmetics. This review paper aims to highlight the recent trends in extraction (conventional and non-conventional), purification and analytic techniques of fruit polysaccharides (FPSs). The chemical structure and biological activities, such as immunomodulatory, anti-cancer, anti-oxidant, anti-inflammatory, anti-viral, anti-coagulant and anti-diabetic effects, of PSs extracted from 53 various fruits were compared and discussed. With this wide coverage, a total of 172 scientific articles were reviewed and discussed. This comprehensive survey from previous studies suggests that the FPSs are non-toxic and highly biocompatible. In addition, this review highlights that FPSs might be excellent functional foods as well as effective therapeutic drugs. Finally, the future research advances of FPSs are also described. The content of this review will promote human wellness-based food product development in the future.

Citrus unshiu peel suppress the metastatic potential of murine melanoma B16F10 cells in vitro and in vivo

The peel of Citrus unshiu Marcow. fruits (CU) has long been used as a traditional medicine that has therapeutic effects against pathogenic diseases, including asthma, vomiting, dyspepsia, blood circulation disorders, and various types of cancer. In this study, we investigated the effect of CU peel on metastatic melanoma, a highly aggressive skin cancer, in B16F10 melanoma cells, and in B16F10 cells inoculated‐C57BL/6 mice. Our results show that ethanol extracts of CU (EECU) inhibited cell growth and increased the apoptotic cells in B16F10 cells. EECU also stimulated the induction of mitochondria‐mediated intrinsic pathway, with reduced mitochondrial membrane potential and increased generation of intracellular reactive oxygen species. Furthermore, EECU suppressed the migration, invasion, and colony formation of B16F10 cells. In addition, the oral administration of EECU reduced serum lactate dehydrogenase activity without weight loss, hepatotoxicity, nor nephrotoxicity in B16F10 cell‐inoculated mice. Moreover, EECU markedly suppressed lung hypertrophy, the number and expression of metastatic tumor nodules, and the expression of inflammatory tumor necrosis factor‐alpha in lung tissue. In conclusion, our findings suggest that the inhibitory effect of EECU on the metastasis of melanoma indicates that it may be regarded as a potential therapeutic herbal drug for melanoma.

Bioactive Exopolysaccharides Reveal Camellia oleifera Infected by the Fungus Exobasidium gracile Could Have a Functional Use

Camellia oleifera is an important Chinese commercial crop. Camellia oleifera can display abnormal leaves due to infection by the parasitic fungus Exobasidium gracile. Exobasidium gracile was isolated from infected leaves and used in fermentation, and exopolysaccharides EP0-1 and EP0.5-1 were purified from the fermentation broth. EP0-1 was an alkaline polysaccharide consisting mainly of the linkages α-d-Manp(1→, →2)-α-d-Manp(1→ and →6)-α-d-Manp(1→, →3)-α-d-Glcp(1→ and→4)-α-d-Glcp(1→, terminal β-d-Galf, (1→5)-β-d-Galf, and terminal β-D-GlcN(1→. EP0.5-1 was an acidic galactofuranose-containing polysaccharide. It contained the linkages of α-d-Manp(1→, →2)-α-d-Manp(1→, →6)-α-d-Manp(1→,→2, 6)-α-d-Manp(1→, →4)-α-d-Glcp(1→, and →4)-α-d-GlcUA(1→. Galactofuranose linkages were composed of terminal β-d-Galf, (1→6)-β-d-Galf and (1→2)-β-d-Galf. Exobasidium gracile exopolysaccharides displayed significant immunoregulatory activity by activating macrophages. This research indicates that infected leaves from Camellia oleifera including the exopolysaccharides produced by the parasitic fungus Exobasidium gracile by are worth further investigation as a functional product.

Advances in Research on Immunoregulation of Macrophages by Plant Polysaccharides

Polysaccharides are among the most important members of the biopolymer family. They are natural macromolecules composed of monosaccharides. To date, more than 300 kinds of natural polysaccharide compounds have been identified. They are present in plants, animals, and microorganisms, and they engage in a variety of physiological functions. In the 1950s, due to the discovery of their immunoregulatory and anti-tumor activities, polysaccharides became a popular topic of research in pharmacology, especially in immunopharmacology. Plants are an important source of natural polysaccharides. Pharmacological and clinical studies have shown that plant polysaccharides have many functions, such as immune regulation, anti-tumor activity, anti-inflammatory activity, anti-viral functions, anti-radiation functions, and a hypoglycaemic effect. The immunomodulatory effects of plant polysaccharides have received much attention. Polysaccharides with these effects are also referred to as biological response modifiers (BRMs), and research on them is one of the most active areas of polysaccharide research. Thus, we summarize immunomodulatory effects of botanical polysaccharides isolated from different species of plants on the macrophage. The primary effect of botanical polysaccharides is to enhance and/or activate macrophage immune responses, including increasing reactive oxygen species (ROS) production, and enhancing secretion of cytokines and chemokines. Therefore, it is believed that botanical polysaccharides have significant therapeutic potential, and represent a new method for discovery and development of novel immunomodulatory medicine.

Effectual components of Polygonum ciliinerve protects against Staphylococcus aureus infection with immunomodulatory functions in C57BL/6 mice1

PURPOSE

To investigate the efficacy and mechanisms of root tuber of Polygonum ciliinerve (Nakai) ohwi (rPC) which has been used to treat bacterial infection in traditional Chinese medicine.

METHODS

With the mouse model of Staphylococcus aureus (S. aureus) pneumonia, the phenotype of rPC treated mice, including body weight, mortality, lung slices and bacterial burden were evaluated. Furthermore, inflammatory factors in bronchoalveolar lavage (BAL) were determined by ELISA and the distribution of T cells in lung was assessed by immunofluorescence assay.

RESULTS

rPC treatment could dose-dependently reduce weight loss and mortality in S. aureus-infected mice. Upon 10 mg/ml rPC treatment, S. aureus-infected mice showed about 8 grams increase in body weight (P<0.001) and 50% enhancement in mortality. The integrity of lung tissue and bacterial burden were also improved by rPC treatment. Moreover, rPC was found to modulate the immune response in infection.

CONCLUSION

rPC has therapeutic potential for S. aureus infections and pneumonia with immunomodulatory functions.