Isolation, Structural Characterization and Macrophage Activation Activity of an Acidic Polysaccharide from Raspberry Pulp

Structural characteristics and antioxidant activities of a novel polysaccharide from Euphorbia himalayensis root

Euphorbia himalayensis Boiss. is an alpine member of the Euphorbiaceae family. Its dried roots have been used to treat digestive problems and chest congestion in traditional Tibetan and Mongolian medicine. Despite thousands of years of use in medicine, the bioactive compounds of the root remain unknown. Herein, we isolated a novel aqueous-soluble polysaccharide (EHP2) from the E. himalayensis root and determined its structural characteristics via high-performance gel permeation chromatography, Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry. The homogeneous molecular weight of EHP2 was 23.6 kDa with narrow polydisperity (Mw/Mn = 1.4), and EHP2 mainly comprised of glucose (86.4%), galactose (11.9%) and mannose (1.7%). The major backbone of EHP2 was →4)-α-D-GalAp-(1 → 4)-α-D-Glcp-(1 → and the branch chain was α-D-Glcp-(1→. The antioxidant activity of the EHP2 was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical scavenging assays, and antioxidant enzyme activity (SOD, GSH and MDA) was determined in human umbilical vein endothelial cells (HUVECs). The EHP2 demonstrated lower potential scavenging effects on DPPH and superoxide free radical scavenger than ascorbic acid, and in HUVECs, it led to increased SOD and GSH activities and decreased MDA levels. This study is the first to describe an E. himalayensis polysaccharide compound with potential antioxidant activity.

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.

Raspberry polysaccharides attenuate hepatic inflammation and oxidative stress in diet-induced obese mice by enhancing butyrate-mediated intestinal barrier function

Obesity and associated liver diseases are becoming global public health challenges. Raspberry (Rubus chingii Hu.), as a medicine food homology plant, possesses a series of health-promoting properties, but its protective effect on obesity-related liver injury and the potential mechanisms remain obscure. Herein high-fat diet (HFD)-fed mice were orally treated with raspberry polysaccharides (RCP) for 14 weeks. Treatment with RCP alleviated obesity and associated symptoms including hyperglycemia, hyperlipemia, endotoxemia, as well as hepatic inflammation and oxidant stress in HFD-induced obese mice. RCP restructured the gut microbiota and host metabolism especially by increasing the levels of Dubosiella and its metabolite butyrate. Besides, exogenous butyrate supplementation protected against intestinal barrier disruption, and thereby reduced inflow of lipopolysaccharide and mitigated inflammation and oxidative injury in the liver of obese mice. Therefore, we suggest that RCP can be utilized as a novel prebiotics to improve obesity-induced hepatic oxidative injury by enhancing butyrate-mediated intestinal barrier function.

Immunomodulatory Activity and Its Mechanisms of Two Polysaccharides from Poria cocos

Polyporaceae is an important fungal family that has been a source of natural products with a range of pharmaceutical activities in China. In our previous study, two polysaccharides, PCWPW and PCWPS, with significant antioxidant and antidepressant activity were obtained from Poria cocos. In this study, we evaluated their potential molecular mechanisms in the immunomodulation of macrophages. PCWPW and PCWPS were characterized by GC-MS analysis to contain 1,3-linked Glcp. ELISA assays results demonstrated that the secretion of TNF-α was significantly enhanced by PCWPW/PCWPS. RNA-seq data demonstrated that PCWPS treatment modulated the expression of immune-related genes in macrophages, which was further confirmed by RT-qPCR assays. The activation of TNF-α secretion was found to be mannose receptor (MR) dependent and suppressed by MR inhibitor pretreatment. Moreover, the amount of TNF-α cytokine secretion in PCWPW/PCWPS-induced RAW264.7 cells was decreased when pretreated with NF-κB or MAPK signaling pathway inhibitors. Collectively, our results suggested that PCWPW and PCWPS possessed immunomodulatory activity that regulates TNF-α expression through the NF-κB/MAPK signaling pathway by binding to mannose receptors. Therefore, PCWPW and PCWPS isolated from Poria cocos have potential as drug candidates for immune-related disease treatment.

Molecular mechanism overview of metabolite biosynthesis in medicinal plants

Medicinal plants are essential and rich resources for plant-based medicines and new drugs. Increasing attentions are paid to the secondary metabolites of medicinal plants due to their unique biological activity, pharmacological action, and high utilization value. However, the development of medicinal plants is constrained by limited natural resources and an unclear understanding of the mechanisms underlying active medicinal ingredients, thereby rendering the utilization and exploration of secondary metabolites more challenging. Besides, with the advancement of research on biosynthesis and molecular metabolism of natural products from medicinal plants, the methods for studying the biological activity and pharmacological effects of these products are constantly evolving. In recent years, significant progress has been made in the biosynthetic pathways and related regulatory genes of secondary metabolites in medicinal plants, which has greatly advanced both basic research and the development of clinical applications for medicinal plants. In this review, we discuss the past two decades of international research on the development of medicinal plant resources, mainly focusing on the biosynthetic pathway of secondary metabolites, intracellular signal transduction processes, multi-omics applications, and the application of gene editing technology in related research progress. We also discuss future development trends to promote the deep mining and development of natural products from medicinal plants, providing a useful reference.

Moringa oleifera leaf polysaccharides exert anti-lung cancer effects upon targeting TLR4 to reverse the tumor-associated macrophage phenotype and promote T-cell infiltration

Tumor-associated macrophages (TAMs) participate in tumorigenesis, growth, invasion as well as metastasis by facilitating an immunosuppressive tumor microenvironment. Reversing the pro-tumoral M2 phenotype of TAMs has become a hot spot in advancing cancer immunotherapy. In the current study, the content of Moringa oleifera leaf polysaccharides (MOLP) was determined and characterized, along with the anti-cancer mechanism of MOLP studied in a Lewis lung cancer (LLC) tumor-bearing mouse model and bone marrow-derived macrophages. The monosaccharide composition and gel permeation chromatography analyses show that MOLP are mainly composed of galactose, glucose, and arabinose, with approximately 17.35 kDa average molecular weight (Mw). In vivo studies demonstrate that MOLP convert TAMs from the immunosuppressive M2 phenotype to the antitumor M1 phenotype, thus inducing CXCL9 and CXCL10 expression and increasing T-cell infiltration in the tumor. Furthermore, macrophage depletion and T cell suppression demonstrated that the tumor suppressive effect of MOLP was reliant on reprogramming macrophage polarization and T cell infiltration. In vitro studies revealed that MOLP could induce the phenotypic switch from M2 macrophages to M1 by targeting TLR4. The current study highlights that MOLP are promising anticancer plant-derived polysaccharides with potential in modulating the immune microenvironment and have a bright application prospect in the immunotherapy of lung cancer.

A novel polysaccharide from Rubus chingii Hu unripe fruits: Extraction optimization, structural characterization and amelioration of colonic inflammation and oxidative stress

Raspberry is used as a medicine food homology species and its polysaccharides are worthy being investigated and developed. In the present study, a novel polysaccharide of unripe raspberry fruits (pRCP) was extracted and characterized. The results show that pRCP was an acidic heteropolysaccharide and its Mw value was 74.86 kDa with a high homogeneity. The main chain of pRCP consisted of → 3,6)-β-Galp(1 → and → 5)-α-Araf(1→, and its side chain was composed of α-Araf(1 → linked to the C3 position of → 3,6)-β-Galp(1 →. In addition, pRCP supplementation increased the gut microbial diversity and reduced harmful bacteria including Erysipelatoclostridium and Negativibacillus in high-fat diet (HFD)-fed mice. Treatment with pRCP also alleviated HFD-induced colonic inflammation and oxidative stress in mice. These beneficial effects can be transferred to recipient mice by faecal microbiota transplantation from pRCP-treated mice. Therefore, our study suggests that pRCP could be used as a potential prebiotics to improve intestinal health by modulating the gut microbiota.

The protective effect and antitumor activity of Aconiti Lateralis Radix Praeparata (Fuzi) polysaccharide on cyclophosphamide-induced immunosuppression in H22 tumor-bearing mice

Background: Aconiti Lateralis Radix Praeparata, also known as Fuzi in Chinese, has been used in Traditional Chinese Medicine for more than 2,000 years. In recent years, some traditional herbal compounds containing Fuzi have achieved positive clinical results in tumor treatment. And the polysaccharide isolated from Fuzi has attracted much attention as a potential immunomodulator. However, its immunomodulatory mechanism remains to be further studied. Aim of the study. Fuzi neutral polysaccharide (FNPS) and cyclophosphamide (CTX) were combined to treat Hepatoma 22 (H22) tumor-bearing mice, and its mechanism of ameliorating immunosuppression caused by CTX was studied. Methods: FNPS was isolated and purified. The molecular weight, functional groups, monosaccharide composition, and apparent morphology were characterized by gel permeation chromatography, Fourier transform infrared spectrometer, ion chromatography and scanning electron microscope, respectively. Through the analysis of tumor, immune organs, and serum cytokine levels of H22 tumor-bearing mice, the immunomodulatory effect and the protective effect on immunosuppressive mice induced by CTX was evaluated. And the immunomodulatory activity of FNPS was further verified by macrophage functional experiments. Results: FNPS was composed of rhamnose, arabinose, galactose, glucose, and mannose in a molar ratio of 0.008:0.017:0.018:0.908:0.048. Its molecular weight was 94 kDa. In vivo experiments showed that 200 mg mL^-1 FNPS could alleviate the suppression of immune organs and immune cells caused by CTX treatment, enhance the antitumor effect of CTX, increase the serum levels of Th1 immune-related pro-inflammatory cytokines (IL-1β and IL-6), and decrease Th2 immune-related anti-inflammatory cytokine (IL-10) and tumor-related pro-inflammatory cytokine (TNF-α) in the chemotherapy mice. Functional experiments revealed that 25 μg mL^-1 FNPS could promote phagocytosis and proliferation of macrophages. When the concentration reached 50 μg mL^-1, it enhanced the migration activity. Conclusion: FNPS has the potential to alleviate the immunosuppressive effect of CTX by activating immune cells and promoting inflammation. It could be used as a potential auxiliary medication for liver cancer treatment.

Structural Characteristics, Antioxidant, and Immunostimulatory Activities of an Acidic Polysaccharide from Raspberry Pulp

The extraction and characterization of new bioactive plant-derived polysaccharides with the potential for use as functional foods and medicine have attracted much attention. In the present study, A novel acidic polysaccharide (RPP-3a) with a weight-average molecular weight (Mw) of 88,997 Da was isolated from the raspberry pulp. RPP-3a was composed of rhamnose, arabinose, galactose, glucose, mannose, and galacturonic acid at a molar ratio of 13.1:28.6:16.8:1.4:6.2:33.9. Structural analysis suggested that the RPP-3a backbone was composed of repeating units of →4)-β-Galp-(1→3,4)-α-Rhap-(1→[4)-α-GalAp-(1→4)-α-GalAp-(1→]_n with branches at the C-4 position of rhamnose. The side chain of RPP-3a, containing two branch levels, was comprised of α-Araf-(1→, →5)-α-Araf-(1→, →3,5)-α-Araf-(1→, →3)-β-Galp-(1→, →3,6)-β-Galp-(1→, →4)-β-Glcp-(1→, and →2,6)-α-Manp-1→ residues. RPP-3a exhibited moderate reducing power and strong hydroxyl and superoxide anion radical scavenging abilities. RPP-3a significantly promoted the viability of RAW264.7 macrophages by increasing the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) at both the expression and transcriptional levels. In summary, the immunostimulatory and antioxidant activities make RPP-3a a viable candidate as a health-beneficial functional dietary supplement.

Removal of Methylene Blue from Aqueous Solutions Using a New Natural Lignocellulosic Adsorbent-Raspberry (Rubus idaeus) Leaves Powder

In this work, raspberry (Rubus idaeus) leaves were converted to powder and used as a new natural lignocellulosic low-cost adsorbent for methylene blue removal from aqueous solutions. Different techniques (FTIR, SEM, color analysis, and pH_PZC determination) were applied for adsorbent characterization. The effects of pH, ionic strength, contact time, adsorbent dose, initial deconcentration, and temperature on adsorption capacity were investigated. Equilibrium, kinetic, and thermodynamic studies have shown that the adsorption is best described by the Sips isotherm and pseudo-second-order kinetic model and that the process is spontaneous, favorable, and endothermic, involving physisorption as the main mechanism. The maximum adsorption capacity was 244.6 (mg g⁻¹) higher compared to other adsorbents based on plant leaves. The Taguchi method and the ANOVA analysis were used to optimize the adsorption conditions. The contact time was the factor with the highest influence on the process, while the temperature had the lowest influence. A desorption study was also performed to determine the possibility of adsorbent regeneration.