Extraction, purification, structural characterization and pharmacological activities of polysaccharides from sea buckthorn (Hippophae rhamnoides L.): A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Sea buckthorn (Hippophae rhamnoides L.) is an edible fruit with a long history in China as a medicinal plant. The fruits of H. rhamnoides are rich in a variety of nutrients and pharmacological active compounds. As one of the most important active ingredients in sea buckthorn, polysaccharides have attracted the attention of researchers due to their antioxidant, anti-fatigue, and liver protective qualities. AIM OF THE REVIEW: This review summarizes recent studies on extraction, purification, structural characterization and pharmacological activities of polysaccharides from sea buckthorn. In addition, the relationship between the structure and the activities of sea buckthorn polysaccharides (SBPS) were discussed. This review would provide important research bases and up-to-date information for the future in-depth development and application of sea buckthorn polysaccharides in the field of pharmaceuticals and functional foods. MATERIALS AND METHODS: By inputting the search term "Sea buckthorn polysaccharides", relevant research information was obtained from databases such as Web of Science, Google Scholar, PubMed, China Knowledge Network (CNKI), China Master Theses Full-text Database, and China Doctoral Dissertations Full-text Database. RESULTS: The main extraction methods of SBPS include hot water extraction (HWE), ultrasonic assisted extraction (UAE), microwave-assisted extraction (MAE), flash extraction (FE), and ethanol extraction. More than 20 polysaccharides have been isolated from sea buckthorn fruits. The chemical structures of sea buckthorn polysaccharides obtained by different extraction, isolation, and purification methods are diverse. Polysaccharides from sea buckthorn display a variety of pharmacological properties, including antioxidant, anti-fatigue, liver protection, anti-obesity, regulation of intestinal flora, immunoregulation, anti-tumor, anti-inflammatory, and hypoglycemic activities. CONCLUSIONS: Sea buckthorn has a long medicinal history and characteristics of an ethnic medicine and food. Polysaccharides are one of the main active components of sea buckthorn, and they have received increasing attention from researchers. Sea buckthorn polysaccharides have remarkable pharmacological activities, health benefits, and broad application prospects. In addition, further exploration of the chemical structure of SBPS, in-depth study of their pharmacological activities, identification of their material basis, characterization of disease resistance mechanisms, and potential health functions are still directions of future research. With the accumulation of research on the extraction and purification processes, chemical structure, pharmacological effects, molecular mechanisms, and structure-activity relationships, sea buckthorn polysaccharides derived from natural resources will ultimately make significant contributions to human health.

Polysaccharides from steam-processed Polygonatum cyrtonema Hua protect against d-galactose-induced oxidative damage in mice by activation of Nrf2/HO-1 signaling.

BACKGROUND: Polygonatum cyrtonema Hua is cultivated for its edible and medical value. The steam-processed rhizome of P. cyrtonema is the main form for daily consumption and it has been used traditionally in tonics for treating various age-related disorders. The aim of our study was to compare the physicochemical properties and antioxidant activity of polysaccharides respectively extracted from crude P. Cyrtonema (PCPC), and steam-processed P. cyrtonema (PCPS), and to explore a possible underlying antioxidant mechanism. RESULTS: The PCPC with a molecular weight of 4.35 × 103 Da mainly consisted of fructose and trace amounts of glucose, whereas PCPS with 4.24 × 104 Da was composed of fructose, arabinose, glucose, xylose, mannose, galacturonic acid and glucuronic acid. The PCPC had a triple-helical conformation whereas PCPS was a random coil. Both exhibited free radicals- scavenging activity in vitro. In a mouse model of oxidative damage, PCPC or PCPS treatment significantly reversed histopathological alterations, reactive oxygen species (ROS) accumulation and the reduction of antioxidant enzyme activity. They both also promoted Nrf2 nuclear transport by decreasing Keap-1 expression and increasing HO-1 expression. Both in vitro and in vivo, PCPS exhibited more potent antioxidant activity than PCPC. CONCLUSION: Overall, the results suggest that PCPS has a stronger effect on the prevention of oxidative damage by activating Nrf2/HO-1 antioxidant signaling. This study demonstrates the role of steam-processed P. cyrtonema rhizome and provides valuable perspective for PCPS as a functional agent. © 2022 Society of Chemical Industry.

Wuzi-Yanzong-Wan prevents oligoasthenospermia due to TAp73 suppression by affecting cellular junction remodeling in testicular tissue in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Wuzi-Yanzong-Wan (WZYZW) is a classic Chinese herbal preparation, which has a significant clinical efficacy in tonifying the kidney and benefiting the sperm, and is widely used in the treatment of oligoasthenospermia with a long history. TAp73 inhibition results in the decrease of sperm quality, but the therapeutic mechanism of WZYZW on oligoasthenospermia caused by TAp73 gene inhibition remains elusive. AIMS OF STUDY: The purpose of this study is to investigate whether TAp73 suppression leads to oligoasthenospermia and the application of WZYZW treatment in condition of TAp73 suppression. METHODOLOGY: C57BL/6 male mice were injected with Pifithrin-α (2.5 mg/kg) intraperitoneally for 30 days to induce TAp73 suppression model, with WZYZW at 1.0, 2.0 and 4.0 g/kg were administrated in parallel. The blood, testis and epididymis were collected, with organ coefficient calculated. Makler sperm counter was used to analyze the density, motility, survival and malformation rate of sperm. Apoptosis of sperm was analyzed by flow cytometry. Serum hormone levels were determined using ELISA. HE staining and transmission electron microscopy (TEM) were used to observe histopathological changes of testis in blood-testis barrier (BTB), ectoplasmic specialization (ES) and other cell junctions. Expressions of cell adhesion factors including TAp73, Integrin-α6, N-cadherin, Nectin-2 and Occludin were determined by RT-PCR and western blotting. RESULTS: Compared to control mice, TAp73 inhibition dramatically decreased the epididymal coefficient, sperm quality, and serum testosterone (T) level, while increasing apoptosis in sperm in mice. HE staining and TEM showed that the tight junction (TJ) and apical ES structure were seriously abnormal in the testis in mice with TAp73 inhibition. Additionally, the expression of Occludin protein was elevated, while that of TAp73, Integrin-α6, N-cadherin, and Nectin-2 reduced in model mice. WZYZW treatment ameliorated testicular spermatogenic dysfunctions in TAp73 suppressed mice, restoring the decreased sperm quality, serum T level and testicular histopathological changes of TJ and ES, as well as decreasing sperm malformation rate and apoptosis. Moreover, WZYZW reversed the expressions of Occludin, TAp73, Integrin-α6, N-cadherin and Nectin-2 in TAp73 suppressed mice. CONCLUSIONS: By impairing spermatogenesis and maturation, TAp73 inhibition led to oligoasthenospermia in mice. WZYZW could rescue the oligoasthenospermia associated with TAp73 inhibition via affecting the dynamic remodeling of cellular junctions in testicular tissues in mice.

Physicochemical, morpho-structural, and biological characterization of polysaccharides from three Polygonatum spp.

Polygonatum species, including P. cyrtonema, P. kingianum, and P. sibiricum, are edible plants with medicinal purposes, which have long been consumed as food due to their high nutritional value. In this study, polysaccharides from P. cyrtonema (PCP), P. kingianum (PKP) and P. sibiricum (PSP) were obtained, and their physicochemical properties and in vitro biological activities were investigated. Our results demonstrated that PCP, PKP, and PSP consist of major fructose and minor glucose, galacturonic acid, and galactose in different molar ratios with the molecular weights of 8.5 × 103 Da, 8.7 × 103 Da, and 1.0 × 104 Da, respectively. The three polysaccharides had triple-helical structures with ß-d-Fruf, α-d-Glcp, α-d-Galp sugar residues, and an O-acetyl group, and displayed peak-shaped structures in different sizes. They also exhibited thermal, shear-thinning behavior and viscoelastic properties, and PCP presented the highest viscoelasticity. Moreover, they exerted strong free radical-scavenging abilities, and significant reducing capacity. PCP was the strongest, followed by PSP and then PKP. They significantly promoted the polarization of the M1 macrophage, with the effect of PCP ranking first. All three had similar effects on GLP-1 secretion. It is, therefore, necessary to identify the various roles of these three Polygonatum polysaccharides as functional agents based on their bioactivities and physicochemical properties.

Polygonatum cyrtonema Hua Polysaccharide Promotes GLP-1 Secretion from Enteroendocrine L-Cells through Sweet Taste Receptor-Mediated cAMP Signaling.

Glucagon-like peptide-1 (GLP-1) secreted from enteroendocrine L-cells is a pleiotropic hormone with beneficial potential related to islet function, diet control, glucose homeostasis, inflammation relief, and cardiovascular protection. The present study aimed at investigating the effect of Polygonatum cyrtonema polysaccharide (PCP) after structural identification on GLP-1 secretion and the possible mechanism involved in the PCP-stimulated secretion of GLP-1. It was found that GLP-1 secretion was effectively promoted (p < 0.01) by PCP both in rats with oral administration for 5 weeks (13.9 ± 0.3-35.8 ± 0.3 pmol/L) and ileal administration within 2 h (13.6 ± 0.4-34.1 ± 1.1 pmol/L) and in enteroendocrine NCI-H716 cells with direct stimulation within 24 h (2.05 ± 0.3-20.7 ± 0.2 pmol/L). The sweet taste receptor T1R2/T1R3 was identified to be essential for NCI-H716 cells to directly recognize PCP. The intervention experiments showed that PCP-stimulated GLP-1 secretion was significantly depressed (p < 0.01) not only by antibodies, siRNA, and the inhibitor of T1R2/T1R3 but also by an adenylate cyclase inhibitor. These results suggest that PCP stimulates GLP-1 secretion from enteroendocrine cells possibly through activation of the T1R2/T1R3-mediated cAMP signaling pathway.

Structural features of an acidic polysaccharide with the potential of promoting osteoblast differentiation from Lycium ruthenicum Murr.

The enhanced osteoblast differentiation is beneficial to the prevention of osteoporosis. In this study, a homogeneous polysaccharide (LRP-S2A) with the potential of promoting osteoblast differentiation was obtained from the fruits of Lycium ruthenicum, a traditional herb for treatment of postmenopausal metabolic disorders. Structural identification indicated that LRP-S2A, with a relative molecular weight of 2.65 × 106 Da and an uronic acid content of 41.8%, contained Rha, Ara, Gal, Glc and GlcA in a molar ratio of 1.00 : 2.07 : 0.57 : 2.59 : 4.33 and was composed of a backbone consisting of 6-O-Me-α-(1→4)-D-GlcpA, 2-O-acetyl-α-(1→4)-D-Glcp, α-(1→2,4)-L-Rhap, ß-(1→3)-D-Galp andα-(1→3,5)-L-Araf, and some branches consisting of 6-O-Me-α-(1→4)-D-GlcpA and terminal α-L-Araf. These results suggested that LRP-S2A with the potential of promoting osteoblast differentiation was a new acidic polysaccharide.

Dendrobium huoshanense polysaccharide regulates intestinal lamina propria immune response by stimulation of intestinal epithelial cells via toll-like receptor 4.

A homogenous polysaccharide (GXG) from Dendrobium huoshanense with stable digestive behavior and effective immunoregulatory function was employed to explore its underlying molecular basis regulating intestinal mucosal immune response from the view of interaction between GXG and intestinal epithelial cells (IECs). Using in vitro established co-culture system consisting of IECs and lamina propria cells (LPCs), we found the immune response of LPCs could be effectively regulated by GXG-stimulated IECs, and three cytokines including IL-6, MCP-1 and CINC-1 produced from GXG-stimulated IECs were the main factors involved in modulating immune response of LPCs. Toll-like receptor 4 (TLR4) was identified as an essential receptor for IECs to directly bind GXG. Receptor intervention experiments demonstrated that TLR4 mediated GXG-induced activation of IECs, which further induces immunomodulating effects on LPCs. These results suggest that GXG could modulate the immune response in LPCs by the direct interaction with IECs via TLR4.

Dendrobium huoshanense polysaccharide regionally regulates intestinal mucosal barrier function and intestinal microbiota in mice.

The present study investigated the effects of a homogeneous Dendrobium huoshanense polysaccharide (GXG) on mucosal barrier function and microbiota composition in different intestinal regions of mice. Results exhibited, besides changing the intestinal physiological status, orally administrated GXG could improve the intestinal physical barrier function by modulating mucosal structures and up-regulating the expression of tight junction proteins, reinforce the intestinal biochemical barrier function by elevating the expression and secretion of mucin-2, ß-defensins and sIgA, and regulate the intestinal immunological barrier function by stimulating the production of cytokines and the functional development of immune cells. Simultaneously, GXG could differentially impact the composition and metabolism of microbiota along intestinal tract. In addition, the immune response in spleen and peripheral blood were effectively regulated by GXG. These results indicated that GXG might be used as functional agent to improve host health.

Digestive behavior of Dendrobium huoshanense polysaccharides in the gastrointestinal tracts of mice.

With fluorescent end-labeling method, a homogenous Dendrobium huoshanense polysaccharide (GXG) that was orally administrated to mice was found to be degraded into a stable fragment (dGXG) in the stomach, where dGXG was propelled into the small intestine and absorbed into the systemic circulation. The residual GXG in the stomach could pass through the gastrointestinal tract and was excreted into faeces with a very slow fermentation in the large intestine. The simulated digestion of GXG indicated that the acidic pH condition in the gastric fluid was responsible for GXG degradation, which was supported by the oral digestion of dGXG. Chemical analysis not only showed a change in the molar ratio of monosaccharide compositions and glycosidic linkage types, but also found the loss of the sugar residue (1→4)-linked Galp after the acid treatment of GXG, suggesting that the cleavage of glycosidic linkage, especially (1→4)-linked Galp linkage, resulted in GXG degradation in the gastrointestinal tract.

Intestinal immunomodulating activity and structural characterization of a new polysaccharide from stems of Dendrobium officinale.

A homogeneous polysaccharide fraction (DOP-W3-b) with a high intestinal immunomodulating activity was obtained from the stems of Dendrobium officinale through a bioactivity-guided sequential isolation procedure based on the screening of Peyer's patch-mediated immunomodulating activity. Oral administration experiments of mice showed that DOP-W3-b could effectively regulate intestinal mucosal immune activity by changing intestinal mucosal structures, promoting the secretions of cytokines from Peyer's patches (PPs) and mesenteric lymph nodes (MLNs), and increasing the production of secretory immunoglobulin A (sIgA) in the lamina propria. Structure analysis indicated that DOP-W3-b was composed of mannose and glucose in a molar ratio of 4.5 with a relatively low molecular weight of 1.543 × 10(4) Da, and its repeat unit contained a backbone consisting of ß-(1→4)-d-Manp, ß-(1→4)-d-Glcp and ß-(1→3,6)-d-Manp residues, a branch consisting of ß-(1→4)-d-Manp, ß-(1→4)-d-Glcp and terminal ß-d-Glcp, and O-acetyl groups attached to O-2 of ß-(1→4)-d-Manp. These results suggested that DOP-W3-b was a new polysaccharide with an essential potential for modulating body's immune functions.

Polysaccharide of Dendrobium huoshanense activates macrophages via toll-like receptor 4-mediated signaling pathways.

The present work aimed at investigating the pattern recognition receptor (PRR) and immunostimulatory mechanism of a purified Dendrobium huoshanense polysaccharide (DHP). We found that DHP could bind to the surface of macrophages and stimulate macrophages to secrete NO, TNF-α and IL-1ß. To unravel the mechanism for the binding of DHP to macrophages, flow cytometry, confocal laser-scanning microscopy, affinity electrophoresis, SDS-PAGE and western blotting were employed to verify the type of PRR responsible for the recognition of DHP by RAW264.7 macrophages and peritoneal macrophages of C3H/HeN and C3H/HeJ macrophages. Results showed that toll-like receptor 4 (TLR4) was an essential receptor for macrophages to directly bind DHP. Further, the phosphorylation of ERK, JNK, Akt and p38 were observed to be time-dependently promoted by DHP, as well as the nuclear translocation of NF-κB p65. These results suggest that DHP activates macrophages via its direct binding to TLR4 to trigger TLR4 signaling pathways.