Structural analysis of a pectic polysaccharide from boat-fruited sterculia seeds

Comparison of structure and the synergistic anti-hepatocellular carcinoma effect of three polysaccharides from vinegar-baked Radix Bupleuri

Three polysaccharides from Vinegar-baked Radix Bupleuri (VR) and their combined effects were studied. VRP3-3 was a branched polysaccharide with a molecular weight (Mw) of 16.05 kDa characterized by 1,5 linked-α-Araf, 1,2,4 linked-α-Rhap and 1,4 linked-α-GalpA as main chain with a small amount of esterification and acetylation groups. And side chains were connected to the O-3 of Araf, O-4 of Rhap. VRP2-3 had a Mw of 95.35 kDa, its backbone comprised of 1,2 linked-α-Galp, 1,4 linked-β-GalpA(O-Ac), 1,2,4 linked-α-Rhap and 1,5 linked α-Araf. The residues of 1,4 linked-β-Galp,1,3 linked-β-Galp and 1,6 linked-β-D-Galp were connected at O-4 of α-L-Rhap and O-3 of α-L-Araf as its side chain. VRP2-4 was a pectin polysaccharide with a Mw of 57.90 kDa. Its main chain was constituted of 1,4 linked-α-Galp, 1,4 linked-α-GalpA(OMe), 1,4 linked-α-GalpA and 1,2,4 linked-α-Rhap, with some acetylation. As the major side chain, 1,5 linked-α-Araf was connected to O-4 of α-Rhap, a small amount of t-α-Galp and t-α-Manp were also included. VRP3-3 showed superior synergistic effect in combination with paclitaxel, methotrexate and cisplatin than the other two polysaccharides. The VR polysaccharide with a ~16 kDa molecular weight, a larger polymerization degree of arabinan in the backbone and the triple helix structure are the key structures for activity. Together, our findings clarify the pharmacodynamic basis of VR and provide promising adjuvants for Hepatocellular Carcinoma (HCC) chemotherapy.

Structural characterization of Astragalus polysaccharide-D1 and its improvement of low-dose metformin effect by enriching Staphylococcus lentus

To explore the adjuvant therapy drugs of low-dose metformin, one homogeneous polysaccharide named APS-D1 was purified from Astragalus membranaceus by DEAE-52 cellulose and Sephadex G-100 column chromatography. Its chemical structure was characterized by molecular weight distribution, monosaccharide composition, infrared spectrum, methylation analysis, and NMR. The results revealed that APS-D1 (7.36 kDa) consisted of glucose, galactose, and arabinose (97.51 %:1.56 %:0.93 %). It consisted of →4)-α-D-Glcp-(1→ residue backbone with →3)-β-D-Galp-(1→ residue and terminal-α/β-D-Glcp-(1→ side chains. APS-D1 could significantly improve inflammation (TNF-α, LPS, and IL-10) in vivo. Moreover, APS-D1 improved the curative effect of low-dose metformin without adverse events. APS-D1 combined with low-dose metformin regulated several gut bacteria, in which APS-D1 enriched Staphylococcus lentus to produce l-carnitine (one of 136 metabolites of S. lentus). S. lentus and l-carnitine could improve diabetes, and reduction of S. lentusl-carnitine production impaired diabetes improvement. The combination, S. lentus, and l-carnitine could promote fatty acid oxidation (CPT1) and inhibit gluconeogenesis (PCK and G6Pase). The results indicated that APS-D1 enhanced the curative effect of low-dose metformin to improve diabetes by enriching S. lentus, in which the effect of S. lentus was mediated by l-carnitine. Collectively, these findings support that low-dose metformin supplemented with APS-D1 may be a favorable therapeutic strategy for type 2 diabetes.

A galacturonic acid-rich polysaccharide from Diospyros kaki peel: Isolation, characterization, rheological properties and antioxidant activities in vitro

This research elucidated the structural characteristics and antioxidant activity of a galacturonic acid-rich polysaccharide (PPP-2) isolated from Diospyros kaki peel. PPP-2 was extracted by subcritical water and subsequently purified by DEAE-Sepharose FF column. PPP-2 (12.28 kDa) mainly contained galacturonic acid, arabinose, and galactose with the molar ratios of 87.15: 5.86: 4.31. The structural characteristics of PPP-2 were revealed through FT-IR, UV, XRD, AFM, SEM, Congo red, methylation, GC/MS assay and NMR spectrum. PPP-2 owned the triple helical structure and degradation temperature of 251.09 ℃. The backbone of PPP-2 was formed by →4)-α-d-GalpA-6-OMe-(1→ and →4)-α-d-GalpA-(1→ with the side chains of →5)-α-l-Araf-(1→, →3)-α-l-Araf-(1→, →3,6)-β-d-Galp-(1→ and α-l-Araf-(1→. Moreover, the inhibitory concentration (IC₅₀) of PPP-2 to ABTS•+, DPPH•, superoxide radical and hydroxyl radical were 1.96, 0.91, 3.63, and 4.08 mg/mL, respectively. Our results suggested that PPP-2 might be a novel candidate of natural antioxidant in pharmaceuticals or functional food.

Pectic polysaccharides from Biluochun Tea: A comparative study in macromolecular characteristics, fine structures and radical scavenging activities in vitro

In this study, two acidic Biluochun Tea polysaccharides (BTP-A₁₁ and BTP-A₁₂) were investigated comparatively, which mainly consisted of Rha, Ara, Gal and GalA, possibly suggesting their pectic nature. Structurally, their galacturonan backbones composed of →4)-α-D-GalpA-(1→ and →2)-α-L-Rhap-(1→ were revealed similar, while Ara- and Gal-based branches attached to the O-2 of →2)-α-L-Rhap-(1→ were in distinctive types, proportions, extensibilities and branching degrees. This could lead to their different macromolecular characteristics, where BTP-A₁₁ with higher M_w presented a more hyper-branched chain conformation and relatively higher structural flexibility/compactness, thereby resulting in a lower exclusion effect and an insufficient hydrodynamic volume. Besides, better radical scavenging activities in vitro were also determined for Gal-enriched BTP-A₁₁, where a larger surface area containing more H-donating groups were related to its higher M_w, more hyper-branched conformation, lower DM and higher DA. Therefore, the understanding of structure-property-activity relationships was improved to some degrees for acidic Biluochun Tea polysaccharides, which could be potentially required for more applications in food, medical and cosmetic fields.

Structural and rheological properties of pectic polysaccharide extracted from Ulmus davidiana esterified by succinic acid

The present study was carried out to investigate the physicochemical and structural properties of pectic polysaccharide extracted from Ulmus davidiana (UDP) and to determine the physicochemical, structural, and rheological properties of esterified UDP with succinic acid (ES-UDP). The results indicated that UDP had high amounts of galacturonic acids and various neutral sugars, such as galactose, rhamnose, and glucose. UDP was identified as a low methoxyl pectin, consisting of 1,4-linked α-d-GalpA (the main backbone chain), supported by the results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, and 1D Nuclear magnetic resonance (NMR) spectroscopy. In the FT-IR and XRD, no difference was detected between UPD and ES-UDPs. However, ¹H and ¹³C NMR spectra revealed that the new ester bonds were formed between a hydroxyl group of UDP and a carboxyl group of succinic acid during esterification. In the steady shear rheological analysis, the consistency index (K) of ES-UDP was significantly higher than that of UDP and increased significantly with increasing concentration of succinic acid. In the dynamic rheological analysis, the tan δ values of all ES-UDP solutions were significantly lower than those of the UDP solution.

Purification, characterization and anti-fatigue activity of polysaccharide fractions from okra (Abelmoschus esculentus (L.) Moench)

The aim of this study was to investigate the anti-fatigue activity of polysaccharide fractions from Abelmoschus esculentus (L.) Moench (AE) in mice. After crude polysaccharide (CAEP) was extracted from AE and purified by DEAE cellulose-52 column, two polysaccharide fractions (AEP-1 and AEP-2) were obtained. The structural analysis suggested that AEP-1 and AEP-2 were a RG-I polysaccharide and an AG-II polysaccharide, respectively. According to the results of the weight-loaded swimming test, compared with the negative control group, the CAEP, AEP-1 and AEP-2 treatment groups could prolong the swimming time, decrease serum urea nitrogen (SUN) and blood lactic acid (BLA), and increase hepatic glycogen (HG) and muscle glycogen (MG), which indicated that okra polysaccharides have an effective anti-fatigue activity. Furthermore, our study exhibited the anti-fatigue mechanism of okra polysaccharide was correlated with retarding the accumulation of creatine kinase (CK) and lactate dehydrogenase (LDH) in serum, and enhancing succinate dehydrogenase (SDH), adenosine triphosphate (ATP) and adenosine triphosphatase (ATPase) levels. In addition, the anti-fatigue activity of AEP-1 was stronger than that of AEP-2, and significantly better than that of CAEP. Therefore, AEP-1 and AEP-2 may be the main active anti-fatigue functional substances of AE.

Computational Chemistry Tools in Glycobiology: Modelling of Carbohydrate–Protein Interactions

Molecular modelling provides a major impact in the field of glycosciences, helping in the characterisation of the molecular basis of the recognition between lectins from pathogens and human glycoconjugates, and in the design of glycocompounds with anti-infectious properties. The conformational properties of oligosaccharides are complex, and therefore, the simulation of these properties is a challenging task. Indeed, the development of suitable force fields is required for the proper simulation of important problems in glycobiology, such as the interatomic interactions responsible for oligosaccharide and glycoprotein dynamics, including O-linkages in oligo- and polysaccharides, and N- and O-linkages in glycoproteins. The computational description of representative examples is discussed, herein, related to biologically active oligosaccharides and their interaction with lectins and other proteins, and the new routes open for the design of glycocompounds with promising biological activities.

Structural elucidation of a pectin-type polysaccharide from Hovenia dulcis peduncles and its proliferative activity on RAW264.7 cells

In this paper, an acidic polysaccharide HDP3A was isolated from Hovenia dulcis peduncles with 45.9% of uronic acid content. Structure of HDP3A was elucidated by chemical and spectroscopic analysis. HDP3A was mainly contained of galacturonic acid, galactose, rhamnose and arabinose with a small quantity of xylose, fucose, mannose, glucose. The structural analysis indicated that HDP3A was a pectin-type polysaccharide with HG and RG-I regions and hairy regions. HG was linear homopolymer with repeating units of (1→4)-α-d-galactopyranosyl uronic (GalA) residues. The GalpA residues in HG domain may be acetylated and/or methyl-esterified. The backbone of RG-I contains repeating units of [→α-GalpA-1,2)-α-Rhap-1,4→]_n and the hairy regions attached in the Rha at position O-4. Hairy regions were mainly composed of galactans, arabinans, arabinogalactans, glucans, mannans and xylans. The immunomodulatory activities of HDP3A and its reduced (HDP3A-R) and hydrolyzed product (HDP3A-0.1) in vitro on macrophages were determined. The three polysaccharide fractions all stimulated the proliferation of RAW264.7 cells and the order of the proliferative effects was HDP3A>HDP3A-R>HDP3A-0.1, indicating that the immune effects of pectin-type polysaccharides were related to branches and molecular weight. Consequently, HDP3A could be as a potential source for the proliferative activity.

Structural, physicochemical, antioxidant and antitumor property of an acidic polysaccharide from Polygonum multiflorum

In this study, the structural characterization, physicochemical property, antioxidant and antitumor activity of an acidic polysaccharide (APS) from Polygonum multiflorum were investigated. Monosaccharide composition analysis showed APS was composed of arabinose, rhamnose, galactose and galacturonic acid in the molar ratio of 1.23:1.32:1.48:1.00. The presence of uronic acid was also confirmed by the bands at 1740, 1645 and 1425cm^-1 on Fourier transform-infrared spectroscopy. Methylation and nuclear magnetic resonance analyses showed APS was mainly composed by the residues of →5)-α-l-Araf-(1→, →3)-β-d-Galp-(1→, →3,6)-β-d-Galp-(1→, →4)-α-d-GalAp-(1→ and →2)-α-l-Rhap-(1→ in the backbone. The non-reducing terminal α-l-Araf-(1→ was probably attached to the O-6 position of →3,6)-β-d-Galp-(1→ residues. Besides, APS exhibited rod-like and flaky shapes with rough surface. The initial decomposition of APS occurred at 172°C, and the rapidest weight loss rate of APS appeared at 320°C. Antioxidant activity assay showed the DPPH radical scavenging activity of APS was 67.5% at 1mg/mL. At the concentration of 400μg/mL, the antiproliferation activities of APS against HepG-2 and BGC-823 cells were 65.28% and 51.57%, respectively. Our results suggested APS could be a potential antioxidant and antitumor agent.

Structural characterization of a novel polysaccharide from pulp tissues of Litchi chinensis and its immunomodulatory activity

A novel polysaccharide (LCP50W) with a molecular weight of 4.72 × 10(4) Da was isolated from the pulp tissues of Litchi chinensis . The chemical structure of LCP50W was characterized using physicochemical and instrumental analyses. The results indicated that the main chain of LCP50W consisted of (1→3)-linked β-L-rhamnopyranosyl, (1→6)-linked α-D-glucopyranosyl, and (1→2,6)-linked α-D-glucopyranosyl residues, which branched at O-6. The three branches consisted of (1→2)-linked α-L-rhamnopyranosyl, (1→3)-linked α-D-galactopyranosyl, and (1→3)-linked α-L-mannopyranosyl residues, terminated with (1→)-linked α-L-arabinopyranosyl residues, respectively. The in vitro immunomodulatory assay revealed that LCP50W promoted the proliferation of mouse splenocytes and enhanced the cytotoxicity of NK cells. LCP50W boosted the secretion of Th1 cytokine IFN-γ while it inhibited the secretion of Th2 cytokine IL-4; it also enhanced the expression of T-bet while it inhibited the expression of GATA-3. Additionally, LCP50W promoted the development of cell cycle toward the S phase.