Structural characterization of an immunoenhancing heteropolysaccharide isolated from hot water extract of the fresh leaves of Catharanthus rosea

Structural characterization of Euglena gracilis polysaccharide and its in vitro hypoglycemic effects by alleviating insulin resistance

Diabetes mellitus, characterized by hyperglycemia and insulin resistance, is a disorder of the endocrine metabolic system which has emerged as a common chronic disease worldwide. Euglena gracilis polysaccharides have ideal development potential in the treatment of diabetes. However, their structure and bioactivity are largely unclear. A novel purified water-soluble polysaccharide (EGP-2A-2A) from E. gracilis with a molecular weight of 130.8 kDa consisted of xylose, rhamnose, galactose, fucose, glucose, arabinose, and glucosamine hydrochloride. The SEM image for EGP-2A-2A suggested a rough surface with the presence of globule-like protrusions. Methylation and NMR spectral analyses revealed that EGP-2A-2A was mainly composed of →6)-β-D-Galp-(1 → 2)-α-D-Glcp-(1 → 2)-α-L-Rhap-(1 → 3)-α-L-Araf-(1 → 6)-β-D-Galp-(1 → 3)-α-D-Araf-(1 → 3)-α-L-Rhap-(1 → 4)-β-D-Xylp-(1 → 6)-β-D-Galp-(1 → with complex branching structure. EGP-2A-2A significantly increased glucose consumption and glycogen content in IR-HeoG2 cells and modulates glucose metabolism disorders by regulating PI3K, AKT, and GLUT4 signaling pathways. EGP-2A-2A significantly suppressed TC, TG, and LDL-c levels, and enhanced that of HDL-c. EGP-2A-2A ameliorated abnormalities caused by disorders of glucose metabolism and the hypoglycemic activity of EGP-2A-2A may be mainly positively related to its high glucose content and the β-configuration in the main chain. These results suggested that EGP-2A-2A played an important role in alleviating disorders of glucose metabolism through insulin resistance and has the potential for development as a novel functional food with nutritional and health benefits.

Isolation, structure identification, and immunostimulatory effects in vitro and in vivo of polysaccharides from Onosma hookeri Clarke var. longiforum Duthie

BACKGROUND

This study characterized an acidic polysaccharide (OHC-LDPA) isolated from the medicinal and edible homologous plant Onosma hookeri Clarke var. longiforum Duthie. The structure of OHC-LDPA was elucidated based on the analysis of infrared, one-/two-dimensional nuclear magnetic resonance, and gas chromatography-mass spectrometry data. The immunostimulatory effects of OHC-LDPA were identified by both in vitro and in vivo models.

RESULTS

The structure of OHC-LDPA was elucidated as a typical pectin polysaccharide, consisting of galacturonic acid, galactose, arabinose, and rhamnose as the primary sugars, with linear galacturonic acid as the main chain and arabinogalacturonic acid as the main branched components. OHC-LDPA could significantly stimulate the proliferation and phagocytosis of RAW264.7 macrophages and the release of nitric oxide in vitro. Also, it could accelerate the recovery of spleen and thymus indexes, enhance the splenic lymphocyte proliferation responses, and restore the levels of interleukin-2, interleukin-10, interferon-γ, and immunoglobulin G in the serum in a cyclophosphamide-induced immunosuppressed-mice model. In addition, OHC-LDPA could restore the intestinal mucosal immunity and reduce the inflammatory damage.

CONCLUSION

OHC-LDPA could improve the immunity both in vitro and in vivo and could be used as a potential immunostimulant agent. © 2022 Society of Chemical Industry.

Structure characterization and lipid-lowering activity of a homogeneous heteropolysaccharide from sweet tea (Rubus Suavissmus S. Lee)

Sweet tea (Rubus Suavissmus S. Lee) is consumed as herbal tea in southwestern China, which has multiple functions such as relieving cough, alleviating allergic responses, and clearing away heat. Here we report the structure and lipid-lowering activity of a sweet tea polysaccharide (STP-60a). STP-60a is a homogeneous heteropolysaccharide with a molecular weight of 9.16 × 10⁴ Da, and composed of rhamnose, arabinose, glucose, galactose and glucuronic acid. The main backbone of STP-60a consists of β-L-Rhap-(1→, →3)-β-D-Galp-(1→, →4)-β-D-Glcp-UA-(1→, →3,6)-β-D-Galp-(1→, →6)-β-D-Galp-(1→, →3)-4-OAc-β-L-Arap-(1→, →3)-α-L-Araf-(1→ and the side chain are α-L-Araf-(1→ and →3)-α-D-Glcp-(1→. Using Caenorhabditis elegans (C. elegans) in a high-sugar diet as a model, we found that STP-60a significantly reduced the fat accumulation in the intestine of C. elegans, and extensively affected lipolysis, fatty acid synthesis and β-oxidation processes. In addition, sbp-1 and nhr-49 were essential for STP-60a to exert a lipid-lowering effect.

O-Methylation in Carbohydrates: An NMR and MD Simulation Study with Application to Methylcellulose

Methylated carbohydrates are important from both biological and technical perspectives. Specifically, methylcellulose is an interesting cellulose derivative that has applications in foods, materials, cosmetics, and many other fields. While the molecular dynamics simulation technique has the potential for both advancing the fundamental understanding of this polymer and aiding in the development of specific applications, a general drawback is the lack of experimentally validated interaction potentials for the methylated moieties. In the present study, simulations using the GROMOS 56 carbohydrate force field are compared to NMR spin–spin coupling constants related to the conformation of the exocyclic torsion angle ω in d-glucopyranose and derivatives containing a 6-O-methyl substituent and a ¹³C-isotopologue thereof. A ³J_CC Karplus-type relationship is proposed for the C5–C6–O6–C_Me torsion angle. Moreover, solvation free energies are compared to experimental data for small model compounds. Alkylation in the form of 6-O-methylation affects exocyclic torsion only marginally. Computed solvation free energies between nonmethylated and methylated molecules were internally consistent, which validates the application of these interaction potentials for more specialized purposes.

Preparation, characterization and wound healing effect of alginate/chitosan microcapsules loaded with polysaccharides from Nostoc Commune Vaucher

Biologically active coating materials could promote the growth of granulation tissue as auxiliary materials, while natural polysaccharides could promote vascular regeneration and wound healing. Therefore, in this study, ultrasound-assisted extract of Nostoc commune Vaucher polysaccharides (UAP) yield after the process optimization was 12.89 ± 0.24%, which was used to prepare microcapsules by emulsification and cross-linking. The effect of alginate/chitosan-UAP composite materials on wound healing in an experimental rat model for 14 d and its physical properties were evaluated. In vitro experiments indicated that the UAP microcapsule material had a porous and loose three-dimensional network structure, and had good biocompatibility and swelling properties as a wound healing material. Animal experiments indicated that UAP microcapsules could extremely significantly promote wound healing (P < 0.01), and wound closure rate reached 79.16 ± 3.91% on 14th day. Meanwhile UAP microcapsules might promote angiogenesis and granulation growth by enhancing immunity and increasing the expression of VEGF and miR-21. Therefore, the composites of UAP microcapsules have shown encouraging results as a potential dressing for wound healing.

Two new glutarimide antibiotics from Streptomyces sp. HS-NF-780

Two new glutarimide antibiotics, 9-methylstreptimidone 2-α-D-glucopyranoside (1), and hydroxyiso-9-methylstreptimidone (2), along with a known compound, 9-methylstreptimidone (3), have been isolated from the broth of Streptomyces sp. HS-NF-780. Their structures were determined on the basis of spectroscopic analysis, including 1D and 2D NMR techniques as well as ESI-MS and comparison with data from the literature. By modified Mosher's method and acid hydrolysis, the absolute configurations of compounds 1 and 2 were established. Compounds 1 and 2 exhibited moderate cytotoxic activity.

Isolation, purification and structural characterization of an acetylated heteroglycan from the unripe fruits of Manilkara zapota L

A water soluble polysaccharide isolated from the hot water extract of the unripe fruits of Manilkara zapota L. was found to consist of 3-O-acyl-L-rhamnose, L-arabinose, 3-O-acetyl-D-methyl galacturonate in a molar proportion of nearly 1:1:1. Structural investigation of the polysaccharide was carried out using total hydrolysis, methylation analysis; periodate oxidation followed by GLC-MS, and NMR experiments. On the basis of the above experiments it is concluded that the following repeating unit is present in the polysaccharide.