Extraction Optimization, Structural Characterization, and Anti-Hepatoma Activity of Polysaccharides from Scutellaria Barbata D. Don

Background The above experimental results show that SBP-2A isolated and purified from Scutellaria barbata may be a candidate drug for further evaluation in cancer prevention, which provides a clue for further studies on the molecular mechanism of its anticancer activity against human liver cancer cells.Methods The crude polysaccharide of Scutellaria barbata (SBP) was extracted with water and precipitated with alcohol. Optimal extraction conditions were determined by response surface methodology: the solid-liquid ratio was 1:25, the extraction time was 2 h, and the extraction temperature was 90 °C. With these conditions, the average extraction efficiency was 3.85 ± 0.13%. SBP was purified with a DEAE-52 cellulose column and Sephadex G-100 dextran gel column to obtain SBP-1A and SBP-2A fractions. The polysaccharide content, molecular weight, monosaccharide composition and basic structure were preliminarily identified. Then, a MTT assay was used to identify the polysaccharide components with anti-hepatoma effects. The antitumor activity of SBP-2A was evaluated by colony formation tests, morphological observations, apoptosis and cell cycle analyses.Results Structural analysis showed that SBP-1A and SBP-2A were mainly composed of arabinose and galactose, but the molar ratios were different; these were homogeneous acidic polysaccharide components with high purity, and the average molecular weights were 1.15 × 105 Da and 1.4 × 105 Da, respectively. FT-IR spectra showed that SBP-1A and SBP-2A contained uronic acid β-glucan, and the sugar residue of the polysaccharide was mainly pyranose. MTT and colony formation assays showed that SBP-2A significantly inhibited the proliferation of HepG2 cells. The cell distribution at different apoptotic stages was determined by the Hoechst 33258 test and Annexin V-FITC/PI staining. Flow cytometric analysis showed that SBP-2A induced HepG2 cell apoptosis by blocking the G1 phase.Conclusions Two polysaccharides (SBP-1A and SBP-2A) had been isolated from Scutellaria barbata. Preliminary characterization of the SBP-1A and SBP-2A was investigated. The anticancer activities were studied in vitro. SBP-2A significantly inhibited the proliferation of HepG2 cells and induced cells apoptosis by blocking the G1 phase.

Structural characterization of polysaccharide from jujube (Ziziphus jujuba Mill.) fruit

Background Jujube (Ziziphus jujuba Mill.) fruit is one of the largest productions in China and its increasing production has drawn considerable attention from researchers. Polysaccharide is one of the most abundant components of jujube, and it represents a major group of biolotegically active constituents. This study intended to investigate the special structure of a homogeneous acidic polysaccharide (PZMP4) produced from Ziziphus Jujuba cv. Muzao fruit using novel methods, including DEAE-Sepharose Fast Flow and Sephacryl S-300 column chromatography. Results The structure of PZMP4 was determined via high-performance gel permeation chromatography (HPGPC), gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), methylation analysis, nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results reveal that PZMP4 with a molecular weight of 27.90 kDa was composed of rhamnose, arabinose, mannose, glucose, galactose, and galacturonic acid at a ratio of 2.32:2.21:0.22:0.88:2.08:8.83. Advanced structural analysis revealed a netted structure with molecular aggregates of PZMP4. Structural features demonstrated that the basic backbone of PZMP4 appeared to mainly consist of (1→4)-linked GalpA with three branches bonded to O-3 of (1→3)-linked Araf, (1→2)-linked Rhap, and terminated with GalpA. Conclusions PZMP4’s unique structure could imply distinct bioactivities and have considerable utilization in functional food. Graphic abstract

The role of calcium binding to the EF-hand-like motif in bacterial solute-binding protein for alginate import

Gram-negative Sphingomonas sp. A1 incorporates acidic polysaccharide alginate into the cytoplasm via a cell-surface alginate-binding protein (AlgQ2)-dependent ATP-binding cassette transporter (AlgM1M2SS). We investigated the function of calcium bound to the EF-hand-like motif in AlgQ2 by introducing mutations at the calcium-binding site. The X-ray crystallography of the AlgQ2 mutant (D179A/E180A) demonstrated the absence of calcium binding and significant disorder of the EF-hand-like motif. Distinct from the wild-type AlgQ2, the mutant was quite unstable at temperature of strain A1 growth, although unsaturated alginate oligosaccharides stabilized the mutant by formation of substrate/protein complex. In the assay of ATPase and alginate transport by AlgM1M2SS reconstructed in the liposome, the wild-type and mutant AlgQ2 induced AlgM1M2SS ATPase activity in the presence of unsaturated alginate tetrasaccharide. These results indicate that the calcium bound to EF-hand-like motif stabilizes the substrate-unbound AlgQ2 but is not required for the complexation of substrate-bound AlgQ2 and AlgM1M2SS.

TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid

Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer’s backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.

Prebiotic, Antioxidant, and Immunomodulatory Properties of Acidic Exopolysaccharide From Marine Rhodotorula RY1801

In this study, an extracellular acidic polysaccharide (EAPS) from marine Rhodotorula sp. RY1801 was extracted, and its biological properties were investigated. EAPS is mainly composed of monosaccharides, including mannose, rhamnose, glucose, galactose, and fucose, had an average molecular weight of 5.902 × 107 Da. The results indicated that EAPS can promote the growth of Lactobacillus acidophilus and L. acidophilus plantarum. EAPS is capable of scavenging both superoxide anion and hydroxyl radicals in vitro. The highest scavenging rate of superoxide anion and hydroxyl radicals is 29 and 84%, respectively. Using in vivo model, we found that the EAPS can expand the lifespan and increase the disease resistance of Caenorhabditis elegans against Klebsiella pneumoniae infection via the DAF-2/DAF-16 pathway. These results suggested that EAPS from marine Rhodotorula sp. RY1801 could promote the growth of beneficial bacteria and can be used as an antioxidant and immunomodulator, which had considerable potential in the food and health industry.

A novel and cleaner bio-polymer Gum Karaya-based Silica nanocomposite fracturing fluid for high-temperature application

A novel polymer nanocomposite has been synthesized in the present study using a bio-polymer Karaya and inorganic SiO2 nanoparticles via sonication for application as a fracturing fluid in stimulating oil and gas wells. Gum Karaya (KG), an acidic polysaccharide, has been investigated for its structural, morphological and rheological characteristics, and the results have been compared with prepared KG–SiO2 nanocomposite at different SiO2 dosing for improved structure, viscoelasticity, viscosity and temperature stability. Steady shear rheology test depicted pseudoplastic nature, while oscillatory study confirms gel characteristics and weak dependence of storage and loss moduli on frequency for all the prepared samples. Dominance of elasticity over viscous nature of the gel assures efficient solid transporting/suspending capability. Experimental results showed that the rheological characteristics of the synthesized gel is comparable with Guar and CMHPG over the shear and temperature ranges under study and suitable for temperatures above 150 °C and pressure conditions. Also, polymer breaking and sandpack regained permeability tests proved synthesized gels to be a cleaner with less residue as compared to the other two.