Konjac Glucomannan Aerogels Modified by Hydrophilic Isocyanate and Expandable Graphite with Excellent Hydrolysis Resistance, Mechanical Strength, and Flame Retardancy.

At present, biomass foamlike materials are a hot research topic, but they need to be improved urgently due to their defects such as large size shrinkage rate, poor mechanical strength, and easy hydrolysis. In this study, the novel konjac glucomannan (KGM) composite aerogels modified with hydrophilic isocyanate and expandable graphite were prepared by a facile vacuum freeze-drying method. Compared with the unmodified KGM aerogel, the volume shrinkage of the KGM composite aerogel (KPU-EG) decreased from 36.36 ± 2.47% to 8.64 ± 1.46%. Additionally, the compressive strength increased by 450%, and the secondary repeated compressive strength increased by 1476%. After soaking in water for 28 days, mass retention after hydrolysis of the KPU-EG aerogel increased from 51.26 ± 2.33% to more than 85%. The UL-94 vertical combustion test showed that the KPU-EG aerogel can achieve a V-0 rating, and the limiting oxygen index (LOI) value of the modified aerogel can reach up to 67.3 ± 1.5%. To sum up, the cross-linking modification of hydrophilic isocyanate can significantly improve the mechanical properties, flame retardancy, and hydrolysis resistance of KGM aerogels. We believe that this work can provide excellent hydrolytic resistance and mechanical properties and has broad application prospects in practical packaging, heat insulation, sewage treatment, and other aspects.

Anti-Inflammatory Activity of Orally Administered Monostroma nitidum Rhamnan Sulfate against Lipopolysaccharide-Induced Damage to Mouse Organs and Vascular Endothelium.

We previously reported that rhamnan sulfate (RS) purified from Monostroma nitidum significantly suppressed lipopolysaccharide (LPS)-induced inflammation in cultured human vascular endothelial cells. Here, we analyzed the effect of orally administered RS on LPS-induced damage to mouse organs and vascular endothelium. RS (1 mg) was orally administered daily to BALB/c mice, 50 µg of LPS was intraperitoneally administered on day 8, and Evans blue was injected into the tail vein 6 h later. After 30 min, LPS-treated mice showed pulmonary Evans blue leakage and elevated plasma levels of liver damage markers, whereas this reaction was suppressed in LPS + RS-treated mice. Immunohistochemical and Western blot analysis of mouse organs 24 h after LPS treatment showed significant neutrophil infiltration into the lung, liver, and jejunum tissues of LPS-treated mice and high expression levels of inflammation-related factors in these tissues. Expression levels of these factors were significantly suppressed in LPS + RS-treated mice. Analysis of lung glycocalyx showed a significant reduction in glycocalyx in LPS-treated mice but not in LPS + RS-treated mice. Levels of syndecan-4, one of the glycocalyx components, decreased in LPS-treated mice and increased in LPS + RS-treated mice. The current results suggest that orally administered RS protects organs and vascular endothelium from LPS-induced inflammation and maintains blood circulation.

Characterization and immunomodulatory effect of an alkali-extracted galactomannan from Morchella esculenta.

In our continuous exploration for bioactive polysaccharides, a novel polysaccharide FMP-2 was isolated and purified from the fruiting bodies of Morchella esculenta by alkali-assisted extraction. FMP-2 had an average molecular weight of 1.09 × 106 Da and contained mannose, glucuronic acid, glucose, galactose, and arabinose in a molar ratio of 4.10:0.22:1.00:5.75:0.44. The backbone of FMP-2 mainly consisted of 1,2-α-D-Galp, 1,6-α-D-Galp, and 1,4-α-D-Manp, with branches of 1,4,6-α-D-Manp and 1,2,6-α-D-Galp. FMP-2 can stimulate phagocytosis and promote the secretion of NO, ROS, and cytokines like IL-6, IL-1ß, and TNF-α in RAW264.7 cells ranging from 25 to 400 µg/mL. FMP-2 had great repairing effect on the immune injury of zebrafish induced by chloramphenicol. The phagocytosis ability of zebrafish macrophages and the proliferation of neutrophils can be greatly enhanced by polysaccharide FMP-2 with concentrations from 50 to 200 µg/mL. These findings suggest that FMP-2 might be used as a potential immunomodulator in the food and pharmaceutical industries.

Structure-function relationship of licorice (Glycyrrhiza glabra) root extract-xanthan/guar gum mixture in a high sugar content system.

BACKGROUND: Foam-gels are one of the most important multicomponent-model systems in aerated confectionery, and an investigation of their microstructure is desirable. In this research, the structure-function relationship of xanthan gum/guar gum (XG/GG) and licorice (Glycyrrhiza glabra) root extract powder (LEP) was investigated in a high-sugar medium. Foam-gel systems were prepared at 4:10% to 8:20% ratios of LEP to biopolymer. RESULTS: The results show that increasing the LEP content reduced both the melting point and enthalpy, probably due to higher overrun and weaker junctions. Boosting the XG/GG ratio led the enhancement of mechanical properties, whereas increasing the LEP concentration weakened all textural parameters, which could be due to the poor structure of the network in the presence of the foaming agent, increased moisture content and overrun. In the whipped mixture samples containing 10 g kg-1 XG/GG, higher foaming capacity was observed. By increasing the level of biopolymers, smaller and more uniform air cells were formed according to a scanning electron microscopical study. At higher concentration of LEP, smaller bubbles and increased porosity were seen, which could be attributed to the availability of surfactant in the interfacial layer. CONCLUSION: Maximum structural strength was achieved at a 4:20 ratio of LEP to XG/GG. In rheological experiments, pseudoplastic behavior was seen in all samples. Generally, this model system can be simulated for other herbal extracts containing natural surfactants such as saponins. Achieving a more detailed understanding of these structures and their interactions could help in formulating novel food products. © 2021 Society of Chemical Industry.

Growth, yield and quality of two guar (Cyamopsis tetragonoloba L.) ecotypes affected by sowing date and planting density in a semi-arid area.

The growth period, phenology, grain yield and gum content of two different guar ecotypes were studied in response to different sowing dates and plant densities. A two-year field experiment was conducted as a split-factorial in a randomized complete block design (RCBD) with three replicates in the research field of Tarbiat Modares University during 2016 and 2017 growing season. Main plots consisted of four sowing dates (May 21, June 4, June 21 and July 5 in 2016 and May 10, May 26, June 10 and June 26 in 2017), and subplots including three plant densities (13, 20 and 40 plants m-2) and two ecotypes (Pakistani and Indian). Based on findings, the phenological traits, plant height, grain yield and harvest index were significantly affected by plant density. The effect of ecotypes was statistically significant (p<0.05) on all traits except harvest index in the first year. Furthermore, the seed sowings on May 21 and May 26 with 13 plants m-2 led to highest grain yield (3004.8 and 2826.10 kg.ha-1 for two consecutive years). The high gum content (33.68 and 33.78% for two consecutive years) was also recorded for Pakistani ecotype while for gravity, Indian ecotype showed higher value in both crop years. By and large, the Pakistani ecotype showed better response compared to the Indian one in both years, especially in 1st and 2nd sowing dates.

Heteropolysaccharides from S. cerevisiae show anti-adhesive properties against E. coli associated with Crohn's disease.

The Saccharomyces cerevisiae CNCM I-3856 was previously reported to strongly inhibit adherent-invasive Escherichia coli (AIEC) adhesion to intestinal epithelial cells in vitro and to favor AIEC elimination from the gut in a murine model of Crohn's disease in vivo. In order to identify which cell wall components of yeast are responsible for AIEC elimination, constituent polysaccharides of yeast were isolated and their anti-adhesive ability against AIEC adhesion in vitro was screened. A fraction containing mannan, ß-glucan and α-glucan extracted from yeast cell-walls was shown to inhibit 95% of AIEC adhesion in vitro and was thus identified as the strongest anti-adhesive yeast cell wall component. Furthermore, this mannan-glucan-containing fraction was shown to accelerate AIEC decolonization from gut in vivo. This fraction could be proposed as a treatment to eliminate AIEC bacteria in patients with Crohn's disease, a microbial trigger of intestinal inflammation.

Chemical structure of native and modified sulfated heterorhamnans from the green seaweed Gayralia brasiliensis and their cytotoxic effect on U87MG human glioma cells.

A water-soluble sulfated heterorhamnan (Gb1) was isolated from the green seaweed Gayralia brasiliensis and purified by ultrafiltration, yielding a homogeneous polysaccharide (Gb1r). Both fractions contained rhamnose, xylose, galacturonic and glucuronic acids, galactose, and glucose. Chemical and spectroscopic methods allowed the determination of Gb1 and Gb1r chemical structure. Their backbones were constituted by 3-, 2-, and 2,3-linked rhamnosyl units (1:0.49:0.13 and 1:0.58:0.17, respectively), which are unsulfated (13.5 and 14.6%), disulfated (16.6 and 17.8%) or monosulfated at C-2 (8 and 8.6%) and C-4 (24.5 and 23.4%). Gb1 was oversulfated giving rise to Gb1-OS, which presented ~2.5-fold higher content of disulfated rhamnosyl units than Gb1, as determined by methylation analyses and NMR spectroscopy. Gb1 and Gb1-OS potently reduced the viability of U87MG human glioblastoma cells. Gb1 caused cell cycle arrest in the G1 phase, increased annexin V-stained cells, and no DNA fragmentation, while Gb1-OS increased the percentage of cells in the S and G2 phases and the levels of fragmented DNA and cells double-stained with annexin V/propidium iodide, suggesting an apoptosis mechanism. The results suggest that the different effects of Gb1 and Gb1-OS were related to differences in the sulfate content and position of these groups along the polysaccharide chains.

Design of facile technology for the efficient removal of hydroxypropyl guar gum from fracturing fluid.

With the increasing demand for energy, fracturing technology is widely used in oilfield operations over the last decades. Typically, fracturing fluids contain various additives such as cross linkers, thickeners and proppants, and so forth, which makes it possess the properties of considerably complicated components and difficult processing procedure. There are still some difficult points needing to be explored and resolved in the hydroxypropyl guar gum (HPG) removal process, e.g., high viscosity and removal of macromolecular organic compounds. Our works provided a facile and economical HPG removal technology for fracturing fluids by designing a series of processes including gel-breaking, coagulation and precipitation according to the diffusion double layer theory. After this treatment process, the fracturing fluid can meet the requirements of reinjection, and the whole process was environment friendly without secondary pollution characteristics. In this work, the fracturing fluid were characterized by scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy technologies, etc. Further, the micro-stabilization and destabilization mechanisms of HPG in fracturing fluid were carefully investigated. This study maybe opens up new perspective for HPG removal technologies, exhibiting a low cost and strong applicability in both fundamental research and practical applications.

Effects of seleno-Sesbania canabina galactomannan on anti-oxidative and immune function of macrophage.

Seleno-polysaccharides have become a major topic for research owing to their high anti-oxidative capacity and immune-enhancing activities. In this study, galactomannan (GM) was isolated from Sesbania cannabina, and next modified using HNO3-Na2SeO3 method to obtain six varieties of seleno-galactomannans (SeGMs). FT-IR and GPC results showed the changes in chemical structure of SeGMs, indicating successful combination of selenium and GM. By measuring superoxide dismutase and malondialdehyde, the SeGMs showed a stronger protective effect against H2O2-induced oxidative damage in vitro than unmodified GM using macrophage RAW264.7 cell as a model, and the effect of SeGMs-14 was prominent. However, the selenylation modification did not show any obvious effect on the immunomodulatory activity of GM, as determined by the index of tumor necrosis factor-α, interleukin-6, and interleukin-1ß. Overall, the prepared SeGMs from galactomannan could potentially serve as a dietary supplement of Se or an organic antioxidant.

Serology anno 2021-fungal infections: from invasive to chronic.

BACKGROUND: Diagnosing invasive or chronic fungal infections is a challenge, particularly in the immunocompromised host. Microscopy and culture remain the reference standard, but are insensitive. The use of non-culture-based techniques is recommended in conjunction with conventional methods to improve the diagnostic yield. OBJECTIVES: The aim was to provide an updated 2021 inventory of fungal antigen and serology tests for diagnosing invasive and chronic fungal infections, the key focus was set on Aspergillus, Candida and Cryptococcus species. SOURCES: Pubmed search for publications with the key words fungal antigen tests, laboratory-based diagnosis of invasive pulmonary aspergillosis, chronic pulmonary aspergillosis, invasive candidiasis, invasive fungal infections and cryptococcal infections published from 2017 to 2020. CONTENT: Antigen assays such as the galactomannan (GM) and ß-d-glucan detection systems are frequently used, but these tests vary in sensitivity and specificity, depending on the patient population involved, specimens inspected, cut-offs defined, test strategy applied and inclusion or exclusion of possible fungal case definitions. Multiple different detection systems are available, with recently introduced new point-of-care tests such as the lateral flow device and the lateral flow assay. Despite a wide heterogeneity in populations evaluated, studies indicate a better diagnostic performance of bronchoalveolar lavage GM in comparison with serum GM, and a suboptimal specificity of GM bronchoalveolar lavages (cut-off ≥1) and serum ß-d-glucan in non-neutropenic individuals. Point-of-care cryptococcal antigen tests show excellent performance. IMPLICATIONS: There are fungal antigen detection tests available with excellent to reasonable clinical performance to diagnose invasive fungal infections. Only a few assays are useful to monitor therapeutic response. There are multiple marketed IgG antibody tests to detect Aspergillus fumigatus antibodies, the titres vary widely and the performance differs significantly. In general, diagnostic tests are vulnerable to being affected by the host, the microbe and laboratory setting.

Conjugation of Hemoglobin and Mannan Markedly Improves the Immunogenicity of Domain III of the Zika Virus E Protein: Structural and Immunological Study.

Zika virus (ZIKV) leads to congenital microcephaly and anomalies and severe neurological diseases such as Guillain-Barre syndrome. Safe and effective vaccines are necessitated to deal with these severe health threats. As an ideal antigen, the domain III of the envelope protein (EDIII) of ZIKV can evoke potent neutralizing antibodies without any antibody-dependent enhancement (ADE) effect. However, EDIII necessitates to be formulated with an antigen delivery system or adjuvants to improve its immunogenicity. Hemoglobin (Hb) regulates inflammation, cytokine levels, and activate macrophage. Mannan is a polysaccharide of the fungal cell wall with an immunomodulatory activity. In this study, EDIII was conjugated with Hb and mannan, using the disulfide bond as the linker. Hb and mannan both functioned as the adjuvants. Conjugation of Hb and mannan acted as the delivery system for EDIII. The structure of EDIII was essentially maintained upon conjugation of Hb and mannan. The intracellular release of EDIII from the conjugate (HM-EDIII-2) was achieved by reduction of the glutathione-sensitive disulfide bond. As compared with EDIII, HM-EDIII-2 elicited high EDIII-specific IgG titers and high levels of Th1-type cytokines (IFN-γ and IL-2) and Th2-type cytokines (IL-5 and IL-10), along with no apparent toxicity to the organs. Moreover, the pharmacokinetic study revealed a prolonged serum exposure of HM-EDIII-2 to the immune cells. Thus, HM-EDIII-2 could boost a strong humoral and cellular immune response to EDIII. Our study was expected to provide the feasibility necessary to develop a robust and potentially safe ZIKV vaccine.

Selective extraction of galactomannan from fenugreek (Trigonella foenum-graecum L.) seed husk and its enzyme inhibitory potential associated with hyperglycaemia.

BACKGROUND: Fenugreek seeds host various bioactive compounds, and galactomannan (GM) is a significant soluble fibre. In this study, selective extraction is adapted to extract fenugreek seed GM to improvise the yield recovery. The seeds are fractionated, separated and classified as husk and cotyledons. Comparative studies have been performed to evaluate the crude and pure GM yield between different groups such as the whole seed, and the classified fractions. Characterization is done using Fourier transform infrared, differential scanning calorimetry, scanning electron microscopy, monosaccharide composition and optical density, and the structure is elucidated through nuclear magnetic resonance. The GM obtained through extraction is used to study its enzyme inhibitory property associated with hyperglycaemia. RESULTS: GM yield extracted from the husk is highly significant compared to other groups. Crude GM and pure GM yield was 2 and 3.25 times higher than that obtained through whole seed samples. The characterization of the pure GM is on a par with the existing reports. The purified GM inhibited α-amylase and α-glucosidase enzymes in vitro, with an IC50 of 21.08 ± 0.085 and 67.17 ± 5.15 µg mL-1 , respectively. CONCLUSION: Selective extraction prompts enhancement in the recovery of the bioactive compound, minimal use of resources, and promotes industrial viability. Characterization of the compound confirms the structure. Its enzyme inhibitory property makes GM a valuable compound in diabetic prevention/treatment. © 2021 Society of Chemical Industry.

Comparison of the Effect of Ceratonia siliqua L. (Carob) Syrup and Vitamin E on Sperm Parameters, Oxidative Stress Index, and Sex Hormones in Infertile Men: a Randomized Controlled Trial.

Herbal products with an antioxidant capacity can boost male reproductive functions. The empiric use of Ceratonia siliqua (carob) for its antioxidant properties is common among infertile men in Iran and Turkey. The objective of this study is to investigate the effects of C. siliqua (carob) on semen parameters, oxidative stress markers, and pregnancy rate in a parallel randomized, controlled study. A total of 60 infertile men with oligozoospermia, asthenospermia, and teratospermia were recruited from April 2018 to March 2019. Participants were divided randomly into the following two groups: carob syrup twice a day or vitamin E 100 mg twice a day for 3 months. Semen analysis was performed and hormonal levels and stress oxidative markers were measured in each treatment arm after 3 months. The quality of semen parameters improved in the carob group compared with Vit E semen count (p = 0.04 Cohen's d = .51), morphology (p = 0.001 Cohen's d = .93) and motility parameters (p = 0.002 Cohen's d = .90) were significantly higher in the carob group. No significant difference can be detected in post-treatment hormonal parameters and oxidative markers between groups, except for total antioxidant capacity(TAC) which was higher after post-treatment in carob group. A significantly higher pregnancy rate was found among the carob group. The administration of carob may be an effective agent for the improvement of semen parameters, probably related both to its involvement in the changing of testosterone level and to its antioxidant properties. Nevertheless, additional studies to evaluate the optimal dose and duration of treatment are needed. The trial has been registered in the Iranian Registry of Clinical Trials (Registration number: IRCT20171209037794N1.

Fabrication of hydrophobic and high-strength packaging films based on the esterification modification of galactomannan.

There is an increasing interest in substituting current packaging films with biologically-derived films without compromising mechanical properties and hydrophobicity. In this work, the esterified galactomannan (E-GM) films with good hydrophobicity, excellent oxygen barrier performance and high tensile mechanical strength were synthesized using anhydride esterification method prior to film formation. The hydrophobicity, mechanical properties, barrier properties, thermal stability and ultraviolet absorption of the prepared films were determined to fully investigate the features of galactomannan-based films. The results indicated that GM films can be successfully obtained by esterification. Compared to neat GM film, E-GM-1.5 film (acetic anhydride to GM of 1.5:1) achieved the highest degree of esterification (0.05), hydrophobicity (107°) and mechanical strength (92.0 MPa). In addition, the esterified GM films had lower toxicity for macrophages cells. The prepared E-GM films may provide more opportunities for further advancement and applications in the development of food packaging from natural resources.

Biosynthesis of low-molecular-weight mannan using metabolically engineered Bacillus subtilis 168.

Mannans are functional polysaccharides with unique biological activities that have been employed widely in food, medicine and pharmaceutics. Recent breakthroughs in plant polysaccharide metabolism identified numerous genes involved in the biosynthesis of mannans. However, constructing highly efficient low-cost microbial cell factories to produce low-molecular-weight (LMW) mannans remains challenging. In this work, we designed a de novo mannan synthetic pathway in food-grade Bacillus subtilis, resulting in mannan accumulation of 0.97 g/L. By co-expressing the identified committed genes (manC, manB, manA and pgi), mannan production was significantly increased to 2.5 g/L. Furthermore, by redirecting the carbon flux using a glucose-repressed promoter to control pfkA expression, mannan production was substantially increased to 4.1 g/L. Production was further enhanced to 12.6 g/L (average MW 6370 Da) in 3-L fed-batch fermentation. This work provides alternative synthetic pathways for metabolic engineering of LMW mannans in B. subtilis, and a useful, optimisable approach to enhance mannans production.

Isolation, structural characterization, and biological activities of galactomannans from Rhizopogon luteolus and Ganoderma adspersum mushrooms.

Polysaccharides are essential compounds that contribute to the biological activities of mushrooms. Two new galactomannans (Galactomannan I and II) were isolated from R. luteolus and G. adspersum. Their structures were characterized using FT-IR, 1D, and 2D-NMR techniques. Both isolated galactomannans I and II mainly include D-mannose and D-galactose in the molar percentages of 0.81:1.0 and 1:1.4, respectively. The GPC calculation demonstrated that the molecular weights are about 5240 and 5090 Da, respectively. Their structures comprise of ß-(1,4)-mannose (Man) backbone units with α-(1,6)-galactose (Gal) single unit as a side group. The anticholinesterase activity of galactomannans was tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), spectrophotometrically. Antioxidant activity was also measured by six assays (ABTS•+, DPPH•, O2•-, ß-carotene-linoleic acid, metal chelating, and CUPRAC assays). Galactomannan II indicated close inhibitory activity to galantamine against AChE (61.04 ±â€¯0.45%) and BChE (59.70 ±â€¯1.15%) at 50 µg/mL concentration. Nevertheless, both galactomannans showed low antioxidant activity in all tests. This study reveals that mainly, Galactomannan II could be used as a new natural promising anticholinesterase agent.

Promising alternative gum: Extraction, characterization, and oxidation of the galactomannan of Cassia fistula.

Galactomannan extracted from Cassia fistula seed endosperm present little data related to the its structural characterization. This study reports the chemical characterization of the galactomannan from Cassia fistula (CF) and their oxidized derivatives. The extracted CF presented a yield of 26.5% (w/w) and the intrinsic viscosity [η] was 9.73 dL/g. 1D and 2D nuclear magnetic resonance spectroscopy (NMR) confirmed that the polysaccharide has a backbone of 4-linked ß-D-mannose units, and contains galactose units as pending groups. These galactose units are linked to the central core through a (1→6) linkage and the galactomannan presented Man/Gal ratio of 3.1/1. The galactomannan from Cassia fistula presents low cytotoxicity in Vero cells with a CC50 > 1000 µg/ml. The properties of CF resemble other commercially important galactomannans such as Locust bean gum. Three oxidized derivatives of CF were produced by periodate oxidation, which were carefully characterized by different structural techniques. It was observed that as the degree of oxidation increased, there was an increase in the Man/Gal ratio and a reduction in molar mass and viscosity. The polialdehyde produced may be explored as a versality material to react with amine group of the protein and amined polysaccharide to produce biomaterials.

Conformational properties and biological activities of α-D-mannan from Sanghuangporus sanghuang in liquid culture.

Sanghuang is a well-known edible and medicinal fungus consumed in Asia for centuries. In the present study, a novel exopolysaccharide named as mannan (SSEPS2) was isolated from the liquid culture broth of Sanghuangporus sanghuang by using ethanol precipitation, anion-exchange chromatography, and size-exclusion chromatography, which was exclusively composed of D-mannose with the molecular weight 9.43 × 104 g/mol. The structural analysis suggested that SSEPS2 consisted of 1,3-linked and 1,2-linked α-D-mannopyranose (Manp), with substitution at O-6 of 1,2-linked α-D-Manp by 1,6-linked α-D-Manp residues and terminal α-D-Manp residues. The exponent of α (0.58) indicated that SSEPS2 existed in a flexible chain conformation, with a coil-like structure in 0.1 M NaNO3 at 25 °C, which was further confirmed by the atomic force microscopy images and a three-dimensional molecular model. It exhibited potential antitumor activity against the growth of HepG2 (human hepatoma) and MCF-7 cell lines in vitro. The IC50 values for inhibiting HepG-2 cells and MCF-7 cells proliferation were 365 and 340 µg/mL, which showed its potential application in the development of anticancer therapeutics.

Structural characteristics of oxalate-soluble polysaccharides from Norway spruce (Picea abies) foliage.

Structurally different polymers were derived from Picea abies foliage by successive extraction with water (PAW), HCl solution (PAA) and (NH4)2C2O4 solution (PAO). The P. abies foliage was found to contain basically low-methoxyl pectin extractable with an (NH4)2C2O4 solution. PAW was shown to comprise primarily arabinogalactan-proteins (AGPs); PAA was composed of mixed AGPs and pectic polysaccharides, with the latter prevailing; and polysaccharide PAO isolated in the highest yield included chiefly pectic polysaccharides. The major constituents of PAO were low-methoxyl and low-acetylated 1,4-α-d-galacturonan and partially acetylated RG-I. The sugar side chains of RG-I contained chiefly highly branched 1,5-α-l-arabinan and arabinogalactan type I as a minor constituent. RG-I whose side chains had 1,5-α-l-arabinan represented short regions alternating with non-acetylated and unmethylesterified galacturonan regions. In addition to pectins, polysaccharide PAO contained AGPs, xylanes and glucomannans, indicating that these polysaccharides are in an intimate interaction.

Extraction, purification, and determination of the gastroprotective activity of glucomannan from Bletilla striata.

In this study, a water-soluble polysaccharide (BSP) was extracted and purified from pseudobulb of Bletilla striata. The preliminary structure and gastroprotective activity of BSP were analyzed. Results indicate that BSP is a glucomannan with a molar ratio of 7.45:2.55 (Man:Glc), and its molecular weight is approximately 1.7 × 105 Da. BSP displayed outstanding protective action against ethanol-induced GES-1 cell injury in vitro, as well as, excellent gastroprotective activity in vivo. Especially, a high-dose of BSP (100 mg/kg) could reduce the ulcer index of the gastric mucosa and increase the percentage of ulcer inhibition, which possibly caused by enhancing the antioxidant capacity and inhibiting the apoptotic pathway in gastric tissue. Interestingly, BSP exhibited a comparative gastroprotective activity to that of positive control (omeprazole). In summary, our results indicated that BSP could be considered as a potential supplement for the prevention of gastric injury.