Dietary fiber guar gum-induced shift in gut microbiota metabolism and intestinal immune activity enhances susceptibility to colonic inflammation.

With an increasing interest in dietary fibers (DFs) to promote intestinal health and the growth of beneficial gut bacteria, there is a continued rise in the incorporation of refined DFs in processed foods. It is still unclear how refined fibers, such as guar gum, affect the gut microbiota activity and pathogenesis of inflammatory bowel disease (IBD). Our study elucidated the effect and underlying mechanisms of guar gum, a fermentable DF (FDF) commonly present in a wide range of processed foods, on colitis development. We report that guar gum containing diet (GuD) increased the susceptibility to colonic inflammation. Specifically, GuD-fed group exhibited severe colitis upon dextran sulfate sodium (DSS) administration, as evidenced by reduced body weight, diarrhea, rectal bleeding, and shortening of colon length compared to cellulose-fed control mice. Elevated levels of pro-inflammatory markers in both serum [serum amyloid A (SAA), lipocalin 2 (Lcn2)] and colon (Lcn2) and extensive disruption of colonic architecture further affirmed that GuD-fed group exhibited more severe colitis than control group upon DSS intervention. Amelioration of colitis in GuD-fed group pre-treated with antibiotics suggest a vital role of intestinal microbiota in GuD-mediated exacerbation of intestinal inflammation. Gut microbiota composition and metabolite analysis in fecal and cecal contents, respectively, revealed that guar gum primarily enriches Actinobacteriota, specifically Bifidobacterium. Guar gum also altered multiple genera belonging to phyla Bacteroidota and Firmicutes. Such shift in gut microbiota composition favored luminal accumulation of intermediary metabolites succinate and lactate in the GuD-fed mice. Colonic IL-18 and tight junction markers were also decreased in the GuD-fed group. Importantly, GuD-fed mice pre-treated with recombinant IL-18 displayed attenuated colitis. Collectively, unfavorable changes in gut microbiota activity leading to luminal accumulation of lactate and succinate, reduced colonic IL-18, and compromised gut barrier function following guar gum feeding contributed to increased colitis susceptibility.

Guar gum increased susceptibility to colitisGuar gum-induced exacerbation of colitis is gut microbiota dependentGuar gum-induced shift in microbiota composition favored the accumulation of luminal intermediate metabolites succinate and lactateGuar gum-fed mice exhibited reduced colonic level of IL-18 and tight junction molecules.Exogenous IL-18 administration partly rescued mice from guar gum-induced colitis susceptibility.

Biocatalytic Conversion of Carrageenans for the Production of 3,6-Anhydro-D-galactose.

Marine biomass stands out as a sustainable resource for generating value-added chemicals. In particular, anhydrosugars derived from carrageenans exhibit a variety of biological functions, rendering them highly promising for utilization and cascading in food, cosmetic, and biotechnological applications. However, the limitation of available sulfatases to break down the complex sulfation patterns of carrageenans poses a significant limitation for the sustainable production of valuable bioproducts from red algae. In this study, we screened several carrageenolytic polysaccharide utilization loci for novel sulfatase activities to assist the efficient conversion of a variety of sulfated galactans into the target product 3,6-anhydro-D-galactose. Inspired by the carrageenolytic pathways in marine heterotrophic bacteria, we systematically combined these novel sulfatases with other carrageenolytic enzymes, facilitating the development of the first enzymatic one-pot biotransformation of ι- and κ-carrageenan to 3,6-anhdyro-D-galactose. We further showed the applicability of this enzymatic bioconversion to a broad series of hybrid carrageenans, rendering this process a promising and sustainable approach for the production of value-added biomolecules from red-algal feedstocks.

Tolerance and Safety of an Anti-Regurgitation Formula Containing Locust Bean Gum, Pre-, and Postbiotics: A Multi-Country Multi-Center Prospective Randomized Controlled Study in Infants with Regurgitation.

This multi-center prospective randomized controlled trial was a tolerance and safety study investigating the thickener locust bean gum (LBG) in infants with regurgitation, to support the re-evaluation of the safety of LBG in infant formula. The primary objective was to demonstrate that after an 8-week intervention, stool consistency was not inferior (i.e., was not looser or more watery) in infants fed an anti-regurgitation (AR) formula containing LBG vs. the stool consistency of infants fed with an unthickened control formula. A total of 103 full-term infants with regurgitation were randomized to the test or control formula. The test formula contained LBG (0.4 g/100 mL), short-chain galacto-oligosaccharides, and long-chain fructo-oligosaccharides (scGOS/lcFOS; 9:1; 0.4 g/100 mL) and postbiotics and the control formula contained scGOS/lcFOS (0.8 g/100 mL), the same amount of postbiotics, and did not contain LBG. The average stool consistency score at the 8th intervention week was the primary outcome parameter. Secondary outcome parameters were stool consistency at other timepoints, stool frequency, Infant Gastrointestinal Symptom Questionnaire (IGSQ) score, growth, (serious) adverse events ([S]AEs), regurgitation severity, and infant well-being. Overall, the infants were 36.9 ± 12.9 [mean ± SD] days old, 62.7% girls in the test, and 50.0% girls in the control group. The primary analysis showed that the test group did not have looser or more watery stools than the control group. IGSQ sum scores decreased comparably in both groups. The frequency of regurgitation was significantly lower in the test group compared to the control group (mixed model repeated measurement, p ≤ 0.028) and parent-reported well-being scores were favorable. Adequate growth was observed in both groups. Both products were well-tolerated and safe and the AR formula with LBG was efficacious in reducing regurgitation frequency. This study provides further evidence for the dietary management of regurgitation by LBG-containing formulae in infants who are not exclusively breastfed, and the reassurance it can bring to parents.

Assessment and Optimization of the Insecticidal Properties of γ-Al2O3 Nanoparticles Derived from Mentha pulegium By-Products to Xylosandrus crassiusculus (Carob Beetle).

This study concentrates on assessing the insecticidal attributes of the γ-Al2O3 nanoparticles derived from the remnants of Mentha pulegium, which include essential oil, ethanolic extract, and plant waste. The synthesis of the γ-Al2O3 nanoparticles was executed using a direct sol-gel procedure, affirming the crystal structure according to extensive physicochemical analyses such as UV-Vis, XRD, FTIR, and SEM. Evaluation of the insecticidal activity in vitro was conducted against Xylosandrus crassiusculus, a pest that infests carob wood, utilizing strains from diverse forests in the Khenifra region, situated in the Moroccan Middle Atlas. The lethal doses 50 ranged from 40 mg/g to 68 mg/g, indicating moderate effectiveness compared to the commercial insecticide Permethrin. Optimization of the conditions for the efficiency of the γ-Al2O3 nanoparticles was determined using experimental plans, revealing that time, humidity, and temperature were influential factors in the lethal dose 50 of these nanomaterials. Moreover, this study encompasses the establishment of correlations using Principal Component Analysis (PCA) and Ascending Hierarchical Classification (AHC) among various geographic, biological, and physical data, amalgamating geographic altitude and γ-Al2O3 nanoparticle insecticide parameters, as well as the attributes of the mechanical tests conducted on the carob wood affected by insects. The correlations highlight the close connections between the effectiveness of the insecticide, mountain altitude, and the mechanical parameters that were examined. Ultimately, these nanoparticles demonstrate promising potential as alternative insecticides, thus opening up encouraging prospects for safeguarding against carob wood pests.

Starch microsphere silicon-boron crosslinker for low concentration hydroxypropyl guar gum based fracturing fluid.

Hydroxypropyl guar gum (HPG) is a critical thickener to increase viscosity and lubrication to improve the water-based hydraulic fracturing efficiency. However, current crosslinkers require a large amount of HPG (>0.3 wt%) to form gel with sufficient viscosity, and high concentrations of HPG may cause adverse effects to the production and the environment. In this study, a novel starch microsphere silica­boron crosslinker (SMSB) was developed using starch microspheres as a carrier and γ-aminopropyl triethoxy silane (KH550) as a modifier with an in-house method. Both the rheology and surface reactions of the SMSB-HPG crosslinking system were studied using multiple laboratory experiments and molecular dynamics simulation. The results showed that SMSB crosslinker caused multi-site cross-linking with low concentration (only 0.2 wt%) of HPG molecules, reducing the twisting of single molecular chain in the crosslinking system, enhancing the cross-linking strength between molecular chains, and making HPG molecular chains stretcher in the aqueous solution. The apparent viscosity and viscoelasticity of the HPG system were substantially higher than the organoboron crosslinker, and the temperature resistance of the SMSB-HPG crosslinking system was up to 140 °C. This study provides an alternative green crosslinker for more sustainable industrial applications and provides theoretical basis for the modification of biomaterials.

A new perspective on structural characterisation and immunomodulatory activity of arabinogalactan in Larix kaempferi from Qinling Mountains.

In this study, crude polysaccharide (LAG-C) and homogeneous arabinogalactan (LAG-W) were isolated from Qinling Larix kaempferi of Shaanxi Province. Bioactivity assays showed that LAG-W and LAG-C enhanced the phagocytic ability, NO secretion, acid phosphatase activity, and cytokine production (IL-6, IL-1ß, and TNF-α) of RAW264.7 macrophages. Notably, LAG-W exhibited a significantly stronger immunomodulatory effect than LAG-C. The primary structure of LAG-W was characterised by chemical methods (monosaccharide composition, methylation analysis, and alkali treatment) and spectroscopic techniques (gas chromatography-mass spectrometry, high-performance liquid chromatography-mass spectrometry, and 1D/2D nuclear magnetic resonance). LAG-W was identified as a 22.08 kilodaltons (kDa) neutral polysaccharide composed of arabinose and galactose at a 1:7.5 molar ratio. Its backbone consisted of repeated →3)-ß-Galp-(1→ residues. Side chains, connected at the O-6 position, were mainly composed of T-ß-Galp-(1→ and T-ß-Galp-(1→6)-ß-Galp-(1→ residues. And it also contained small amounts of T-ß-Arap-(1→, T-α-Araf-(1→6)-ß-Galp-(1→6)-ß-Galp-(1→, and T-α-Araf-(1→3)-α-Araf-(1→6)-ß-Galp-(1→ residues. By structurally and functionally characterising L. kaempferi polysaccharides, this study opens the way for the valorisation of this species.

Recent updates on guar gum derivatives in colon specific drug delivery.

Colon specific delivery of therapeutics have gained much attention of pharmaceutical researchers in the recent past. Colonic specific targeting of drugs is used not only for facilitating absorption of protein or peptide drugs, but also localization of therapeutic agents in colon to treat several colonic disorders. Among various biopolymers, guar gum (GG) exhibits pH dependent swelling, which allows colon specific release of drug. GG also shows microbial degradation in the colonic environment which makes it a suitable excipient for developing colon specific drug delivery systems. The uncontrolled swelling and hydration of GG can be controlled by structural modification or by grafting with another polymeric moiety. Several graft copolymerized guar gum derivatives are investigated for colon targeting of drugs. The efficacy of various guar gum derivatives are evaluated for colon specific delivery of drugs. The reviewed literature evidenced the potentiality of guar gum in localizing drugs in the colonic environment. This review focuses on the synthesis of several guar gum derivatives and their application in developing various colon specific drug delivery systems including matrix tablets, coated formulations, nano or microparticulate delivery systems and hydrogels.

Pimobendan controlled release guar gum printlets: Tailoring drug doses for personalised veterinary medicines.

Treating chronic heart diseases in dogs is challenging due to variations in mass within and between species. Pimobendan (PBD), a veterinary drug only, is prescribed in specific cases of chronic heart disease in dogs and is available on the market in only a few different doses. Furthermore, the therapy itself is challenging due to the large size of the chewable tablets and the requirement for twice-daily administration. The development of customised and on-demand PBD medicines by three-dimensional (3D) printing has been proposed to circumvent these disadvantages. In this study, we designed controlled-release flavoured printlets containing PBD. We evaluated the use of two natural polymers, guar or xanthan gums, as the main component of the printing inks. Guar gum showed the better rheological behavior and printability by semisolid extrusion. The printlets were produced in three different shapes and sizes to allow dose customisation. Guar gum printlets showed a PBD controlled release profile, regardless of their shape or size. Therefore, we have demonstrated a novel approach for controlling PBD drug release and tailoring the dose by employing a natural polymer to produce 3D-printed tablets. This study represents a significant step towards the development of 3D-printed guar gum controlled-release formulations for veterinary applications.

Chromatography based profiling of feruloylated arabinans and galactans.

Profiling of pectic arabinans and galactans by analysis of the released oligosaccharides after backbone cleavage provides information on the complexity of the polymer structure. In plants of the family Amaranthaceae, arabinan and galactan substitution with ferulates extends the polysaccharide complexity, changing its chemical properties. Knowledge of the ferulate environment is crucial to understand structure-function-relationships of feruloylated pectins. Here, we present an approach to separate enzymatically generated feruloylated and non-feruloylated arabino- and galactooligosaccharides, followed by deesterification and semiquantitative analysis by HPAEC-PAD using previously reported relative response factors. Application of this approach to sugar beet pectins and insoluble and soluble dietary fiber preparations of amaranth and quinoa suggests that ferulates are preferably incorporated into more complex structures, as nicely demonstrated for feruloylated galactans. Also, ferulate substitution appears to negatively affect enzymatic cleavage by using endo-enzymes. As a consequence, we were able to tentatively identify new feruloylated tri- and tetrasaccharides of galactans isolated from sugar beet pectins.

Structural elucidation and immunomodulatory activities in vitro of type I and II arabinogalactans from different origins of Astragalus membranaceus.

Astragalus membranaceus polysaccharide (APS) possesses excellent immunomodulatory activity. However, there are several studies on the structural characterization of APS. Here, we aimed to elucidate the repeating units of polysaccharides (APS1, 106.5 kDa; APS2, 114.5 kDa) obtained from different Astragalus membranaceus origins and further investigated their immunomodulatory activities. Based on structural analysis, types of the two polysaccharides were identified as arabinogalactan-I (AG-I) and arabinogalactan-II (AG-II), and co-elution of arabinogalactans (AGs) and α-glucan was observed. The backbone of AG-I was 1,4-linked ß-Galp occasionally substituted by α-Araf at O-2 and/or O-3. AG-II was a highly branched polysaccharide with long branches of α-Araf, which were attached to the O-3 of 1,6-linked ß-Galp of the backbone. The presence of AGs in A. membranaceus was confirmed for the first time. The two polysaccharides could promote the expression of IL-6, IL-1ß and TNF-α in RAW264.7 cells via MAPKs and NF-κB signaling pathways. The constants for APS1 and APS2 binding to Toll-like receptor 4 (TLR4) were 1.83 × 10-5 and 2.08 × 10-6, respectively. Notably, APS2 showed better immunomodulatory activity than APS1, possibly because APS2 contained more AGs. Hence, the results suggested that AGs were the vital components of APS in the immunomodulatory effect.

Characterization of the fiber-like cortical cells in moss gametophytes.

MAIN CONCLUSION: Fiber-like cells with thickened cell walls of specific structure and polymer composition that includes (1 → 4)-ß-galactans develop in the outer stem cortex of several moss species gametophytes. The early land plants evolved several specialized cell types and tissues that did not exist in their aquatic ancestors. Of these, water-conducting elements and reproductive organs have received most of the research attention. The evolution of tissues specialized to fulfill a mechanical function is by far less studied despite their wide distribution in land plants. For vascular plants following a homoiohydric trajectory, the evolutionary emergence of mechanical tissues is mainly discussed starting with the fern-like plants with their hypodermal sterome or sclerified fibers that have xylan and lignin-based cell walls. However, mechanical challenges were also faced by bryophytes, which lack lignified cell-walls. To characterize mechanical tissues in the bryophyte lineage, following a poikilohydric trajectory, we used six wild moss species (Polytrichum juniperinum, Dicranum sp., Rhodobryum roseum, Eurhynchiadelphus sp., Climacium dendroides, and Hylocomium splendens) and analyzed the structure and composition of their cell walls. In all of them, the outer stem cortex of the leafy gametophytic generation had fiber-like cells with a thickened but non-lignified cell wall. Such cells have a spindle-like shape with pointed tips. The additional thick cell wall layer in those fiber-like cells is composed of sublayers with structural evidence for different cellulose microfibril orientation, and with specific polymer composition that includes (1 → 4)-ß-galactans. Thus, the basic cellular characters of the cells that provide mechanical support in vascular plant taxa (elongated cell shape, location at the periphery of a primary organ, the thickened cell wall and its peculiar composition and structure) also exist in mosses.

Jasmonates and Ethylene Shape Floridoside Synthesis during Carposporogenesis in the Red Seaweed Grateloupia imbricata.

Floridoside is a galactosyl-glycerol compound that acts to supply UDP-galactose and functions as an organic osmolyte in response to salinity in Rhodophyta. Significantly, the UDP-galactose pool is shared for sulfated cell wall galactan synthesis, and, in turn, affected by thallus development alongside carposporogenesis induced by volatile growth regulators, such as ethylene and methyl jasmonate, in the red seaweed Grateloupia imbricata. In this study, we monitored changes in the floridoside reservoir through gene expression controlling both the galactose pool and glyceride pool under different reproductive stages of G. imbricata and we considered changing salinity conditions. Floridoside synthesis was followed by expression analysis of galactose-1-phosphate uridyltransferase (GALT) as UDP-galactose is obtained from UDP-glucose and glucose-1P, and through α-galactosidase gene expression as degradation of floridoside occurs through the cleavage of galactosyl residues. Meanwhile, glycerol 3-phosphate is connected with the galactoglyceride biosynthetic pathway by glycerol 3-phosphate dehydrogenase (G3PD), monogalactosyl diacylglyceride synthase (MGDGS), and digalactosyl diacylglyceride synthase (DGDGS). The results of our study confirm that low GALT transcripts are correlated with thalli softness to locate reproductive structures, as well as constricting the synthesis of UDP-hexoses for galactan backbone synthesis in the presence of two volatile regulators and methionine. Meanwhile, α-galactosidase modulates expression according to cystocarp maturation, and we found high transcripts in late development stages, as occurred in the presence of methyljasmonate, compared to early stages in ethylene. Regarding the acylglyceride pool, the upregulation of G3PD, MGDGS, and DGDGS gene expression in G. imbricata treated with MEJA supports lipid remodeling, as high levels of transcripts for MGDGS and DGDGS provide membrane stability during late development stages of cystocarps. Similar behavior is assumed in three naturally collected thalli development stages-namely, fertile, fertilized, and fertile-under 65 psu salinity conditions. Low transcripts for α-galactosidase and high for G3PD are reported in infertile and fertilized thalli, which is the opposite to high transcripts for α-galactosidase and low for G3PD encountered in fertile thalli within visible cystocarps compared to each of their corresponding stages in 35 psu. No significant changes are reported for MGDGS and DGDGS. It is concluded that cystocarp and thallus development stages affect galactose and glycerides pools with interwoven effects on cell wall polysaccharides.

RN0D, a galactoglucan from Panax notoginseng flower induces cancer cell death via PINK1/Parkin mitophagy.

Metabolic alterations within mitochondria, encompassing processes such as autophagy and energy metabolism, play a pivotal role in facilitating the swift proliferation, invasion, and metastasis of cancer cells. Despite this, there is a scarcity of currently available medications with proven anticancer efficacy through the modulation of mitochondrial dysfunction in a clinical setting. Here, we introduce the structural characteristics of RN0D, a galactoglucan isolated and purified from Panax notoginseng flowers, mainly composed of ß-1,4-galactan and ß-1,3/1,6-glucan. RN0D demonstrates the capacity to induce mitochondrial impairment in cancer cells, leading to the accumulation of reactive oxygen species, initiation of mitophagy, and reduction in both mitochondrial number and size. This sequence of events ultimately results in the inhibition of mitochondrial and glycolytic bioenergetics, culminating in the demise of cancer cells due to adenosine triphosphate (ATP) deprivation. Notably, the observed bioactivity is attributed to RN0D's direct targeting of Galectin-3, as affirmed by surface plasmon resonance studies. Furthermore, RN0D is identified as an activator of the PTEN-induced kinase 1 (PINK1)/Parkin pathway, ultimately instigating cytotoxic mitophagy in tumor cells. This comprehensive study substantiates the rationale for advancing RN0D as a potentially efficacious anticancer therapeutic.

Effects of synergistic modification using alkalis and guar gum on the pasting, rheological, and microstructural properties of germinated highland barley starch gels.

Germination treatment of highland barley enhances its nutritional value while weakening the starch gel properties. This study aims to enhance the characteristics of germinated highland barley starch (GBS) by exploring the synergistic effects of two alkalis (Na2CO3 and NaHCO3) and guar gum (GG) on GBS gel properties. The combined action of alkalis and GG significantly improved the peak viscosity, setback viscosity, and hardness compared with GG alone. The highest G' and G" reached 998 and 204 Pa at 0.4% Na2CO3 addition, which were increased by nearly 44% and 50%, respectively. Fourier-transform infrared spectral analysis revealed that the alkalis strengthened interaction forces, particularly with intensified absorption peaks at 3200-3700 cm-1 and 1550-1750 cm-1. The Na2CO3 and NaHCO3 reduced the spin-spin relaxation time (T2), resulting in a dense starch gel network. This study contributes to enhancing the market application of GBS and offers innovative insights for modifying other starches.

Structural changes in cell wall pectic polymers contribute to freezing tolerance induced by cold acclimation in plants.

Subzero temperatures are often lethal to plants. Many temperate herbaceous plants have a cold acclimation mechanism that allows them to sense a drop in temperature and prepare for freezing stress through accumulation of soluble sugars and cryoprotective proteins. As ice formation primarily occurs in the apoplast (the cell wall space), cell wall functional properties are important for plant freezing tolerance. Although previous studies have shown that the amounts of constituent sugars of the cell wall, in particular those of pectic polysaccharides, are altered by cold acclimation, the significance of this change during cold acclimation has not been clarified. We found that ß-1,4-galactan, which forms neutral side chains of the acidic pectic rhamnogalacturonan-I, accumulates in the cell walls of Arabidopsis and various freezing-tolerant vegetables during cold acclimation. The gals1 gals2 gals3 triple mutant, which has reduced ß-1,4-galactan in the cell wall, exhibited impaired freezing tolerance compared with wild-type Arabidopsis during initial stages of cold acclimation. Expression of genes involved in the galactan biosynthesis pathway, such as galactan synthases and UDP-glucose 4-epimerases, was induced during cold acclimation in Arabidopsis, explaining the galactan accumulation. Cold acclimation resulted in a decrease in extensibility and an increase in rigidity of the cell wall in the wild type, whereas these changes were not observed in the gals1 gals2 gals3 triple mutant. These results indicate that the accumulation of pectic ß-1,4-galactan contributes to acquired freezing tolerance by cold acclimation, likely via changes in cell wall mechanical properties.

Ag Nanoparticle Incorporated Guar Gum-Sodium Alginate-I-Carrageenan Tribiopolymer Blended Cloth Waste Lint Extracted Cellulose Nanocrystal Antimicrobial Composite Film.

A biopolymer-based formulation for robust and active food packaging material was developed. This material consisted of a blend of three biopolymers (guar gum-sodium alginate-i-carrageenan) reinforced by cellulose nanocrystals (CNC) alongside the integration of silver nanoparticles (AgNPs) with varying sizes. The CNC utilized in this process was derived from cloth waste lint (CWL) generated from a household cloth dryer machine. This CNC synthesis underwent a series of solvent treatments to yield the CNC used in the composite. CNC and AgNPs were incorporated into the tribiopolymeric blend matrix to construct a nanocomposite film that showed excellent tensile strength (∼90 MPa). The nanocomposite film also exhibited antimicrobial activity against Escherichia coli ATCC 25922 and Bacillus cereus MTCC 1272. In this report, it was demonstrated that the zone of inhibition against E. coli and B. cereus depends on the variation of size and amount of AgNPs inside the polymeric matrix. The practical applicability of such a film was also demonstrated by applying it to sliced bread and the enhancement of the shelf life of the raped bread was compared with a control. Thus, the guar gum-sodium alginate-i-carrageenan tribiopolymer blend with a cloth waste lint extracted cellulose nanocrystal composite film is antimicrobial, hence, an excellent candidate as an active packaging film.

Compartmentalization of galactan biosynthesis in mycobacteria.

Galactan polymer is a prominent component of the mycobacterial cell wall core. Its biogenesis starts at the cytoplasmic side of the plasma membrane by a build-up of the linker disaccharide [rhamnosyl (Rha) - N-acetyl-glucosaminyl (GlcNAc) phosphate] on the decaprenyl-phosphate carrier. This decaprenyl-P-P-GlcNAc-Rha intermediate is extended by two bifunctional galactosyl transferases, GlfT1 and GlfT2, and then it is translocated to the periplasmic space by an ABC transporter Wzm-Wzt. The cell wall core synthesis is finalized by the action of an array of arabinosyl transferases, mycolyl transferases, and ligases that catalyze an attachment of the arabinogalactan polymer to peptidoglycan through the linker region. Based on visualization of the GlfT2 enzyme fused with fluorescent tags it was proposed that galactan polymerization takes place in a specific compartment of the mycobacterial cell envelope, the intracellular membrane domain, representing pure plasma membrane free of cell wall components (previously denoted as the "PMf" domain), which localizes to the polar region of mycobacteria. In this work, we examined the activity of the galactan-producing cellular machine in the cell-wall containing cell envelope fraction and in the cell wall-free plasma membrane fraction prepared from Mycobacterium smegmatis by the enzyme assays using radioactively labeled substrate UDP-[14C]-galactose as a tracer. We found that despite a high abundance of GlfT2 in both of these fractions as confirmed by their thorough proteomic analyses, galactan is produced only in the reaction mixtures containing the cell wall components. Our findings open the discussion about the distribution of GlfT2 and the regulation of its activity in mycobacteria.

Formulization and characterization of guar gum and almond gum based composite coating and their application for shelf-life extension of okra (Hibiscus esculentus).

The current novel study aims was to development and characterization of gum based (guar gum: almond gum) composite formulations with or without addition of oregano essential oils to extend the shelf life of okra at ambient condition. In this study, the optimized composite of guar gum: almond gum (75:25 V/V) prepared with addition of different concentrations (0.05, 0.1 and 0.15 % (V/V) of oregano essential oils to study their physicochemical, rheological, antimicrobial and particle size & zeta potential distribution. In addition, the effects of prepared edible coatings on shelf-life of okra vegetables were also investigated by assessing their postharvest quality attributes at ambient (23 °C) storage up to 7 days storage. The results revealed, increasing concentration of essential oils in composite coating significantly increased in pH, TSS, particle size, antimicrobial (Apergillus. niger, Escherichia coli, Staphylococcus aureus) activity respectively. Furthermore, the increasing EOs improved viscosity (n) and stability of the coatings matrix. In addition, the applications of guar gum (0.25 %): almond gum (0.5 %) composite ratio (75,25) with oregano essential oils exhibited excellent properties and potential to maintain the postharvest characteristics of okra throughout the storage period. The results of this study revealed that the addition of higher concentration (0.15 %) of essential oils in composite formulation of 75 % guar gum +25 % almond gum (03) showed higher value of pH (5.45), antioxidant activity (20.87 %), particle size (899.1 nm), zeta potential (-8.6 mV), polydispersity index (50.6 %) and higher antimicrobial activity against E.coli (19 mm), S. aureus (29 mm) and A. niger (35 mm) as compared to other formulations. Therefore, the lower composite formulation (01) with lower concentration (0.05 %) of oregano essential oil was found most effective formulation to maintain the shelf life of okra for up to 4 days as compared to other treated and control okra samples at ambient temperature by retarded the weight loss (12.74 %), maintained higher firmness (0.998 N), lower respiration rate (484.32 ml Co2/kg/h) respectively on 7 days of storage. The microbial load in the okra samples treated with different guar gum: almond gum composite showed lower microbial load in terms of total plate count and yeast & mold counts as compared to control samples. Samples treated with O3 coating showed lowest TPC (0.1 × 108 cfu/g) and YMC (6.63 × 106 cfu/g) followed by O2 (0.48 × 108 cfu/g, 7.9 × 106 cfu/g) and O1 (0.78 × 108 cfu/g, 9.45 × 106 cfu/g) respectively on 6rd day of storage, overall results indicated that the application of composite coating with different concentrations of oregano essential oils were effective to maintained postharvest shelf life of okra up to 4 days at ambient condition.

Carboxymethyl hydroxypropyl guar gum physicochemical properties in dilute aqueous media.

We investigate carboxymethyl hydroxypropyl guar gum (CMHPG) solution properties in water and NaCl, KCl, and CaCl2 aqueous solutions. The Huggins, Kraemer, and Rao models were applied by fitting specific and relative viscosity of CMHPG/water and CMHPG/salt/water to determine the intrinsic viscosity [η]. The Rao models yielded better results (R2 = 0.779-0.999) than Huggins and Kraemer equations. [η] decreased up to 84% in salt solution over the range 0.9-100 mM compared to water. Salt effects screened the CMHPG charged side groups chains leading to a compacted structure. In 0.9 mM NaCl(aq), the hydrodynamic coil radius (Rcoil) was 28% smaller and 45% smaller in 100 mM NaCl solution relative to water. Similar decreases were seen in KCl and CaCl2 solutions. KCl and CaCl2 were more effective than NaCl. CMHPG is salt-tolerant and shows comparatively less viscosity change than native guar gum, with modest reduced viscosity increases with CMHPG dilution at all salt concentrations. The electrostatic interactions were effective up to 100 mM salt. The activation energy of viscous flow for CMHPG solutions was computed and compared to measured xanthan gum and several literature values. These data show that the barrier to CMHPG flow is higher than for xanthan gum.

Tamarind seed polysaccharide-guar gum buccal films loaded with resveratrol-bovine serum albumin nanoparticles: Preparation, characterization, and mucoadhesiveness assessment.

Mucoadhesive films based on tamarind seed polysaccharide and guar gum (TSP-GG) were formulated for buccal delivery of resveratrol. Resveratrol-bovine serum albumin nanoparticles (Res-BSA) were prepared and dispersed in TSP-GG to improve its buccal mucoadhesiveness. The impregnation of Res-BSA induced the dense internal structures of TSP-GG and improved its strength and rigidity. Structural characterization showed that resveratrol existed in an amorphous state in the films containing Res-BSA, and hydrogen bonding was formed between Res-BSA and the film matrices. The films containing Res-BSA exhibited good uniformity in thickness, weight, and resveratrol content, and their surface pH was near neutral, ranging between 6.78 and 7.09. Increasing Res-BSA content reduced the water contact angle of TSP-GG (from 75.9° to 59.6°). The swelling and erosion studies indicated the favorable hydration capacity and erosion resistance of the films containing Res-BSA. Additionally, the addition of Res-BSA imparted enhanced ex vivo mucoadhesive force, in the range of 1.53 N to 1.98 N, and extended ex vivo residence time, between 17.9 h and 18.9 h, to TSP-GG. The current study implied that the composite systems of TSP-GG and Res-BSA may be a novel platform for buccal mucosal delivery of resveratrol.