Glycosides Research Articles

ISOLATION, PURIFICATION AND PHYTOCHEMICAL SCREENING OF POLYSACCHARIDE FRACTIONS FROM APIUM GRAVEOLENS’ L. BOTANICAL FORMS

The study of natural polysaccharides is an important area of research due to their pharmacological effects, including antiviral activity and the ability to regulate metabolic disorders. In addition, these polymeric structures realize several properties (sorption, shaping, transport (and delivery systems), which increases the interest of scientists in their isolation and analysis. This study aims to comparatively investigate the polysaccharide fractions in different botanical forms of celery odouriferous. The objectives of the study include the isolation of polysaccharide fractions, their purification by the Sevag method, estimation of monomeric composition of the fractions after acid hydrolysis by the HPTLC method, and determination of structural characteristics of the molecules by IR spectroscopy. Alcohol-soluble polysaccharides (ASPS), water-soluble polysaccharides (WSPS), and pectin substances (PS) were isolated from leaf, petiole, and root botanical forms of celery. After purification, the obtained substances were amorphous powders of light brown or light beige colour and odourless. The root botanical form of celery showed the highest yield of the target compounds (total (13.54±1.07)% after purification), while the petiole form (total (5.51±0.04)% after purification) showed the lowest yield. The monomeric composition of pectins and WSPS showed a predominance of galactose and arabinose, whereas the alcoholic ones showed a predominance of fructose and glucose. The interpretation of IR spectra showed the presence of absorption bands characteristic of free and bound carboxyl groups, C-O-C valence vibrations, α-configuration of the glycosidic bond, and C1-α-conformation of galacturonic acid in different polysaccharide fractions, which allows us to draw some conclusions regarding the structure of the substances. A comparative study of polysaccharide fractions of different botanical forms of odorous celery was carried out for the first time. Based on the results obtained, it is possible to single out WSPS and PS of celery root crops as the most promising phytosubstances for further development of products of functional, specialized nutrition and potential medicines on their basis. The methods of analysis used in the study can be proposed as part of the regulatory documentation for the control of these products.

A fast, reliable, low‐cost, and efficient xylan extraction for xylooligosaccharides production

AbstractA fast, reliable, low‐cost, and efficient method for the recovery of xylan from agro‐residue materials is needed to improve the use of xylan in industrial processes. Xylan was extracted from two agrowastes (corncobs and wheat bran) using a cost‐effective alkali extraction method. The characteristic band patterns and bending vibrations associated with hemicellulose and beta glycoside linkage could be seen in the corncob‐extracted xylan (CCEx) and wheatbran‐extracted xylan (WBEx). Scanning electron microscopy (SEM) analysis showed that the extracted xylans consisted of aggregated and nonaggregated particles with irregular morphology and rough surfaces. Particle‐size analysis displayed average sizes of 205.6, 210.8, and 794.2 nm for commercial beechwood xylan (Bx), CCEx, and WBEx, respectively. Alkali extraction was performed with different concentrations of NaOH, from 5% to 20%, with a solid–liquid ratio of 1:20. It was found that 82.90 and 76.77% of xylan were extracted from corncob and wheat bran, respectively, which represents a higher yield obtained in a shorter duration in comparison with studies in the literature. The enzymatic hydrolysis of wheat bran and corncob that used 250 IU/mL of Enterobacter hormaechie KS1 xylanase yielded 334.38 and 162.35 mg/g of xylooligosaccharides. Their properties were studied and were found to be very similar to those of commercial xylan. They could reduce costs if applied in industry.

Total Synthesis of the Conjugation-Ready Tetrasaccharide Repeating Unit of Shewanella japonica Type Strain KMM 3299T.

Here we report the first total synthesis of the conjugation-ready tetrasaccharide repeating unit of Shewanella japonica type strain KMM 3299T. The presence of rare deoxyamino sugars and installation of three consecutive 1,2-cis glycosidic linkages makes the synthesis formidable. The challenging late-stage oxidation was overcome by using a galacturonate donor. The total synthesis was completed via a longest linear sequence of 22 steps in an overall yield of 3.5% starting from d-mannose.

Selective impact of three homogenous polysaccharides with different structural characteristics from Grifola frondosa on human gut microbial composition and the structure-activity relationship

Natural polysaccharides interact with gut microbes to enhance human well-being. Grifola frondosa is a polysaccharides-rich edible and medicinal mushroom. The prebiotic potential of G. frondosa polysaccharides has been explored in recent years, however, the relationship between their various structural features and prebiotic activities is poorly understood. In this study, three homogenous polysaccharides GFP10, GFP21 and GFP22 having different molecular weights (Mw), monosaccharide compositions and glycosidic linkages were purified from G. frondosa, and their effects on intestinal microbial composition were compared. GFP10 was a fucomannogalactan with an Mw of 23.0 kDa, and it selectively inhibited Enterobacter, while GFP21 was a fucomannogalactoglucan with an Mw of 18.6 kDa, and it stimulated Catenibacterium. GFP22 was a 4.9 kDa mannoglucan that selectively inhibited Klebsiella and boosted Bifidobacterium, Catenibacterium and Phascolarctobacterium, and prominently promoted the production of short-chain fatty acids (SCFAs). The selective modulation of gut microbiota by polysaccharides was structure-dependent. A relatively lower Mw and a high proportion of glycosidic linkages like T-Glcp, 1,3-Glcp, 1,3,6-Glcp and 1,4-Glcp might be more easily utilized to produce SCFAs and beneficial for the proliferation of Catenibacterium and Phascolarctobacterium. This research provided a valuable resource for further exploring the structure-activity relationship and prebiotic activity of G. frondosa polysaccharides.

The isolation, structure characterizations and anti-photoaging activities of sulfated polysaccharides isolated from Sargassum fusiforme

BackgroundOur previous study found that crude polysaccharide extracted from Sargassum fusiforme (PSF) exhibited excellent anti-photoaging activity, but the composition responsible for this activity remained unknown.ResultsIn this study, three fractions (P1, P2 and P3) obtained by hot water extraction and column chromatographic separation from PSF were structurally characterized. The anti-photoaging activities of these isolated polysaccharides were evaluated using HaCaT cells. The results showed that P1, P2 and P3 were acidic polysaccharides with 42.94%, 40.75% and 2.21% uronic acid. In addition, the contents of sulfate groups were 3.01%, 10.05% and 7.44%, respectively. Moreover, their content of reducing sugar was low, and none of the fractions had a triple-stranded helical structure. P1 had the largest average molecular weight of 208.89 kDa, while P2 and P3 had a relatively lower molecular weight of 154.09 and 151.71 kDa, respectively. Treatment with P2 effectively safeguarded the viability of HaCaT cells exposed to UVB irradiation. Additionally, it inhibited the secretion of MMP-1 and MMP-3 while elevating the content of hydroxyproline (HYP) in the cell supernatant. Methylation and NMR analysis suggested the main structure of P2 might be → [4)-β-ManA-(1]23 → 4)-β-ManA-(1 → 3)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → . The two terminal groups of β-ManA-(1 → and β-d-Glcp-(1 → were connected via the glycosidic bonds of → 3, 4)-O-3 in β-ManA-(1 → and O-6 in → 4, 6)-β-d-Glcp-(1 → , respectively.ConclusionsThese findings will open new avenues for exploring the potential use of Sargassum fusiforme polysaccharide, particularly P2, as a functional ingredient with anti-photoaging activity.Graphical

Revisiting gas-chromatography/mass-spectrometry molar response factors for quantitative analysis (FID or TIC) of glycosidic linkages in polysaccharides produced by oral bacterial biofilms

Methylation analysis was performed on methylated alditol acetate standards and Streptococcus mutans extracellular polymeric substances (EPS) produced from wild-type and Gtf knockout strains (∆GtfB, ∆GtfB, and ∆GtfD). The methylated alditol acetate standards were representative of glycosidic linkages found in S. mutans EPS and were used to calibrate the GC–MS system for an FID detector and MS (TIC) and produce molar response factor, a necessary step in quantitative analysis. FID response factors were consistent with literature values (Sweet et al., 1975) and found to be the superior option for quantitative results, although the TIC response factors now give researchers without access to an FID detector a needed option for molar response factor correction. The GC–MS analysis is then used to deliver the ratio of the linkage types within a biofilm.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction of Ipomoea alba seeds

Resin glycosides act as laxatives in crude drugs derived from plants of the Convolvulaceae family. These compounds have exhibited antibacterial, ionophoric, anti-inflammatory, antiviral, and multidrug resistance-modulating properties, as well as cytotoxicity against cancer cells. This study investigated the organic acid, hydroxyl fatty acid, monosaccharide, and glycosidic acid components of the crude resin glycoside fraction obtained from the methanol extract of Ipomoea alba L. (Convolvulaceae) seeds, which was subjected to alkaline and acidic hydrolysis. The alkaline hydrolysis yielded acetic, isobutyric, (E)-2-methylbut-2-enoic, and 2S-methyl-3S-hydroxybutyric acids as organic acid components, along with a glycosidic acid fraction. The acidic hydrolysis of the glycosidic acid fraction resulted in the isolation of 11S-hydroxytetradecanoic and 11S-hydroxyhexadecanoic acids as hydroxyl fatty acid components, as well as d-glucose, d-quinovose, d-fucose, d-xylose, and l-rhamnose as monosaccharide components. In addition, 10 new glycosidic acid methyl esters were isolated from the glycosidic acid fraction treated with trimethylsilyldiazomethane–hexane, along with one known glycosidic acid methyl ester. Of these, eight compounds contained new glycans. Four of these compounds were unusual natural glycosides with four glycosidic linkages to one monosaccharide. Their structures were determined using MS and NMR spectral analyses, which provided valuable insights into the unique glycosidic composition of I. alba seeds.

Effect of Phenol and Alkylamide Interaction on α-Glucosidase Inhibition and Cellular Antioxidant Activity during In Vitro Digestion: Using Szechuan Pepper (Zanthoxylum genus) as a Model.

Although recent evidence indicated significant phenol and alkylamide interaction in aqueous solutions, the gastrointestinal digestion influence of the combination remains unclear. This study aims to investigate phenol and alkylamide interaction during in vitro digestion, focusing on bioaccessibility and bioactivity, including α-glucosidase inhibition and cellular antioxidant activity. Additionally, the structural mechanism of phenol and alkylamide interaction during in vitro digestion was explored. The results indicated that the presence of phenols and alkylamides significantly increased or decreased their respective bioaccessibility, depending on the Zanthoxylum varieties. Furthermore, although antagonistic phenol/alkylamide interaction was evident during α-glucosidase inhibition, cellular oxidative stress alleviation, and antioxidant gene transcription upregulation, this effect weakened gradually as digestion progressed. Glycoside bond cleavage and the methylation of phenols as well as alkylamide isomerization and addition were observed during digestion, modifying the hydrogen bonding sites and interaction behavior. This study provided insights into the phenol/alkylamide interaction in the gastrointestinal tract.

Theoretical Insights into N-Glycoside Bond Cleavage of 5-Carboxycytosine by Thymine DNA Glycosylase: A QM/MM Study.

Thymine DNA glycosylase (TDG)-mediated excision of 5-formylcytosine and 5-carboxylcytosine (5-caC) is a critical step in active DNA demethylation. Herein, we employed a combined quantum mechanics/molecular mechanics approach to investigate the reaction mechanism of TDG-catalyzed N-glycosidic bond cleavage of 5-caC. The calculated results show that TDG-catalyzed 5-caC excision follows a concerted (SN2) mechanism in which glycosidic bond dissociation is coupled with nucleophile attack. Protonation of the 5-caC anion contributes to the cleavage of the N-glycoside bond, in which the N3-protonated zwitterion and imino tautomers are more favorable than carboxyl-protonated amino tautomers. This is consistent with the experimental data. Furthermore, our results reveal that the configuration rearrangement process of the protonated 5-caC would lower the stability of the N-glycoside bond and substantially reduce the barrier height for the subsequent C1'-N1 bond cleavage. This should be attributed to the smaller electrostatic repulsion between the leaving base and the negative phosphate group as a result of the structural rearrangement.

Exploring the prebiotic characteristics of crude polysaccharides from coconut testa flour: A comparative analysis of local cultivar

Crude polysaccharides (CPs) of coconut testa flour (CTF) of five local cultivars; Commercial hybrid (COM), Gon Thembili (GT), Ran Thembili (RT), San Ramon (SR), and Tall×Tall (TT) were isolated in this study to examine to evaluate potential prebiotic properties and structural characteristics. The isolated CPs were subjected to FTIR analysis to identify functional groups of biomolecules. Digestibility tests were performed on CPs of different coconut cultivars using artificial human gastric juice. CPs were applied to Lactobacillus sp. and Escherichia coli to evaluate their proliferation in vitro. FTIR results showed that the occurrence of peaks between 1200cm-1 - 1000cm-1 was indicative of the presence of C-O side groups and C-O-C glycosidic bonds. CPs of all cultivars displayed strong resistance to hydrolysis (94-97 %) by human gastric juice when compared to inulin and fructooligosaccharides (FOS). The higher proliferation of Lactobacillus sp. was detected on all five CPs when compared to that of glucose. The SR cultivar (1.09) showed a higher prebiotic activity score compared to fructooligosaccharides (0.92) and inulin (0.81). These findings suggest that CPs isolated from CTF of local coconut cultivars possess potential prebiotic characteristics that can be used in the preparation of functional foods. Further studies on this aspect are granted to enable the effective use of CTF in promoting human gut health.

A novel GH3-β-glucosidase from soda lake metagenomic libraries with desirable properties for biomass degradation.

Beta-glucosidases catalyze the hydrolysis of the glycosidic bonds of cellobiose, producing glucose, which is a rate-limiting step in cellulose biomass degradation. In industrial processes, β-glucosidases that are tolerant to glucose and stable under harsh industrial reaction conditions are required for efficient cellulose hydrolysis. In this study, we report the molecular cloning, Escherichia coli expression, and functional characterization of a β-glucosidase from the gene, CelGH3_f17, identified from metagenomics libraries of an Ethiopian soda lake. The CelGH3_f17 gene sequence contains a glycoside hydrolase family 3 catalytic domain (GH3). The heterologous expressed and purified enzyme exhibited optimal activity at 50°C and pH 8.5. In addition, supplementation of 1M salt and 300mM glucose enhanced the β-glucosidase activity. Most of the metal ions and organic solvents tested did not affect the β-glucosidase activity. However, Cu2+ and Mn2+ ions, Mercaptoethanol and Triton X-100 reduce the activity of the enzyme. The studied β-glucosidase enzyme has multiple industrially desirable properties including thermostability, andalkaline, salt, and glucose tolerance.

Hydrolytic purification of industrially extracted mimosa tannin

Tannins, which can be extracted from certain tree barks, are polyphenolic compounds, that gain a lot of interest in industry, as they can be utilized to replace petroleum-based chemicals. Currently, they are used in the leather industry, as flocculants or as adhesives. To further increase their potential, an increase in purity is necessary. To do so, various methods are available, in this study we present a 2-step approach consisting of (i) depolymerization and cleavage of glycosidic bonds and (ii) separation of phenolic-rich and phenolic-poor fractions. Commercially available mimosa tannin is treated with various concentrations of hydrochloric and sulfuric acid (0.4 M and 0.8 M) and separated with chromatographic resin. Resulting fractions are characterized by UV/Vis spectroscopy for phenolic content and antioxidant activity, infrared spectroscopy, NMR, HPLC-DAD and GPC to determine their composition and molecular size as well as their reactivity towards formaldehyde. It was observed that mild acidic cleavage with 0.4 M HCl results in more phenol-rich material (TPC 1124 µgGAE mg−1) while 0.8 M sulfuric acid leads to tannin fractions with higher antioxidative properties. Amberlite resin yields fractions with higher reactivity towards formaldehyde (gel time below 60 s compared to over 90 originally) while the Sephadex fractions present the highest values for total phenolic content.

Dynamic changes in the aggregation-depolymerization behavior of Ovomucin-Complex and its binding to urease during in vitro simulated gastric digestion

Ovomucin-Complex extracted from egg white is expected to have a barrier function similar to gastric mucin. In this study, the dynamic changes in structure, rheological properties and binding ability of Ovomucin-Complex during in vitro simulated gastric digestion were investigated. The results from HPLC and CLSM showed that extremely acidic pH (pH = 2.0) promoted Ovomucin-Complex to form aggregation. Acid-induced aggregation may hinder its binding to pepsin, thus rendering Ovomucin-Complex resistant to pepsin. Consequently, most of the polymer structure and weak gel properties of Ovomucin-Complex retained after simulated gastric digestion as verified by HPLC, CLSM and rheological measurement, although there was a small breakdown of the glycosidic bond as confirmed by the increased content of reducing sugar. The significantly reduced hydrophobic interactions of Ovomucin-Complex were observed under extremely acidic conditions and simulated gastric digestion compared with the native. Noticeably, the undigested Ovomucin-Complex after simulated gastric digestion showed a higher affinity (KD = 5.0 ± 3.2 nm) for urease - the key surface antigen of Helicobacter pylori. The interaction mechanism between Ovomucin-Complex and urease during gastric digestion deserves further studies. This finding provides a new insight to develop an artificial physical mucus barrier to reduce Helicobacter pylori infection.

Enhancing Xylanase Production from Aspergillus tamarii Kita and Its Application in the Bioconversion of Agro-Industrial Residues into Fermentable Sugars Using Factorial Design

The endo-1,4-β-xylanases (EC 3.2.1.8) are the largest group of hydrolytic enzymes that degrade xylan, the major component of hemicelluloses, by catalyzing the hydrolysis of glycosidic bonds β-1,4 in this polymer, releasing xylooligosaccharides of different sizes. Xylanases have considerable potential in producing bread, animal feed, food, beverages, xylitol, and bioethanol. The fungus Aspergillus tamarii Kita produced xylanases in Adams’ media supplemented with barley bagasse (brewer’s spent grains), a by-product from brewery industries. The culture extract exhibited two xylanase activities in the zymogram, identified by mass spectrometry as glycosyl hydrolase (GH) families 10 and 11 (GH 10 and GH 11). The central composite design (CCD) showed excellent predictive capacity for xylanase production (23.083 U mL−1). Additionally, other enzyme activities took place during the submerged fermentation. Moreover, enzymatic saccharification based on a mixture design (MD) of three different lignocellulosic residues was helpful in the production of fermentable sugars by the A. tamarii Kita crude extract.

Direct and Stereoselective Protecting‐Group‐Free N‐ADP‐Ribosylation through Traceless Staudinger Ligation

AbstractAdenine diphosphate (ADP)‐ribosylation catalyzed by bacterial toxins is the addition of an ADP‐ribose moiety to specific amino acid residues in target proteins such as arginine, asparagine, glutamine, and histidine through 1,2‐cis(α)‐glycosidic bond formation. ADP‐ribosylation modifies host cell functions, altering normal cellular processes to facilitate their survival, and replication. Despite the development of click chemistry and solid‐phase peptide synthesis‐based approaches, the synthesis of structurally well‐defined naturally occurring N‐linked ADP‐ribosyl molecules remains challenging. Herein, we report a direct and α‐selective N‐ADP‐ribosylation using unprotected β‐ADP‐ribosyl azide and triphenylphosphine esters through traceless Staudinger ligation. The stereoselectivity of this protecting‐group‐free N‐ADP‐ribosylation was validated by enzymatic degradation experiment and high‐performance liquid chromatography, referencing synthetic standards. This method facilitated the facile and rapid synthesis of N‐ADP‐ribosyl acetamide, biotin, fluorescent dye, amino acids, and tripeptide with complete α‐selectivity and moderate yields (37–55 %).

Study on the mechanism of lignin and lignin-carbohydrate complex hydrolysis under alkaline conditions by density functional theory

Lignin hydrolyzes during alkali-heat pretreatment of lignocellulose, due to the cleavage of covalent linkages between lignin and lignin-carbohydrate complex. Various structure of lignin monomers are responsible of the complicated hydrolysis mechanism of lignin and lignin-carbohydrate complex. This study used density functional theory to reveal the hydrolysis mechanism of lignin with various substituents and lignin-carbohydrates complex with different linkages. The results indicated that the SN2 reaction was observed to take place in the lignin. Methoxy groups and methyl group had an insignificant influence on hydrolysis reaction pathway of lignin, whereas the presence of a methyl group on the α-carbon atom had a hindering effect on the nucleophilic attack during alkaline pretreatment. The lignin-carbohydrate complex with different linkage showed a significant difference in hydrolysis reaction pathway. Additionally, the reaction energy barrier of ester bond hydrolysis was lowest among the hydrolysis of ester bond, phenyl glycosidic bond, benzyl ether bond, γ-ester bond, coumarin ester bond and acetal bond under alkaline condition. This study provides valuable insights into the process control, reactor design, and performance enhancement for lignocellulose pretreatment.

Structural and Dynamic Features of the Recognition of 8-oxoguanosine Paired with an 8-oxoG-clamp by Human 8-oxoguanine-DNA Glycosylase

8-oxoguanine (oxoG) is formed in DNA by the action of reactive oxygen species. As a highly mutagenic and the most common oxidative DNA lesion, it is an important marker of oxidative stress. Human 8-oxoguanine-DNA glycosylase (OGG1) is responsible for its prompt removal in human cells. OGG1 is a bifunctional DNA glycosylase with N-glycosylase and AP lyase activities. Aspects of the detailed mechanism underlying the recognition of 8-oxoguanine among numerous intact bases and its subsequent interaction with the enzyme’s active site amino acid residues are still debated. The main objective of our work was to determine the effect (structural and thermodynamic) of introducing an oxoG-clamp in model DNA substrates on the process of 8-oxoG excision by OGG1. Towards that end, we used DNA duplexes modeling OGG1-specific lesions: 8-oxoguanine or an apurinic/apyrimidinic site with either cytidine or the oxoG-clamp in the complementary strand opposite to the lesion. It was revealed that there was neither hydrolysis of the N-glycosidic bond at oxoG nor cleavage of the sugar–phosphate backbone during the reaction between OGG1 and oxoG-clamp-containing duplexes. Possible structural reasons for the absence of OGG1 enzymatic activity were studied via the stopped-flow kinetic approach and molecular dynamics simulations. The base opposite the damage was found to have a critical effect on the formation of the enzyme–substrate complex and the initiation of DNA cleavage. The oxoG-clamp residue prevented the eversion of the oxoG base into the OGG1 active site pocket and impeded the correct convergence of the apurinic/apyrimidinic site of DNA and the attacking nucleophilic group of the enzyme. An obtained three-dimensional model of the OGG1 complex with DNA containing the oxoG-clamp, together with kinetic data, allowed us to clarify the role of the contact of amino acid residues with DNA in the formation of (and rearrangements in) the enzyme–substrate complex.

Methionine inducing carbohydrate esterase secretion of Trichoderma harzianum enhances the accessibility of substrate glycosidic bonds

BackgroundThe conversion of plant biomass into biochemicals is a promising way to alleviate energy shortage, which depends on efficient microbial saccharification and cellular metabolism. Trichoderma spp. have plentiful CAZymes systems that can utilize all-components of lignocellulose. Acetylation of polysaccharides causes nanostructure densification and hydrophobicity enhancement, which is an obstacle for glycoside hydrolases to hydrolyze glycosidic bonds. The improvement of deacetylation ability can effectively release the potential for polysaccharide degradation.ResultsAmmonium sulfate addition facilitated the deacetylation of xylan by inducing the up-regulation of multiple carbohydrate esterases (CE3/CE4/CE15/CE16) of Trichoderma harzianum. Mainly, the pathway of ammonium-sulfate's cellular assimilates inducing up-regulation of the deacetylase gene (Thce3) was revealed. The intracellular metabolite changes were revealed through metabonomic analysis. Whole genome bisulfite sequencing identified a novel differentially methylated region (DMR) that existed in the ThgsfR2 promoter, and the DMR was closely related to lignocellulolytic response. ThGsfR2 was identified as a negative regulatory factor of Thce3, and methylation in ThgsfR2 promoter released the expression of Thce3. The up-regulation of CEs facilitated the substrate deacetylation.ConclusionAmmonium sulfate increased the polysaccharide deacetylation capacity by inducing the up-regulation of multiple carbohydrate esterases of T. harzianum, which removed the spatial barrier of the glycosidic bond and improved hydrophilicity, and ultimately increased the accessibility of glycosidic bond to glycoside hydrolases.

Biomass to green surfactants: Microwave-assisted transglycosylation of wheat bran for alkyl glycosides production

Depolymerization of carbohydrate biomass using a long-chain alcohol (transglycosylation) to produce alkyl glycoside-based bio-surfactants has been gaining industrial interest. This study introduces microwave-assisted transglycosylation in transforming wheat bran, a substantial agricultural side stream, into these valuable compounds. Compared to traditional heating, microwave-assisted processing significantly enhances the product yield by 53 % while reducing the reaction time by 72 %, achieving a yield of 29 % within 5 h. This enhancement results from the microwave's capacity to activate intermolecular hydrogen and glycosidic bonds, thereby facilitating transglycosylation. Life-cycle assessment and techno-economic analysis demonstrate the benefits of microwave heating in reducing energy consumption by 42 %, CO2 emissions by 56 %, and equipment, operational and production costs by 44 %, 35 % and 30 %, respectively. The study suggests that microwave heating is a promising approach for efficiently producing bio-surfactants from agricultural wastes, with potential cost reductions and environmental benefits that could enhance industrial biomass conversion processes.

Effects of the Charge Density of Nanopapers Based on Carboxymethylated Cellulose Nanofibrils Investigated by Complementary Techniques.

Cellulose nanofibrils (CNFs) with different charge densities were prepared and investigated by a combination of different complementary techniques sensitive to the structure and molecular dynamics of the system. The morphology of the materials was investigated by scanning electron microscopy (SEM) and X-ray scattering (SAXS/WAXS). The latter measurements were quantitatively analyzed yielding to molecular parameters in dependence of the charge density like the diameter of the fibrils, the distance between the fibrils, and the dimension of bundles of nanofibrils, including pores. The influence of water on the properties and the charge density is studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy. The TGA measurements reveal two mass loss processes. The one at lower temperatures was related to the loss of water, and the second process at higher temperatures was related to the chemical decomposition. The resulting char yield could be correlated to the distance between the microfibrils. The DSC investigation for hydrated CNFs revealed three glass transitions due to the cellulose segments surrounded by water molecules in different states. In the second heating scan, only one broad glass transition is observed. The dielectric spectra reveal two relaxation processes. At low temperatures or higher frequencies, the β-relaxation is observed, which is assigned to localized fluctuation of the glycosidic linkage. At higher temperatures and lower frequencies, the α-relaxation takes places. This relaxation is due to cooperative fluctuations in the cellulose segments. Both processes were quantitatively analyzed. The obtained parameters such as the relaxation rates were related to both the morphological data, the charge density, and the content of water for the first time.