Hot-water extracts from the inner bark of Norway spruce with immunomodulating activities

Enhanced biobased carbon materials made from softwood bark via a steam explosion preprocessing step for reactive orange 16 dye adsorption

The growing textile industry produces large volumes of hazardous wastewater containing dyes, which stresses the need for cheap, efficient adsorbing technologies. This study investigates a novel preprocessing method for producing activated carbons from abundantly available softwood bark. The preprocessing involved a continuous steam explosion preconditioning step, chemical activation with ZnCl2, pyrolysis at 600 and 800 °C, and washing. The activated carbons were subsequently characterized by SEM, XPS, Raman and FTIR prior to evaluation for their effectiveness in adsorbing reactive orange 16 and two synthetic dyehouse effluents. Results showed that the steam-exploded carbon, pyrolyzed at 600 °C, obtained the highest BET specific surface area (1308 m2/g), the best Langmuir maximum adsorption of reactive orange 16 (218 mg g-1) and synthetic dyehouse effluents (>70 % removal) of the tested carbons. Finally, steam explosion preconditioning could open up new and potentially more sustainable process routes for producing functionalized active carbons.

Subcritical water extraction of Equisetum arvense biomass withdraws cell wall fractions that trigger plant immune responses and disease resistance

Plant cell walls are complex structures mainly made up of carbohydrate and phenolic polymers. In addition to their structural roles, cell walls function as external barriers against pathogens and are also reservoirs of glycan structures that can be perceived by plant receptors, activating Pattern-Triggered Immunity (PTI). Since these PTI-active glycans are usually released upon plant cell wall degradation, they are classified as Damage Associated Molecular Patterns (DAMPs). Identification of DAMPs imply their extraction from plant cell walls by using multistep methodologies and hazardous chemicals. Subcritical water extraction (SWE) has been shown to be an environmentally sustainable alternative and a simplified methodology for the generation of glycan-enriched fractions from different cell wall sources, since it only involves the use of water. Starting from Equisetum arvense cell walls, we have explored two different SWE sequential extractions (isothermal at 160 ºC and using a ramp of temperature from 100 to 160 ºC) to obtain glycans-enriched fractions, and we have compared them with those generated with a standard chemical-based wall extraction. We obtained SWE fractions enriched in pectins that triggered PTI hallmarks in Arabidopsis thaliana such as calcium influxes, reactive oxygen species production, phosphorylation of mitogen activated protein kinases and overexpression of immune-related genes. Notably, application of selected SWE fractions to pepper plants enhanced their disease resistance against the fungal pathogen Sclerotinia sclerotiorum. These data support the potential of SWE technology in extracting PTI-active fractions from plant cell wall biomass containing DAMPs and the use of SWE fractions in sustainable crop production.

Water-soluble polysaccharides from Piper regnellii (Pariparoba) leaves: Structural characterization and antinociceptive and anti-inflammatory activities

Piper regnellii is a plant popularly known as "Pariparoba" and it is widely used in folk medicine to treat pain, inflammation, among others. This work presents the extraction, purification and characterization of polysaccharides present in the plant leaves and evaluation of their anti-inflammatory and antinociceptive activities. From the crude aqueous extract of P. regnellii leaves, a polysaccharide fraction named PR30R, predominantly constituted of arabinose, galactose and galacturonic acid monosaccharide units, was obtained. Methylation and NMR analysis showed that the main polysaccharides of PR30R are a type II arabinogalactan, formed by a β-D-Galp-(1 → 3) main chain, substituted at O-6 by side chains of β-D-Galp-(1 → 6), which are substituted at O-3 by non-reducing α-L-Araf ends, and a homogalacturonan, formed by →4)-α-D-GalpA-(1→ units. Intraperitoneal administration of the crude polysaccharide fraction PRSF reduced significantly nociception induced by acetic acid in mice at the doses tested, and the PR30R fraction, derived from PRSF, presented antinociceptive and anti-inflammatory effects at a dose of 0.1096 mg/kg (PRSF ED50). These data support the use of the plant leaves in folk medicine as an herbal tea to treat pain and inflammation.

Polysaccharides of Salsola passerina: Extraction, Structural Characterization and Antioxidant Activity

The above-ground part of the Salsola passerine was found to contain ~13% (w/w) of polysaccharides extractable with water and aqueous solutions of ammonium oxalate and sodium carbonate. The fractions extracted with aqueous sodium carbonate solutions had the highest yield. The polysaccharides of majority fractions are characterized by similar monosaccharide composition; namely, galacturonic acid and arabinose residues are the principal components of their carbohydrate chains. The present study focused on the determination of antioxidant activity of the extracted polysaccharide fractions and elucidation of the structure of polysaccharides using nuclear magnetic resonance (NMR) spectroscopy. Homogalacturonan (HG), consisting of 1,4-linked residues of α-D-galactopyranosyluronic acid (GalpA), rhamnogalacturonan-I (RG-I), which contains a diglycosyl repeating unit with a strictly alternating sequence of 1,4-linked D-GalpA and 1,2-linked L-rhamnopyranose (Rhap) residues in the backbone, and arabinan, were identified as the structural units of the obtained polysaccharides. HMBC spectra showed that arabinan consisted of alternating regions formed by 3,5-substituted and 1,5-linked arabinofuranose residues, but there was no alternation of these residues in the arabinan structure. Polysaccharide fractions scavenged the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical at 0.2-1.8 mg/mL. The correlation analysis showed that the DPPH scavenging activity of polysaccharide fractions was associated with the content of phenolic compounds (PCs).

Fundamental Insights on the Physical and Chemical Properties of Organosolv Lignin from Norway Spruce Bark

The interest in the bark and the attempt to add value to its utilization have increased over the last decade. By applying an integrated bark biorefinery approach, it is possible to investigate the recovery of compounds that can be used to develop green and sustainable alternatives to fossil-based materials. In this work, the focus is on extracting Norway spruce (Picea abies) bark lignin via organosolv extraction. Following the removal of the extractives and the subcritical water extraction to remove the polysaccharides, a novel cyclic organosolv extraction procedure was applied, which enabled the recovery of lignin with high quality and preserved structure. Main indicators for low degradation and preservation of the lignin structure were a high β-O-4' content and low amounts of condensed structures. Furthermore, high purity and low polydispersity of the lignin were observed. Thus, the obtained lignin exhibits high potential for use in the direct development of polymer precursors and other bio-based materials. During the extraction sequence, around 70% of the bark was extracted. Besides the lignin, the extractives as well as pectic polysaccharides and hemicelluloses were recovered with only minor degradation, which could potentially be used for the production of biofuel or other high-value products such as emulsifiers or adhesives.

Molecular Characteristics and Antioxidant Activity of Spruce (Picea abies) Hemicelluloses Isolated by Catalytic Oxidative Delignification

Spruce (Piceaabies) wood hemicelluloses have been obtained by the noncatalytic and catalytic oxidative delignification in the acetic acid-water-hydrogen peroxide medium in a processing time of 3–4 h and temperatures of 90–100 °C. In the catalytic process, the H₂SO₄, MnSO₄, TiO₂, and (NH₄)₆Mo₇O₂₄ catalysts have been used. A polysaccharide yield of up to 11.7 wt% has been found. The hemicellulose composition and structure have been studied by a complex of physicochemical methods, including gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The galactose:mannose:glucose:arabinose:xylose monomeric units in a ratio of 5:3:2:1:1 have been identified in the hemicelluloses by gas chromatography. Using gel permeation chromatography, the weight average molar mass M_w of hemicelluloses has been found to attain 47,654 g/mol in noncatalytic delignification and up to 42,793 g/mol in catalytic delignification. Based on the same technique, a method for determining the α and k parameters of the Mark–Kuhn–Houwink equation for hemicelluloses has been developed; it has been established that these parameters change between 0.33–1.01 and 1.57–472.17, respectively, depending on the catalyst concentration and process temperature and time. Moreover, the FTIR spectra of the hemicellulose samples contain all the bands characteristic of heteropolysaccharides, specifically, 1069 cm⁻¹ (C–O–C and C–O–H), 1738 cm⁻¹ (ester C=O), 1375 cm⁻¹ (–C–CH₃), 1243 cm⁻¹ (–C–O–), etc. It has been determined by the thermogravimetric analysis that the hemicelluloses isolated from spruce wood are resistant to heating to temperatures of up to ~100 °C and, upon further heating, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses has been examined using the compounds simulating the 2,2-diphenyl-2-picrylhydrazyl free radicals.

Holistic review of polysaccharides isolated from pumpkin: Preparation methods, structures and bioactivities

Pumpkin polysaccharides have arrested researchers' attention in fields of food supplements for healthy product and traditional Chinese medicine due to their multiple bioactivities with non-toxic and highly biocompatible. This review emphatically summarized recent progresses in the primary and spatial structural features, various bioactivities, structure-to-function associations, different preparation techniques, and absorption characteristics across intestinal epithelial and in vivo bio-distribution of pumpkin polysaccharides. Additionally, current challenges and future trends in development of pumpkin polysaccharides were pointed out. We found that pumpkin polysaccharides were primary structure (e.g. glucan, galactoglucan, galactomannan, galactan, homogalacturonan (HG), and rhamnogalacturonan-Ι (RG-Ι)) and special structure diverse (e.g. hollow helix, linear, and sphere-like) and significant functional foods or therapeutic agents (e.g. oral hypoglycemic agents). Moreover, we found that the molecular weight (Mw), uronic acid, linkage types, and modifications all could affect their bioactivities (e.g. anti-oxidant, anti-coagulant, and anti-diabetic activities), and pumpkin polysaccharides may across intestinal epithelial into the blood reaching to target organs. Collectively, the structures diversity and pharmacological values of pumpkin polysaccharides support their therapeutic potentials and sanitarian functions.

Macromolecular Model of the Pectic Polysaccharides Isolated from the Bark of Norway Spruce (Picea abies)

The bark of Norway spruce (Picea abies) contains up to 13% pectins that can be extracted by pressurized hot water, which constitute a valuable renewable resource in second-generation lignocellulosic biorefineries. This article proposes, for the first time, structural molecular models for the pectins present in spruce bark. Pectin fractions of tailored molar masses were obtained by fractionation of the pressurized hot water extract of the inner bark using preparative size-exclusion chromatography. The monosaccharide composition, average molar mass distribution, and the glycosidic linkage patterns were analyzed for each fraction. The pectin fraction with high molecular weight (M_w of 59,000 Da) contained a highly branched RG-I domain, which accounted for 80% of the fraction and was mainly substituted with arabinan and arabinogalactan (type I and II) side chains. On the other hand, the fractions with lower molar masses (M_w = 15,000 and 9000 Da) were enriched with linear homogalacturonan domains, and also branched arabinan populations. The integration of the analytical information from the macromolecular size distributions, domain composition, and branch lengths of each pectin fraction, results in a comprehensive understanding of the macromolecular architecture of the pectins extracted from the bark of Norway spruce. This paves the way for the valorization of spruce bark pectic polymers in targeted applications based on their distinct polymeric structures and properties.

Polysaccharide fractions from Handroanthus heptaphyllus and Handroanthus albus barks: Structural characterization and cytotoxic activity

Barks of trees of the genus Handroanthus are known for their antitumor activity, which is attributed to naphthoquinones. Another class of molecules that has shown antitumor activity are the polysaccharides, however those from Handroanthus barks have never been studied. Accordingly, the aim of this study was to extract polysaccharides from H. heptaphyllus and H. albus barks, to characterize them structurally and to evaluate their cytotoxic effects on the human colon and human breast cancer cell lines, Caco-2 and MCF-7, respectively. The polysaccharides were extracted with boiling water and fractionated by freeze-thawing process. The soluble polysaccharide fractions HHBSF and HABSF were characterized by monosaccharide composition, methylation and NMR analyses, and their effects on proliferation of Caco-2 and MCF-7 cells were evaluated using MTT cell viability assay. HHBSF and HABSF were mainly constituted of galactoglucomannan, type II arabinogalactan (AGII) and type I rhamnogalacturonan (RGI), however, only HABSF significantly inhibited the growth of MCF-7 (CC50 = 327 μg/mL) and Caco-2 (CC50 = 2258 μg/mL) cells. Differences in the fine structure and proportion of their polysaccharides, and maybe in the composition of associated phenolic compounds could explain the different effects of HHBSF and HABSF.

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 (PA_W), HCl solution (PA_A) and (NH₄)₂C₂O₄ solution (PA_O). The P. abies foliage was found to contain basically low-methoxyl pectin extractable with an (NH₄)₂C₂O₄ solution. PA_W was shown to comprise primarily arabinogalactan-proteins (AGPs); PA_A was composed of mixed AGPs and pectic polysaccharides, with the latter prevailing; and polysaccharide PA_O isolated in the highest yield included chiefly pectic polysaccharides. The major constituents of PA_O 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 PA_O contained AGPs, xylanes and glucomannans, indicating that these polysaccharides are in an intimate interaction.

Determination of chemical structure of pea pectin by using pectinolytic enzymes

The chemical structure of pea pectin was delineated using pectin-degrading enzymes and biochemical methods. The molecular weight of the pea pectin preparation was 488,000, with 50 % arabinose content, and neutral sugar side chains attached to approximately 60 % of the rhamnose residues in rhamnogalacturonan-I (RG-I). Arabinan, an RG-I side chain, was highly branched, and the main chain was comprised of α-1,5-l-arabinan. Galactose and galactooligosaccharides were attached to approximately 35 % of the rhamnose residues in RG-I. Long chain β-1,4-galactan was also present. The xylose substitution rate in xylogalacturonan (XGA) was 63 %. The molar ratio of RG-I/homogalacturonan (HG)/XGA in the backbone of the pea pectin was approximately 3:3:4. When considering neutral sugar side chain content (arabinose, galactose, and xylose), the molar ratio of RG-I/HG/XGA regions in the pea pectin was 7:1:2. These data will help understand the properties of pea pectin.

Rethinking the impact of RG-I mainly from fruits and vegetables on dietary health

Rhamnogalacturonan I (RG-I) pectin is composed of backbone of repeating disaccharide units →2)-α-L-Rhap-(1→4)-α-D-GalpA-(1→ and neutral sugar side-chains mainly consisting of arabinose and galactose having variable types of linkages. However, since traditional pectin extraction methods damages the RG-I structure, the characteristics and health effects of RG-I remains unclear. Recently, many studies have focused on RG-I, which is often more active than the homogalacturonan (HG) portion of pectic polysaccharides. In food products, RG-I is common to fruits and vegetables and possesses many health benefits. This timely and comprehensive review describes the many different facets of RG-I, including its dietary sources, history, metabolism and potential functionalities, all of which have been compiled to establish a platform for taking full advantage of the functional value of RG-I pectin.

A Polysaccharide Isolated from Codonopsis pilosula with Immunomodulation Effects Both In Vitro and In Vivo

In this study, an acidic polysaccharide from Codonopsis pilosula Nannf. var. modesta (Nannf.) L. T. Shen (WCP-I) and its main fragment, WCP-Ia, obtained after pectinase digestion, were structurally elucidated and found to consist of a rhamnogalacturonan I (RG-I) region containing both arabinogalactan type I (AG-I) and type II (AG-II) as sidechains. They both expressed immunomodulating activity against Peyer’s patch cells. Endo-1,4-β-galactanase degradation gave a decrease of interleukine 6 (IL-6) production compared with native WCP-I and WCP-Ia, but exo-α-l-arabinofuranosidase digestion showed no changes in activity. This demonstrated that the stimulation activity partly disappeared with removal of β-d-(1→4)-galactan chains, proving that the AG-I side chain plays an important role in immunoregulation activity. WCP-Ia had a better promotion effect than WCP-I in vivo, shown through an increased spleen index, higher concentrations of IL-6, transforming growth factor-β (TGF-β), and tumor necrosis factor-α (TNF-α) in serum, and a slight increment in the secretory immunoglobulin A (sIgA) and CD4⁺/CD8⁺ T lymphocyte ratio. These results suggest that β-d-(1→4)-galactan-containing chains in WCP-I play an essential role in the expression of immunomodulating activity. Combining all the results in this and previous studies, the intestinal immune system might be the target site of WCP-Ia.

Sources, Extraction and Biomedical Properties of Polysaccharides

In the recent era, bioactive compounds from plants have received great attention because of their vital health-related activities, such as antimicrobial activity, antioxidant activity, anticoagulant activity, anti-diabetic activity, UV protection, antiviral activity, hypoglycemia, etc. Previous studies have already shown that polysaccharides found in plants are not likely to be toxic. Based on these inspirational comments, most research focused on the isolation, identification, and bioactivities of polysaccharides. A large number of biologically active polysaccharides have been isolated with varying structural and biological activities. In this review, a comprehensive summary is provided of the recent developments in the physical and chemical properties as well as biological activities of polysaccharides from a number of important natural sources, such as wheat bran, orange peel, barely, fungi, algae, lichen, etc. This review also focused on biomedical applications of polysaccharides. The contents presented in this review will be useful as a reference for future research as well as for the extraction and application of these bioactive polysaccharides as a therapeutic agent.

An integrated characterization of Picea abies industrial bark regarding chemical composition, thermal properties and polar extracts activity

The present work determines the chemical and thermal characteristics as well as the phytochemical and antioxidant potential of the polar extractives of the Picea abies bark from an industrial mill, their wood and bark components and also different bark fractions obtained by mechanical fractionation (fine B1, Φ<0.180 mm, medium B3, 0.450 < Φ<0.850 mm and coarse B6, 2 < Φ<10 mm). The aim is to increase the knowledge on the Picea abies bark to better determine possible uses other than burning for energy production and to test an initial size reduction process to achieve fractions with different characteristics. Compared to wood, bark presented similar lignin (27%), higher mineral (3.9% vs 0.4%) and extractives (20.3% vs 3.8%) and lower polysaccharides (48% vs 71%) contents. Regarding bark fractions the fines showed higher ash (6.3%), extractives (25%) and lignin (29%) than the coarse fraction (3.9%, 19% and 25% respectively). Polysaccharide contents increased with particle size of the bark fractions (38% vs 52% for B1 and B6) but showed the same relative composition. The phytochemical profile of ethanol and water extracts presented higher contents for bark than wood of total phenols (2x higher), flavonoids (3x higher) and tannins (4-10x higher) with an increasing tendency with particle size. Bark antioxidant activity was higher than that of wood for ferric-reducing antioxidant power (FRAP, 10 vs 6 mmolFe2+/gExt for the ethanol extract) and free radical scavenging activity (DPPH, 6 vs 18 mg/L IC50 for the ethanol extract) methods. The different bark fractions antioxidant activity was very similar. Bark thermal properties showed a much lower volatiles to fixed carbon ratio (V/FC) than wood (3.1 vs 5.2) although the same higher heating value (20.3 MJ/kg). The fractions were quite similar. Bark presented chemical features that point to their possible upgrade, whether by taking advantage of the high extractives with bioactive compounds or the production potential for hemicellulose-derived oligomers with possible use in nutraceutical and pharmaceutical industries.

Nutrients, Antioxidant Capacity and Safety of Hot Water Extract from Sugar Maple (Acer saccharum M.) and Red Maple (Acer rubrum L.) Bark

Sugar maple (Acer saccharum M.) and red maple (Acer rubrum L.) barks were treated with hot water to extract nutrients in order to explore, for the first time, its potential as safe dietary antioxidants. The organic and inorganic nutrients of these extracts, as well as their safety on human PLB-985 cells differentiated into neutrophils-like cells, were determined. Proximate analysis showed that both bark extracts were low in moisture and fat. Sugar maple bark extract (SM-BX) showed crude protein and ash content higher than those found in red maple bark extract (RM-BX). In addition, SM-BX had total sugars higher than those evaluated in RM-BX, while complex sugars (oligo- and/or poly-saccharides) were similarly abundant in both bark extracts. Furthermore, SM-BX demonstrated a wide array of vital minerals (K, Ca, Mg, P, Na, Fe and Cu) in quantity larger than that evaluated in RM-BX, whereas RM-BX have Zn and Mn levels higher than those found in SM-BX. Phytochemical analyses showed that RM-BX exhibited total phenolic and flavonoid contents higher than those measured in SM-BX. Consequently, RM-BX presented an antioxidant activity higher than that of SM-BX: 2.85-fold ABTS radical cation scavenging capacity and 1.9-fold oxygen radical absorbance capacity. Finally, RM-BX and SM-BX were greatly safe since, at concentration up to 100 μg/ml, they did not modify the viability of neutrophils as determined by flow-cytometry assay using Annexin V-FITC/Propidum Iodide as markers. In conclusion, our in vitro studies indicate that both red and sugar maple bark extracts have a real potential as food additives.

Removal of Water-Soluble Extractives Improves the Enzymatic Digestibility of Steam-Pretreated Softwood Barks

Softwood bark contains a large amounts of extractives—i.e., soluble lipophilic (such as resin acids) and hydrophilic components (phenolic compounds, stilbenes). The effects of the partial removal of water-soluble extractives before acid-catalyzed steam pretreatment on enzymatic digestibility were assessed for two softwood barks—Norway spruce and Scots pine. A simple hot water extraction step removed more than half of the water-soluble extractives from the barks, which improved the enzymatic digestibility of both steam-pretreated materials. This effect was more pronounced for the spruce than the pine bark, as evidenced by the 30 and 11% glucose yield improvement, respectively, in the enzymatic digestibility. Furthermore, analysis of the chemical composition showed that the acid-insoluble lignin content of the pretreated materials decreased when water-soluble extractives were removed prior to steam pretreatment. This can be explained by a decreased formation of water-insoluble “pseudo-lignin” from water-soluble bark phenolics during the acid-catalyzed pretreatment, which otherwise results in distorted lignin analysis and may also contribute to the impaired enzymatic digestibility of the barks. Thus, this study advocates the removal of extractives as the first step in the processing of bark or bark-rich materials in a sugar platform biorefinery.

In vitro macrophage nitric oxide production by Pterospartum tridentatum (L.) Willk. inflorescence polysaccharides

Pterospartum tridentatum (L.) Willk. decoctions of dried inflorescences are used in Portugal due to their claimed beneficial properties for various health disorders. To disclose the potential contribution of its polysaccharides to health benefits, in this work, hot water extracts from P. tridentatum inflorescences were prepared and fractionated by ethanol precipitation and anion exchange chromatography. The fraction rich in acetylated galactomannans evidenced an increase in nitric oxide (NO) production by macrophages. This activity decreased 60-75% after saponification, confirming that acetylation is an important structural feature for this biological property. In addition, the treatment of pectic polysaccharides with endo-polygalacturonase showed that type-I and type-II arabinogalactans, as well as low molecular weight galacturonans and xyloglucans, may also contribute to macrophage NO production. Thus, the polysaccharides present in P. tridentatum dried inflorescences may contribute to the health beneficial properties frequently attributed to the decoctions of this plant.

Molecular structure, chemical properties and biological activities of Pinto bean pod polysaccharide

Pinto bean pod polysaccharide (PBPP) was successfully extracted with yield of 38.5g/100g and the PBPP gave total carbohydrate and uronic acid contents of 286.2mg maltose equivalent/g and 374.3mgGal/g, respectively. The Mw of PBPP was 270.6kDa with intrinsic viscosity of 0.262dm(3)/g, which composed of mannose (2.5%), galacturonic acid (15.0%), rhamnose (4.0%), glucose (9.0%), galactose (62.2%), xylose (2.9%) and arabinose (4.3%) with trace amount of ribose and fucose. The result suggested that PBPP has a spherical conformation with a highly branched structure. Fourier Transform Infrared analysis showed that PBPP has a similar structure as commercial pectin with an esterification degree of 59.9%, whereas scanning electron microscopy study showed that the crude polysaccharide formed a thin layer of film that was made of multiple micro strands of fibre. PBPP exhibited substantial free radical scavenging activity (7.7%), metal reducing capability (2.04mmol/dm(3)) and α-amylase inhibitory activity (97.6%) at a total amount of 1mg. PBPP also exhibited high water- and oil-holding capacities (3.6g/g and 2.8g/g, respectively). At a low concentration, PBPP exhibited emulsifying activity of 39.6% with stability of 38.6%. Apart from that, PBPP was able to show thickening capability at low concentration (0.005kg/dm(3)).

Characterization of condensed tannins and carbohydrates in hot water bark extracts of European softwood species

Condensed tannins extracted from European softwood bark are recognized as alternatives to synthetic phenolics. The extraction is generally performed in hot water, leading to simultaneous extraction of other bark constituents such as carbohydrates, phenolic monomers and salts. Characterization of the extract's composition and identification of the extracted tannins' molecular structure are needed to better identify potential applications. Bark from Silver fir (Abies alba [Mill.]), European larch (Larix decidua [Mill.]), Norway spruce (Picea abies [Karst.]), Douglas fir (Pseudotsuga menziesii [Mirb.]) and Scots pine (Pinus sylvestris [L.]) were extracted in water at 60°C. The amounts of phenolic monomers, condensed tannins, carbohydrates, and inorganic compounds in the extract were determined. The molecular structures of condensed tannins and carbohydrates were also investigated (HPLC-UV combined with thiolysis, MALDI-TOF mass spectrometry, anion exchange chromatography). Distinct extract compositions and tannin structures were found in each of the analysed species. Procyanidins were the most ubiquitous tannins. The presence of phenolic glucosides in the tannin oligomers was suggested. Polysaccharides such as arabinans, arabinogalactans and glucans represented an important fraction of all extracts. Compared to traditionally used species (Mimosa and Quebracho) higher viscosities as well as faster chemical reactivities are expected in the analysed species. The most promising species for a bark tannin extraction was found to be larch, while the least encouraging results were detected in pine. A better knowledge of the interaction between the various extracted compounds is deemed an important matter for investigation in the context of industrial applications of such extracts.

Complement fixing polysaccharides from Terminalia macroptera root bark, stem bark and leaves

The root bark, stem bark and leaves of Terminalia macroptera were sequentially extracted with ethanol, 50% ethanol-water, and 50 °C and 100 °C water using an accelerated solvent extractor. Ten bioactive purified polysaccharide fractions were obtained from those crude extracts after anion exchange chromatography and gel filtration. The polysaccharides and their native extracts were characterized with respect to molecular weight, chemical compositions and effects in the complement assay. The chemical compositions showed that the polysaccharides are of pectic nature. The results indicated that there was no great difference of the complement fixation activities in the crude extracts from the different plant parts when extracting with the accelerated solvent extraction system. The purified polysaccharide fractions 100WTSBH-I-I and 100WTRBH-I-I isolated from the 100 °C water extracts of stem and root bark respectively, showed the highest complement fixation activities. These two fractions have rhamnogalacturonan type I backbone, but only 100WTSBH-I-I contains side chains of both arabinogalactan type I and II. Based on the yield and activities of the fractions studied those from the root bark gave highest results, followed by those from leaves and stem bark. But in total, all plant materials are good sources for fractions containing bioactive polysaccharides.

Isolation and characterization of cellulose nanocrystals from spruce bark in a biorefinery perspective

The present study reports for the first time the isolation of cellulose fibers and cellulose nanocrystals (CNCs) from the bark of Norway spruce. The upgrading of bark cellulose to value-added products, such as CNCs, is part of the "bark biorefinery" concept. The removal of non-cellulosic constituents was monitored throughout the isolation process by detailed chemical composition analyses. The morphological investigation of the CNCs was performed using AFM and showed the presence of nanocrystals with an average length of 175.3 nm and a diameter of 2.8 nm, giving an aspect ratio of around 63. X-ray diffraction (XRD) analyses showed that the crystallinity index increased with successive treatments to reach a final value greater than 80% for CNCs. The thermal degradation of the isolated bark CNCs started at 190 °C. Spruce bark appeared to be a new promising industrial source of cellulose fibers and CNCs.