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Wood treatments based on oleoresins from Aucoumea Klaineana, Canarium schweinfurthii and Dacryodes edulis have shown interesting anti-termites properties but poor resistance to fungi and leaching. Oleoresins were combined with tebuconazole to produce both antifungal and anti-termite wood preservatives formulations with an expected better fixation of chemicals mixtures in the wood. Beech and Scots pine wood block samples were impregnated by these different formulations and exposed to white and brown rot, respectively, as well as to European termite (Reticulitermes flavipes). The use of aqueous formulations of each oleoresin of combined to tebuconazole improved the wood resistance against termites and mainly brown rot. In addition, the best formulation was found by using the raw resin from Aucoumea Klaineana. These results are mainly due to the antifungal activity of tebuconazole. In addition, the presence of antioxidant chemicals in the wood resins inhibits the wood decay fungi growth and acts as enzyme and metabolism inhibitors disturbing the treated wood digestion process by termites. For the future, the promising protection obtained should be formulated to be resistant to leaching.

This paper presents mechanical properties and biological durability properties against soft-rot (soil bed test) and subterranean termites (grave-yard test) of the wood modified with a vinylic deriv...

This article presents the effect of the addition of condensed tannins, used as a reticulation agent, on the polymerization of furfuryl alcohol during wood furfurylation, as well as the effect of these condensed tannins on the thermal stability of modified wood. Three kinds of dicarboxylic acids (adipic acid, succinic acid, and tartaric acid), as well as glyoxal, used as model of a wood reticulation agent, were used to catalyze the polymerization of furfuryl alcohol or tannin-furfuryl alcohol solutions. Impregnation of furfuryl alcohol or tannin-furfuryl alcohol solution into the wood, followed by curing at 103 °C for a specific duration, was performed for the wood modification. The thermal stability of the obtained tannin-furfuryl alcohol polymers and their corresponding modified woods was investigated. The leaching resistance and dimensional stability of the modified woods were also evaluated. Results indicated that the partial substitution of furfuryl alcohol by the tannins improved the polymerization reactivity in conditions where furfuryl alcohol alone did not lead to the formation of a solid polymeric material. The thermal stability and leaching resistance of the furfurylated wood in the presence of tannins were improved. Dimensional stability was also improved for furfurylated samples, but the effect of tannin addition was not so obvious, depending on the acidic catalyst used.

International audience; Key messageWe present a methodological framework that both scientists and supply chain actors can mobilise to organise information at different scales of observation, and further make informed decisions regarding the supply and extraction of bio-molecules from forest biomass. We demonstrate its usefulness for extracting bio-molecules contained in silver fir growing in France.ContextNumerous bio-active molecules can be extracted from trees at an industrial scale. Supply chain actors play a central role in this emerging bio-economy. However, they do not have enough information and tools to make informed decisions with respect to species, growing locations, or identities of potential suppliers of relevant wood biomass.AimsWe explore and demonstrate an information chain and methodological framework that can help make three critical decisions regarding the selection of (1) the species containing the desired bio-molecules, (2) the locations where the resource is collected, and (3) the supply chain partners and types of industrial wood by-products necessary to obtain sufficient biomass for industrial extraction.MethodsThe methodological framework provides detailed guidelines and references to select the right combination of sampling protocol, allometric models, chemical analyses, GIS tools, and forest growth and supply chain models in order to produce information for the three decision steps within various regional contexts.ResultsWe apply the framework within the context of supply chain actors who are interested in estimating the quantity and diversity of bio-molecules contained in silver fir (Abies alba Mill.) growing in the Grand Est region of France. We show how conflicting environmental, legal and economic constraints can affect the results. We discuss future challenges that need to be tackled to improve the methodological framework.ConclusionThis study represents a highly detailed overview of the potential bio-molecules contained in a tree species, from its natural habitat or plantation to the end of the regional supply chain. It also represents a step towards the development of a generic knowledge infrastructure and methodology that is necessary to solve various decision-making problems regarding the industrial supply and extraction of high-value bio-molecules.

International audience; Tree bark is rich in commercially valuable secondary metabolites such as polyphenolic compounds like flavonoids and tannins. The yield and composition of bark extractives from Abies alba varies longitudinally within the stem. A. alba bark above the crown had the greatest extractive content, but the concentration of polyphenolic compounds was greatest below the crown. Here, we use a nonlinear model describing how bark extractive yields of A. alba, Picea abies and Pseudotsuga menziesii change with height, where differences among species are accounted for using different model coefficients. For all species there is longitudinal variability in extract yield. For P. abies and P. menziesii, the form of that variation differs depending on whether the bark was located at the same position in the stem as branches. Although the relationship form of total extractive yield differs between branched and un-branched samples, the relationship forms for individual compound yields does not change depending on branch presence. Despite trees from thinned stands having longer crowns and faster growth rates, indicative of greater photosynthetic activity, there was no evidence that thinning had affected either the yield or composition of extractives in these species. In P. abies, the proportions of flavonoids was higher in bark from the top of the tree, whereas epi-gallocatechin gallate was found in high proportions at the stem base. In P. menziesii bark extracts, taxifolin was the dominant compound, present in significantly higher proportions in bark towards the base of the stem.

International audience; Catalytic depolymerization of lignin is a challenging process due to competitive repolymerization reactions. In this paper, the oxidative depolymerization of lignin was catalyzed by a commercial laccase both in a batch experiment and in a membrane bioreactor using the same catalytic conditions. The membrane bioreactor was previously optimized to reach high permeation flux (25 L.h−1.m−2) during lignin diafiltration. While the lignin was exclusively condensed in the batch experiment leading to high molecular weight macromolecules (from 9 to 16 kDa), its depolymerization was effective in the bioreactor producing fragments of less than 1 kDa thanks to the in-situ extraction of the reaction products. This paper demonstrates that the reactor configuration is playing an essential role in triggering or preventing lignin condensation. It also reports the first proof-of-concept demonstrating that in-situ membrane extraction of the reactive fragments of lignin from the bulk medium can be useful against detrimental repolymerization reactions.

Dacryodes edulis (G. Don) H.J. Lam resin was hydro-distilled to recover essential oil (EO), and further purified to produce a heavy fraction constituting less volatile compounds. Chemical composition was investigated by gas chromatography-mass spectrometry (GC-MS), and indicated that different monoterpenes and triterpenes were present depending on the analyzed fraction. Bioassays were performed on the different fractions to evaluate their anti-fungal and anti-termite properties. Results indicated that crude resin, its heavy fraction and its EO all had proved termicidal properties, which decrease on drying for EO and crude resin due to evaporation of monoterpenes. Conversely, no anti-fungal properties were observed for any fraction. Dacryodes edulis resin is therefore a new valuable bioactive ingredient for the formulation of wood protection products with anti-termite properties.

International audience; The development of zero-waste biorefineries is a promising yet challenging pathway toward a sustainable bioeconomy. Deep insights on the composition of biorefineries side streams along with the development of green technologies are mandatory to achieve such a goal. In this Article, a sustainable pilot-scale membrane process was used to recover valuable organic matter dissolved in the main side stream of a thermomechanical pulping (TMP) plant. A great number of analytical tools were combined to get an extensive characterization of the generated fraction, including inductively coupled plasma atomic emission spectroscopy (ICP-AES), high-performance ion chromatography coupled with pulse amperometric detection (HPIC-PAD), Fourier transform infrared (FTIR), size-exclusion chromatography (SEC), and C-13 and 2D heteronuclear single quantum correlation (HSQC) NMR. The results revealed the presence of a considerable amount of native lignin-carbohydrate complexes (LCCs) in the fraction representing 40% of the dry weight. The LCCs are composed of partially acetylated galactoglucomannans (GGMs) covalently linked to low condensed and ) beta-O-4-rich lignin through phenyl glycosidic bonds (25.5 bonds/100 aromatic rings (ar)) and characterized by a relatively low molecular weight around 7 kDa. Such complexes present an interesting potential for valorization with unique properties resulting from the combination of their aromatic and sugar moieties. Different applications are discussed in regards to the generated data in this work as an industrial sourcing of LCC is reported.

In this study, modification of European beech wood (Fagus sylvatica) through in situ esterification of sorbitol and citric acid (SorCA) was investigated at two curing temperatures, 140 and 160 °C. In order to determine the optimum condition for modification, an aqueous solution of SorCA at varying concentrations was evaluated (10, 20, 30, and 55% w/w). Physical, mechanical, chemical, and durability properties of the modified wood were examined. Results have disclosed that among different SorCA concentrations, treatment with SorCA at 30% w/w was considered as the optimum concentration independent of the curing temperature. Under these conditions, anti-swelling efficiency increased to approx. 55% and modulus of elasticity increased slightly with approx. 9% in comparison with untreated wood. Decay resistance against white-rot (Trametes versicolor), brown-rot (Coniphora puteana), and soft-rotting microfungi classified the SorCA-30%-modified wood as very durable. In addition, thermogravimetric study evidenced that SorCA 30%-modified wood has a lower thermal decomposition temperature in comparison with untreated wood/wood control by 20 °C difference, indicating that the SorCA-modified wood possibly has fire-retardant properties. However, due to the acidic properties of the SorCA solution, modulus of rupture (MOR) and mainly work to maximum load in bending decreased considerably.

International audience

Extensive evidence showed that the efficiency of fungal wood degradation is closely dependent on their ability to cope with the myriad of putative toxic compounds called extractives released during this process. By analysing global gene expression of Phanerochaete chrysosporium after short oak extractive treatment (1, 3 and 6 h), we show that the early molecular response of the fungus concerns first mitochondrial stress rescue followed by the oxidation and finally conjugation of the compounds. During these early responses, the lignolytic degradative system is not induced, rather some small secreted proteins could play an important role in cell protection or signaling. By focusing on the functional characterization of an hitherto uncharacterized glutathione transferase, we show that this enzyme interacts with wood molecules suggesting that it could be involved in the detoxification of some of them, or act as a scavenger to prevent their cytosolic toxicity and favour their transport.

International audience; The natural durability of wood is linked to its chemical composition and in particular the presence of metabolites called extractives that often possess chemical reactivity. For dealing with these compounds, wood degraders have developed detoxification systems usually involving enzyme families. Among these enzymes, glutathione transferases (GSTs) are involved in the decrease of the reactivity of toxic compounds. In this study, the hypothesis that the detoxification systems of wood decaying fungi could be indicators of the chemical reactivity of wood extracts has been tested. This approach has been evaluated using 32 wood extracts coming from French Guiana species, testing their antimicrobial ability, antioxidative properties, and reactivity against six GSTs from the white rot Trametes versicolor. From the obtained data, a significant correlation between the antimicrobial and antioxidative properties of the tested wood extracts and GST interactions was established. In addition, the chemical analysis performed on one of the most reactive extracts (an acetonic extract of Bagassa guianensis) has demonstrated oxyresveratrol as a major constituent. We were able to cocrystallize one GST with this commercially interesting compound. Taken together, the presented data support the hypothesis that detoxifying enzymes could be used to identify the presence of molecules of industrial interest in wood extracts.

International audience; Fractionation of phenolic compounds in thermomechanical pulp mills was performed with a coupling of a prior treatment realized by flotation and a ceramic membrane process. Two lines of membranes filtration were tested. After a common 150 kDa clarification, 1 kDa filtration was performed with or without previous 5 kDa filtration. Flotation was shown to be inevitable to retain lipophilic compounds which cause severe membrane fouling. 150 kDa permeate flux was 20% higher when process water was firstly floated and was around 260 L h−1 m−2. 1 kDa membrane was fouled with 31% of irreversible fouling without previous 5 kDa filtration and phenolic compounds purity reached only 26% in this 1 kDa permeate. Phenolic compounds as lignin-like substances which might be attached to hemicelluloses were recovered in 5 kDa retentate. Retentate of 1 kDa might contain a major fraction of lignin derivatives with molecular weights around 1 kDa free or linked with phenolic acids. Permeate of 1 kDa contained 14% of phenolic compounds such as lignans and free phenolic acids purified at 50%.

In thermo-mechanical process water, lignin presents an attractive potential for industrial applications due to the preservation of its native structure as free polymer or as part of ligno-carbohydrate complexes. In such effluent, lignin concentration is low, therefore its recovery with membrane process presents some advantages. As lignin tends to precipitate and forms lignin clusters with a pH decrease, assessing the influence of pH is relevant to understand membrane selectivity towards lignin and the related membrane productivity. It constitutes the main objective of the present study, as it was never done for thermo-mechanical process water. Two ceramic membranes with cutoff of 5 and 1 kDa were used alone or in a series and three pH were tested (4, 6.2 (native pH) and 10). For each condition, an in-depth fouling study was realized. pH 10 was not promising as a rapid flux drop was observed at low volume reduction of 40% due to the compact deposit of lignin provoking 7% of irreversible fouling and 83% of fouling removed by cleaning with acid and base. The utilization of both membranes in a series was not pertinent as lignin was partly fractionated in both retentates. Process water filtration at pH 4 with a unique 1 kDa nanofiltration step gave encouraging results with 40 and 70% of lignin and hemicelluloses respectively recovered. High flux of 33 L.h−1.m−2 was maintained at a volume reduction of 80%. Fouling was easily eliminated as it was composed at 70% of fouling removed with water rinsing which was largely due to hemicelluloses which tend to agglomerate at pH 4 in the membrane surrounding.

International audience; Key message Total bark extractive content increases at positions higher in the trunk ofAbies albaMill. trees. The greatest proportions of bark polyphenolic extractives are found in the lower section of the trunk, below the crown. Context The bark of commercially grown softwood trees is a potentially valuable source of secondary metabolites including polyphenols such as tannins, used in the manufacture of adhesives and resins. There is little information about how the yield and composition of bark extracts vary longitudinally within trees and with respect to the presence or absence of branches. Aims We examined the variability of bark secondary metabolites in the softwood Abies alba both longitudinally within trees and among trees at specific sample heights. The aim was to determine whether specific bark fractions within this species contain more extractable secondary metabolites than others. Methods Eight trees of A. alba were harvested, and up to 13 discs were cut along the trunk from 30 cm above the ground to where the trunk was only 10 cm in diameter. Milled bark was extracted with water:ethanol (1:1) using an accelerated solvent extractor and the dry yield calculated. Extract composition was examined by liquid chromatography followed by mass spectrometry. Results Total extract yield increased from the base of the tree towards the top. The yield of the most abundant polyphenolic compounds decreased from the base of the tree towards the top, indicating the total extracts included compounds that were not detectable with the chromatographic method used. Conclusion Although extract yield is highest at the top of the tree, the composition of the extracts indicates that compounds with known marketable value, and present in detectable proportions, are found at the base of the tree.

Termite resistance of European beech (Fagus sylvatica) modified with a combination of chemical and thermal methods was investigated in field tests. Modification was performed by impregnating different aqueous solutions of glycerol maleate or polyglycerol maleate at different concentrations (10 or 40%, w/w) into the wood, followed by thermal treatment at different temperatures (180, 200, or 220 °C). Field tests were conducted for one-year at Bogor, West Java, Indonesia. All wood samples treated with the combination of chemical and thermal modifications presented significantly higher termite resistance than thermally modified and untreated wood samples. Curing at 200 or 220 °C resulted in better performance with mass losses due to termite attack of less than 5%.

The general objective of this work was to evaluate the quality of the little-known tropical woods of the Congo Basin, particularly Coula edulis, while looking for new biocidal products. The natural durability of the hazel tree of Gabon Coula edulis versus basidiomycete fungi was evaluated with native and extracted samples of heartwood against brown rot (Rhodonia placenta and Coniophora puteana) and white rot (Trametes versicolor and Pycnoporus sanguineus) fungi. The results showed that non-extracted samples were more durable. Fungal growth inhibition tests using different concentrations of extractives confirmed the fungicidal effects. Percentage of the different wood polymers and GC–MS analysis of wood extractives were carried out to examine correlations between durability and wood chemistry. Natural durability of Coula edulis could be explained by the unusually high lignin content and the presence of high amounts of polyphenols like gallic and ellagic acids and tannins. Coula edulis could therefore be a local alternative to help alleviate wood shortages in Gabon.

Wood offers important potential for biofuel or chemical production by fast pyrolysis but exhibits variable chemical composition that impacts pyrolysis product composition. Here, fast pyrolysis of heartwood, sapwood, and bark isolated from Douglas fir (softwood) and oak (hardwood) was studied by a microfluidized bed reactor (MFBR) combined with single photoionization mass spectrometry (SPI–MS) to provide insights into the wood zone effects on the composition of pyrolysis volatiles. The difference in pyrolysis volatile composition has been clearly unraveled by principle component analysis (PCA) based on the major ions detected by SPI–MS. Some specific product markers have been defined for each wood zone (heartwood, sapwood, and bark) and related to the chemical composition of wood samples (lignin, carbohydrates, and minerals). The catalytic effect of minerals (notably potassium) has a higher impact on carbohydrate decomposition than on lignin decomposition for a given wood type. Therefore, sapwood and heart...

Evaluation of commercially available polyurethane resins used up to now for coating applications to develop non-biocidal wood preservation treatments has been conducted. A simple method of vacuum impregnation of these resins into beech wood (Fagus sylvatica L.) and pine wood (Pinus sylvestris L.) samples followed by varied curing processes at ambient temperature, 103, and 200 A degrees C has been performed. Based on the analysis of weight percent gain before and after leaching, treatment resistance to leaching, anti-swelling efficiency, wettability and decay durability measured for treated and untreated blocks after leaching with the white-rot fungus Coriolus versicolor for both wood species and the brown-rot fungi Poria placenta and Gloeophyllum trabeum for pine wood, it can be concluded that such treatment can be considered as potential valuable non-biocidal treatments.

European beech (Fagus sylvatica L.) is a major tree species of European forest which is underexploited because of its low dimensional stability and durability. Similarly to what has been developed with radiata pine, furfurylation might be the answer to optimize the utilization of local beech wood. Beech wood furfurylation process was studied using five different catalysts: maleic anhydride, maleic acid, citric acid, itaconic acid, and tartaric acid. Optimization of the furfurylation process was investigated for different catalyst and furfuryl alcohol (FA) contents, and different duration of polymerization. The following properties were studied: weight percent gain (WPG), leachability, anti-swelling efficiency (ASE), wettability, modulus of elasticity, modulus of rupture, Brinell hardness, and decay durability. Tartaric acid, never investigated up to now, was retained as catalyst to perform furfurylation due to its efficacy compared to other catalysts and its novelty. Wood modification with FA and tartaric acid as catalyst led to samples with high WPG even after leaching, improved ASE, and lower wettability with water. Increasing the polymerization duration increased the fixation of FA in treated wood. Most of all, treatment gave a significant improvement in mechanical properties and resistance to wood decaying fungi.

Many wood processing industries use short rotation teak, which has lower quality especially in durability and dimensional stability. Heat treatment is an eco-friendly method to improve dimensional stability and durability of wood. The objectives of the study were to investigate the effects of thermal modification on chemical composition, colour, dimensional stability and durability as well as coating’s performance after accelerated weathering of short and long rotation teak for exterior utilization. In this study, the samples were heated in oven at 220 °C for 20 h under nitrogen atmosphere. Results showed that independently of growth conditions teak woods underwent hemicelluloses degradation and an increase of lignin content after heat treatment. Extractives contents were lower in short rotation than in long rotation teak, and decreased in all cases after heat treatments. Dimensional stability was considerably improved as indicated by anti-swelling efficiency values of 64,9% and 58,9% for short and long rotation teak, respectively. Heated teak woods were more resistant against Trametes versicolor and the durability of short-rotation teak increased from moderate to very durable. Coatings on heat treated teaks had better bonding quality and better photo-stability when compared to unheated. Heated short rotation teak could be considered for exterior application.

Environmental pressures in France and in most European countries during the last decade have considerably changed the practises for wood protection. In this context, legislation and regulations, among which the Biocidal Products Directive (BPD) and Biocidal Products Regulations (BPR), are more and more constraining leading to the development of more environmentally acceptable preservation formulations and to an increasing interest in non-biocidal alternatives like thermal or chemical modifications. Wood heat treatment has been one of the most investigated alternative methods during the last years. However, even if some of the wood properties, like its decay resistance or and dimensional stability, are improved, the overall durability of the material is not sufficient to envisage use class 3 and 4 applications, where the wood is in direct contact with soil and termites. Impregnation of borax associated to polyglycerolmethacrylate (PGMA) before thermal treatment could be an attractive alternative to improve the performance of thermally modified wood in ground contact and especially its resistance to termites taking advantage of thermal treatment to initiate polymerization of PGMA within the wood structure to limit boron mobility. Thermo-modification with or without combination of boron impregnation and PGMA improved the durability of all wood samples. Thermal treatment alone or after boron impregnation and leaching was unable to effectively protect wood blocks against termites after leaching, while bocks treated with boron and PGMA were shown to be fully resistant to termites. More surprisingly, association of thermal treatment and PGMA impregnation without boron impregnation also produced protection against termite attack. Such treatments may be valuable alternatives to extend the scope of utilization of thermally modified wood in outdoor conditions.

International audience; Previous studies reported that knotwood of several European Pinus sp. contains extractives contents much higher than stemwood consisting mainly of phenolic compounds which may find valuable applications in cosmetic, nutraceutic or pharmaceutic sectors. At the same time, no comprehensive studies on the tropical species Pinus merkusii have been reported. Determination of extractives amounts present in sapwood, heartwood and knotwood of P. merkusii has been performed and their chemical composition analyzed using GC-MS and LC-MS. Antioxidant and antifungal activities were also evaluated by DPPH method and growth inhibition method, respectively. The results showed that knotwood contains more extractives than heartwood, the latter containing more extractives than sapwood. Knotwood extracts contain mainly lignans, especially nortrachelogenin, stilbenes and resin acids, while heartwood extracts were constituted mainly of stilbenes, especially pinosylvin monomethyl ether, pinosylvin and pinosylvin dimethyl ether and of flavonoid like pinocembrin. Acetone knotwood extract presents the higher antioxidant activity, while acetone heartwood extract possesses the higher antifungal activities against the two tested fungi Trametes versicolor and Poria placenta.

International audience; Key message Teak (Tectona grandis L.f.) is one of the most important tropical hardwood tree species, which is widely planted in Indonesia. Wood properties are strongly influenced by forest management conditioning further utilization of wood.Context In Indonesia, teak wood has been supplied from the state forests (Perhutani) for long rotation teak and from community teak plantations for short rotation teak. Short rotation teak has been harvested at 7-10 years and long rotation teak at 40-60 years.Aims This paper discusses the characterization of technical properties of short and long rotation teak wood based on the chemical, anatomical, physical, and mechanical properties.Methods The properties of short rotation and long rotation teak woods were characterized by measuring their density, extractive contents, chemical composition, swelling, wettability, water sorption isotherm, decay resistance, anatomical properties, bending strength (modulus of rupture (MOR), modulus of elasticity (MOE)), and hardness.Results The results indicate that short rotation teak was not particularly different in swelling, MOE and MOR, and Brinell hardness compared to long rotation teak, although it was less dense and less durable due to lower heartwood and extractive contents. Therefore, careful attention should be given to the use of short rotation teak in some wood-processing technologies.Conclusion Lower wood density and durability of the short rotation compared to the long rotation teak will restrict its utilization to some extent for both indoor and outdoor applications. Fast-growing teak from community cannot be used as usual heartwood teak from Perhutani because of the very low proportion of useful heartwood in the stem.

International audience; Barks are available as waste material and by-product of wood industry. They have been reported to contain interesting molecules and show some bioactivity such as antioxidant and antifungal. This study aimed at evaluating the amounts of extractives in Acacia mangium (acacia), Poraserianthes falcataria (sengon) and Swietenia mahagoni (mahoni) barks, to evaluate their extractive contents and the presence of potential valuable molecules. The extraction method used soxhlet with four different solvents. Antioxidant activity assays were carried out using methyl linoleate and 2,2-diphenyl-1-picrilhidrazyl (DPPH) and the antifungal activity was determinate by fungal growth inhibitions assays. 5.3%-18.5% extraction yields were obtained. All acetone and toluene ethanol extracts show high antioxidant activity by DPPH. The highest antioxidant value obtained by DPPH was obtained for mahoni bark acetone extract with 3.9 mg/L of EC50, followed by mahoni bark toluene ethanol 6.8 mg/L, acacia bark acetone 7 mg/L, and acacia bark toluene ethanol extract 7.4 mg/L. Sengon bark extracts had the greatest antifungal activity inhibition. The greatest antioxidant and antifungal activity were obtained with phenolic compounds which were contained in the extracts.

The lignan 7′-hydroxymatairesinol (1), extracted from the knotwoods of fir (Abies alba), spruce (Picea abies), and Douglas fir (Pseudotsuga menziesii), exhibited unexpected reactivity when esterification reactions were attempted on the hydroxy group at position C-7′. To circumvent the rapid intramolecular cyclization procedure, leading quantitatively to the lignan conidendrin (7), a simple strategy for 7′-esterification of 1 under mild conditions (three steps, up to 80% overall yield) was developed. Compared to hydroxymatairesinol (1) (log K′w = 1.49), the derivatives (2–5) had increased lipophilicity with log K′w > 3.1, as determined by a UHPLC method. Compounds 1–5 exhibited potent antioxidant properties in the same range as the standards ascorbic acid and α-tocopherol (IC50 = 20–25 μM) and higher than that of BHT using a DPPH radical-scavenging assay.

International audience; Membrane process is a viable option for valuable compounds such as lignin and lignans recovery in aqueous discharges of thermomechanical pulp industries. Recovery of lignin and lignans with continuous mode ultrafiltration/nanofiltration installation has not been studied in detail previously. After flotation used to remove lipophilic matter of pulp mill effluent, the three steps membrane process was composed of a clarification step by a 150 kDa ultrafiltration used to remove suspended matter, followed by two nanofiltrations of 1 kDa and 300 Da to respectively retain lignin and lignans. A techno-economic evaluation of this process has been performed. The process with a plant capacity of 60 m(3) h(-1) was able to produce 12 tons of lignin and 825 kg of lignans per month. The influence of plant capacity between 0.1 and 60 m(3) h(-1) on extracts production cost allows determining a production cost equal or below 10 V.kg(-1) as plant capacity reached 10 m(3) h(-1). Valorization of lignin and lignans as parts of the formulas of high added value products could allow thermomechanical plants to head towards biorefinery and cleaner production concepts. Furthemore, the 300 Da permeate possessed the required characteristics to be re used and save fresh water utilization. (C) 2019 Elsevier Ltd. All rights reserved.

International audience; Glutathionyl-hydroquinone reductases (GHRs) catalyze the deglutathionylation of quinones via a catalytic cysteine. The two GHR genes in the Populus trichocarpa genome, Pt-GHR1 and Pt-GHR2, are primarily expressed in reproductive organs. Both proteins are localized in plastids. More specifically, Pt-GHR2 localizes in nucleoids. At the structural level, Pt-GHR1 adopts a typical GHR fold, with a dimerization interface comparable to that of the bacterial and fungal GHR counterparts. Pt-GHR1 catalyzes the deglutathionylation of both reduced and oxidized glutathionylated quinones, but the enzyme is more catalytically efficient with the reduced forms.

Extractives are present in much larger amounts in knotwood than in heartwood in the 12 tested hardwood and softwood species. The chemical identity of the extractives varies largely among species, lignans being only present in softwood species. Extractives from knotwood may constitute an important source of new chemicals and remain still poorly known. The content of extractives (and particularly lignans) in knots was compared to that of heartwood in a number of different European softwood and hardwood species. Twelve species characteristic of European forests were sampled. Extractions were carried out with four solvents of increasing polarity (dichloromethane, acetone, toluene/ethanol and water). Gas chromatography-mass spectrometry (GC-MS) was used for the identification of the compounds present in acetone extracts which are expected to contain lignans. In all tested species, knotwood presented larger contents of extractives than heartwood. The main compounds were lignans, stilbenes and flavonoids, lignans being present only in softwood species. With the exception of oak, knotwood in softwood species contain larger amounts of extractives than that in hardwood species. The chemical nature of extractives present in knotwood varies with species. Their amount is generally much higher in softwood than heartwood species.

International audience; Identification of volatile degradation products generated and released during wood mild pyrolysis is important to better understand thermodegradation mechanisms. Previous studies have shown that thermodesorption coupled to GC-MS is an attractive tool to characterize and quantify products formed during wood thermal treatment indicating higher susceptibility of hardwoods to thermodegradation compare to softwoods. The aim of this study is to elucidate wood thermodegradation pathways with special emphasis on the kinetics reactions. To achieve this objective, one hardwood species (beech) and one softwood species (Silver fir) were subjected to thermal treatment directly in the thermal desorption glass tube of thermodesorber connected to GC-MS using helium as carrier and at temperatures of 210 and 230 degrees C for different times ranging from 10 to 80 min. The volatiles compounds formed were analyzed by gas chromatography coupled to mass spectroscopy. From GC-MS data collected in this study, the kinetic curves of the formation of some of the products as a function of thermal treatment duration were established. Assuming that acetic acid and furfural were formed from hemicelluloses and vanillin from lignin. Arrhenius equation was used to estimate the mean activation energy formation of these two degradation by-products allowing obtaining indirect information on the thermal stability of both polymer.

Effect of heat treatment intensity on some conferred properties like elemental composition, durability, anti-swelling efficiency (ASE) and equilibrium moisture content (EMC) of different European softwood and hardwood species subjected to mild pyrolysis at 230 °C under nitrogen for different durations has been investigated. Independently of the wood species studied, elemental composition is strongly correlated with the mass losses due to thermal degradations which are directly connected to treatment intensity (duration). In all cases, an important increase in the carbon content associated with a decrease in the oxygen content was observed. Heat-treated specimens were exposed to several brown rot fungi, and the weight losses due to fungal degradation were determined after 16 weeks, while effect of wood extractives before and after thermal treatment was investigated on mycelium growth. ASE and EMC were also evaluated. Results indicated important correlations between treatment intensity and all of the wood conferred properties like its elemental composition, durability, ASE or EMC. These results clearly indicated that chemical modifications of wood cell wall polymers are directly responsible for wood decay durability improvement, but also for its improved dimensional stability as well as its reduced capability for water adsorption. All these modifications of wood properties appeared simultaneously and progressively with the increase in treatment intensity depending on treatment duration. At the same time, effect of extractives generated during thermal treatment on Poria placenta growth indicated that these latter ones have no beneficial effect on wood durability.

Wood heat treatment is an attractive alternative to improve decay resistance of low natural durability wood species. Nowadays, several types of thermal treatments of wood exist. These treatments differ mainly by the nature of the inert atmosphere used to avoid wood combustion which may correspond to: nitrogen, vacuum, steam or oil. Decay resistance is strongly correlated to thermal degradation of wood cells wall components and consequently of treatment conditions from which depend chemical modifications. The aim of this study is to determine the effect of a new generation of treatment performed under vacuum on the chemical modifications occurring during treatment. For this purpose, one hardwood (beech) has been treated under different conditions (vacuum, nitrogen, steam). All treatments were performed at 220 °C for mass losses resulting from wood thermodegradation of approximately 12%. For each treatment condition extractives, Klason lignin, hemicelluloses and α-celluloses content were determined as well as monosaccharide composition. Intensity of thermodegradation was also evaluated by TD-GC-MS. Results show that extracts content were lower in the case of wood samples treated under vacuum, while lignin, hemicelluloses and α-celluloses contents were higher in the case of samples treated under steam and nitrogen, indicating lower wood degradation under vacuum treatment. These results were confirmed by chromatography analyses according to the nature and quantity of thermodegradation volatile products formed during TD-GC-MS analyses.

International audience; Pistacia lentiscus (Anacardiaceae) is commonly used in folk medicine to treat various diseases. The aim of the present study was to evaluate the hepatoprotective and antioxidant activities of extracts of P. lentiscus leaves (PL) and fruits (PF) against experimentally induced liver damage. Furthermore, characterization of extracts was attempted by a spectroscopic methodology (Fourier transform infrared spectroscopy) and high-performance liquid chromatography with diode array detection analysis. A hepatoprotective potential against paracetamol [165 mg/kg body weight (b.w.)] toxicity was noticed in mice pretreated with the same dose of PL or PF extract (125 mg/kg b.w.) or a combination of both (PL/PF 63/63 mg/kg b.w.), as revealed by an analysis of biochemical parameters (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase activities and total bilirubin). These results were confirmed by histological examination of the liver, which revealed significant protection against paracetamol-induced hepatic necrosis. Furthermore, PF extract exhibited a promising antidiabetic activity in streptozotocin-induced diabetic rats, similar to the reference drug glibenclamide (0.91 g/L), a result confirmed by in vitro inhibition of amylase. We demonstrated that the leaf crude extract showed the best effect in all tested methods, compared to its fruit counterpart, probably due to the presence of higher amounts of phenolic compounds, as determined by phytochemical and Fourier transform infrared spectroscopy analyses. Moreover, high-performance liquid chromatography with diode array detection led to the identification of six compounds for each part of the plant. Gallic acid, a characteristic compound of Pistacia species, was most abundant in leaves and fruits, while luteolin was detected for the first time in fruits. Obtained activities of P. lentiscus extracts may well be due, at least in part, to the presence of the above compounds.

The white rot fungus Phanerochaete chrysosporium, a saprophytic basidiomycete, possesses a large number of cytosolic glutathione transferases, eight of them showing similarity to the Omega class. PcGSTO1 (subclass I, the bacterial homologs of which were recently proposed, based on their enzymatic function, to constitute a new class of glutathione transferase named S-glutathionyl-(chloro)hydroquinone reductases) and PcGSTO3 (subclass II related to mammalian homologs) have been investigated in this study. Biochemical investigations demonstrate that both enzymes are able to catalyze deglutathionylation reactions thanks to the presence of a catalytic cysteinyl residue. This reaction leads to the formation of a disulfide bridge between the conserved cysteine and the removed glutathione from their substrate. The substrate specificity of each isoform differs. In particular PcGSTO1, in contrast to PcGSTO3, was found to catalyze deglutathionylation of S-glutathionyl-p-hydroquinone substrates. The three-dimensional structure of PcGSTO1 presented here confirms the hypothesis that it belongs not only to a new biological class but also to a new structural class that we propose to name GST xi. Indeed, it shows specific features, the most striking ones being a new dimerization mode and a catalytic site that is buried due to the presence of long loops and that contains the catalytic cysteine.

International audience; A large amount of flavonoid has been extracted and isolated from the heartwood of Prosopis juliflora, an exogenous wood species of Kenya. Structural and physicochemical elucidation based on FTIR, 1H and 13C NMR, GC-MS and HPLC analysis clearly demonstrated the presence of (-)-mesquitol as the sole compound without any noticeable impurities. The product was able to slow down oxidation of methyl linoleate induced by AIBN. The important amount and high purity of (-)-mesquitol present in the acetonic extract of P. juliflora could therefore be of valuable interest as a potential source of antioxidants from a renewable origin.

International audience; Abstract Key messageContent and type of extractives vary considerably among woody species in the Congo Basin tropical forest. They influence the natural durability of wood with respect to fungal and insect degradation. Species containing higher amounts of extractives and Klason lignin were generally less susceptible to fungal colonization. Phenolic extractives with large anti-fungal and high antioxidant activities were the main chemical family of compounds extracted from the tested species, which suggests a potential chemical valorization of these extractives.ContextSeveral woody species from the Congo Basin are known for their natural durability, but the causes of this natural durability are not always fully elucidated. This is particularly the case for the resistance to white rotting fungi decay.AimsThe chemical composition as well as the antioxidant activity of the heartwood extractives of several species were quantified and correlated to the ability of different fungi to colonize wood sawdusts in order to better understand their decay resistance.MethodsThe chemical screening of extracts was conducted using colorimetric methods. The quantity of lignin, extracts and total phenolic compounds, as well as antioxidant activities were determined. Extracted and unextracted heartwood sawdusts were exposed to two white rot fungi to assess the effect of extractives on their colonization.ResultsExtractives and lignin contents ranged from 2.7 to 16.0 % and from 26.5 to 35.9 %, respectively. Antioxidant activity was directly connected to total phenolic contents. The phytochemical screening revealed the presence of different chemical groups in all extracts. Resistance to fungi was correlated to the amount of extractives and in most cases to the lignin content.ConclusionPhenolic compounds associated with antioxidant activities influenced the natural resistance of heartwood.