Characterization of extracts from the bark of the Gabon hazel tree (Coula edulis baill) for antioxidant, antifungal and anti-termite products

Chemical composition of the bark extracts ofCoula eduliswas inves-tigated tofind potential antioxidant, anti-termite and antifungal compounds whichcanfind useful applications in thefields of food, nutraceuticals, cosmetics or agro-chemical. Phytochemical screening revealed the presence of several groups ofactive molecules such as alkaloids, polyphenols,flavonoids, saponins and sterolsand/or terpenes in the different extracts. Total phenols, condensed tannins andfla-vonoids contents corroborated phytochemical screening. Gas chromatography-mass spectrometry (GC-MS) analysis revealed compounds in dichloromethaneextract different from those obtained with all the other solvents. Hexadecanoicand trans-9-octadecenoic acids, as well as stigmasterol andβ-sitosterol have beenidentified as the major compounds in the dichloromethane extract. Extractsobtained with acetone and toluene/ethanol mixture (2/1, v/v) indicated the pre-sence of few amounts of fatty acids and sugars, catechin in small amount andhuge amounts of phenolic acids like gallic and ellagic acids. The radical 2,2-diphenyl-1-picrylhydrazyle (DPPH) and the cationic radical 2,2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS+) were used for evaluation of antioxidantproperties of the different extracts. The dichloromethane extracts had a very lowantioxidant activity, while acetone and toluene/ethanol extracts presented EC50values similar to those of catechin and BHT used as reference antioxidant com-pounds. Effect of the different extracts of the bark ofC. edulison fungal growthinhibition indicated better inhibition of the mycelium growth of brown rot fungicompared to white rot fungi. Low anti-termite activities were recorded with theaqueous extracts, while stronger activities were recorded with dichloromethane,acetone and toluene/ethanol extracts

Derivatives of the Lignan 7'-Hydroxymatairesinol with Antioxidant Properties and Enhanced Lipophilicity

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

State of progress of utilisation of supramolecular gels for formulations of water-soluble wood preservation salts

International audienceThis article is a compilation of the work done so far concerning the utilization of supramolecular hydrogels, built on low-molecular-weight amphiphilic molecules and containing boron salts conferring fungicidal properties. Mixing boron with thermoreversible hydrogels allows the formation of a supra molecular network incorporating boron and important amount of water upon gelification of the solution when the temperature decreases. Hydrogels obtained from several amphiphilic peptides, pseudo-peptides or various gelling molecules were impregnated in pine wood block using vacuum pressure treatment and subjected to leaching. Results indicated that incorporation of boron salts in the hydrogel network, allowed to protect effectively wood from degradation caused by the brown rot fungus Poria placenta even after leaching. It was assumed that these hydrogels are able to limit the leachability of boron salts

Effect of Tannins Addition on Thermal Stability of Furfurylated Wood

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

Tartaric acid catalyzed furfurylation of beech wood

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

Hydrogels obtained from an original catanionic system for efficient formulation of boron wood-preservatives

International audienceA new catanionic system associating amphiphilic carnosine (beta AlaHisC8) and lauric acid forms supramolecular hydrogel at a very low concentration. This gel was investigated and we checked the validity of the concept of hydrogel utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) fosters improvement in the resistance of Scots pine sapwood subjected to water leaching toward the brown-rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood