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Variabilité intra spécifique de la composition chimique des connexes issus de la première transformation du bois de différentes essences gabonaises et valorisations chimiques potentielles

Abstract : During this work, the rate of bark, heartwood and sapwood extracts of four Gabonese species was evaluated using the ASE 200 accelerated extraction technique and the Soxhlet for successive extractions with dichloromethane, acetone, toluene/ethanol and water. Also, parallel extractions with ethanol, water/ethanol and water whose extracts allowed the continuation of the work with the rate of extracts varying from 05 to 26%. The total phenols contained in the extractives were evaluated by the Folin-Ciocalteu method using gallic acid as the standard. The content varies from 1.36 to 383.2 mg gallic acid eq/g extracts. The identification of compounds contained in the extracts by GC-MS allowed the identification of chlorophorin and resveratrol in Iroko extracts. The extracts of the other essences as a whole, allowed the identification of sugar molecules, acid molecules and sterols. Growth inhibition tests on decay fungi showed that at concentrations of 300 ppm the extractives were fungistatic and at concentrations of 500 ppm some extractives were fungicidal (Azobe extractive). The evaluation of the antioxidant and colouring properties of the extracts to consider potential industrial applications was carried out. The anti-radical power of the extracts was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH.) radical. The concentrations required to consume 50% of the radical range from 2.3 to 6.2 mg/L. The ability of aqueous and alkaline extracts to dye cotton was evaluated. The measurement of the colouring taken by the fibres was done using a Datacolor D65°10 colorimeter. The results show that these extracts give a yellow coloration with Iroko and Dabéma extracts and a red coloration with Tali and Azobé extracts. The use of extractives to inhibit bacterial growth showed that the extractives were bacteriostatic and bacteriocidal for the concentrations tested.
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Submitted on : Monday, March 29, 2021 - 4:54:29 PM
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Henri Meyo Degboevi. Variabilité intra spécifique de la composition chimique des connexes issus de la première transformation du bois de différentes essences gabonaises et valorisations chimiques potentielles. Chimie organique. Université de Lorraine, 2020. Français. ⟨NNT : 2020LORR0203⟩. ⟨tel-03184667⟩

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