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Variability study and chemical modification of Mesquitol, a polyphenolic extractive of Prosopis juliflora : Application to wood preservation

Abstract : Earlier work from the laboratory (LERMaB, France) helped to highlight that the heartwood of Prosopis juliflora contains significant amounts of mesquitol, a relatively rare flavonoid with antioxidant properties, otherwise identified as 2-(3,4-dihydroxyphenyl)chromane-3,7,8-triol. P. juliflora has been rated among the worst world invasive species and therefore this study aimed at finding solutions to this menace that is fast spreading into areas that are otherwise intended for useful purposes like farming or grazing. With no data existing on the exact amounts of mesquitol present in P. juliflora or its variability depending on the geographic location of the tree or the tree’s age, the study commenced by first availing this data. This was done by a substantive study on P. juliflora stem samples that had been collected from three different geographic regions in Kenya (Baringo County, Garissa County and Turkana County). Compounds identification and quantification were done one using the GC-MS and the LC-ESI-MS/MS. A systematic study on the mass spectra and the observed fragmentations illustrated a rich array of phenolic compounds present in P. juliflora. Among these compounds is a mesquitol dimer, which has been identified for the very first time here. The results also showed that mesquitol compound is the most abundant compound in P. juliflora with high amounts of 11 % being found in the heartwood of the big trees from Baringo County. The second part of the study focused on the chemical modification of mesquitol targeting specific derivatives which could enhance the lipophilicity of mesquitol hence help in decreasing leachability. Various reactions of mesquitol with various carboxylic acids were performed allowing grafting of long fatty chains (lipophilic part) onto mesquitol through the aliphatic 3-OH position. Some of these derivatives were used to evaluate their ability to protect wood against fungal attack from both a white-rot and a brown-rot fungus. From the results of this study, it is evident that mesquitol derivatives obtained from reaction with carboxylic acids can be used as wood preservatives when used together with low amounts of tebuconazole.
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Theses
File URL :
http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2019_0258_CHEPKWONY.pdf
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https://hal.univ-lorraine.fr/tel-02558238
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Submitted on : Wednesday, April 29, 2020 - 1:45:16 PM
Last modification on : Thursday, April 30, 2020 - 1:19:37 AM

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  • HAL Id : tel-02558238, version 1

Citation

Sarah Cherono Chepkwony. Variability study and chemical modification of Mesquitol, a polyphenolic extractive of Prosopis juliflora : Application to wood preservation. Materials. Université de Lorraine; Moi University, 2019. English. ⟨NNT : 2019LORR0258⟩. ⟨tel-02558238⟩

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