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

Bopenga Bopenga C.S.A., Meyo Degboevi H., Candelier K., Edou Engonga P., Dumarçay S., Thévenon M.F., Gérardin Charbonnier C., Gérardin P.. 2020. Journal of Renewable Materials : 17 p..

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 andß-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.

Thématique : Maladies des plantes; Ravageurs des plantes; Technologie des produits forestiers

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