Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

The aim of the study was to evaluate natural antioxidant properties of Populus alba. The antioxidant effects in plants are mainly due to the presence of phenolic compounds such as flavonoids, phenolic acids, tannins and phenolic diterpenes. Oxidative damage is implicated in most diseases processes. In vitro studies are able to demonstrate for flavonols and flavones a considerable antioxidative activity, mainly based on scavenging of oxygen radicals. The antioxidative potential of different fractions (respective organic fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Populus alba was evaluated using free radical-scavenging activity on DPPH (1,1-diphenyl-2-picrylhydrazyl ) assays. The methanol extract showed significant (p<0.05) activities in all antioxidant assays and contained a high level of total phenolic content. It was observed that the level of hydrophilic phenolic content was higher than that of hydrophobics. Among those organic solvent fractions, ethyl acetate fraction exhibited significant activities due to the highest level of total phenolic content and their IC50 values were 0.18±0.02 mg/mL, 0.26±0.03mg/mL and 0.28±0.02 mg/mL in DPPH, respectively. These activities were superior to those of a commercial natural antioxidants tested. The chloroform and hexan fractions also exhibited significant (p<0.05) free radical-scavenging activity, attributed to the high amount of hydrophilic phenolics.