COMME EXIGENCE PARTIELLE DE LA MAÎTRISE EN RESSOURCES RENOUVELABLES PAR KARL GIRARD-LALANCETTE BACHELIER ES SCIENCES (BIOLOGIE) ÉVALUATION DU POTENTIEL ANTIOXYDANT DE LA BIOMASSE FORESTIÈRE ET MARINE Février 2009 RÉSUMÉ Depuis que les radicaux libres ont été découverts, leur implication dan

The bark of boreal forest conifers bas been, traditionally used, by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In the context of this study, ultrasonic assisted extraction has been performed uader various soiveat conditions (water:ethanol mixtures) on tke bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Firms banksiana, Picea mariana. Picea glauca. Larix lancina aad Abies balsamea. The total phenol content, as well as ORACpi, potency and cellular antioxidant activity (IC50X were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritime/ bark (pycnogenol), which showed clinical efficiency to prevent ROS deleterious effects. Considering all conifers aad all extraction conditions, our results reveal higher total phenol content wad antioxidant potency than pycnogenol. Moreover., all extracts revealed only a. weak or an absence of toxicity oa human ftbrobla&ts (WSI). When taking all tested conditions into account, s moderate but significant corrélation is found between total phenol content and ORAC-H, (R=§.555; pO.OS) or aatioxidant IC5& values (R~=Q.449, p<0.05). Moreover, we found a good and sïgpificaïit correlation when considering water extracts oaly^ suggesting that phenolic compounds may be responsible, in part, for theaatioxidaat activity of water extracts measured with OKACn. (RN).93; p<0.05) and the cell-based antioxidaat assay (R=G.81; p<0.05).