Quercus coccifera L., Quercus suber L., fruit extracts: a suitable natural source ofantioxidants and antimicrobial, namely against phytopathogen fungi

Abstract: The application of insecticides and synthetic antibiotics is currently the commonmethod to control or eradicate pest animals and plants. Many of these chemicals have nonspecific properties and side effects. Plants synthesise a vast array of secondary metabolites thatare gaining importance for their biotechnological applications. The aim of this work was to assessthe effect of different solvents on the antifungal and the antioxidant activity of some extractsobtained from the healthy acorns of Tunisian Quercus coccifera L. and the infested acorns ofAlgerian Quercus suber L., found fallen on the soil. Water and organic solvents such as acetone,ethanol and chloroform significantly affected the total polyphenol content (44.6 to 173mg GAE/gdry weight extract). Results showed a strong correlation between polyphenol contents and theantioxidant potential of these extracts (correlation ranging between R2 = 0.82 and R2 = 0.91).It is also noteworthy that most of the extracts, obtained from both populations of Quercus,showed a significant and dose-dependant antifungal activity as assessed by the well diffusionassay against the majority of tested phytopathogens. It is worth to note that extracts from infestedfruits of Q. suber exhibited greater antifungal activity apparently associated with a differentphenolic compounds pattern, after infestation by larvae; probably responsible for a deepbiochemical transformation that gave a disparate chemical profile. The results could be veryhelpful to formulate an alternative explanation for the apparent relationship between changes inphenolic content and insect predation. Thereby, some of these extracts could be suitable for use inbiological control namely as safe anti-fungal in agriculture to control or eradicate crops, fruits andpostharvest pests.