Chemical composition and biological activities of essential oils of Salvia officinalis aerial parts as affected by diurnal variations

The main objective of this work is to evaluate the impact of the diurnal variation on the essential oil (EO) of Salvia officinalis and on their antioxidant, antifungal and insecticidal potentials. Obtained results showed that the chemical composition of EOs of sage varied significantly during the day. For the EO, the 7 am extract was characterized by the most significant antiradical activity. The EOs of 12 and 5 pm used at a dose of 10 μL were found to have the most effective potential to inhibit the growth of Botrytis cinerea whereas, the EO of 5 pm used at the same dose (10 μL) was the most effective against Fusarium sambucinum. For the fumigant test, the EO from 7 am had the highest activity against Spodoptera littoralis. The EO of 12 pm had the largest repellency activity against Trogoderma granarium. In addition, the EO from 7 am belongs to the repulsive class III, those of 12 and 5 pm belong to the repulsive class IV. The results of this study indicate how to optimize the best harvesting hour to obtain extracts characterized by the best yield of active compounds and by the more effective biological activity.