Chemical profiles and antioxidant activities of the essential oils of two medicinal plant species grown in Tunisia

A comparison of leaves essential oil composition and antioxidant activity of the two medicinal plant species Juniperus oxycedrus and Juniperus phoenicea grown in Tunisia is reported in this study. The highest yield of essential oil was recorded for J. phoenicea (0.34%, w/w) whereas J. oxycedrus exhibited the lowest yield (0.18%). Qualitative and quantitative variations in the composition of oils according to species were shown. Tunisian sample of those species are especially rich of β-phellandrene. Based on both tests DPPH (2,2-di-phenyl-1-picrilhydrazyl) and FRAP (ferric reducing antioxidant power), the two species presented high levels of antioxidant capacities. The DPPH test shows the highest antioxidant activity (ic₅₀=20.1±0.1 μg/mL) for the species J. oxycedrus while J. phoenicea presented the lowest antioxidant activity (ic₅₀=25.4±0.3 μg/mL). The highest level of ferric reducing ability of volatile oils is recorded for J. oxycedrus (15.90±0.87 μmol Fe²⁺/g), whereas J. phoenicea exhibits the lowest level (10.99±0.52 μmol Fe²⁺/g).