Chemical Composition and Antioxidant Activity of Fraxinus ornus L. and Fraxinus excelsior L.

Abstract

In this work, the total content of phenolics, flavonoids, and phenolic acids in the leaves and bark extracts of <i>Fraxinus ornus</i> L. and <i>Fraxinus excelsior</i> L. was determined. In addition, the identification and quantification of phenolic acids was performed using the HPLC-DAD technique. Samples were tested for antioxidant activity using the ABTS and DPPH methods. Eight extract samples were prepared by Soxhlet and ultrasound extraction using 70 % ethanol as solvent. The content of phenolic compounds ranged from 7.59 for <i>F. ornus</i> to 88.93 mg GAE/g for <i>F. excelsior</i> in the bark extracts obtained by Soxhlet extraction. The highest content of total flavonoids in <i>F. ornus</i> and <i>F. excelsior</i> was found in the leaves extracts obtained by ultrasound extraction, which was 5.68 and 1.74 mg GAE/g extract, respectively. The results also showed that the highest content of total phenolic acids was found in <i>F. ornus</i> (105.33 mg CAE/g) and <i>F. excelsior</i> (97.97 mg CAE/g) in the bark extract obtained by Soxhlet extraction. The highest content of gallic acid (112.96 ± 1.32 mg g<sup>–1</sup> extracts) and chlorogenic acid (246.94 ± 0.82 mg g<sup>–1</sup> extracts) was found in the <i>F. ornus</i> bark extract obtained by ultrasound extraction. As for antioxidant activity, the bark extract obtained by Soxhlet extraction of <i>F. ornus</i> showed the best antioxidant activity by ABTS method with IC<sub>50</sub> value of 0.062 mg ml<sup>–1</sup>. The results of the DPPH method show that the leaves extract obtained by Soxhlet extraction had the best antioxidant activity for the <i>F. ornus</i> sample, with an IC<sub>50</sub> value of 0.23 mg ml<sup>–1</sup>.