DETERMINATION OF PHENOLIC CONTENT AND ANTIOXIDANT CAPACITY OF Fraxinus excelsior L. AND Fraxinus angustifolia VAHL. LEAVES AND BARK EXTRACTS

Abstract

UDK: 581.19:547.56]:582.916.16 
 In this work, Fraxinus excelsior L. and Fraxinus angustifolia Vahl. leaves and branches bark extracts have been estimated for their phenolic content and antioxidant capacity. The antioxidant capacity was examined by DPPH and FRAP methods.
 Higher contents of total phenols (23.94- 46.98 mg GAE g-1) and flavonoids (6.30 – 9.14 mg RE g-1 and 3.67 – 5.34 mg QE g-1) have been determined in leaves than in the bark for both species. The bark contained higher amounts of total phenolic acids (17.79 – 36.67 mg CAE g-1), coumarins (27.91 – 70.98 mg CE g-1) than the leaves. F. excelsior bark had higher content of proanthocyanidins (4.14 – 7.95 mg LCE g-1) while F. angustifolia leaves were richer in proanthocyanidins (5.76 – 11.16 mg LCE g-1). Generally, higher amounts of bioactive compounds and better antioxidant capacity was found for F. angustifolia. Also, extracts of F. excelsior bark and F. angustifolia leaves displayed higher antioxidant activities. Established correlations between phenols (r2 = 0.8381 – 0.9228), phenolic acids (r2 = 0.8799 – 0.9843), coumarins (r2 = 0.9223 – 0.9716) and antioxidant capacity determined by DPPH and FRAP shown these compounds are the main contributors to the antioxidant capacity in leaves and bark of investigated species.