Oxidative stress is thought to be the main cause of several pathologies; that is why research is focussing on the characterization of bioactive natural substances with antioxidant activity to replace synthetic molecules. The antioxidant activity of extracts of Fraxinus angustifolia Reut. ex Nyman and Pistacia lentiscus L., two medicinal plants used to treat inflammatory-related disorders was determined.
The results indicated that aqueous chloroform extract of Pistacia lentiscus exhibited a great reducing power of 657.86±35.25mg Ascorbic Acid Equivalent/g of the extract, compared to that of the aqueous extract from Fraxinus angustifolia (260.73±22.38mg Ascorbic Acid Eq/g of extract). Extracts issued from both plants showed an outstanding capacity in scavenging the (DPPH) 2, 2-diphenyl-1-picrylhydrazyl (90%) and (ABTS) 2,2-azobis-ethylbenzothiazoline-6-sulphonic acid (85%) radicals at a concentration of 100µg/ml, even higher than that of the standards: (BHA) butylhydroxyanisol and quercetin. Moreover, Pistacia lentiscus extracts showed relatively high scavenging activity (64.86% at 100µg/m) against hydrogen peroxide, better than that of ascorbic acid (40.09%) and caffeic acid (45.59%) at the same concentration, while Fraxinus angustifolia extracts showed significant activity only at high doses (400µg/ml).
Column chromatography associated with thin layer chromatography analysis of plant extracts allowed the recovery of fractions responsible for high antiradical activity. Determination of total phenols and tannins plead for a major role of these compounds in the observed high antioxidant activity and may well explain the use of these plants in traditional medicine.
Keywords:
Fraxinus angustifolia, Pistacia lentiscus, Phenolic compounds, antioxidant, active fractions
Acknowledgement:
We wish to thank the Ministry of Education and Scientific Research of Algeria for sponsoring this work Grant number: F00620070022
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