Antioxidant activity and total phenolic content of selected Jordanian plant species

There is currently an upsurge of interest in phytochemicals as new sources of natural antioxidants. The aim is to use them in foods and pharmaceutical preparations in order to replace synthetic antioxidants, which are being restricted due to their potential health risks and toxicity. The relative levels of antioxidant activity and the total phenolic content of aqueous and methanolic extracts of a total of 51 plant species of Jordanian origin have been determined using the improved ABTS+ method and the Folin–Ciocalteu colorimetric method. The total phenolic content of aqueous and methanolic extracts of the investigated plant species ranged from 2.8 to 70.3 and from 2.6 to 59.6 mg GAE/g dry weight, respectively, while the total antioxidant capacity ranged from 12.9 to 731 and from 10.1 to 720 μmol TE/g dry weight, respectively. Based on our results, a number of plant species, namely, Arbutus andrachne, Hypericum triquetrifolium and Rosmarinus officinalis, were identified as among the best sources of free radical-scavenging compounds. There was positive linear correlation between antioxidant activity and total phenolic content for aqueous and methanolic extracts. Thus, it was concluded that phenolic compounds were the predominant antioxidant components in the investigated plant species.