When the native possibilities of the body antioxidant defence are exceeded, the oxidative stress is installed;  the excessive amount of reactive oxygen and nitrogen species (ROS and RNS) generates numerous various diseases. As a result, scientific research around the world aims to discover new substances for neutralizing them. Because the plant world is a reliable source of antioxidant compounds, this study proposes to evaluate the antioxidant potential of the extracts of Usnea barbata (L.) F.H.Wigg. (U. barbata). Known in traditional Chinese medicine as Song Luo and used for over 2000 years in treating various diseases, this species contains phenolic compounds, which can neutralize ROS.  U. barbata extracts in ethanol, water and acetone were obtained by hot reflux, 30 min.  Their antioxidant potential (AP) was determined by reducing 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals; for the phenolic content (PC), the reagent Folin Ciocalteu (phosphomolybdotungstic acid) was used. The obtained results indicate that AP and PC are directly proportional to the concentration of each extract tested. The ethanol extract has the highest AP, followed, in descending order, by the aqueous and acetone ones. The highest PC is found in the acetone extract, followed by the ethanol and aqueous extract. The classical polyphenols with free hydroxyl radicals and the most increased antioxidant activity, extracted in principal in ethanol and water, could explain these AP and PC variations.

Acknowledgments: This work is supported by the project “ANTREPRENORDOC”, in the framework of Human Resources Development Operational Programme 2014-2020, financed from the European Social Fund under the contract number 36355/23.05.2019 HRD OP /380/6/13 – SMIS Code: 123847.