In Vitro Antioxidant Activity and Total Phenolic Content of Root Extracts from Phragmanthera glaucocarpa (Peyr.) Balle

Background: Africa has a rich diversity of plant species, which can be considered important sources of new chemical compounds that can be used in the development of novel therapeutic drugs. Objectives: The present study aimed at investigating the antioxidant activity and total phenolic content of extracts obtained from the roots of Phragmanthera glaucocarpa (Peyr.) Balle, a plant used in Angola folk medicine. Methods: The prepared extracts were tested for their antioxidant activity using ABTS (2,2’-azinobis-(3-ethyl-benzothiazoline-6- sulfonic acid), DPPH (1’,1’-diphenyl-2-picrylhydrazyl), and peroxide value methods. Total phenolics were evaluated by the Folin- Ciocalteu method. Results: For ABTS, the best EC50 result was obtained with the ethyl acetate fraction (1.060.30 mg/mL). For the DPPH method, the methanol extract and aqueous fraction presented the best EC50 results, 0.100.01 mg/mL and 0.100.00 mg/mL, respectively. The ethyl acetate fraction had the highest phenolic content (280.42 0.15 mg G.A.E. /g of dry extract). The best result for the peroxide reduction value on the eighth day of sunflower oil oxidation was obtained for the aqueous fraction, with 131.401.05 meq O2/g of lipid sample. Conclusions: The results of the present study demonstrate that the roots of the medicinal plant Phragmanthera glaucocarpa (Peyr.) Balle represent a promising source of natural phenolic compounds with antioxidant activity.