Evaluation of the in vitro antioxidant activities of Xylopia aethiopica methanolic extract

Abstract

Xylopia aethiopica (Xae) (the popular name is Guirani) is a medicinal plant that belongs to Annonaceae family, it is used in African folk medicine to treat rheumatism, bronchitis, asthma, stomach-aches along with a wide range of disorders. The aim of this study was to evaluate the antioxidant activity of Xae fruit’s methanolic extract that was obtained by Soxhlet extraction with a yield of 38.5 %. The total phenolic contents were determined using Folin-Ciocalteu reagent (49.52 ± 2.68 μg GAE/mg ext). While, total flavonoid contents were determined using aluminum trichloride reagent (1.93 ± 0.06 mg QE/g ext). The antioxidant activity was evaluated using DPPH radical scavenging, ferrous iron chelating and ferric reducing antioxidant abilities as well as β-carotene bleaching assay. In DPPH radical scavenging test, the extract exhibited an IC50 of 0.14 ± 0.002 mg/ml, which is lower than that of BHT standard. Also, a low ability of ferrous chelating (1.33 ± 0.03 mg/ml) was observed compared to EDTA that have an IC50 of 0.006 mg/ml). Extract had a low ability to reduce ferric ion (EC50 = 0.07 ± 0.01 mg/ml) compared to ascorbic acid (EC50 = 0.05 ± 0.001 mg/ml). Xae extract showed a lower inhibitory activity of β-carotene oxidation with a value of 47.79 %, less effective than BHT (98.16 %). Based on these results, Xylopia aethiopica is a poor source for polyphenols and flavonoids and possesses, generally, low antioxidant activities.