Evaluation of the Antioxidant Activity of Aqueous and Hydro-Ethanolic Extracts of Ficus capensis, Newbouldia laevis and Carpolobia lutea

Abstract

Scientific interest in the search for natural antioxidants (secondary metabolites) in medicinal plants has increased considerably in recent years, as free radicals are at the root of many diseases. The aim of this study was to evaluate the antioxidant activity of aqueous and hydroethanol extracts from the leaves of a basic plant product consisting of equal quantities of Ficus capensis, Newbouldia laevis and Carpolobia lutea. Quantitative determination of antioxidant activity was based on the flavonoid content of the base plant product. It was assessed by DPPH (2, 2-diphenyl-l-picrylhydrazyl) reduction tests and ferric ion reducing power (FRAP). The results of this study showed that the hydro-ethanol extract of the basic plant product is richer in flavonoids than that of the aqueous extract. In addition, the ICs50 of the aqueous and hydro-ethanolic extracts of the base plant product with DPPH were 2.13 ± 0.01 µg/mL and 1.19 ± 0.03 µg/mL respectively. In the FRAP test, the reducing powers of the hydroethanolic extract were generally higher than those of the aqueous extract at all concentrations tested. Particularly at the high concentration of 10 µg/mL, the reducing powers of the aqueous and hydroethanol extracts of the base plant product are 435.86 ± 1.29 µg/mL and 453.68 ± 0.71 µg/mL respectively. The hydroethanol extract therefore has better antioxidant activity than the aqueous extract.