Phenolic compounds and in vitro antioxidant activity of Moringa stenopetala grown in South Ethiopia

Moringa stenopetala is a traditional medicinal and nutritional plant in Ethiopia. The aim of this work was to carry out a chemical analysis focusing on secondary metabolites, particularly phenolic compounds, and antioxidant activity of aqueous and methanol extracts of Moringa stenopetala leaf. The phenolic compounds were analyzed by high-performance liquid chromatography diode array detector (HPLC-DAD). Hydroxycinnamic acid (538 ± 6 µg/g), 3-Hydroxbenzoic acid (31 ± 6 µg/g), and quercetin-3-O-rutinoside (1155 ± 65 µg/g) were the major components in methanol extract. Whereas, syringic (84 ± 13 µg/g), chlorogenic (165 ± 19 µg/g), succinnic (1811 ± 105 µg/g), and fumaric (1582 ± 65 µg/g) acids were the major organic acids in the aqueous extract. Methanol extract had higher total flavonoid (11 ± 2 mg of catechin equivalent per gram of dried extract) and total phenolic (39 ± 3 mg of gallic acid equivalent per gram of dried extract) contents. This extract showed stronger DPPH scavenging (EC50 = 78 ± 6 μg/mL) and ferrous chelating (EC50 = 239 ± 12 μg/mL) activities. Due to the abundance sources of bioactive compounds and antioxidant activity, the dried leaf of M. stenopetala could be used for the development of nutraceuticals or incorporated into functional foods.