RESUMO
<p><b>OBJECTIVE</b>To evaluate the antioxidant capacity of four leaf-derived solvent extracts of Artemisia annua (A. annua), a medicinal plant widely touted for its vast phyto-therapeutic potential.</p><p><b>METHODS</b>A. annua leaves were extracted with four solvents (absolute ethanol, absolute methanol, 70% ethanol and 70% methanol), and extracts obtained studied by five complementary in vitro antioxidant test systems using ascorbic acid (vitamin C) and rutin as standard references.</p><p><b>RESULTS</b>The extracts remarkably inhibited lipid peroxidation (79.81%-86.70%), and erythrocyte haemolysis (40.02%-49.91%). Their IC50 values for hydroxyl, nitric oxide and hydrogen peroxide radical scavenging activities ranged from 2.39-3.81 mg/mL (superior to the standards), 107.24-144.49 µg/mL and 28.53-53.20 µg/mL, respectively. 70% alcohol extracts generally showed better antioxidant activity than absolute alcohol extracts.</p><p><b>CONCLUSIONS</b>The results indicate that A. annua leaf extracts have potent antioxidant activities that would have beneficial effect on human health, and aqueous organic solvents are superior to the absolute counterparts in yielding extracts with better antioxidant potential.</p>