Antioxidant effect of the marine green alga Ulva rigida ethanolic precipitate in yeast cells and zebrafish embryos

The antioxidant potential of the ethanolic precipitate (EP) of the marine green alga Ulva rigida was evaluated via its scavenging ability on 1, 1-dipheny-2-picrylhydrazyl (DPPH) and cytoprotection against H 2 O 2 -induced damage in yeast cells and zebrafish embryos. The EP exhibited substantially stronger DPPH scavenging activity (92.5%) at 1 μg/mL than the positive control, gallic acid (84%) at 18 μg/mL. Pretreatment with different concentrations of EP (0.005, 0.3, 0.5 or 1 μg/mL) significantly protected yeast cell and zebrafish embryo from death induced by H 2 O 2 and blocked H 2 O 2 -induced modifications of superoxide dismutase (SOD) and catalase (CAT) activities when administrated at 0.3 μg/ml. The protective effect of the EP was comparable to the effect produced by the antioxidant, N-acetylcysteine (NAC) at 50 μM. In addition, the antioxidant potential of the EP was stable up to a temperature of 60 °C. In sum, these findings demonstrate that the PE of U . rigida exhibited a preventive action against H 2 O 2 -induced oxidative stress.