Walnut (Juglans regia) leaf extracts are strong scavengers of pro-oxidant reactive species
2008
Almeida, I.F. | Fernandes, E. | Lima, J.L.F.C. | Costa, P.C. | Bahia, M.F.
The growing interest in the substitution of synthetic food antioxidants by natural ones has fostered research on vegetable sources and on the screening of raw materials, for identifying new antioxidants. In the present study, an ethanol:water (4:6) extract from Juglans regia leaves was evaluated for its putative in vitro scavenging effects on reactive oxygen species (ROS) [hydroxyl radical, superoxide radical, peroxyl radical and hydrogen peroxide (H₂O₂)] and reactive nitrogen species (RNS) [nitric oxide and peroxynitrite anion (ONOO⁻)]. The extract presented a potent scavenging activity against all the reactive species tested, all the IC₅₀s being found at the μg/mL level. IC₅₀s (mean ± SE) for the ROS superoxide radical and H₂O₂ were 47.6 ± 4.6, 383 ± 17 μg/mL, respectively. The oxygen radical absorbance capacity (ORAC) value obtained for ROO was 2.17 ± 0.22 μmol Trolox equivalents/mg extract. The IC₅₀s for nitric oxide and ONOO⁻ were 1.95 ± 0.29 and 1.66 ± 0.10 μg/mL, respectively. The content of total phenolics was 270 ± 3 mg of gallic acid equivalents (GAE)/g of lyophilised extract. These results showed that J. regia leaf extracts can be used as an easily accessible source of natural antioxidants.
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