Antioxidant activity of yellow dock (Rumex crispus L., Polygonaceae) fruit extract.

The methanol extract of ripe Rumex crispus L. fruits was evaluated for its antioxidant potential by assays for ferric-reducing antioxidant power (FRAP), DPPH-free radical scavenging activity (DPPH) and the influence on lipid peroxidation in liposomes (LP). Considerable activity was observed in all test systems (FRAP: 9.9 mmol Fe(2+) /g; DPPH IC(50) : 3.7 μg/mL; LP IC(50) : 4.9 μg/mL), comparable to that of BHT (FRAP: 8.0 μg/mL; DPPH IC(50) : 19.4 μg/mL; LP IC(50) : 3.5 μg/mL), but lower than the activity of ascorbic acid, rutin and quercetin, used as positive control substances. The in vivo effects were evaluated in several hepatic antioxidant systems (activities of LPx, GSH-Px, Px, CAT and XOD, as well as GSH content), after treatment with the studied yellow dock extract in different doses, or in combination with carbon tetrachloride (CCl(4) ). Pretreatment with the R. crispus extract inhibited CCl(4) -induced oxidative stress by decreasing LPx and increasing GSH content in a dose dependent manner, bringing the levels of antioxidant enzymes to near control values.