Evaluation of antioxidant and antigenotoxic activity of two flavonoids from Rhamnus alaternus L. (Rhamnaceae): kaempferol 3-O-ß-isorhamninoside and rhamnocitrin 3-O-ß-isorhamninoside.

The antioxidant activity of kaempferol 3-O-ß-isorhamninoside (K3O-ir) and rhamnocitrin 3-O-ß-isorhamninoside (R3O-ir), isolated from the leaves of Rhamnus alaternus L., was determined by the ability of each compound to inhibit NBT photoreduction and to scavenge the free radical ABTS(+)(.). Genotoxic and antigenotoxic activities were assessed using the SOS chromotest. At a concentration of 150 µg/assay the two compounds showed the most potent inhibitory activity against superoxide anion by respectively 80.4% and 85.6%. K3O-ir was a very potent radical scavenger with an IC(50) value of 18.75 µg/ml. Moreover, these two compounds exhibit an inhibitory activity against genotoxicity induced by nitrofurantoine and aflatoxine B1 using the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain. In this study, we have also evaluated correlation between antigenotoxic and antioxidant effects of K3O-ir and R3O-ir. The highest correlation was showed with R3O-ir (r=0.999).

Phenolic constituents of galla Rhois with hepatoprotective effects on tacrine- and nitrofurantoin-induced cytotoxicity in Hep G2 cells.

The bioassay-guided fractionation of the MeOH extract of Galla Rhois furnished two hepatoprotective compounds, an equilibrium mixture of 3-galloyl-gallic acid and 4-galloyl-gallic acid isomers (3), 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (4), and two inactive phenolic compounds, gallic acid methyl ester (1) and gallic acid (2). Compounds 3 and 4 showed significant hepatoprotective effects with EC50 values of 70.39+/-5.4 and 29.51+/-0.7 microM, respectively, against tacrine-induced cytotoxicity, and 150.9+/-6.4 and 23.81+/-0.5 microM, respectively, against nitrofurantoin-induced cytotoxicity in Hep G2 cells.