DNA CLEAVAGE PROTECTING ACTIVITY AND IN VITRO ANTIOXIDANT POTENTIAL OF AQUEOUS EXTRACT FROM FRESH STEMS OF RHEUM RIBES

Rheum ribes L. (Polygonaceae) is a common species of rhubarb in Turkey, which is also found in Iraq, Iran, Pakistan, Afghanistan, and Russia. The antioxidant potency of stems was investigated employing various in vitro systems, such as lipid peroxidation in rat brain homogenate, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical scavenging, ferric reducing power, metal chelation activity. R. ribes stem parts showed strong inhibitory activity toward lipid peroxidation of rat brain homogenate induced by the FeCl3-ascorbic acid system. R. ribes extract was able to reduce the stable free radical DPPH 83.9+/-1.90% at 150 mu g ml(-1). The reducing power of the extract was 0.46+/-0.074 at 250 mu g ml(-1). The effect of extract of R. ribes on DNA cleavage induced by UV-photolysis of H2O2 using pBluescript M13+ plasmid DNA was also investigated. This extract significantly inhibited DNA damage induced by reactive oxygen species (ROS). These findings demonstrate that aqueous extract from fresh stems of R. ribes has antioxidant activity and thus have great potential as a source for natural health products.