Chemiluminescence assay for reactive oxygen species scavenging activities and inhibition on oxidative damage of DNA in Deinococcus radiodurans

Free radical scavenging effects of the cellular protein extracts from two strains of Deinococcus radiodurans and Escherichia coli against O-2(-), H2O, and (OH)-O-. were investigated by chemiluminescence (CL) methods. The cellular protein extracts of D. radiodurans R1 and KD8301 showed higher scavenging effects on O-2(-) than that of E. coli. D. radiodurans RI and KD8301 also strongly scavenged H2O2 with an EC50 (50% effective concentration) of 0.12 and 0.2 mg/mL, respectively, compared to that of E. coli (EC50 = 3.56 mg/mL). The two strains of D. radiodurans were effective in scavenging (OH)-O-. generated by the Fenton reaction, with EC50 of 0.059 and 0.1 mg/mL, respectively, compared to that of E. coli (EC50 > 1 mg/mL). Results from the chemiluminescence assay of (OH)-O-.-induced DNA damage and the plasmid pUC18 DNA double-strand break (DSB) model in vitro showed that D. radiodurans had remarkably inhibitory effect on the (OH)-O-.-induced oxidative damage of DNA. The scavenging effects of D. radiodurans on reactive oxygen species (ROS) played an important role in the response to oxidation stress and preventing against DNA oxidative damage, and may be attributed to intracellular scavenging proteins, including superoxide dismutase (SOD) and catalase. Copyright (C) 2004 John Wiley Sons, Ltd.