Beta ray-induced scission of DNA in tritiated water and protection by a green tea percolate and (-)-epigallocatechin gallate.

The beta-ray induced scission of puC18 plasmid DNA from E. coli in tritiated water was examined in the presence or absence of a green tea percolate (TP) and the main constituent, (-)-epigallocatechin gallate (EGCg). An analysis of the ratio of the original closed-circular to the open-circular form of DNA, which was formed by the strand scission of DNA, revealed that TP and EGCg showed a protective effect on DNA scission depending on their concentrations. A new technique, named solid state spin trapping, was applied to examine this scavenging ability toward the hydroxyl (OH) radical generated in tritiated water. The result was kinetically analyzed to reveal that TP and EGCg showed the scavenging effect, suggesting that the protective effect on DNA scission was attributable to the scavenging effect on the OH radical.