Biphenyl compounds are hydroxyl radical scavengers: their effective inhibition for UV-induced mutation in Salmonella typhimurium TA102.

In our previous study, we found several hydroxylated biphenyl compounds have a great scavenging effect for hydroxyl radicals (.OH). In this study, to elucidate the relationship between generation of the .OH and photo-mutagenesis, six biphenyl compounds such as dehydrodieugenol, dehydrodivanillyl alcohol, dehydrodidihydroeugenol, dehydrodicreosol, magnolol and honokiol, respectively, were examined for their ability to inhibit UV-induced mutation in Salmonella typhimurium TA102. The relative mutagenic activities (RMA, %) indicated the mutation frequency of treated cells divided by the mutation frequency of control cells times 100%. The RMA (%) are as follows: 28 +/- 1, 31 +/- 1, 33 +/- 1, 41 +/- 2, 62 +/- 1, and 62 +/- 4 at concentrations of 5 micrograms per plate for dehydrodieugenol, dehydrodivanillyl alcohol, dehydrodidihydroeugenol, dehydrodicreosol, magnolol, and honokiol, respectively. These values indicate that low concentrations of these biphenyl compounds effectively suppress UV-induced mutagenesis. Also, these compounds acted as effective antimutagens in a dose-dependent manner (0.00005-5 micrograms per plate). These compounds are effective .OH scavengers. Consequently, the results obtained above suggest that these compounds could inhibit against UV-induced mutations by scavenging of .OH generated by UV irradiation. The results also suggest that .OH are associated with UV-induced mutation in Salmonella typhimurium TA102.