Formation of Spiroiminodihydantoin Nucleosides from 8-Oxo-7,8-dihydro-2'-deoxyguanosine by Ultraviolet Light

摘要

When 8-oxo-7,8-dihydro-2'-deoxyguanosine in potassi-um phosphate buffer of pH 7.4 was irradiated by UV light from a mercury lamp, two major products were formed. They were identified as the diastereomers of spiroiminodi-hydantoin deoxyribonucleoside on the basis of their identi-cal ESI-MS and UV spectra and HPLC retention times with those of the authentic samples. Degradation of 8-oxo-7,8- dihydro-2'-deoxyguanosine by UV light was faster than those of 2'-deoxyguanosine, 2'-deoxycytidine, 2'-deoxy-adenosine, and thymidine. Sunlight also generated the di-astereomers of spiroiminodihydantoin from 8-oxo-7,8-di-hydro-2'-deoxyguanosine. The results suggest that sun-light may induce 8-oxo-7,8-dihydroguanine oxidation in DNA, generating spiroiminodihydantoin in humans.