Characterization of spiroiminodihydantoin as a product of one-electron oxidation of 8-oxo-7,8-dihydroguanosine

[GRAPHICS] Further oxidation of the common DNA lesion 8-oxo-7,8-dihydroguanosine by one-electron oxidants such as IrCl62-, Fe(CN)(6)(3-), or SO4- leads to two major products, depending upon reaction conditions. In nucleosides at pH 7, 22 degrees C, the principal product is shown herein to be a spiroiminodihydantoin nucleoside, as a diastereomeric mixture, that can be characterized by NMR, ESI-MS/MS, and independent synthesis.