A novel C-14-postlabeling assay using accelerator mass spectrometry for the detection of O-6-methyldeoxy-guanosine adducts

摘要

Accelerator mass spectrometry (AMS) is currently one of the most sensitive methods available for the trace detection of DNA adducts and is particularly valuable for measuring adducts in humans or animal models. However, the standard approach requires administration of a radiolabeled compound. As an alternative, we have developed a preliminary C-14-postlabeling assay for detection of the highly mutagenic O-6-methyldeoxyguanosine (O-6-MedG), by AMS. Procedures were developed for derivatising O-6-MedG using unlabeled acetic anhydride. Using conventional liquid chromatography/mass spectrometry (LC/MS) analysis, the limit of detection (LOD) for the major product, triacetylated O-6-MedG, was 10 fmol. On reaction of O-6-MedG with C-14-acetic anhydride, using a specially designed enclosed system, the predominant product was C-14-di-acetyl O-6-MedG. This change in reaction profile was due to a modification of the reaction procedure, introduced as a necessary safety precaution. The LOD for C-14-di-acetyl O-6-MedG by AMS was determined as 79 amol, similar to 18 000-fold lower than that achievable by liquid scintillation counting (LSC). Although the assay has so far only been carried out with labeled standards, the degree of sensitivity obtained illustrates the potential of this assay for measuring O-6-MedG levels in humans. Copyright (c) 2006 John Wiley & Sons, Ltd.