| Summary: | 碩士 === 國立中正大學 === 化學暨生物化學研究所 === 99 === The promutagenic etheno DNA adducts, including 1,N6-ethenoadensine (εAde), 3,N4-ethenocytosine (εCyt), and 1,N2-ethenoguansine (1,N2-εGua), are derived from exogenous as well as endogenous sources, such as lipid peroxidation. And oxidation DNA adduct, 8-hydroxy-2’-deoxyguanosine (8OHdG) is derived from oxidation stress. The levels of etheno DNA adducts are elevated in cancer-prone tissues, and increasing to high oxidation stress. In this study, we developed a highly specific and sensitive method for simultaneous quantification of etheno DNA adducts: εAde, εCyt , 1,N2-εGua, and 8OHdG in human urine by stable isotope dilution capillary LC-nanospray ionization tandem mass spectrometry (capillary LC-NSI/MS/MS) under the highly selective reaction monitoring (H-SRM) mode. A C18-OH solid phase extraction column was used to enrich the εAde and 8OHdG, which were analyzed by capillary LC-NSI/MS/MS on a triple quadrupole instrument. Also tried is the mixed-mode cation exchange cartridge , that to enrich εCyt and 1,N2-εGua. The detection limit of εAde, εCyt and 1,N2-εGua injected on-column was 0.63, 0.74 and 2.27 fmol, respectively. With a minimum amount of urine (10 μl), this capillary LC-NSI/MS/MS method provides a useful assay in measuring etheno adducts and oxidative adduct as noninvasive biomarkers in cancer risk assessment.
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