Quantitative analysis of malondialdehyde-guanine adducts in genomic DNA samples by liquid chromatography/tandem mass
Sally A Yates1, Nicola M Dempster1, Mark F Murphy1
1School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK.
Rationale:
The lipid peroxidation product malondialdehyde forms M1 dG adducts with guanine bases in genomic DNA. The analysis of these adducts is important as a biomarker of lipid peroxidation, oxidative stress and inflammation which may be linked to disease risk or exposure to a range of chemicals.
Methods:
Genomic DNA samples were subjected to acid hydrolysis to release the adducts in the base form (M1 G) alongside the other purines. A liquid chromatography/mass spectrometry method was optimised for the quantitation of the M1 G adducts in genomic DNA samples using product ion and multiple reaction monitoring (MRM) scans.
Results:
Product ion scans revealed four product ions from the precursor ion; m/z 188 → 160, 133, 106 and 79. The two smallest ions have not been observed previously and optimisation of the method revealed that these gave better sensitivity (LOQ m/z 79: 162 adducts per 107 nucleotides; m/z 106: 147 adducts per 107 nucleotides) than the other two ions. An MRM method gave similar sensitivity but the two smallest product ions gave better accuracy (94-95%). Genomic DNA treated with malondialdehyde showed a linear dose-response relationship.
Conclusions:
A fast reliable sample preparation method was used to release adducts in the base form rather than the nucleoside. The methods were optimised to selectively analyse the adducts in the presence of other DNA bases without the need for further sample clean-up. Analysis of genomic DNA gave results consistent with previous work and was applied to new samples. Thus, the method is suitable for the analysis of M1 (d)G adducts in biological samples. Copyright © 2017 John Wiley & Sons, Ltd.
