Analytical Sciences

Preparation of Cyclic-1,N²-propano-2′-deoxyguanosine-d₇ as an Internal Standard for ESI-MS/MS Determination of DNA Damage from Acetaldehyde

Yukihiro ESAKA,*,** Saki KUNISHIMA,* Hiromitsu ARUGA,* Takuhei YAMAMOTO,* Hiroya MURAKAMI,*** Norio TESHIMA,*** and Bunji UNO*,**

*Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
**United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, 1-1 Yanaido, Gifu 501-1194, Japan
***Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan

Cyclic-1,N²-propano-2′-deoxyguanosine-d₇ (CPr-dG-d₇) was prepared as an isotopic internal standard (IS) for electrospray ionization tandem mass spectrometry (ESI-MS/MS) quantification of CPr-dG in DNA as a candidate cancer risk marker of acetaldehyde intake, mainly from drinking. The deuterated compound was reasonably synthesized from acetaldehyde-d₄ and 2′-deoxyguanosine in deuterium oxide (D₂O), preventing the deuterium atoms of acetaldehyde-d₄ from being substituted by hydrogen atoms, which occurred seriously in aqueous synthesis media via keto–enol tautomerism. Furthermore, another deuterium atom was added from D₂O to form CPr-dG-d₇. After four weeks of storage in H₂O at 10°C, CPr-dG-d₇ was found to be sufficiently stable for practical use. The calibration curve of CPr-dG by using a hydrophilic interaction chromatography–ESI-MS/MS system with CPr-dG-d₇ as the IS showed sufficient linearity from 1.0 × 10⁻¹⁰ to 4.0 × 10⁻⁹ M with r² = 0.998.

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