title: Chemical decomposition of 5-aza-2'-deoxycytidine (Decitabine): kinetic analyses and identification of products by NMR, HPLC, and mass spectrometry.
abstract: The nucleoside analogue 5-aza-2'-deoxycytidine (Decitabine, DAC) is one of several drugs in clinical use that inhibit DNA methyltransferases, leading to a decrease of 5-methylcytosine in newly replicated DNA and subsequent transcriptional activation of genes silenced by cytosine methylation. In addition to methyltransferase inhibition, DAC has demonstrated toxicity and potential mutagenicity, and can induce a DNA-repair response. The mechanisms accounting for these events are not well understood. DAC is chemically unstable in aqueous solutions, but there is little consensus between previous reports as to its half-life and corresponding products of decomposition at physiological temperature and pH, potentially confounding studies on its mechanism of action and long-term use in humans. Here, we have employed a battery of analytical methods to estimate kinetic rates and to characterize DAC decomposition products under conditions of physiological temperature and pH. Our results indicate that DAC decomposes into a plethora of products, formed by hydrolytic opening and deformylation of the triazine ring, in addition to anomerization and possibly other changes in the sugar ring structure. We also discuss the advantages and problems associated with each analytical method used. The results reported here will facilitate ongoing studies and clinical trials aimed at understanding the mechanisms of action, toxicity, and possible mutagenicity of DAC and related analogues.
authors.affiliation: Department of Basic Sciences, Loma Linda University School of Medicine, Alumni Hall for Basic Science, Room 101, 11021 Campus Street, Loma Linda, California 92350, USA.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Rogstad
authors.forename: Jason L
authors.initials: JL
authors.lastname: Herring
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Theruvathu
authors.forename: Artur
authors.initials: A
authors.lastname: Burdzy
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Perry
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Neidigh
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Sowers
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine