HR-MS Analysis of the Covalent Binding of Edaravone to 5-Formylpyrimidine Bases and a DNA Oligonucleotide Containing a 5-Formylcytidine Residue

Rationale

Edaravone (EDA) is a radical scavenger and an antioxidant drug approved to treat amyotrophic lateral sclerosis and used as a research tool to explore treatment of neurodegenerative diseases and cancers. It is also a reactive agent, known as PMP (1-phenyl-3-methyl-5-pyrazolone), used for the analysis of polysaccharides composition. EDA can react with sugars and aromatic aldehydes. In this context, we have investigated the reactivity of EDA toward the biologically relevant formylated nucleobases, nucleosides, and an oligonucleotide containing a formylated residue.

Methods

The formation of both mono- and bis-adducts between EDA and the formylated nucleobases (5-formyluracil (5fU) and 5-formylcytosine (5fC)) or the corresponding nucleosides 5-fdU and 5-fdC was characterized using high-resolution mass spectrometry (HR-MS). Similarly, the covalent binding of EDA to an 8-mer palindromic oligonucleotide d (TATG[*C]ATA) containing a single 5-fdC residue [*C] under physiological conditions was investigated using mass spectrometry.

Results

For the first time, EDA is shown to react with formylated pyrimidines. Covalent and stable adducts were identified. EDA was found to react efficiently with the formylated oligonucleotide to generate mono- and bis-adducts. The rate of formation of the mono-adduct was five times higher than that of the bis-adduct. The reaction of EDA with aldehydic DNA modifications such as 5fU/5fC may have important consequences in terms of gene expression.

Conclusions

These observations raise implications for an epigenetic contribution to the mechanism of action of EDA. The biological implications of our in vitro results are discussed, notably in the frame of neurodegenerative diseases and cancers.