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Reaction between metabolically activated acetaminophen and phosphorothioate oligonucleotides
B L Copple1, W M Gmeiner, P L Iversen
1Department of Pharmacology, University of Nebraska Medical Center, Omaha 68198-6260, USA.
Toxicology and Applied Pharmacology
|July 1, 1995
Summary
Phosphorothioate oligonucleotides (PTOs) show reactivity with acetaminophen (ACAP) metabolites in vitro. Despite forming adducts, these interactions are neither toxic nor mutagenic, with larger PTOs offering protection against ACAP toxicity.
Area of Science:
- Oligonucleotide chemistry
- Drug metabolism and toxicology
- Molecular interactions
Background:
- Phosphorothioate oligonucleotides (PTOs) are generally considered non-toxic and non-mutagenic.
- Potential interactions between PTOs and other compounds, particularly drugs, remain underexplored.
- The sulfur atom in PTOs presents a potential site for novel drug interactions.
Purpose of the Study:
- To investigate the interaction between phosphorothioate oligonucleotides (PTOs) and acetaminophen (ACAP), a model drug.
- To assess the toxicity and mutagenicity of these interactions.
- To evaluate the protective effect of PTOs against ACAP-induced toxicity.
Main Methods:
- Reaction of dCTP(S) with activated ACAP (NAPQI) and analysis by mass spectrometry.
- Incubation of fluorescein-labeled PTOs with NAPQI, followed by polyacrylamide gel electrophoresis.
- 31P NMR analysis to confirm adduct formation.
- Assessment of cell viability and mutagenicity assays (LacZ and HGPRT locus).
Main Results:
- A distinct product formed from the reaction of dCTP(S) with NAPQI, indicating NAPQI binding to sulfur.
- Higher-molecular-weight adducts were observed between PTOs and NAPQI, but not with phosphodiester oligonucleotides.
- 31P NMR confirmed heterogeneous adduct formation between PTOs and NAPQI.
- Larger PTOs demonstrated a protective effect against ACAP toxicity, enhancing cell viability.
- No mutations were detected in the LacZ or HGPRT assays, indicating non-mutagenicity.
Conclusions:
- Activated acetaminophen (NAPQI) reacts with phosphorothioate oligonucleotides in vitro.
- These interactions, while reactive, are non-toxic and non-mutagenic.
- Phosphorothioate oligonucleotides may offer a protective effect against acetaminophen toxicity, particularly larger molecules.