Fluoranthene-DNA adducts: identification and quantification by an HPLC-32P-postlabeling method

Area of Science:

• Biochemistry
• Molecular Biology
• Environmental Chemistry

Background:

• Fluoranthene (FA) is a polycyclic aromatic hydrocarbon found in environmental pollutants.
• FA can form DNA adducts, which are markers of potential genotoxicity.
• Accurate methods are needed to detect and quantify FA-DNA adducts for risk assessment.

Purpose of the Study:

• To develop and optimize a sensitive 32P-postlabeling method for identifying and quantifying fluoranthene-DNA adducts.
• To confirm the identity of major FA-DNA adducts formed by microsomally-activated FA.
• To assess the method's reproducibility and detection limits.

Main Methods:

• Modification of the Randerath 32P-postlabeling technique.
• Digestion of FA-modified DNA to nucleotide 3'-monophosphates.
• Separation of adducts from nucleotides using C18 cartridges.
• Enzymatic removal of residual nucleotides using nuclease P1.
• 5'-phosphorylation of adducts with [gamma-32P]ATP and polynucleotide kinase.
• HPLC separation and liquid scintillation counting for quantification.
• Confirmation of adduct identity using [3H]FA recovery studies.

Main Results:

• The developed method successfully identified and quantified FA-DNA adducts.
• The major adduct was confirmed as anti-2,3-dihydroxy-1,10b-epoxy-fluoranthene nucleotide adduct.
• Reproducibility was approximately 5% for repeated analyses.
• The method achieved a detection limit of approximately 0.1 fmol adduct, enabling sensitive detection of low adduct levels.
• Recovery rates of [3H]FA were 10-15% for major adducts.

Conclusions:

• The optimized HPLC-32P-postlabeling procedure is a sensitive and reproducible method for FA-DNA adduct analysis.
• The method allows for enhanced detection sensitivity by analyzing larger DNA quantities.
• This technique is valuable for studying FA genotoxicity and exposure in environmental and toxicological research.