Development of a Novel Method to Quantify Quinolinic Acid in Biological Samples

Area of Science:

• Biochemistry
• Analytical Chemistry
• Neuroscience

Background:

• Quinolinic acid (QUIN) accumulation in biological fluids may indicate neuropsychiatric and inflammatory diseases.
• Developing sensitive biomarkers is crucial for diagnosing and monitoring these conditions.

Purpose of the Study:

• To develop a highly sensitive method for quantifying quinolinic acid (QUIN) in biological samples.
• To establish a novel assay for QUIN measurement suitable for research laboratories.

Main Methods:

• Enzymatic conversion of QUIN to nicotinic acid mononucleotide using recombinant enzymes.
• Fluorescence detection of a BODIPY-labeled deamido-NAD product via reverse-phase high-performance liquid chromatography (HPLC).

Main Results:

• The developed HPLC method achieved a sensitivity at least 30-fold higher than previous HPLC methods for QUIN.
• The assay demonstrated a low limit of detection (5.0 nmol/L) and good precision and recovery for biological fluid analysis.
• QUIN quantitation results from cerebrospinal fluid samples correlated well with gas chromatography/mass spectrometry (GC/MS) methods.

Conclusions:

• A novel, highly sensitive method for quantifying QUIN in biological samples was successfully established.
• The assay's high sensitivity and independence from MS instrumentation facilitate its potential widespread adoption in research settings.