A sensitive post-column derivatization approach for enhancing hydroxyl metabolites detection

Background: Chemical derivatization is a common technique in liquid chromatography-mass spectrometry (LC-MS) metabolomics used to improve the ionizability and chromatographic properties of metabolites in complex biological samples. This process facilitates better detection and separation of a wide array of compounds. The reagent 2-(4-boronobenzyl) isoquinolin-2-ium bromide (BBII), developed as a glucose labeling reagent for matrix-assisted laser desorption/ionization MS, enhances ionization for glucose and other hydroxyl metabolites. Its quaternary ammonium group increases ionization efficiency, and its rapid reaction time simplifies pretreatment procedures. Results: We developed a novel post-column derivatization (PCD) method using BBII to boost the detection sensitivity of hydroxyl metabolites in LC-MS. By optimizing this BBII PCD approach with 14 hydroxyl-containing compounds, we were able to detect previously undetectable metabolites such as glucose, ribose, and long-chain alcohols. Sensitivity enhancements for these metabolites ranged from 1.1 to 42.9-fold. Applying this method to metabolic profiling of hydroxyl metabolites in the DBTRG-05MG glioblastoma cell line, with and without treatment with the new drug MFB [1-(4-chlorobenzyl)-2-(5-methyl-2-furfurylideneamino)benzimidazole], revealed several hydroxyl metabolites with significantly reduced levels post-treatment. Significance and novelty: This study presents a new BBII PCD method that substantially improves the detection sensitivity of hydroxyl metabolites in LC-MS. This innovative approach is highly valuable for untargeted metabolomics studies in biological and clinical research, offering a robust tool for identifying metabolite changes and advancing our understanding of metabolic processes in disease and therapeutic contexts.