Gas chromatography–mass spectrometry‐based profiling of serum fatty acids in acetaminophen‐induced liver injured rats

In this study, we have developed and validated a simple, accurate and sensitive gas chromatography–mass spectrometry (GC‐MS) method for simultaneous quantification of 18 fatty acids in rat serum, including both non‐esterified (NEFA) and esterified (EFA) fatty acids, and subsequent analysis of fatty acid metabolic profiles. This novel method was used to evaluate the serum levels of fatty acids from vehicle‐ and acetaminophen (APAP)‐treated rats. Serum levels of 7 NEFAs and 14 EFAs were significantly higher in APAP‐treated rats 24 h after APAP administration at 1500 mg kg^–1 when compared with vehicle‐treated controls. Control and APAP‐treated rats could be differentiated based on their metabolic profiles using two different chemometric analysis methods: principle component analysis (PCA) and partial least squares‐discriminant analysis (PLS‐DA). More importantly, we identified the following NEFAs as potential biomarkers of APAP‐induced liver injury: oleic acid (C18:1n9), linoleic acid (C18:2n6), docosahexaenoic acid (C22:6n3) and arachidonic acid (C20:4n6). The serum concentrations of C18:1n9, C18:2n6 and C22:6n3 were all positively correlated (r > 0.8; Pearson's correlation analysis) with the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). These results suggest that a novel targeted metabolomics method based on the metabolic profiling of fatty acids analyzed by GC‐MS provides exact serum concentrations of fatty acids as well as a prospective methodology to evaluate chemically induced hepatotoxicity. Copyright © 2012 John Wiley & Sons, Ltd.