We present here a definitive metabonomic analysis in order to detect novel
biomarker and metabolite information, implicating specific putative
protein targets in the toxicological mechanism of
bromobenzene-induced centrilobular hepatic
necrosis. Male Han-Wistar rats were dosed with
bromobenzene (1.5 g/kg, n = 25) and blood plasma, urine and liver samples were collected for NMR and magic angle spinning (MAS) NMR spectroscopy at various time-points postdose, with histopathology and clinical pathology performed in parallel. Liver samples were analyzed by 600 MHz 1H MAS NMR techniques and the resultant spectra were correlated to sequential 1H NMR measurements in urine and blood plasma using pattern recognition methods. 1D 1H NMR spectra were data-reduced and analyzed using principal components analysis (PCA) to show the time-dependent biochemical variations induced by
bromobenzene toxicity. In addition to a holistic view of the effect of hepatic toxicity on the metabolome, a number of putative
protein targets of
bromobenzene and its metabolites were identified including those
enzymes of the
glutathione cycle, exemplified by the presence of a novel
biomarker,
5-oxoproline, in liver tissue, blood plasma, and urine. As such, this work establishes the importance of metabonomics technology in resolving the mechanistic complexity of
drug toxicity as well as the benefits of frontloading this approach in
drug safety evaluation and
biomarker discovery.