1H NMR-based Metabolomic Analysis of Nine Organophosphate Flame Retardants Metabolic Disturbance in Hep G2 Cell Line

Organophosphate flame retardants (OPFRs) are frequently found in the environment and could be adversely affecting organisms. In fact, nine OPFRs have been shown to cause endocrine disruptions, but information on the metabolism-perturbing properties of these OPFRs remains unclear. In this study, the 1H-nuclear magnetic resonance (NMR) based metabolomic method was applied to evaluate the metabolic disturbances caused by these nine OPFRs. From the analysis of the metabolic phenotypes, we found that TDBPP, TMPP and TPHP could be clustered into one group; TBOEP, TCIPP, TCEP and TEHP could be clustered into another group; and the residual OPFRs could be clustered into another. The classification results agree with the antagonistic activities of glucocorticoid and mineralocorticoid receptors. Then, we found that when HepG2 cells were exposed to TMPP, TPHP and TDBPP, the main metabolic sub-network disturbances focused on metabolism linked with oxidative stress, osmotic pressure equilibrium, and glucocorticoid and mineralocorticoid receptor antagonist activities; this was also true for TNBP and TDCIPP. Meanwhile, the other OPFRs mainly affected oxidative stress and amino acid metabolism. With multivariate statistical analysis, we found many differential metabolites in each group. Notably, Trimethylamine‑N‑oxide (TMAO) was the differential metabolite in six of the tested OPFRs, excluding TMPP, TPHP and TDBPP, and was one of the potential cardiovascular biomarkers. The data provided here could be helpful in gaining a more in-depth understanding of the metabolic disturbances of these nine OPFRs and may offer a new perspective for understanding potential pollutants with endocrine-disrupting effects on host metabolism.