Biotransformation Process Of Organic Phosphorus Flame Retardants And Cellular Metabolomics Research

Organic phosphorus flame retardants(OPFRs),as a substitute for conventional flame retardants,are widely used in the furniture,electronic devices and baby products,and are frequently detected in various environmental mediums and organisms.Previous studies have shown that OPFRs can not only cause neurotoxicity,reproductive toxicity,heart toxicity,and liver toxicity,but also interfere with the normal functions of the endocrine system.Given the wide exsist of OPFRs in the environment and the environmental problems and health risks have aroused people's increasing attention.In the current study,9 common OPFRs were used to evaluate the endocrine disrupting effect mediated by retinoid X receptor(RXR).Then the effect of OPFRs on the metabolism phenotype of liver cell were investigated based on nuclear magnetic resonance(NMR).In addition the underlying mechanisms of biological transformation of the typical OPFRs were analyzed by using human liver microsomal.The main research work and achievements include the following three parts:(1)The evaluation of the endocrine-disrupting effects of RXRa:RXRa plays an important role in the balance of normal metabolism of organisms.Herein,Chinese Hamster Ovary(CHO-K1)Cells,combining with molecular docking technology,were used as an in vitro modelto examine the potential endocrine disrupting effects of the OPFRs mediated by RXRa.The results showed that partial OPFRs exhibited RXRadisrupting effects with the order of TMPP > TPHP > TDBPP > TNBP.Results of molecular docking showed that TMPP exhibited the highest grade of binding energy with receptors RXRa.All these results can help to understand the endocrine disruptor effects of phosphorus-containing flame retardant and reveals the potential health risks.(2)The effects of OPFRs to the metabolism phenotype liver cell: Herein,byanalyzing the change tendency of cell metabolism of endogenous compounds structures and building biological pathways network structure,the toxicity characteristics and metabolic perturbation effect of OPFRs to liver cells were investigated by the NMR based cell metabonomics.Results of NMR have identified33 metabolites in HepG2 cells Principal component analysis of the NMR spectrum have found that all the 9 OPFRs could significantly affect the metabolism phenotype changes of HepG2 cell.OPFRs could obviously interfere the Krebs cycle metabolism pathways by changing the relative levels of metabolites,thus revealed the possible toxicity features of OPFRs in cell metabolism level.(3)CYP450 mediated biological transformation: Herein,the Cytochrome P450 enzyme metabolism and biotransformation of typical phosphorus-containing flame retardant TPHP were investigated using human liver microsomal cytochrome isoenzyme in the incubation degradation system.The acquired human liver microsomal curve is in accordance with the the pseudo-first-order reaction kinetics equation of degradation of TPHP.Three main metabolites of TPHP were also detected(S1,S2 and the DPP).The cytochrome isozyme different subtype inhibitor screening study also showed thay CYP1A2 and CYP2E1 is the main CYP450 subtypes of TPHP degradation,which exhibited higher ability to degrade TPHP than CYP2A6,CYP2C9,and CYP2D6.While,CYP2C19 and CYP3A4 have no catalytic activity of TPHP metabolism.