The Application Of Identification And Quantification Of Endogenous Metabolites Using LC-MS/MS

LC-MS/MS,which incorporates the advantages of LC and MS,is a powerful analytical tool and is widely used in drug analysis,proteomics and many other fields.High-resolution mass spectrometry,such as QTOF、LTQ Orbitrap,is highly suitable for global identification of metabolites.On the other hand,the MRM scan mode using low-resolution mass spectrometry,such as QQQ、QTRAP,is very suitable for targeted quantification.Due to their respective characteristics of the two kinds of mass spectrometry,we used both of them to identify and quantify endogenous metabolites.1.Global identification of serum phospholipids using LC-QTOF-MS/MS.Nowadays,phospholipidomics has made great progress with the rapid development of mass spectrometry.However,the coverage of phospholipids is limited and there is little research about the choice of animal models in phospholipidomics.Through fully optimization of mass spectrometric and chromatographic conditions,we developed a LC-QTOF-MS/MS method for the global identification of serum phospholipids,and applied it to comprehensive characterization of serum phospholipids in human and four rodent species for the first time.Using the method,we detected 217 phospholipids in human serum and found that the qualitative distributions of serum phospholipids in rat were more similar to human than the other three rodent species.This result might provide evidences for the choice of optimal animal models in phospholipidomics studies.2.Targeted quantification of plasma,urine and feces bile acids using LC-QTRAP-MS/MS with MRM scan mode.Previous studies indicated that the occurrence of type 2 diabetes was usually accompanied by a significant change of bile acid profiles.Most studies focused on several major bile acids or the analytical methods,thus systematic studies of bile acid profiles of animals or human suffering from type 2 diabetes are lacking.This study developed a LC-QTRAP-MS/MS method with MRM scan mode,which could quantify 25 bile acids.Then,we firstly used this method to systematically investigate bile acid profiles in plasma,urine and feces of db/db mice,an acknowledged diabetic animal model,and their wild type littermates.Based on multivariate statistical analysis,we confirmed that there was a significant difference between db/db mice and their wild type littermates in bile acid profiles,and found a series of potential bile acid biomarkers for type 2 diabetes.This study might have some reference values for early diagnosis and prevention of type 2 diabetes.