title: Identification of molecular species of oxidized triglyceride in plasma and its distribution in lipoproteins.
abstract: BACKGROUND
  The role of triglycerides carried in the triglyceride-rich lipoproteins (TRL) in the progression of atherosclerosis is uncertain. Identification of oxidized triglycerides and its possible association with atherosclerosis were largely ignored. Here we applied mass spectrometric approach to detect and identify triglyceride hydroperoxides (TGOOH) in human plasma and lipoproteins.
  
  
  METHODS
  EDTA plasma was collected from healthy human volunteers (n=9) after 14-16 h of fasting. Very low-density lipoprotein (VLDL) (d<1.006) and intermediate-density lipoprotein (IDL) (d=1.006-1.019) were isolated from the plasma (n=6) by sequential ultracentrifugation in KBr, followed by the isolation of LDL and high-density lipoprotein (HDL) using size-exclusion high-performance liquid chromatography (HPLC). Total lipids from the plasma and isolated lipoproteins were extracted, and analyzed for the detection and identification of TGOOH using liquid chromatography/LTQ ion trap Orbitrap mass spectrometry. All the processes, from specimen collection to the mass spectrometric analysis, were carried out at 4 °C in the presence of antioxidant to prevent oxidation of lipoproteins.
  
  
  RESULTS
  We identified 11 molecular species of TGOOH in either plasma or VLDL and IDL, of which TGOOH-18:1/18:2/16:0, TGOOH-18:1/18:1/16:0, TGOOH-16:0/18:2/16:0, TGOOH-18:1/18:1/18:1, and TGOOH-16:0/20:4/16:0 were most dominant. These TGOOH molecules are carried by TRL but not by LDL and HDL. Mean concentration of TGOOH in plasma, VLDL and IDL were, respectively, 56.1 ± 25.6, 349.8 ± 253.6 and 512.5 ± 173.2 μmol/mol of triglycerides.
  
  
  CONCLUSIONS
  This is the first report to identify several molecular species of oxidized triglycerides in TRL. Presence of oxidized triglyceride may contribute to the atherogenicity of TRL. Further work is needed to elucidate the association of the oxidized triglyceride in atherosclerosis.
authors.forename: Rojeet
authors.initials: R
authors.lastname: Shrestha
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Hui
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Miura
authors.forename: Akiko
authors.initials: A
authors.lastname: Yagi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Takeda
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Fuda
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Chiba
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood*; D008077:Lipoproteins, LDL / Q000097:blood*; D008297:Male; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D014280:Triglycerides / Q000097:blood*; D055815:Young Adult
chemical_list: D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides