TY - JOUR
T1 - Liquid chromatography-tandem mass spectrometry analysis of free and esterified fatty acid N-acyl ethanolamines in plasma and blood cells
AU - Balvers, Michiel G.J.
AU - Wortelboer, Heleen M.
AU - Witkamp, Renger F.
AU - Verhoeckx, Kitty C.M.
PY - 2013/3/15
Y1 - 2013/3/15
N2 - The origin of N-acyl ethanolamides (NAEs) in plasma is not well understood, and it is possible that NAEs are present in plasma in esterified form. To test this hypothesis, a new and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of arachidonoyl ethanolamide, 2-arachidonoyl glycerol, docosahexaenoyl ethanolamide, dihomo-γ-linolenoyl ethanolamide, oleoyl ethanolamide, palmitoyl ethanolamide, and stearoyl ethanolamide in 100 μl of human plasma using a simple acetonitrile extraction step. Using this method, we determined (i) free and esterified NAE levels in human plasma, (ii) free and esterified NAE levels in plasma of mice fed with diets with different amounts of n-3 fatty acids, and (iii) esterified NAE levels in blood cells. Murine and human plasma extracts contained 20- to 60-fold higher levels of esterified NAEs than free NAEs. Moreover, the effect of dietary n-3 fatty acids on murine free plasma NAE profiles was similar for esterified NAEs. Finally, esterified NAEs were also present in murine blood cells, and their pattern followed the same diet effect as observed for free and esterified NAEs in plasma. Together, these data point to the presence of previously ignored pools of esterified NAEs in plasma and blood cells that correlated well with free NAE levels in plasma.
AB - The origin of N-acyl ethanolamides (NAEs) in plasma is not well understood, and it is possible that NAEs are present in plasma in esterified form. To test this hypothesis, a new and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of arachidonoyl ethanolamide, 2-arachidonoyl glycerol, docosahexaenoyl ethanolamide, dihomo-γ-linolenoyl ethanolamide, oleoyl ethanolamide, palmitoyl ethanolamide, and stearoyl ethanolamide in 100 μl of human plasma using a simple acetonitrile extraction step. Using this method, we determined (i) free and esterified NAE levels in human plasma, (ii) free and esterified NAE levels in plasma of mice fed with diets with different amounts of n-3 fatty acids, and (iii) esterified NAE levels in blood cells. Murine and human plasma extracts contained 20- to 60-fold higher levels of esterified NAEs than free NAEs. Moreover, the effect of dietary n-3 fatty acids on murine free plasma NAE profiles was similar for esterified NAEs. Finally, esterified NAEs were also present in murine blood cells, and their pattern followed the same diet effect as observed for free and esterified NAEs in plasma. Together, these data point to the presence of previously ignored pools of esterified NAEs in plasma and blood cells that correlated well with free NAE levels in plasma.
KW - Diet
KW - Endocannabinoids
KW - LC-MS/MS
KW - NAEs
KW - Plasma
KW - Validation
UR - https://www.scopus.com/pages/publications/84873371906
U2 - 10.1016/j.ab.2012.11.008
DO - 10.1016/j.ab.2012.11.008
M3 - Article
C2 - 23201387
AN - SCOPUS:84873371906
SN - 0003-2697
VL - 434
SP - 275
EP - 283
JO - Analytical Biochemistry
JF - Analytical Biochemistry
IS - 2
ER -