Leukotriene A4-d5 methyl ester

Leukotriene A₄-d₅ (LTA₄-d₅) methyl ester contains four deuterium atoms at the 19, 19', 20, 20, and 20 positions. It is intended for use as an internal standard for the quantification of LTA₄ methyl ester by GC- or LC-mass spectrometry. LTA₄ is synthesized in mast cells, eosinophils, and neutrophils from arachidonic acid by 5-lipoxygenase (5-LO), which exhibits both lipoxygenase and LTA₄ synthase activities.^1,2 LTA₄ is rapidly metabolized by LTA₄ hydrolase or LTC₄ synthase to LTB₄ or LTC₄, respectively.² LTA₄, from leukocytes, is known to undergo transcellular metabolism in platelets, erythrocytes, and endothelial cells.³ Further metabolism of LTA₄ by 15-LO leads to lipoxin biosynthesis.² LTA₄ as a free acid is highly unstable. The methyl ester is stable and can be readily hydrolyzed to the free acid as needed.

1.Shimizu, T., RÅdmark, O., and Samuelsson, B.Enzyme with dual lipoxygenase activities catalyzes leukotriene A4 synthesis from arachidonic acidProc. Natl. Acad. Sci. U.S.A.81689-693(1984) 2.Samuelsson, B., DahlÉn, S.E., Lindgren, J.Å., et al.Leukotrienes and lipoxins: Structures, biosynthesis, and biological effectsScience2371171-1176(1987) 3.Maclouf, J.A., and Murphy, R.C.Transcellular metabolism of neutrophil-derived leukotriene A4 by human platelets. A potential cellular source of leukotriene C4J. Biol. Chem.263(1)174-181(1988)