lipoxin b4

Lipoxin B4 is a metabolite of arachidonic acid that inhibits leukocyte infiltration and mucus secretion in the nasal mucosa of the upper respiratory tract, exhibiting mucosal protective effects. It is commonly used in studies of allergic inflammation in the upper and lower respiratory tracts.

Lipoxin B4 (LXB4) methyl ester is a lipid-soluble prodrug form of the transcellular metabolite LXB4, which is a positional isomer of LXA4 produced by the metabolism of 15-HETE or 15-HpETE by human leukocytes. At 100 nM, LXB4 inhibits polymorphonuclear leukocyte (PMN) migration stimulated by leukotriene B4 and inhibits LTB4-induced adhesion of PMNs with an IC50 of 0.3 nM.

Lipoxin A4 methyl ester (LXA4 methyl ester) is a more lipid soluble, prodrug formulation of the transcellular metabolite LXA4. LXA4 is a trihydroxy fatty acid containing a conjugated tetraene, produced by the metabolism of 15-HETE or 15-HpETE with human leukocytes.[1] LXA4 is equipotent to leukotriene B4 (LTB4) in inducing superoxide generation in human neutrophils at 0.1 μM.[2] LXA4 is associated with several other biological functions including leukocyte activation, chemotaxis effects, natural killer cell inhibition, and monocyte migration and adhesion.[2],[3],[4]

15(R)-HETE, a monohydroxy fatty acid, is synthesized from arachidonic acid via aspirin-acetylated COX-2, leading to the formation of specialized pro-resolving mediators 15(R)-lipoxin A4 and B4 through a transcellular mechanism involving 5-lipoxygenase (5-LO). Additionally, this compound is produced by the cytochrome P450 (CYP) isoform CYP2C9 and can be generated from arachidonic acid by COX-1 in human mast cells, where it accumulates due to its resistance to conversion into 15-KETE by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). As an agonist of PPARβ/δ, 15(R)-HETE induces the expression of a target gene in NIH3T3 cells, demonstrating its biological significance.