Epi-lipoxin
Epi-lipoxins are trihydroxy (i.e. containing 3
hydroxyl residues) metabolites of arachidonic acid. They are 15R-epimers of their lipoxin counterparts; that is, the epi-lipoxins, 15-epi-lipoxin A4 (15-epi-LxA4) and 15-epi-lipoxin B4 (15-epi-LXB4), differ from their respective lipoxin A4 (LxA4) and lipoxin B4 (LxB4) epimers in that their 15-hydroxy residue has R rather than S chirality
. Formulae for these lipoxins (Lx) are:
- LxA4: 5S,6R,15S-trihydroxy-7E,9E,11Z,13E-ETE
- LxB4: 5S,14R,15S-trihydroxy-6E,8Z,10E,12E-ETE
- 15-epi-LxA4: 5S,6R,15R-trihydroxy-7E,9E,11Z,13E-eicosatetraenoic acid
- 15-epi-LxB4: 5S,14R,15R-trihydroxy-6E,8Z,10E,12E-eicosatrienoic acid
The two-epi-Lx's as well as the two lx's are
cyclooxygenase 2 or a cytochrome P450 enzyme which adds a 15R-hydroxyl residue to arachidonic acid.[4]
In acknowledgement of the role played by aspirin-treated cyclooxygenase 2 in forming these products, the epi-lipoxins are sometimes termed ATL which stands for Aspirin-Triggered Lipoxins.
The counter-regulatory role of the epi-lipoxins in serving as stop signals for diverse inflammation responses is detailed at the lipoxin site.
See also
References
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