Maresin conjugates in tissue regeneration 2 (MCTR2) is a specialized pro-resolving mediator (SPM) synthesized from docosahexaenoic acid (DHA) in macrophages at the site of inflammation.^1,2 DHA is oxidized to maresin 1 (MaR1), which is converted to MCTR1 by glutathione S-transferase Mu 4 or leukotriene C4 synthase then to MCTR2 by γ-glutamyl transferase.³ MCTR2 accelerates tissue regeneration in planaria (1 and 100 nM).² Pretreatment with MCTR2 prior to E. coli administration reduces neutrophil infiltration, shortens the inflammatory resolution period, and increases phagocytosis of E. coli by macrophages.² When administered at a dose of 100 ng 12h post E. coli infection in a mouse model of peritonitis, MCTR2 selectively reduced the amount of the eicosanoids PGD2 and PGF2α in the exudate.²