Resolvins are a family of potent lipid mediators derived from both eicosapentaenoic acid and docosahexaenoic acid.[1] In addition to being anti-inflammatory, resolvins promote the resolution of the inflammatory response back to a non-inflamed state.[2] Resolvin D1 is produced physiologically from the sequential oxygenation of DHA by 15- and 5-lipoxygenase.[1] 17(R)-RvD1 is an aspirin-triggered epimer of RvD1 that reduces human polymorphonuclear leukocyte (PMN) transendothelial migration, the earliest event in acute inflammation, with equipotency to RvD1 (EC50 = ~30 nM).[3] 17(R)-RvD1 exhibits a dose-dependent reduction in leukocyte infiltration in a mouse model of peritonitis with maximal inhibition of ~35% at a 100 ng dose.[3] In contrast to RvD1, the aspirin-triggered form resists rapid inactivation by eicosanoid oxidoreductases. Analytical and biological comparisons of synthetic 17(R)-RvD1 with endogenously derived 17(R)-RvD1 have confirmed its identity as matching the natural product.[4]