Resolvin D2-d5 (RvD2-d5) is intended for use as an internal standard for the quantification of resolvin D2 by GC- or LC-MS. Resolvins are a family of potent lipid mediators derived from both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).¹ In addition to being anti-inflammatory, resolvins promote the resolution of the inflammatory response back to a non-inflamed state.² Resolvin D2 is produced physiologically from the sequential oxygenation of DHA by 15- and 5-lipoxygenase and functions to dampen excessive neutrophil trafficking to sites of inflammation.³ It reduces zymosan-stimulated PMN infiltration by 70% at doses as low as 10 pg per mouse and significantly reduces PAF-stimulated leukocyte adherence and emigration at 1 nM.³ Also, by stimulating nitric oxide production, resolvin D2 dose dependently decreases leukocyte-endothelial interactions. In a murine model of sepsis, resolvin D2 reduces leukocyte and PMN infiltration, decreases production of pro-inflammatory cytokines, and promotes phagocyte-mediated bacterial clearance.³