Prostaglandin E2 (PGE2) inhibitor 3 is a selective inhibitor targeting microsomal prostaglandin E synthase-1 (mPGES-1; IC50 = 0.2 µM), demonstrating greater selectivity for mPGES-1 over COX-1, COX-2, 5-lipoxygenase (5-LO), and soluble epoxide hydrolase (sEH) in assays at 10 µM. This compound effectively reduces IL-1β-induced PGE2 production in A549 cells and decreases LPS-induced IL-6 and PGE2 in J774A.1 macrophages at concentrations of 10 and 1 µM, respectively. Additionally, it blocks the production of 5-LO-derived products, including leukotriene B4 (LTB4) and 5-H(p)ETE, in response to calcium ionophore A23187 alone or combined with arachidonic acid, with IC50 values of 4.9 and 5.2 µM, respectively. When administered in vivo at doses of 10 mg/kg, PGE2 inhibitor 3 effectively prevents leukocyte infiltration in a mouse model of zymosan-induced peritonitis.