5-Nitro-2-(3-phenylpropylamino)benzoic Acid (NPPB) is a potent Cl- channel blocker, identified through an optimization study of the diphenylamine-2-carboxylate core which demonstrates the basic Cl- channel blocking activity. NPPB also demonstrates suppression of prostaglandin E2 release with an IC50 of 8 μM, presumed to be a Cox (cyclooxygenase) inhibitor given its structural similarity to fenamic acid-type Cox inhibitors. It is also a GPR35 agonist. NPPB activates the GPR35-Gi/o and GPR35-G16 pathways in human embryonic kidney 293 (HEK293) cells and induces intracellular calcium mobilization in a concentration-dependent manner in HEK293 cells coexpressing human, rat or mouse GPR35 and the chimeric G protein G(qi5).