Water-Soluble MMP‑9 Inhibitor Prodrug Generates Active Metabolites That Cross the Blood–Brain Barrier

MMP-9 plays a detrimental role in the pathology of several neurological diseases and, thus, represents an important target for intervention. The water-soluble prodrug ND-478 is hydrolyzed to the active MMP-9 inhibitor ND-322, which in turn is <i>N</i>-acetylated to the even more potent metabolite ND-364. We used a sensitive bioanalytical method based on ultraperformance liquid chromatography with multiple-reaction monitoring detection to measure levels of ND-478, ND-322, and ND-364 in plasma and brain after administration of ND-478 and the metabolites. ND-478 did not cross the blood–brain barrier, as was expected; however the active metabolites ND-322 and ND-364 distributed to the brain. The active compound after administration of either ND-478 or ND-322 is likely ND-364. ND-322 is <i>N</i>-acetylated in both brain and liver, but it is so metabolized preferentially in liver. Since <i>N</i>-acetyltransferases involved in the metabolism of ND-322 to ND-364 are polymorphic, direct administration of the <i>N</i>-acetylated ND-364 would achieve the requisite therapeutic levels in the brain