The Ameliorating Effect of Phenylsulfonamide Derivatives on Scopolamine-Induced Memory Impairment in Mice via Inhibition of mPGES-1

Our previous research showed that a novel series of phenylsulfonyl hydrazide derivatives reduced LPS-induced PGE2 levels in RAW 264.7 macrophage cells via an inhibition of mPGES-1 enzyme. As a continuous work, new phenylsulfonamide derivatives (5a-5k) as methylene analogues of phenylsulfonyl hydrazide derivatives, including MPO-0063, were synthesized and biologically evaluated in vitro. Among synthetic compounds, 5a (MPO-0112) showed decreased inhibitory activity against PGE2 production (IC50: 0.34 µM) compared to MPO-0063 (IC50: 0.04 µM) but inhibited the mPGES-1 enzyme (IC50: 7.37 µM) similar to MPO-0063 (IC50: 0.10 µM) together with excellent selectivity over COX-enzymes (COX-1 and 2). According to recent studies on the close correlation between up-regulation of mPGES-1 and Alzheimer's disease, we investigated whether 5a could ameliorate scopolamine-induced memory impairment using the passive avoidance test. The memory impairment-ameliorating effect of 5a (1.0 mg/kg, p.o.) was found to be effective, comparable to that of donepezil (5 mg/kg, p.o.) as a positive control. On the other hand, 5a exhibited little or weak AChE and BuChE inhibitory activity, which implies that 5a could ameliorate scopolamine-induced memory impairment by inhibiting mPGES-1 enzyme instead of cholinesterase enzymes. In addition, MPO-0112 exhibited a favorable in vitro CYP profile, which is suggestive of no potential drug−drug interactions. Therefore, these overall results suggest that 5a as a selective mPGES-1 inhibitor may be a novel therapeutic agent for diseases associated with cognitive deficits, such as Alzheimer’s disease.