Design, synthesis and structure-activity relationship (SAR) studies of 2,4-disubstituted pyrimidine derivatives: Dual activity as cholinesterase and Aβ-aggregation inhibitors

Article abstract of DOI:10.1016/j.bmc.2011.02.030

A novel class of 2,4-disubstituted pyrimidines (7a-u, 8a-f, 9a-e) that possess substituents with varying steric and electronic properties at the C-2 and C-4 positions, were designed, synthesized and evaluated as dual cholinesterase and amyloid-β (Aβ)-aggregation inhibitors. In vitro screening identified N-(naphth-1-ylmethyl)-2-(pyrrolidin-1-yl)pyrimidin-4-amine (9a) as the most potent AChE inhibitor (IC₅₀ = 5.5 μM). Among this class of compounds, 2-(4-methylpiperidin-1-yl)-N-(naphth-1-ylmethyl)pyrimidin- 4-amine (9e) was identified as the most potent and selective BuChE inhibitor (IC₅₀ = 2.2 μM, selectivity index = 11.7) and was about 5.7-fold more potent compared to the commercial, approved reference drug galanthamine (BuChE IC₅₀ = 12.6 μM). In addition, the selective AChE inhibitor N-benzyl-2-(4-methylpiperazin-1-yl)pyrimidin-4-amine (7d), exhibited good inhibition of hAChE-induced aggregation of Aβ_1-40 fibrils (59% inhibition). Furthermore, molecular modeling studies indicate that a central pyrimidine ring serves as a suitable template to develop dual inhibitors of cholinesterase and AChE-induced Aβ aggregation thereby targeting multiple pathological routes in AD.