Selective Butyrylcholinesterase Inhibitors Using Polyphenol-polyphenol Hybrid Molecules

Polyphenols (PPs) are known as antioxidant compounds having benign biological activities. In this paper, a series of hybrid molecules between the free or acetyl protected polyphenol compounds were synthesized and their in vitro antioxidant activity (DPPH assay) and cholinesterase [acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE)] inhibition activities were evaluated. As expected, free phenolic hybrid compounds (6 and 8) showed better antioxidant activity than acetyl protected hybrid compounds (5 and 7) from DPPH assay. But the contrast result was obtained from BuChE inhibition assay. Acetyl protected hybrid compounds (5 and 7) showed better inhibition activity for BuChE than free phenolic hybrid compounds (6 and 8). Specifically, 10 (AcFA-AcFA) were shown as an effective inhibitor of BuChE ($IC_{50}=2.3{\pm}0.3{\mu}M$) and also had a great selectivity for BuChE over AChE (more than 170 fold). Inhibition kinetic studies with acetyl protected compounds (5, 7, 9, and 10) indicated that 5, 7 and 10 are a hyperbolic mixed-type inhibition and 10 is a competitive inhibition type. The binding affinity (Ki) value of 10 to BuChE is $2.32{\pm}0.15{\mu}M$.