Oh_2021_Sci.Rep_11_13953

Among 276 herbal extracts, a methanol extract of Castanopsis cuspidata var. sieboldii stems was selected as an experimental source for novel acetylcholinesterase (AChE) inhibitors. Five compounds were isolated from the extract by activity-guided screening, and their inhibitory activities against butyrylcholinesterase (BChE), monoamine oxidases (MAOs), and beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1) were also evaluated. Of these compounds, 4'-O-(alpha-L-rhamnopyranosyl)-3,3',4-tri-O-methylellagic acid (3) and 3,3',4-tri-O-methylellagic acid (4) effectively inhibited AChE with IC(50) values of 10.1 and 10.7 microM, respectively. Ellagic acid (5) inhibited AChE (IC(50) = 41.7 microM) less than 3 and 4. In addition, 3 effectively inhibited MAO-B (IC(50) = 7.27 microM) followed by 5 (IC(50) = 9.21 microM). All five compounds weakly inhibited BChE and BACE-1. Compounds 3, 4, and 5 reversibly and competitively inhibited AChE, and were slightly or non-toxic to MDCK cells. The binding energies of 3 and 4 (- 8.5 and - 9.2 kcal/mol, respectively) for AChE were greater than that of 5 (- 8.3 kcal/mol), and 3 and 4 formed a hydrogen bond with Tyr124 in AChE. These results suggest 3 is a dual-targeting inhibitor of AChE and MAO-B, and that these compounds should be viewed as potential therapeutics for the treatment of Alzheimer's disease.