Kinetics and molecular docking studies of loganin, morroniside and 7-O-galloyl-d-sedoheptulose derived from Corni fructus as cholinesterase and β-secretase 1 inhibitors

We evaluated the major active components isolated from Corni Fructus: loganin, morroniside, and 7-O-galloyl-d-sedoheptulose as inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) for use in Alzheimer's disease treatment. These compounds exhibited predominant cholinesterase (ChEs) inhibitory effects with IC50 values of 0.33, 3.95, and 10.50 +/- 1.16 A mu M, respectively, for AChE, and 33.02, 37.78, and 87.94 +/- 4.66 A mu M, respectively, for BChE. Kinetics studies revealed that loganin and 7-O-galloyl-d-sedoheptulose inhibited AChE with characteristics typical of mixed inhibitors, while morroniside was found to be a noncompetitive inhibitor against AChE and also exerted mixed BChE inhibitory activities. For BACE1, loganin showed noncompetitive type inhibitory effects, while morroniside and 7-O-galloyl-d-sedoheptulose were found to be mixed inhibitors. Furthermore, these compounds exhibited dose-dependent inhibitory activity with ONOO--mediated protein tyrosine nitration. Molecular docking simulation of these compounds demonstrated negative binding energies for ChEs, and BACE1, indicating high affinity and tighter binding capacity for the active site of the enzyme. Loganin was the most potent inhibitor against both ChEs and BACE1. The data suggest that these compounds together can act as a triple inhibitor of AChE, BChE, and BACE1, providing a preventive and therapeutic strategy for Alzheimer's disease treatment.