Chemical Constituents from the Wild Atractylodes macrocephala Koidz and Acetylcholinesterase Inhibitory Activity Evaluation as Well as Molecular Docking Study

Screening the lead compounds which could interact both with PAS and CAS of acetylcholinesterase (AChE) is an important trend in finding innovative drugs for Alzheimer’s disease (AD). In this paper, four sesquiterpenes, i.e., atractylenolide III (1), atractylenolide IV (2), 3-acetyl-atractylon (3) and β-eudesmol (4), were obtained from the wild Atractylode macrocephala grown in Qimen for the first time. Their structures were elucidated mainly by NMR spectroscopy. To screen the potential dual site inhibitors of AChE, the compounds 1, 2, 3, as well as a novel and rare bisesquiterpenoid lactone, biatractylenolide II (5), which was also obtained from the tilted plant in our previous investigation, were evaluated their AChE inhibitory activities by using Ellman’s colorimetric method. The results showed that biatractylenolide II displayed moderate inhibitory activity (IC(50) = 19.61 ± 1.11 μg/mL) on AChE. A further molecular docking study revealed that biatractylenolide II can interact with both the peripheral anionic site (PAS) and the catalytic active site (CAS) of AChE. These data suggest that biatractylenolide II can be considered a new lead compound to research and develop more potential dual site inhibitors of AChE.