Research Article Anticholinesterase Activity of Eight Medicinal Plant Species: In Vitro and In Silico Studies in the Search for Therapeutic Agents against Alzheimer’s Disease Md Josim Uddin , 1 Daniela Russo , 2,3 Md Mahbubur Rahman , 4 Shaikh Bokhtear Uddin , 5 Mohammad A. Halim , 6 Christian Zidorn , 1 and Luigi Milella 2 1 Pharmazeutisches Institut, Abteilung Pharmazeutische Biologie, Christian-Albrechts-Universit¨ at Zu Kiel, Gutenbergstraße 76, Kiel 24118, Germany 2 Department of Science, University of Basilicata, Viale Dell’Ateneo Lucano 10, Potenza 85100, Italy 3 Spinoff BioActiPlant s.r.l., Department of Science, University of Basilicata, Potenza, Italy 4 Division of Infectious Diseases and Division of Computer-Aided Drug Design, e Red-Green Research Centre, BICCB, Tejgaon, Dhaka, Bangladesh 5 Department of Botany, University of Chittagong, Chattogram 4331, Bangladesh 6 Department of Physical Sciences, University of Arkansas-Fort Smith, Fort Smith, AR, USA Correspondence should be addressed to Luigi Milella; luigi.milella@unibas.it Received 22 March 2021; Revised 29 May 2021; Accepted 8 June 2021; Published 25 June 2021 Academic Editor: Ghulam Ashraf Copyright © 2021 Md Josim Uddin et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Many Bangladeshi medicinal plants have been used to treat Alzheimer’s disease and other neurodegenerative diseases. In the present study, the anticholinesterase effects of eight selected Bangladeshi medicinal plant species were investigated. Species were selected based on the traditional uses against CNS-related diseases. Extracts were prepared using a gentle cold extraction method. In vitro cholinesterase inhibitory effects were measured by Ellman’s method in 96-well microplates. Blumea lacera (Compositae) and Cyclea barbata (Menispermaceae) were found to have the highest acetylcholinesterase inhibitory (IC 50, 150 ± 11 and 176 ± 14 µg/mL, respectively) and butyrylcholinesterase inhibitory effect (IC 50 , 297 ± 13 and 124 ± 2 µg/mL, respectively). Cyclea barbata demon- strated competitive inhibition, where Blumea lacera showed an uncompetitive inhibition mode for acetylcholinesterase. Smilax guianensis (Smilacaceae) and Byttneria pilosa (Malvaceae) were also found to show moderate AChE inhibition (IC 50, 205 ± 31 and 221 ± 2 µg/mL, respectively), although no significant BChE inhibitory effect was observed for extracts from these plant species. Among others, unbergia grandiflora (Acanthaceae) and Mikania micrantha (Compositae) were found to display noticeable AChE (IC 50 , 252 ± 22 µg/mL) and BChE (IC 50 , 314 ± 15 µg/mL) inhibitory effects, respectively. Molecular docking experiment suggested that compounds 5-hydroxy-3,6,7,3′,4′-pentamethoxyflavone (BL4) and kaempferol-3-O-α-L-rhamnopyranosyl-(1⟶6)-β-D-glu- copyranoside (BL5) from Blumea lacera bound stably to the binding groove of the AChE and BChE by hydrogen-bond interactions, respectively. erefore, these compounds could be candidates for cholinesterase inhibitors. e present findings demonstrated that Blumea lacera and Cyclea barbata are interesting objects for further studies aiming at future therapeutics for Alzheimer’s disease. 1. Introduction Alzheimer’s disease (AD) is a devastating neurodegenerative disorder linked with the two most common symptoms, memory dysfunction and cognition impairment. In the neuropathological symptoms of AD, cognitive deficit is consistent with the presence of cholinergic deficit, due to the degeneration or atrophy of cholinergic neurons in the basal forebrain, including senile plaques and neurofibrillary tangles [1]. Acetylcholine (ACh), the brain’s important Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2021, Article ID 9995614, 14 pages https://doi.org/10.1155/2021/9995614