www.ijpsonline.com catalepsy, which is comparable to the standard 13. Zhang S, Li H, Yang SJ. Tribulosin protects rat hearts from drug trihexyphenidyl. Our study indicates ischemia/perfusion injury. Acta Pharmacol 2010;31:671‑88. 14. Amin A, Lotfy M, Shafiullah M, Adeghate E. The protective effect of that Tribulus terrestris could be used as an Tribulus terrestris in diabetes. Ann NY Acad Sci 2006;84:391‑401. alternative/adjuvant drug in preventing and treating 15. Gauthaman K, Ganesan AP. The hormonal effects of Tribulus terrestris the extrapyramidal side effects of antipsychotic agents and its role in the management of male erectile dysfunction‑An evaluation using primates, rabbit and rat. Phytomedicine 2008;15:44‑54. in clinical practice. However, it requires further 16. Balanathan K, Omar MH, Zainul MR, Ong FB, Nurshaireen A, preclinical and clinical studies to prove it. Jamil MA. 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Indian J Pharm Sci 2014;76(6):564-567 Flavanone Glycosides as Acetylcholinesterase Inhibitors: Computational and Experimental Evidence C. REMYA, K. V. DILEEP, I. TINTU, E. J. VARIYAR AND C. SADASIVAN* Department of Biotechnology and Microbiology and Inter-University Centre for Bioscience, Kannur University, Thalassery Campus, Palayad‑670 661, India Remya, et al.: Inhibitory Effect of Flavanone Glycosides on AChE Acetylcholinesterase hydrolyzes the neurotransmitter called acetylcholine and is crucially involved in the regulation of neurotransmission. One of the observable facts in the neurodegenerative disorders like Alzheimer’s disease is the decrease in the level of acetylcholine. Available drugs that are used for the treatment of Alzheimer’s disease are *Address for correspondence E-mail: [email protected] November - December 2014 Indian Journal of Pharmaceutical Sciences 567 www.ijpsonline.com primarily acetylcholinesterase inhibitors with multiple activities. They maintain the level of acetylcholine in the brain by inhibiting the acetylcholinesterase function. Hence acetylcholinesterase inhibitors can be used as lead compounds for the development of drugs against AD. In the present study, the binding potential of four flavanone glycosides such as naringin, hesperidin, poncirin and sakuranin against acetylcholinesterase was analysed by using the method of molecular modeling and docking. The activity of the top scored compound, naringin was further investigated by enzyme inhibition studies and its inhibitory concentration (IC50) towards acetylcholinesterase was also determined. Key words: Acetylcholinesterase, Alzheimer’s disease, flavanone glycosides, naringin, induced fit docking Alzheimer’s disease (AD) is one of the progressive determined. It has already been reported that naringin neurodegenerative disorders characterized can alleviate cognitive impairment and oxidative stress by impairment in memory and cognition. AD is induced neuronal injury and it possesses memory associated with the loss of cholinergic neurons in enhancement property[11,12]. the brain regions related to memory and learning, and is also characterized by the presence of amyloid All the molecular docking studies were deposits and neurofibrillary tangles in the brain[1]. performed using Induced Fit Docking (IFD) Studies have proved that the memory loss and method (Schrödinger, LLC, New York, USA)[13]. The learning inabilities were linked with decreased level atomic coordinates of AChE (PDB ID: 1B41) were of acetylcholine (ACh), a neurotransmitter, in the downloaded from Protein Data Bank. The protein brain. This finding has led to research on methods to structure was prepared for docking studies using enhance the level of the cholinergic neurotransmitter the protein preparation wizard of Schrödinger suit. by the inhibition of acetylcholinesterase (AChE)[2]. The Initially, all the crystallographic water molecules were inhibition of AChE not only enhance the cholinergic deleted and hydrogen atoms were added. The bond transmission, but also reduce the aggregation of orders, partial charges and protonation states were amyloid beta (Aβ) peptide and the formation of the corrected properly. Finally the energy minimization neurotoxic fibrils in AD[3]. Recently, it has been shown was carried out using OPLS‑2005 force field. that AChE interacts with Aβ peptides and promotes the formation of amyloid fibril through a group of Similarly the structures of flavanone glycosides (fig. 1) amino acids located in the proximity of the peripheral were downloaded from PubChem database and the anionic binding site (PAS) of the enzyme[4]. It has geometries were optimized using LigPrep module. also been suggested that those molecules, which can OPLS‑2005 force field was again used for the energy interacts with PAS and catalytic sites may prevent the minimization process. The IFD protocol considers aggregation of Aβ mediated by AChE[5]. Aging is one of the main risk factors for AD and is reported that oxidative stress on the central nervous system increases upon aging. A number of studies has also been reported on the protective effects of various polyphenols against aging and related neurodegenerative diseases[6]. The main objective of the present study is to investigate whether selected flavone glycosides (naringin, hesperidin, poncirin and sakuranin) can inhibit the enzyme AChE. Molecular modeling and docking studies have been carried out to assess the relative binding affinity of the compounds towards AChE. The most promising compound has been tested using in vitro enzyme inhibition assay. The selected compounds have already been reported to possess anti oxidant and antiinflammatory properties[7‑10]. The top Fig. 1: Schematic representation of flavanone glycosides. scored compound in the docking studies was found The structures of flavanone and its different glycosides selected for to be naringin. The IC50 value of the compound was the study are shown. 568 Indian Journal