Molecular docking study on columbin isolated from Tinospora cordifolia as a cholinesterase inhibitor

Abstract

Purpose: To investigate the acetylcholinesterase (AChE) inhibitory potential of columbin and also to assess its binding affinity against AChE protein. Methods: Crystals of columbin were isolated from the ethyl acetate fraction of Tinospora cordifolia using column chromatography and its structure was determined using x-ray crystallography. Ellman colorimetric assay was used to determine the AChE inhibitory effect in vitro while molecular docking was performed using the MOE 2015.010 software. The selected protein data bank (PDB) was modeled using PDB ID: 10CE (pacific electric ray). Results: The crystal and structure refinement data of columbin were: C20H22O6, Orthorhombic, P212121, a = 7.4951(2) Å (α = 90°), b = 11.6451(3) Å (β = 90°), c = 19.5882(5) Å (γ = 90°), V=1709.68(8) Å3, Z = 4, Density (calculated) = 1.392 Mg/m3, absorption coefficient = 0.851 mm-1, goodness-of-fit on F2 =1.091, T = 100(2) K. Columbin demonstrated good AChE inhibitory effect with half-maximal inhibitory concentration (IC50) of 1.2993 ± 0.17 mg/mL. Molecular docking data revealed that it exhibited hydrophobic and hydrogen bonding interactions with the surrounding residues, and this accelerated complexation between the ligands and the active site of the enzyme. Conclusion: Columbin may be useful in the management of neurodegenerative conditions such as Alzheimer’s disease.