Inhibitory effects of phytochemicals of spices on human monoamine oxidase B through molecular docking, molecular dynamics simulation, and DFT study
Ram Lal Swagat Shrestha, Prabhat Neupane, Sujan Dhital, Nirmal Parajuli, Binita Maharjan, Timila Shrestha, Samjhana Bharati, Bishnu P. Marasini, Jhashanath Adhikari Subin
Abstract
Spices are an integral part of cuisines, with their phytochemicals possessing therapeutic potential for managing various health conditions. Rapidly increasing neurodegenerative disease, Parkinson’s, could be treated through inhibition of monoamine oxidase B (MAO-B) enzyme. This study aims to identify chemical components of spices as potential inhibitors of MAO-B by computational methods. From molecular docking calculation, 5′-methoxycurcumin, conferol, and farnesiferol A demonstrated firm binding with the receptor with binding affinities of −11.738 kcal/mol, −11.689 kcal/mol, and −11.559 kcal/mol, respectively better than that of the native ligand with −10.551 kcal/mol. The complexes of conferol, farnesiferol A, and 5′-methoxucurcumin exhibited good geometrical stability with smooth curves and RMSD of ligand at approximately 2.0 Å, 3.0 Å, and 4.5 Å, respectively from Molecular Dynamics Simulation (200 ns). Thermo-dynamical stability assessed from binding free energy changes using the MMPBSA method revealed sustained spontaneity and feasibility of complex formation reaction. The DFT approximation (B3LYP/6-31G*) was used for constructing frontier molecular orbitals and estimating the HOMO–LUMO energy gaps of the top molecules. Various physical descriptors were calculated to compare the molecules based on their reactivity. The three phytochemicals could be proposed as potent drug-like candidates in the treatment of Parkinson’s disease and are recommended for experimental verifications.