1 Molecular dynamics simulation and free energy calculations of the binding characteristics of multi-target anti-Alzheimer natural compounds isolated from Psoralea Fructus to amyloid β-peptide42 Awwad Radwan *, Fares Al-Anazi , Kayyali Scientific Chair for. Pharmaceutical Industry, College of Pharmacy, King Saud University , Riyadh 11451, Saudi Arabia. * Corresponding author: aradwan@ksu.edu.sa