Targeted studies on the interaction of nicotine and morin molecules with amyloid β-protein

Alzheimer's disease (AD) is a neurodegenerative disorder that occurs due to progressive deposition of amyloid beta-protein (A beta) in the brain. Stable conformations of solvated A beta(1-42) protein were predicted by molecular dynamics (MD) simulation using the OPLSAA force field. The seven residue peptide (Lys-Leu-Val-Phe-Phe-Ala-Glu) A beta(16-22) associated with AD was studied and reported in this paper. Since effective therapeutic agents have not yet been studied in detail, attention has focused on the use of natural products as effective anti-aggregation compounds, targeting the A beta(1-42) protein directly. Experimental and theoretical investigation suggests that some compounds extracted from natural products might be useful, but detailed insights into the mechanism by which they might act remains elusive. The molecules nicotine and morin are found in cigarettes and beverages. Here, we report the results of interaction studies of these compounds at each hydrophobic residue of A beta(16-22) peptide using the hybrid ONIOM (B3LYP/6-31G**:UFF) method. It was found that interaction with nicotine produced higher deformation in the A beta(16-22) peptide than interaction with morin. MD simulation studies revealed that interaction of the nicotine molecule with the beta-sheet of A beta(16-22) peptide transforms the beta-sheet to an alpha-helical structure, which helps prohibit the aggregation of A beta-protein.