π-stacking interactions between curcumin and aromatic ring of amino acids in amyloid fibrils: A theoretical study

The aggregation of amyloid-β peptides into amyloid fibrils is considered as one of the possible causes of Alzheimer's disease. Curcumin is a well-known inhibitor for aggregation of Aβ1-42 peptides and has the ability to disintegrate preformed Aβ fibrils and amyloid plaques. This study provides an insight on the magnitude of π-stacking interactions between the aromatic AAs of Aβ and curcumin via quantum mechanical methods in gas phase and in water solvent. The results showed stacking interaction energies for CurK and amino acids are greater. The calculated charges on carbon atoms showed that B ring in CurE is more susceptible to π-stacking interaction. HOMO-LUMO energy gap showed that CurE is a better antioxidant than CurK. It was shown that the sum of electron densities, Ʃρ/n, calculated at BCPs and RCPs can be useful as descriptors for prediction of π-stacking interaction in the complexes.