A Molecular Docking Study of Aloysia citrodora Palau. Leaf Essential Oil Constituents towards Human Acetylcholinesterase: Implications for Alzheimer’s disease

Aloysia citrodora essential oil has been described as a potential new candidate for treating Alzheimer’s disease (AD). It displays a range of pharmacological properties, including acetylcholinesterase (AChE) inhibition worthy of investigation. The essential oil of the fresh leaves of A. citrodora was obtained by hydrodistillation, and the composition of the essential oil was investigated using GC-MS (Gas Chromatography-Mass Spectrometry). Sixty compounds were identified, which were composed of oxygenated monoterpenes and sesquiterpenes. In the evaluation of the anticholinesterase activity of the essential oil through virtual screening, molecular docking and bioassay were used. Seven main components were identified namely caryophyllene oxide, geranyl acetate, β-sesquiphellandrene β-curcumene, γ-/ar-curcumene, β-/(Z)-α-bisabolene, trans-calamenene, and β-sesquiphellandrene. Three compounds (geranyl acetate, caryophyllene oxide and bisabolene) were available commercially and assessed for AChE inhibitory activity to validate the approach. The dose-response relationship showed that AChE inhibitory with IC₅₀= 5.3 µM for caryophyllene oxide and 244.5 µM for geranyl acetate. The molecular docking study revealed that A. citrodora may yield new selective inhibitors of AChE from plant-originated essential oils.