Chemical and enantioselective GC–MS characterization of Minthostachys mollis (Benth.) Griseb. Essential oil from Peru and its acetylcholinesterase inhibitory activity

Background – Minthostachys mollis (Benth.) Griseb., an aromatic medicinal plant widely used in traditional medicine in Peru, was investigated using an integrated chemical, enantioselective, and acetylcholinesterase (AChE) inhibitory approach. Aim – To characterize the chemical and enantiomeric composition of M. mollis essential oil by GC–MS, evaluate its AChE inhibitory activity in vitro, and explore the molecular interactions of its volatile constituents with human AChE through molecular docking and molecular dynamics simulations. Methods – The essential oil (EO) collected from the leaves via steam distillation was analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). Enantioselective GC–MS analysis was performed for the first time on this species. AChE inhibitory activity was evaluated in vitro using Ellman’s assay, and molecular docking and molecular dynamics studies were performed on human AChE (PDB: 4EY7). Results – GC–MS analysis revealed 33 volatile compounds, of which 30 were structurally identified, accounting for 100% of the total EO composition. Oxygenated monoterpenes were the predominant chemical class (86.24%), with pulegone (63.82%) as the major constituent, followed by carvacrol (5.52%), 1, 8-cineole (5.50%), and (E)-isocitral (4.98%). Enantioselective analysis revealed a marked stereochemical preference, including enantiomerically pure (S)-(−)-limonene and (1R, 5R)-(+)-sabinene, as well as the predominance of (1S, 5S)-(−)-α-pinene (92.54%, e.e. = 84.97%) and (1S, 5S)-(−)-β-pinene (80.63%, e.e. = 61.86%). The AChE inhibitory activity showed a moderate inhibitory effect of the EO, with an IC₅₀ value of 466.4 ± 1.01 μg/mL. Sesquiterpenes such as γ-muurolene, δ-amorphene, and β-bourbonene exhibited the most favorable binding affinities (ΔG values ranging from −7.3 to −7.0 kcal/mol), mainly mediated by hydrophobic interactions within the catalytic and peripheral anionic sites. Conclusion – This study provides a comprehensive chemical and stereochemical characterization of M. mollis EO, supporting its relevance as a source of bioactive volatile compounds with moderate AChE inhibitory activity.