Essential oils constituents are a diverse family of low molecular weight organic
compounds with comprehensive biological activity. According to their chemical structure,
these active compounds can be divided into four major groups: terpenes, terpenoids, phenylpropenes,
and "others". In addition, they may contain diverse functional groups according
to which they can be classified as hydrocarbons (monoterpenes, sesquiterpenes, and aliphatic
hydrocarbons); oxygenated compounds (monoterpene and sesquiterpene alcohols, aldehydes,
ketones, esters, and other oxygenated compounds); and sulfur and/or nitrogen containing
compounds (thioesters, sulfides, isothiocyanates, nitriles, and others).
Compounds that act as cholinesterase inhibitors still represent the only pharmacological
treatment of Alzheimer´s disease. Numerous in vitro studies showed that some compounds,
found in essential oils, have a promising cholinesterase inhibitory activity, such as α-pinene,
δ-3-carene, 1,8-cineole, carvacrol, thymohydroquinone, α- and β-asarone, anethole, etc.
This review summarizes the most relevant research published to date on essential oil constituents
and their acetylcholinesterase/butyrylcholinesterase inhibitory potential as well as their
structure related activity, synergistic and antagonistic effects.