Aromatic plant-derived essential oils: bioactive compounds and their neuroprotective functions in neurological health

Essential oils (EOs), complex mixtures of volatile organic compounds derived from aromatic plants, have demonstrated significant therapeutic potential for neurological and psychiatric disorders through multi-targeted mechanisms. This comprehensive review synthesizes current evidence regarding the neurological effects of essential oil components, with emphasis on psychiatric disorders (depression and anxiety), sleep disorders (insomnia), and neurodegenerative diseases (particularly Alzheimer’s disease). The major bioactive constituents—including monoterpenes (linalool, α-pinene, limonene, 1,8-cineole), sesquiterpenes (β-caryophyllene, patchoulol), and phenylpropanoids (cinnamaldehyde, eugenol)—exert neuroprotective effects through convergent mechanisms despite compositional diversity. These mechanisms encompass modulation of neurotransmitter systems (GABAergic, serotonergic, dopaminergic, cholinergic), regulation of the hypothalamic-pituitary-adrenal axis, anti-inflammatory and antioxidant activities, inhibition of pathological protein aggregation, enhancement of neurotrophic factor expression, and receptor-mediated neuroprotection involving GABAA and cannabinoid type 2 (CB2) receptors. The convergence of diverse phytochemical compositions on common therapeutic targets suggests potential for personalized approaches based on individual tolerability profiles, while the multi-targeted nature of EOs aligns with the multifactorial pathogenesis of neurological disorders, supporting their investigation as complementary therapeutic strategies.