Anti-cholinesterase profile of Murraya koenigii (L.) Spreng essential oil and its chemical constituents

Traditionally, Murraya koenigii (L.) Spreng has been used as an ingredient in medicinal formulations. Several studies have reported on the potential of M. koenigii leaves to enhance learning and memory functions in animal models. This study aimed to identify the chemical constituents and evaluate the anti-cholinesterase activity of the essential oil extracted from M. koenigii leaves. The essential oil extracted via hydrodistillation was analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of 41 constituents were identified, with β-phellandrene (35.42%), β-caryophyllene (16.79%) and α-pinene (17.75%) predominating in the essential oil. Using Ellman’s colorimetric method, the M. koenigii essential oil demonstrated potent inhibitory activity against acetylcholinesterase (AChE), with an IC₅₀ value of 36.89 μg/mL. Interestingly, a mixture of the three major constituents (β-phellandrene, β-caryophyllene, and α-pinene) was more effective than the individual constituents (β-caryophyllene and α-pinene). In conclusion, the study on the neuroprotective effects of M. koenigii essential oil has yielded promising results.