Inhibitory Effects of Essential Oil Extracts From Panax ginseng Against β-Secretase and Cholinesterases

Panax ginseng C.A. Meyer is recognized as one of the most important crude drugs in ancient Chinese medicine. Numerous pharmacological studies investigated P. ginseng; however, these studies were limited to ginsenosides, which are typical constituents in P. ginseng. We focused on the essential oil (EO) from P. ginseng as it has a typical aroma. Herein, we report the inhibitory activities of EO against beta-secretase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), which were investigated in order to demonstrate the potential of EO as a preventative and therapeutic agent against Alzheimer's disease (AD). Essential oil (250 mu g/mL) showed 41.4% inhibition against beta-secretase, 77.4% inhibition against AChE, and 94.1% inhibition against BChE. In addition, spathulenol (8.82%, content % in EO), bicyclogermacrene (6.23%), beta-elemene (3.94%), and alpha-humulene (3.69%) were identified as high content by Gas chromatography mass spectrometry (GC/MS) analysis. Furthermore, beta-elemene and alpha-humulene showed high activity among 3 compounds with 50% inhibitory concentration (IC50) values of 77.2 and 137.3 mu M for AChE, and 298.2 and >2000 mu M for BChE, respectively. In this report, we showed the inhibitory activity of EO from P. ginseng against beta-secretase, AChE, and BChE, and demonstrated that EO could be a candidate to treat AD. This is the first research to report the anti-AD effect of EO and determination of its volatile components. Especially, beta-elemene and alpha-humulene are expected to be highly bio-available compounds due to their small molecular size and lipophilicity. From these results, EO from P. ginseng may be a promising candidate for AD treatment.