Abstract: Objective To study the difference of chemical constituents in the essential oils of crude and salt-fried Alpiniae Oxyphyllae Fructus, which often occurred in the anti-dementia prescription of traditional Chinese medicines in clinic, and evaluate their inhibitory activities against acetylcholinesterase (AChE). Methods Essential oil was extracted from Alpiniae Oxyphyllae Fructus by steam distillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Thin-layer chromatography (TLC)-bioautography was used to evaluate their anti-AChE activity. Results The extraction ratio of essential oils from Alpiniae Oxyphyllae Fructus decreased after salt-fried. Twenty-nine components were identified respectively from the essential oils of crude Alpiniae Oxyphyllae Fructus and salt-fried one, among which the content of nootkatone was the highest (25%), followed by valencene (7%). Four components in the volatile oils changed after salt-fried. Calamenene (1.12%), ledol (1.05%), caryophyllene oxide (0.99%) and β-cyperene (0.32%) were only identified in the crude Alpiniae Oxyphyllae Fructus, however, eudesm-11-en-1a-ol (1.32%), 9,10-dehydroisolongifolene (1.17%), gurjunenepoxide (0.91%) and 1R,4R,7R,11R-1,3,4,7-tetramethyltricyclo[5.3.1.0(4,11)]undec-2-ene (0.38%) were only identified in the salt-fried Alpiniae Oxyphyllae Fructus. Both of volatile oils from crude and salt-fried Alpiniae Oxyphyllae Fructus possessed anti-AChE activity. Conclusion Some components in the volatile oil of Alpiniae Oxyphyllae Fructus change after salt-fried, especially a potential toxic sesquiterpenoid ledol disappears. The AChE-inhibitory activity of Alpiniae Oxyphyllae Fructus essential oil may have some close relationship with its anti-dementia function in clinic.

Key words: Alpiniae Oxyphyllae Fructus, Salt-fried, Essential oil, Gas chromatography-mass spectrometry, Acetylcholinesterase inhibitory activity