Identification and characterisation of coumarins from the roots of Angelica dahurica and their inhibitory effects against cholinesterase

• The ethanol extract of A. dahurica roots showed cholinesterase inhibitory activities.
• Ten coumarins were identified using NMR spectroscopy.
• Oxypeucedanin was the predominant coumarin with 8710.9 μg/g in A. dahurica roots.
• t-OMe-Byakangelicin of noncompetitive inhibitor showed potent hAChE and BChE effects.
• Each coumarin exhibited remarkable differences in content and inhibitory effect.

The current research was the first to investigate coumarins and their cholinesterase inhibitory activities from Angelica dahurica roots. The ethanol extract of this species (100 μg/ml) possessed inhibitory effects against human acetylcholinesterase (hAChE) and butylcholinesterase (BChE) with IC50 values of 26.40 and 14.71 μg/ml, respectively. To evaluate the compounds responsible for these activities, the ethanol extract was chromatographed, which yielded ten coumarins, including isoimperatorin (1), imperatorin (2), senbyakangelicol (3), oxypeucedanin (4), byakangelicol (5), t-OMe-oxypeucedanin hydrate (6), t-OMe-byakangelicin (7), angelol H (8), byakangelicin (9), and oxypeucedanin hydrate (10). Among them, coumarin 5, 7, and 9 showed potent inhibition with IC50s of 46.3, 39.0, and 55.4 μM (hAChE) as well as 45.2, 25.6, and 42.4 μM (BChE), respectively. Moreover, their inhibition modes against two cholinesterases exhibited noncompetitive. The individual coumarin contents were remarkable differences, especially, oxypeucedanin (4) was the most predominant compound (8710.9 μg/g), representing approximately 55.0% of the total content.