Alkaloids from Stephania cephalantha and their enzyme inhibitory activities

A new protoberberine type alkaloid, 11-diethylaminomethyl corydalmine (1), and 27 known alkaloids (2-28) were isolated from the tuberous roots of Stephania cephalantha. Their structures were identified by spectral analysis. Enzyme inhibitory activities of the compounds on acetylcholinesterase (AChE), tyrosinase and α-glucosidase were evaluated. Compounds 13, 16 and 18 exhibited comparable AChE inhibitory activities to the positive control huperzine A, with the IC₅₀ values of 0.046, 0.048, and 0.057 mg/mL, respectively.