Cholinesterase inhibitory and anti-amnesic activity of alkaloids from Corydalis turtschaninovii

In the course of screening plants used in Korean folk medicine as memory enhancers, a 70% ethanol extract of tuber from Corydalis turtschaninovii Besser (Papaveraceae) showed significant acetylcholinesterase (AChE) inhibitory activity. Repeated column chromatography led to the isolation of a new aporphine alkaloid, oxoglaucidaline ( 9), and a new protoberberine, pseudodehydrocorydaline ( 13) together with 14 known compounds ( 1– 8, 10– 12, and 14– 16). The chemical structures of isolated compounds were elucidated base on extensive 1D and 2D NMR spectroscopic data. Compounds 1– 16 were investigated in vitro for their anti-cholinesterase activity using the mice cortex AChE enzyme. In further study, the anti-amnesic activities of pseudoberberine ( 16) in mice on the learning and memory impairments induced by scopolamine (1.0 mg/kg, i.p.) were examined. This alkaloid (5.0 mg/kg, p.o.) administration significantly reversed cognitive impairments in mice by passive avoidance test ( P < 0.05). It also reduced escape latencies in training trials and prolonged swimming times in the target quadrant during the probe trial in the water maze task ( P < 0.05). These results indicated that Corydalis turtschaninovii due to its alkaloids have anti-cholinesterase activity and pseudoberberine and other alkaloids have anti-amnesic activities that may be useful for cognitive impairment treatment.