Norditerpenoid alkaloids of Delphinium denudatum as cholinesterase inhibitors

Abstract Three new norditerpenoids alkaloids, 1 β -hydroxy,14 β -acetyl condelphine ( 1 ), jadwarine-A ( 2 ), jadwarine-B ( 3 ) along with two known alkaloids isotalatizidine hydrate ( 4 ) and dihydropentagynine ( 5 ) were isolated from medicinal plant Delphinium denudatum . The structures of natural products 1 – 5 were established on the basis of HR-EIMS, 1 H and 13 C NMR (1D & 2D) spectroscopic data as well as by comparison from literature data. The structures of compound 1 and 4 were also confirmed by single crystal X-ray diffraction studies. In - vitro AChE and BChE enzyme inhibitory activities of compounds 1 – 5 and molecular docking studies were performed to investigate the possible molecular inhibitory mechanism of the isolated natural products. Compound 2, 4 and 5 showed competitive inhibitory effects by inhibiting AChE and BChE, respectively, while 1 and 3 showed non-competitive inhibition. This work is the first report that provides a supporting evidence about the use of constituents of Delphinium denudatum in cerebral dementia and Alzheimer diseases.