Cholinesterase and Beta-Amyloid aggregation inhibitors from flowers of indian devil tree alstonia scholaris L.R. Br.

Abstract

Six compounds were isolated from the flower extract of Alstonia scholaris by column chromatoghaphy. The chemical structures of all isolated compounds were elucidated by NMR analysis as α-amyrin acetate (1), stigmasterol (2), betulin (3), ursolic acid (4), β-sitosterol-3-O-β-D-glucopyranoside (5) and nareline (6). These compounds were further evaluated for their anti-cholinesterase, anti-amyloid aggregation and anti-lipid peroxidation activities. The IC₅₀ values toward acetylcholinesterase and butyrylcholinesterase of these isolated compounds were in the range of 0.070 -0.231 and 0.282-0.721 mM, respectively. Alkaloid 6 showed the highest inhibition toward both enzymes. Moreover, α-mangostin showed the acetylcholinesterase synergistic effect with compound 5. All five triterpenoids (1-5) displayed low anti-amyloid aggregation and anti-lipid peroxidation activities. Alkaloid 6 exhibited moderate amyloid aggregation inhibition with 28.1% at the final concentrations of 100 µM and showed low anti-lipid peroxidation activity.