Chemical constituents and acetylcholinesterase inhibitory activity of piper abbreviatum opiz

Abstract

Plants of the genus Piper have long been used as medicinal herbs. The chemistry of Piper species has been widely investigated and phytochemical investigations conducted in all parts of the world have led to the isolation of a number of physiologically active compounds. Thus, this study was carried out to investigate the phytochemicals from Piper abbreviatum and their acetylcholinesterase inhibitory activity, which has not been previously investigated. Fractionation and purification of the aerial parts of P. abbreviatum led to the isolation and identification of five methoxylated flavonoids, namely 5,7-dimethoxyflavone, 4,5,7-Trimethoxyflavone, 3',4',5,7-tetramethoxyflavone, 5-hydroxy-7-methoxyflavone, 5-hydroxy-4,7-dimethoxyflavone, together with lupeol, lupenone, β-sitosterol, and β-sitostenone. The structures of these compounds were obtained by analysis of their spectroscopic data, as well as the comparison with that of reported data. Acetylcholinesterase inhibitory activity revealed that all isolated flavones were found to inhibit AChE with percentage inhibition values ranged from 24.2 to 58.2%. This is the first report on the isolation of methoxylated flavonoid from P. abbreviatum. The high variants of flavonoid compounds from this species may be used as chemotaxonomic markers for this Piper species.