A new flavonol C-glycoside and a rare bioactive lignanamide from Piper wallichii Miq. Hand.-Mazz

This study was conducted to investigate the chemical constituents of Piper wallichii (Miq.) Hand.-Mazz. and evaluate their biological activity. Compounds were isolated by various column chromatographic methods, and their structures were elucidated on the basis of physical characteristics and spectral data. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging activity and acetylcholinesterase (AChE)-inhibitory activity of the compounds were evaluated. Five compounds were obtained and identified as 8- C -β-D-glucopyranosylkaempferol-3- O -β-D-glucopyranoside ( 1 ), 1, 2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3, 5-dimethoxy-4-hydroxyphenyl)- N 1 , N 2 -bis-[2-(4-hydroxyphenyl)ethyl]-2, 3-naphthalene dicarboxamide ( 2 ), goniothalactam ( 3 ), aristololactam A IIIa ( 4 ) and piperlonguminine ( 5 ). Compound 1 was a new flavonol C -glycoside, 2 was a rare lignanamide, which was isolated from the family Piperaceae for the first time, and compound 3 was isolated from this plant for the first time. Among them, 2 showed potent DPPH-scavenging activity, with IC 50 of 31.38 ± 0.97 μmol·L −1 ; Compounds 2 , 3 , and 4 showed AChE inhibitory activity at 100 μmol·L −1 , with inhibition rates of 28.57% ± 1.47%, 18.48% ± 2.41% and 17.4% ± 3.03%, respectively.