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--D-glucopyranosylkaempferol-3-O--D-glucopyranoside(1),1,2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3,5-dimethoxy-4-hydroxyphenyl)-N1,N2-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 IC50 of 31.380.97 molL-1;Compounds 2,3,and 4 showed AChE inhibitory activity at 100 molL-1,with inhibition rates of 28.57%1.47%,18.48%2.41% and 17.4%3.03%,respectively.