Four new neolignans isolated from Eleutherococcus senticosus and their protein tyrosine phosphatase 1B inhibitory activity (PTP1B)

Four new compounds, erythro-7'E-4-hydroxy-3,3'-dimethoxy-8,5'-oxyneoligna-7'-ene-7,9-dio1-9'-al (1), (7S,8S)4-hydroxy-3,1',3'-trimethoxy-4',7-epoxy-8,5'-neolign-9-ol (5), (75,85,7'E)-5-hydroxy-3,3'-dimethoxy-4',7-epoxy8,5'-neolign-7'-ene-9,9'-diol (6) and (75,85,7'E)-5-hydroxy-3,3',9'-trimethoxy-4'-7-epoxy-8,5'-neolign-7'-ene-9ol (7). Along with four known compounds (2-4, 8) were isolated from the EtOAc-soluble extract of Eleutherococcus senticosus. Their structures were elucidated on the basis of spectroscopic and physicochemical analyses. All the compounds were evaluated for in vitro inhibitory activity against PTP1B, VHR and PPl. Among them, compounds 1-4 and 6-8 were found to exhibit selective inhibitory activity on PTP1B with IC50 values ranging from 17.2 1.6 to 32.7 1.2 M.