A novel lignan, identified as 4-(3,4-dihydroxyphenyl)-6,7-dimethoxy-3a,4-dihydronaphtho[2,3-c]furan-1(3H)-one, named oleralignan A (1), together with six known compounds, loliolide (2), isololiolide (3), dehydrololiolide (4), daphnetin (5), esculetin (6), and trans-coumaric acid methyl ester (7) was obtained from Portulaca oleracea L., while compounds 3, 4, 6, and 7 were isolated from the plant for the first time. Their structures were elucidated using spectroscopic methods, including one- and two-dimensional NMR and high-resolution electrospray ionization time-of-flight mass spectrometry. In addition, the results of activity assay demonstrated that compounds 1-7 have anticholinesterase activities.
Keywords: Portulaca oleracea L.; anticholinesterase activity; isolation; lignan.