Novel norlignan glucosides from rhizomes of Curculigo sinensis.

Eight norlignan glucosides, including two novel skeleton-rearranged compounds, sinenside A (1) and B (2), and six known compounds, crassifoside D (3), capituloside (4), a mixture of (1S,2R)-1-O-methylnyasicoside (5), (1R,2R)-1-O-methylisonyasicoside (6), and a mixture of (1S,2R)-1-O-methylcurculigine (7) and (1R,2R)-1-O-methylisocurculigine (8), were isolated from the rhizomes of Curculigo sinensis. Compounds 3-8 were isolated for the first time from this plant. Structures of the isolated compounds were established by spectroscopic analysis, including UV, IR, HRESI-MS, and 1D/2D NMR, and hydrolysis experiments. The free radical scavenging activity of the isolated compounds was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. All the isolated compounds showed strong radical scavenging activities.