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.

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► Chemical investigation of the rhizomes of Curculigo sinensis (Hypoxidaceae).
► Eight norlignan glucosides including two novel ones were obtained.
► The structures of two new compounds were elucidated mainly by spectroscopic methods.
► The free radical scavenging activity was evaluated by DPPH assay.
► All the isolated compounds showed strong radical scavenging activities.