Two new lignan glycosides forsythiayanoside A (1) and forsythiayanoside B (2), one new stereoisomer of lignan glycoside (+)-8-hydroxyepipinoresinol-4-O-β-D-glucopyranoside (3), together with seven known compounds (4-10), were isolated from the fruits of Forsythia suspense (Thunb.) Vahl. Compounds 4 and 10 were isolated from this species for the first time. The structures of 1-3 were elucidated on the basis of chemical and spectral analyses, including 1D and 2D NMR data and HR-ESI-MS. The absolute configurations were determined by the circular dichroism method. All isolates were tested for their cytotoxicities against five human cancer cell lines (A549, Colo-205, Hep-3B, HL60, and KB). In particular, compound 3 showed significant cytotoxicity with IC50 values of 9.48, 7.75, 0.59, 4.06, and 38.38 μM, respectively.
Keywords: CD; Forsythia suspense; NMR; cytotoxic activity; lignan glycosides.