Three new lignan glycosides from the fruits of Forsythia suspense

Abstract

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::

• Forsythia suspense
• lignan glycosides
• NMR
• CD
• cytotoxic activity

Acknowledgment

Authors thank Mrs Wen Li and Mr Yi Sha of Shenyang Pharmaceutical University for the recording of NMR spectra.