Govanosides C-F, unprecedented steroidal saponins with rare sugars from rhizomes of Trillium govanianum and their antagonistic effects on acetylcholinesterase.

Four previously undescribed steroidal saponins named govanosides C-F (1-4) and nine known compounds (5-13) were isolated from the rhizomes of Trillium govanianum Wall. ex D.Don. Govanosides C-E contained a rare sugar moiety i.e., 6-deoxy allose, while govanoside F has acetylated rhamnose moiety in its glycan part. Also, this is the first report on the isolation of feruloyl sucrose derivatives (11-12) and (E)-4-hydroxy-dodec-2-enedioic acid (13) from the Trillium genus. The structure of isolated compounds was deduced using 1D and 2D NMR, HRESIMS, LC-MS/MS, GC-MS, and saccharide linkage analysis. Steroidal scaffold isolates (1-10) were evaluated for their antagonistic effects on acetylcholinesterase inhibitory activity. Govanoside C (1) significantly inhibited acetylcholinesterase (IC: 2.38 μM). Molecular docking experiments have also been performed to depict the molecule's interaction and binding free energy with acetylcholinesterase.