Stereochemical assignment of five new lignan glycosides from Viscum album by NMR study combined with CD spectroscopy

Abstract

The chemical study of the leaves and twigs of Viscum album led to the isolation of five new lignan glycosides, namely, ligalbumosides A-E (2-6) and one known lignan glycoside, alangilignoside C (1). The structures of five new lignan glycosides were determined to be (7R,8S,8'S)-4,9,4'-trihydroxy-3,5,3',5'-tetramethoxy-7,9'-epoxylignan 9-O-β-D-glucopyranoside (2), (7S,8S,7'S,8'R)-4,9,4'-trihydroxy-3,5,3',5',7'-pentamethoxy-7,9'-epoxylignan 9-O-β-D-glucopyranoside (3), (7R,8R,7'S,8'S)-4,9,4'-trihydroxy-3,5,3',5',7'-pentamethoxy-7,9'-epoxylignan 9-O-β-D-glucopyranoside (4), (7S,8R,7'S,8'R)-4,9,4'-trihydroxy-3,5,3',5',7'-pentamethoxy-7,9'-epoxylignan 9-O-β-D-glucopyranoside (5), and (7R,8S,7'R,8'S)-4,9,4',7'-tetrahydroxy-3,5,3',5'-tetramethoxy-7,9'-epoxylignan 9-O-β-D-glucopyranoside (6) using 1D-, 2D-NMR, and CD spectra, chemical methods, as well as comparing the results with those reported in the literature.