Glycosides of arylnaphthalene lignans from Acanthus mollis having axial chirality

Abstract

Glycosides of arylnaphthalene lignans having axial chirality were isolated from Acanthus mollis. Owing to the axial chirality, their structure, including absolute configuration, was determined by means of extensive spectroscopic data such as UV, IR, MS, 1D and 2D NMR spectra, and computational chiroptical methods. A compound, 2′,4-dihydroxyretrohelioxanthin (2′-hydroxy-justirumalin), has a structure containing two aromatic moieties with substituents hindering rotation about the biaryl axis. The aglycone was connected to a saccharide moiety linked at C-4 or C-2′ and made up of one or four sugars (rhamnose or quinovose, and tetrasaccharide 4- O-β- d-xylopyranosyl-(1′′′′′-6′′)- O-[β- d-rhamnopyranosyl-(1′′′′-3′′)]- O-β- d-apiofuranosyl-(1′′′′-2′′)- O-β- d-glucopyranoside and quinovose). Two mono- and one tetraglycoside gave positive results in the sea urchin eggs test ( Paracentrotus lividus) of cytotoxicity and in a crown gall tumor on potato disks test ( Agrobacterium tumefaciens).