8,4′-Oxyneolignane glucosides from an aqueous extract of “ban lan gen” ( Isatis indigotica root) and their absolute configurations

摘要

Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A?F ( 1 – 6 ), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of Δ δ _C8-C7 values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1 – 6 and their aglycones ( 1a – 6a ) are discussed.