Studies on the constituents of asclepiadaceae plants-LII : The structures of five glycosides glaucoside-A, -B, -C. -D. and -E from chinese drug “Pai-ch'ien” Cynanchum glaucescens HAND-MAZZ

Abstract

The glycosides of Chinese crude drug “Pai-ch'ien”. dried root of Cynanchum glaucescens HAND-MAZZ (Asclepiadaceae) have been studied. Five new glycosides named glaucoside-A( 4), -B( 5), -C( 6), -D( 7). and -E( 10) were isolated by silica gel column chromatography, and their structures were deduced by combination of analyses of their hydrolysates and spectroscopic methods using 1H NMR, 13C NMR, and FD-MS. Interestingly 5, 6, 7, and 10 were found to carry α-glycosyl linked L-cymaropyranoses in the terminal of their sugar chains while the other mode of linkages are β.