Steroidal glycosides from the fresh stem of Stephanotis lutchuensis var. japonica (Asclepiadaceae). Chemical structures of stephanosides K-Q.

The structural elucidation of seven related oxypregnane-oligoglycosides stephanosides K (1), L (2), M (3), N (4), O (5), P (6), and Q (7) from the fresh stem of Stephanotis lutchuensis var. japonica (Asclepiadaceae) was achieved through on a detailed study of their high-field 1H- and 13C-NMR spectra. The results show that all the sugars are beta (1-->4)-linked. The aglycones of stephanosides K, M, and O, and stephanosides L, N, and P were identified as 12-O-cinnamoyl-20-O-(E)-2-methyl-2-butenoyl, and 12-O-cinnamoyl-20-O-nicotinoyl derivatives of (20S)-pregn-6-ene-3 beta,5 alpha,8 beta,12 beta,14 beta,17 beta,20-heptaol, respectively. The aglycone of stephanoside Q was 12-O-cinnamoyldeacetylmetaplexigenin (kidjoranin).