Steroidal Glycosides from the Fresh Stem of Stephanotis lutchuensis var. japonica (Asclepiadaceae). Chemical Structures of Stephanosides K-Q.

Abstract

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).

New Pregnane Glycosides from Gymnema sylvestre

“…Comparing to the 13 C-NMR data of 1 , the benzoyl signals at δ C 133.2, 128.7 (overlapped), 130.2 (overlapped), 131.2 and 165.6 disappeared in the spectrum of 2 , while signals for another acyl group were observed at δ C 12.2, 14.1, 129.4, 137.7 and 166.7. This group was identified as 2-methyl-2-butenoyl by inspection of the 1 H, 1 H-COSY, HMQC and HMBC spectra and comparison with reported data [31,32,33]. The HMBC coupling between H-20 (δ H 5.11) and the carbonyl carbon (δ C 166.7) of the 2-methyl-2-butenoyl group confirmed the connection of this group to C-20.…”

“…reported the isolation of a series of pregnane glycosides from the species G. alternifolium [31,32]. In our study on the hypoglycemic constituents of G. sylvestre , four new pregnane glycosides 1 – 4 were isolated from the 50% ethanol extract of the dry stem of G. sylvestre and named as gymsylvestrosides A–D.…”

Bioactive C21 Steroidal Glycosides from the Roots of Cynanchum otophyllum That Suppress the Seizure-like Locomotor Activity of Zebrafish Caused by Pentylenetetrazole

“…35 (Figure 2). 37 On the basis of the above evidence, the aglycone was identified as gagaminin. β-Cymaropyranosyl and β-digitoxopyranosyl moieties were deduced to exist in the structure of 6 according to two anomeric proton signals at δ H 5.…”

Two New C21 Steroidal Glycosides from Marsdenia tenacissima (ROXB.) WIGHT et ARN

“…A molecular formula of C 42 C-NMR spectra are the same as those in previous studies. 9,10) So, the sugar moieties were comprised of two moles of b-D-cymaropyranoses and one of b-D-thevetopyranose. In addition, all the glycosidic linkages were suggested to be in b-form since the coupling constants of three anomeric proton signals were all in the range of 7-10 Hz.…”