Five new C21 steroidal glycosides from Periploca sepium

C21 steroidal glycosides and oligosaccharides from the root bark of Periploca sepium

“…The assignment of all the carbon and proton signals of the aglycone and the sugar moiety was determined from HSQC and HMBC experiments, and the sugar unit was identified as a β-digitoxopyranose unit on the basis of comparison of their 1 H and 13 C NMR data with those in the literature [15]. The β-configuration of the anomeric proton of sugar moiety was determined by the large coupling constant (J = 9.56 Hz) [16]. The β-digitoxopyranose unit was located at C-3 on the basis of the carbon signal at C-3 shifted downfield due to the glycosidation shifts, and the 1 H\ \…”

“…Thus, compound 3 was identified as (3β,14β,17α)-3,14,17-trihydroxy-21-methoxypregn-5-en-20-one-3-O- NMR spectrum of 4 exhibited five methyls, a methoxyl, nine methylenes, fifteen methines and four quaternary carbons (Tables 1 and 2). Based on NMR data of 4, it is deduced that 4 was consistent with a C-21 steroidal aglycone and two sugar residues with β-linkages [16]. A detailed comparison of the 13 C NMR data of 4 with periplocoside N (9) [20] indicated that the structure of 4 was similar to that of periplocoside N, expect for the presence of an additional sugar residue attached to C-3 in 4.…”

“…Based on HSQC, HMBC experiments, the four sugar residues were identified to be three β-cymaropyranose units and one β-oleandropyranose unit by comparison of their 1 H NMR and 13 C NMR data with those in the literature [17][18]. The sequence and linkage sites of these three sugar units linked C-3 of the aglycone was illustrated by distinct HMBC correlations ( [16]. In the 13 C NMR and DEPT spectra, 57 carbon signals were observed, including one carbonyl group, seven methyls, six methoxyl, fourteen methylenes, 24 methines and five quaternary carbons (Tables 1 and 2).…”

Immunosuppressive C21 steroidal glycosides from the root of Cynanchum atratum

“…As a kind of characteristic and bioactive constituents, more than 200 C 21 steroidal glycosides have been isolated from Cynanchum species [7] and at least 50 ones have been found from C. atratum [3,4,6,8,9]. Previous researches revealed that C 21 steroids have anti-tumor, immunosuppressive, antidepressant, neuroprotective, antivirus, and appetite-suppressing activities [10][11][12][13][14][15]. Of them, the immune suppressive activity is one of research focuses owing to the significant effects presented by most C 21 steroidal glycosides [11,16].…”

“…Previous researches revealed that C 21 steroids have anti-tumor, immunosuppressive, antidepressant, neuroprotective, antivirus, and appetite-suppressing activities [10][11][12][13][14][15]. Of them, the immune suppressive activity is one of research focuses owing to the significant effects presented by most C 21 steroidal glycosides [11,16].…”