Pregnane glycosides from Dregea volubilis and their α-glucosidase inhibitory activity

Identification and Cytotoxic Evaluation of Pregnane Saponins from the Twigs and Leaves of Dregea volubilis

“…The 1 H-NMR spectrum (Table 1) of compound 5 showed signals for five methyl groups [δ H 1.19 (3H, d, J = 6.0 Hz), 1.21 (3H, d, J = 6.5 Hz), 1.24 (3H, d, J = 6.5 Hz), 1.30 (3H, s), and 1.31 (3H, d, J = 6.0 Hz)], three methoxy groups [δ H 3.45 (3H, s), 3.46 (3H, s), and 3.62 (3H, s)], four oxymethines [δ H 3.17 (1H, d, J = 10.0 Hz), 3.57 (1H, m), 3.75 (1H, t, J = 7.0 Hz), and 3.99 (1H, t, J = 10.0 Hz)], and an olefinic proton at δ H 5.55 (1H, d, J = 5.5 Hz). The 13 13 C-NMR spectra for compound 5 were similar to those of volubiloside E (4), [25] except for the replacement of a methyl group δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] CymII ). [26] This suggests that the configuration at H-17 is α configuration.…”

“…An acid hydrolysis experiment revealed that the sugar units in compound 3 consisted of d-cymarose and d-allose. NMR spectra of the sugar chain showed similarities to those of δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] δH (J in Hz) [a] δC [b] dregeoside D a1 (1), dregeoside K a1 (2), and volubiloside E (4), [10,11,25] S23). The IR data of compound 5 showed a hydroxyl band at 3342 cm À 1 , a carbonyl band at 1688 cm À 1 , and olefin band at 1653 cm À 1 .…”

“…The structures of three known secondary metabolites were determined by comparing their spectroscopic data to those of reference: dregeoside D a1 (1), [11] dregeoside K a1 (2), [10] and volubiloside E (4). [25] Cytotoxic activity of the isolated compounds Isolated compounds (1-7) were assessed for their cytotoxic activity against eight cancer cell lines: MB49, K562, MKN-7, HT29, A549, MCF-7, MDA-MB-231, and HepG2. Doxorubicin was used as a positive control (Table 2).…”

Polyhydroxypregnane Glycosides From Dregea Volubilis

“…The chemical constituents of this plant have been then studied and showed to contain a lot of polyhydroxypregnanes and polyhydroxypregnane glycosides [5,6], pentacyclic triterpenes [7], and flavonoids [8]. In our previous study, three new pregnane glycosides from the leaves of D. volubilis and their α-glucosidase inhibitory activity were reported [9]. Chemical structure of pregnane glycosides from D. volubilis contained interesting sugar units such as 6-deoxy-3-O-methyl-D-allose, D-cymarose, D-digitoxose, and D-oleandrose which are rarely found in natural occurring compounds [5,6].…”