Acylated pregnane glycosides from Caralluma tuberculata and their antiparasitic activity

Five pregnane glycosides were isolated from Caralluma tuberculata (1-5), in addition to a known one (russelioside E, 6). The structures of the isolated compounds were elucidated by the analysis of NMR data and FAB-MS experiments. All the isolated compounds were tested for their antimalarial and antitrypanosomal activities as well as their cytotoxicity against human diploid embryonic cell line (MRC5).     

Immunosuppressive pregnane glycosides from Periploca sepium and Periploca forrestii

Nine pregnane glycosides containing peroxy functions in their sugar moieties (1-5 and 11-14), five oligosaccharides (6-10), six pregnane glycosides (15-20), and five cardiac glycosides (21-25) were isolated from the root barks of Periploca sepium Bge. (Asclepiadaceae) and the roots of Periploca forrestii Schltr. (Asclepiadaceae), two traditional Chinese medicines used for the treatment of rheumatoid arthritis. Among them, 1-8 are hitherto unknown. Their structures were characterized on the basis of spectroscopic analyses. In pharmacological testing, compounds 1-5 and 11-14 were found to exhibit inhibitory activity against the proliferation of T lymphocyte in vitro with IC50 values ranging from 0.29microM to 1.97microM, while the other components showed no significant inhibitory activity.     

New unusual pregnane glycosides with antiproliferative activity from Solenostemma argel

Seven new 15-keto pregnane glycosides, namely Stemmosides E--K, were isolated from Solenostemma argel. Stemmosides E--J are characterized by the occurrence of an uncommon 14 beta proton configuration while stemmosides E and F possess in addition a rare enolic function in C-16. On the other hand, stemmosides G-J display an unusual C-17 alpha side chain. Their structures were established by ESI-MS and NMR experiments. Moreover, the effect of these compounds on the VEGF-induced in Kaposi's sarcoma cell proliferation was tested. Results indicated that all the compounds reduced the cell proliferation in a dose dependent manner.     

Structural revision of periplocosides and periperoxides, natural immunosuppressive agents from the genus Periploca

The structures of a series of peroxy function containing pregnane glycosides isolated from Periploca sepium and Periploca forrestii were revised to be orthoester group bearing ones using 2D NMR spectroscopic techniques, as well as chemical transformations and X-ray crystallographic diffraction analysis. The orthoester function appears to be an essential structural feature for immunosuppressive activity.     

New calogenin glycosides from Hoodia gordonii

Ten new pregnane glycosides (1, 3-11) were isolated from organic extracts of aerial parts of Hoodia gordonii, which is sold as an appetite suppressant herbal supplement. The aglycone was identified as calogenin, based on the spectroscopic data of products obtained upon chemical and enzymatic degradation of parent glycoside. The structures of the glycosides were established by chemical degradation studies and extensive spectroscopic techniques that included one-dimensional and two-dimensional NMR.     

Steroidal saponins from the stem of Yucca elephantipes

Ten steroidal saponins with cis-fused A/B ring, including a smilagenin glycoside, elephanoside A (4), and the five furostanol bisdesmosides, elephanosides B-F (6-10), were isolated from the stems of Yucca elephantipes Regel. (Agavaceae). Their structures were determined by detailed chemical and spectroscopic analysis. All the isolated compounds were tested for their in vitro antifungal and antibacterial activities. Only the two known spirostanol glycosides Ys-II (1) and Ys-IV (2) showed moderate inhibitory activity against the growth of Candida albicans and Cryptococcus neoformans.     

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.     

Lanosterol and tetranorlanosterol glycosides from the bulbs of Muscari paradoxum

Three tetranorlanostane glycosides, named lucilianosides C-E, and three lanostane glycosides, named scillasaponins E-G, together with a known lanostane glycoside, were isolated from the MeOH extract of Muscari paradoxum (Liliaceae) bulbs, as confirmed by detailed analysis of their 1H, 13C, and two-dimensional NMR spectroscopic data, and by the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HSC-2 human oral squamous cell carcinoma cells.     

Acylated pregnane glycosides from Caralluma russeliana

The chloroform extract of the aerial parts of Caralluma russeliana yielded four acylated pregnane glycosides, namely russeliosides E-H, three were found now. The structures of the compounds were elucidated using MS, 1H NMR, 13C NMR, 1H-1H COSY, HMQC, NOESY and HMBC experiments.     

Pregnane glycosides from Cynanchum atratum

Five new pregnane glycosides, cynanosides K-O (1-5) with a 14,15-seco-pregnane-type skeleton as the aglycon, together with five known compounds, cynascyroside C, sublanceoside E(1), sublanceoside I(1), atratoside A and atratoside B, were isolated from the roots of Cynanchum atratum. Their structures were determined on the basis of spectroscopic analysis and chemical evidence.     

Steroidal glycosides from the underground parts of Trillium erectum and their cytotoxic activity

Six steroidal glycosides, along with 14 known compounds, were isolated from the underground parts of Trillium erectum L. (Liliaceae). The structures of 1-6 were determined on the basis of extensive spectroscopic analysis, including two-dimensional (2D) NMR data, and a few chemical transformations. The isolated compounds were evaluated for their cytotoxic activity against HL-60 human promyelocytic leukemia cells.     

Cycloartane glycosides from Astragalus stereocalyx Bornm

Six cycloartane-type triterpene glycosides were isolated from Astragalus stereocalyx along with six known cycloartane-type glycosides. Their structures were established by the extensive use of 1D and 2D-NMR experiments along with ESIMS and HRMS analysis. Three compounds are based on an aglycon characterized by the occurrence of an unusual hydroxyl group at position 20, whereas three other compounds are based on cycloasgenin C as aglycon, so far reported from Astragalus spp. All the compounds were tested for their cytotoxic activity against a number of cancer cell lines. One compound exhibited activity versus human cervical cancer (Hela) with an IC(50) value = 10 μM.     

Two novel immunosuppressive pregnane glycosides from the roots of Stephanotis mucronata

Two novel pregnane glycosides, together with one new aglycone, were isolated from the roots of Stephanotis mucronata. Their structures were determined by means of chemical evidence and extensive spectroscopic methods including 1D and 2D NMR. The two pregnane glycosides displayed significant immunosuppressive activities in vitro.     

Amurensiosides A-K, 11 new pregnane glycosides from the roots of Adonis amurensis

Five new pregnane tetraglycosides, amurensiosides A-E (1-5), two new pregnane hexaglycosides, amurensiosides F (6) and I (9), two new 18-norpregnane hexaglycosides, amurensiosides G (7) and H (8), and two new pregnane octaglycosides, amurensiosides J (10) and K (11), were isolated from the MeOH extract of the roots of Adonis amurensis. The structures of the new compounds were determined on the basis of extensive spectroscopic analysis, including two-dimensional (2D) NMR data, and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HSC-2 human oral squamous cell carcinoma cells.     

Expeditious and convenient synthesis of pregnanes and its glycosides as potential anti-dyslipidemic and anti-oxidant agents

A series of new pregnane derivatives and its glycosides were synthesized in order to find new 'leads' against some important targets. The 3beta-hydroxy-16alpha-(2-hydroxy ethoxy) pregn-5-en-20-one (5) was synthesized from 3beta-hydroxy-5,16-pregnadiene-20-one (2) by adopting general modified procedure using BF(3):Et(2)O as a catalyst. Reduction of 5, with sodium borohydride yielded 3beta,20beta-dihydroxy-16alpha-(2-hydroxy ethoxy) pregn-5-en (7) as the major isolable product. O-alkylation of the C-20-oxime-pregnadiene (9) with 1,5-dibromopentane yielded 20-(O-5-bromopentyl)-oximino-3beta-hydroxy-pregn-5,16-diene (11). Synthesis of C-16 substituted pregnane glycosides (20) and (21) were accomplished with the imidate method using BF(3):Et(2)O. The synthesis of 4-chlorobenzoate (3) and 2-chlorobenzoate (4), derivatives of 2 were also accomplished. These compounds were evaluated for their anti-dyslipidemic and anti-oxidant activity and amongst them compounds 3 and 7 showed more lipid lowering and anti-oxidant activity.     

ent-Labdane glycosides from the aquatic plant Potamogeton lucens and analytical evaluation of the lipophilic extract constituents of various Potamogeton species

Two new ent-labdane glycosides, one known furano-ent-labdane and a new hydroxylated fatty acid were isolated from the dichloromethane extract of the freshwater aquatic plant Potamogeton lucens. The new compounds were assigned the structures of beta-d-glucopyranosyl-8(17),13-ent-labdadien-16,15-olid-18-oate, 18-beta-d-glucopyranosyloxy-8(17),13-ent-labdadien-16,15-olide and 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trien-oic acid by spectroscopic means. The algicidal activity of these compounds was tested against Raphidocelis subcapitata. Based on our previous study of Potamogeton pectinatus, other constituents were identified in P. lucens by LC-UV-MS, LC-NMR and GC-MS. The lipophilic extract profiles of both species are presented. Two other species, Potamogeton perfoliatus and P. crispus, were also investigated by analytical comparison of their non-polar extracts. The distribution of ent-labdanes characterized in Potamogeton is summarized.     

Synthesis of Hoodigogenin A, aglycone of natural appetite suppressant glycosteroids extracted from Hoodia gordonii

14β-hydroxy pregnane glycosides extracted from Hoodia gordonii, a succulent plant isolated from Apocynaceae are suggested to have appetite suppressant properties in animals and humans. However, limited reports on biological studies concerning the appetite suppressant properties are available in the open literature. One reason for that is the poor availability of these glycosteroids because H. gordonii is a protected plant and the yield of extraction lies between 0.003% and 0.02%. Starting from 3α,12α-diacetoxy-pregnanone 1, we disclose in this report the synthesis of Hoodigogenin A, the aglycone of the natural 14β-hydroxy pregnane glycosides extracted from H. Gordonii.     

8,12;8,20-diepoxy-8,14-secopregnane glycosides from roots of Asclepias tuberosa and their effect on proliferation of human skin fibroblasts

A pregnane glycoside fraction from the roots of Asclepias tuberosa L. caused normal human skin fibroblasts to proliferate. This fraction contained 21 pregnane glycosides whose structures were established using NMR spectroscopic analysis and chemical evidence. The aglycones of most of these compounds were identified as 8,12;8,20-diepoxy-8,14-secopregnanes, such as tuberogenin or 5,6-didehydrotuberogenin, the same aglycones as constituents of the aerial parts of this plant. Some of these compounds also caused proliferation of skin fibroblasts.     

Clerodane and labdane diterpene glycosides from a Malagasy endemic plant,Cussonia racemosa

Four clerodane glycosides, cussosides A-D, and one labdane glycoside, cussoside E were isolated from the dried leaves of Cussonia racemosa, along with two known flavonol glycosides identified as rutin and kaempferol rutinoside. The structures of the compounds were deduced on the basis of their physical and spectral data.