New pregnane glycosides from the roots of Cynanchum otophyllum

Six new pregnane glycosides with an acyl at C-12 and a straight sugar chain at C-3, namely otophyllosides H-M (1-6), were isolated from the roots of Cynanchum otophyllum (Asclepiadaceae) collected from Eryuan County in Yunnan province of China. Their structures were characterized to be qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-digitoxopyranoside (1), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (2), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (3), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (4), caudatin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranoside (5), caudatin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside (6), respectively, on the basis of detailed spectroscopic analysis and chemical method.     

Caudatin inhibits carcinomic human alveolar basal epithelial cell growth and angiogenesis through modulating GSK3β/β-catenin pathway

In this study, we investigate the anti‐cancer activity of caudatin in carcinomic human alveolar basal epithelial cell line A549 and anti‐angiogenic activity in human umbilical vein endothelial cells (HUVECs). We show that caudatin impairs the cell viability and induces G₀/G₁ phase arrest in A549 cells with a dose dependent manner. A549 cells, not HUVECs, dealing with caudatin exhibited typical characteristics of apoptosis, which were accompanied by activation of caspase‐3, caspase‐9 and Poly(ADP–Ribose) Polymerase (PARP). In addition, caudatin treatment resulted in a decrease of β‐catenin and increase of phosphorylation of β‐catenin, and inhibited phosphorylation levels of GSK3β (Ser 9) in A549 cells. Conditional medium of A549 cells‐induced or growth factors‐induced tube formation of HUVECs was markedly inhibited by caudatin treatment, which was associated with the inhibiting VEGF secretion from A549 cells by caudatin. Our findings suggest that caudatin inhibits carcinomic human alveolar basal epithelial cell growth and angiogenesis by targeting GSK3β/β‐catenin pathway and suppressing VEGF production. J. Cell. Biochem. 113: 3403–3410, 2012. © 2012 Wiley Periodicals, Inc.     

Caudatin suppresses adipogenesis in 3T3-L1 adipocytes and reduces body weight gain in high-fat diet-fed mice through activation of hedgehog signaling

BackgroundThe regulative effects of caudatin, a C-21 steroid that is identified from Cynanchum bungee roots, on adipogenesis and obesity have not been studied. Many studies have demonstrated that the activation of hedgehog (Hh) signaling can help prevent obesity. Therefore, we hypothesized that caudatin can inhibit adipogenesis and obesity via activating the Hh signaling pathway.MethodsTo investigate the effects of caudatin on adipogenesis in 3T3-L1 preadipocytes and high-fat diet induced obesity in C57BL/6 mice, in vitro and in vivo experiments were performed. For in vitro evaluation, Oil red O staining were used to represent lipid accumulation in differentiated 3T3-L1 adipocytes. For in vivo assessment, male 5 week-old C57BL/6 mice were fed with standard chow diet, high-fat diet (HFD), HFD with 25 mg/kg caudatin, HFD with 1mg/kg purmorpharmine for 10 weeks, respectively. Hh signaling and key adipogenic marker involved in adipogenesis were evaluated by real-time PCR and western blot. The adipocyte size of white adopose tissue and lipid storage of liver were visualized by hematoxylin and eosin staining. In addition, the expression of Gli1 and peroxisome proliferator-activated receptor γ (PPARγ) in white adipose tissue were investigated by immunohistochemistry staining.ResultsCaudatin suppressed the accumulation of lipid droplets and downregulated the expression of key adipogenic factors, i.e., peroxisome proliferator-activated receptor γ PPARγ and CCAAT-enhancer binding protein α (C/EBPα), through activating Hh signaling in differentiated 3T3-L1 cells. Furthermore, caudatin and the Hh activator purmorpharmine significantly decreased body weight gain and white adipose tissue (WAT) weight in HFD-induced mice and affected adipogenic markers and Hh signaling mediators in WAT, which were in line with the in vitro experimental results.ConclusionTo our best knowledge, it is the first report to demonstrate that caudatin downregulated adipocyte differentiation and suppressed HFD-induced body weight gain through activating the Hh signaling pathway, suggesting that caudatin can potentially counteract obesity.     

Caudatin induces cell cycle arrest and caspase-dependent apoptosis in HepG2 cell

In the present study, we investigate the anti-cancer activity and mechanism of caudatin, the C-21 steroidal glycosides, on human hepatoma cell line HepG2. The MTT assay and flow cytometry were used to evaluate HepG2 cell proliferation and cell cycle. Annexin-V/PI and DAPI staining were used to investigate cell apoptosis. Western blotting analysis was used to evaluate the expression levels of proteins. It is found that caudatin inhibits HepG2 cell growth and induces of G₀/G₁ phase arrest in a dose dependent manner, which is associated with a decreased in the expression of cyclinD₁ and increased the levels of p21 and p53. HepG2 cells dealing with caudatin showed typical characteristics of apoptosis. Western blotting analysis indicated that the levels of Bcl-2 were down-regulated after caudatin treatment, whereas the expression of Bax was up-regulated. Furthermore, caudatin-induced apoptosis was accompanied by activation of caspase-3, -9, and poly(ADP-Ribose) Polymerase (PARP). Treatment with caudatin also induced phosphorylation of extracellular-signal regulating kinase (ERK) and c-Jun N-terminal kinase (JNK). These results demonstrate that caudatin inhibits cell proliferation via DNA synthesis reduction and induces caspase-dependent apoptosis in HepG2 cell. Activation of ERK and JNK may be involved in caudatin-induced hepatoma cell apoptosis.     

Identification of new qingyangshengenin and caudatin glycosides from the roots of Cynanchum otophyllum

HPLC analysis of the roots of Cynanchum otophyllum Scheind (Asclepiadaceae) led to the isolation of six new pregnane glycosides, specifically otophyllosides N-P (2-4) and otophyllosides Q-S (7-9), in addition to the identification of three known C-21 steroidal glycosides, otophylloside A (1), otophylloside B (5) and caudatin 3-O-β-D-glucopyranosyl-(1→4)-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-β-D-cymaropyranoside (6). The structure of each glycoside was determined by detailed spectroscopic analysis and chemical methods. All compounds contain qingyangshengenin or caudatin aglycones and a straight sugar chain consisting of 4-7 hexosyl moieties with the mode of 1→4 linkage. The optically isomeric monosaccharides, D- and L-cymarose, coexisted in both otophyllosides R (8) and S (9).     

Synthesis, structure-activity relationships and biological evaluation of caudatin derivatives as novel anti-hepatitis B virus agents

A series of caudatin derivatives were synthesized, and their anti-hepatitis B virus (HBV) activity was evaluated in HepG 2.2.15 cells. Most of the 3-O-substituted caudatin derivatives showed effective anti-HBV activity. Among the tested compounds, six compounds (2e-2h, 2l, 2r) exhibited significantly inhibitory activity against HBV DNA replication with IC(50) values in the range of 2.82-7.48 μM. Interestingly, two compounds (2e, 2f) had potent activity inhibiting not only the secretion of HBsAg (IC(50)=18.68 μM, 21.71 μM), HBeAg (IC(50)=13.16 μM, 33.73 μM), but also HBV DNA replication (IC(50)=7.48 μM, 3.63 μM). The structure-activity relationships (SARs) of caudatin derivatives had been discussed, which were useful for caudatin derivatives to be explored and developed as novel anti-HBV agents.     

Caudatin induces caspase-dependent apoptosis in human glioma cells with involvement of mitochondrial dysfunction and reactive oxygen species generation

Caudatin as one species of C-21 steroidal from Cynanchum bungei decne displays potential anticancer activity. However, the underlying mechanisms remain elusive. In the present study, the growth suppressive effect and mechanism of caudatin on human glioma U251 and U87 cells were evaluated in vitro. The results indicated that caudatin significantly inhibited U251 and U87 cell growth in both a time- and dose-dependent manner. Flow cytometry analysis revealed that caudatin-induced cell growth inhibition was achieved by induction of cell apoptosis, as convinced by the increase of Sub-G1 peak, PARP cleavage and activation of caspase-3, caspase-7 and caspase-9. Caudatin treatment also resulted in mitochondrial dysfunction which correlated with an imbalance of Bcl-2 family members. Further investigation revealed that caudatin triggered U251 cell apoptosis by inducing reactive oxygen species (ROS) generation through disturbing the redox homeostasis. Moreover, pretreatment of caspase inhibitors apparently weakens caudatin-induced cell killing, PARP cleavage and caspase activation and eventually reverses caudatin-mediated apoptosis. Importantly, caudatin significantly inhibited U251 tumour xenografts in vivo through induction of cell apoptosis involving the inhibition of cell proliferation and angiogenesis, which further validate its value in combating human glioma in vivo. Taken together, the results described above all suggest that caudatin inhibited human glioma cell growth by induction of caspase-dependent apoptosis with involvement of mitochondrial dysfunction and ROS generation.     

Synthesis of spacer-equipped di-, tri-, and the tetrasaccharide fragments of the deacetylated O-PS1 of Citrobacter gillenii O9a,9b, and a related pentasaccharide

The title rhamnooligosaccharides [alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, alpha-D-Rhap4NAc-(1-->2)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, and alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->2)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe] were synthesized in a stepwise fashion from 5-methoxycarbonylpentyl 4-azido-4,6-dideoxy-2-O-benzyl-alpha-D-mannopyranoside and orthogonally protected 1-thioglycoside glycosyl donors. The amorphous, final products were fully characterized as corresponding per-O-acetyl derivatives.     

Polyoxypregnane glycosides from the flowers of Dregea volubilis

Three novel polyoxypregnane glycosides, volubiloside A, B and C (1-3), were isolated from the flowers of Dregea volubilis Linn., and their structures were elucidated as drevogenin D-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-cymaropyranoside, drevogenin D-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-digitoxopyranoside and drevogenin P-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-cymaropyranoside, respectively, on the basis of extensive NMR experiments, MALDI-TOF MS, and some chemical strategies.     

Triterpenoid saponins from Schefflera arboricola

Nine triterpenoid saponins were isolated from the leaves and stems of Schefflera arboricola. The saponins were characterised, on the basis of chemical and spectral evidence, as 3-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucuronopyranosyl] oleanolic acid, 3-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucuronopyranosyl] echinocystic acid, 3-O-[beta-D-apiofuranosyl-(1-->4)-beta-D-glucuronopyranosyl] oleanolic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-ramnopyranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid, 3-O-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-rhamnopyranosyl-(1-->4)-[beta-D-galactopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid, 3-O-alpha-L-rhamnopyranosyl-(1-->4)-[beta-D-galactopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester, 3-O-beta-D-apiofuranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid and 3-O-beta-D-apiofuranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->2)-] beta-D-glucuronopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester.     

Chemoenzymatic synthesis of 2-azidoethyl-ganglio-oligosaccharides GD3, GT3, GM2, GD2, GT2, GM1, and GD1a

We have synthesized several ganglio-oligosaccharide structures using glycosyltransferases from Campylobacter jejuni. The enzymes, alpha-(2-->3/8)-sialyltransferase (Cst-II), beta-(1-->4)-N-acetylgalactosaminyltransferase (CgtA), and beta-(1-->3)-galactosyltransferase (CgtB), were produced in large-scale fermentation from Escherichia coli and further characterized based on their acceptor specificities. 2-Azidoethyl-glycosides corresponding to the oligosaccharides of GD3 (alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->3)-beta-D-Galp-(1-->4)-beta-D-Glcp-), GT3 (alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->3)-beta-D-Galp-(1-->4)-beta-D-Glcp-), GM2 (beta-D-GalpNAc-(1-->4)-[alpha-D-Neup5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-), GD2 (beta-D-GalpNAc-(1-->4)-[alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-), GT2 (beta-D-GalpNAc-(1-->4)-[alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->8)-alpha-D-Neup5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-), and GM1 (beta-D-Galp-(1-->3)-beta-D-GalpNAc-(1-->4)-[alpha-D-Neup5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-) were synthesized in high yields (gram-scale). In addition, a mammalian alpha-(2-->3)-sialyltransferase (ST3Gal I) was used to sialylate GM1 and generate GD1a (alpha-D-Neup5Ac-(2-->3)-beta-D-Galp-(1-->3)-beta-D-GalpNAc-(1-->4)-[alpha-D-Neup5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-) oligosaccharide. We also cloned and expressed a rat UDP-N-acetylglucosamine-4'epimerase (GalNAcE) in E. coli AD202 cells for cost saving in situ conversion of less expensive UDP-GlcNAc to UDP-GalNAc.     

Synthesis of tetra- and pentasaccharides corresponding to the capsular polysaccharide of Streptococcus pneumoniae type 9A&L, 9N and 9A

Two tetrasaccharides, alpha-D-GlcAp-(1-->3)-alpha-D-Galp-(1-->3)-beta-D-ManpNAc-(1-->4)-beta-D-Glcp and alpha-D-GlcAp-(1-->3)-alpha-D-Glcp-(1-->3)-beta-D-ManpNAc-(1-->4)-beta-D-Glcp (protected form), and a pentasaccharide, alpha-D-Glcp-(1-->4)-alpha-D-GlcAp-(1-->3)-alpha-D-Galp-(1-->3)-beta-D-ManpNAc-(1-->4)-beta-D-Glcp have been synthesised from 2-aminoethyl glycoside trisaccharide acceptors in a linear approach via consecutive alpha-glycosylations. Ethyl thioglycosides were used as glycosyl donors and DMTST in Et(2)O or NIS/TfOH in CH(2)Cl(2) were employed as promoters.     

Convenient enzymatic synthesis of a p-nitrophenyl oligosaccharide series of sialyl N-acetyllactosamine, sialyl Le x and relevant compounds

From the beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (1) prepared by the transglycosylation of beta-galactosidase from Bacillus circulans, alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (9) and alpha-D-Neu5Ac-(2-->6)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (10) were effectively synthesized with an equimolar ratio of CMP-Neu5Ac by recombinant rat alpha-(2-->3)-N-sialyltransferase and rat liver alpha-(2-->6)-N-sialyltransferase, respectively. The former enzyme also transferred effectively the Neu5Ac residue from CMP-Neu5Ac to the location of OH-3 in the non-reducing terminal of beta-D-Gal-(1-->4)-beta-D-Gal-OC6H4NO2-p or beta-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p, while the latter enzyme did not. In the case of equimolar ratio of GDP-Fuc/acceptor, 1 and 9 were further fucosylated quantitatively to form beta-D-Gal-(1-->4)-beta-D-(alpha-l-Fuc-(1-->3)-)-GlcNAc-OC6H4NO2-p (14) and alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-beta-D-(alpha-l-Fuc-(1-->3)-)-GlcNAc-OC6H4NO2-p (13) by recombinant human alpha-(1-->3)-fucosyltransferase VII, respectively.     

Polyhydroxypregnane glycosides from Oxystelma esculentum var. alpini

Three new polyhydroxypregnane glycosides named alpinoside A [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside], alpinoside B [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside], and alpinoside C [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside] were isolated from the leaves of Oxystelma esculentum var. alpini. The structure elucidation was accomplished by extensive spectroscopic analysis and acid-catalyzed hydrolysis.     

Triterpenoid saponins from Meryta lanceolata

Four new oleanane-type saponins and a known one were isolated from the leaves and stems of Meryta lanceolata. The new saponins were characterised by spectroscopic means and chemical hydrolysis as 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester, 3-O-[beta-D- glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-6-O-acetyl glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester, 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester and 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl]echinocystic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester. The NMR assignments were made by means of HOHAHA, 1H-1H COSY, HMQC, HMBC and NOE difference studies.     

Polyoxypregnane glycosides from Caralluma retrospiciens

Six related polyoxypregnane glycosides were isolated and characterised from Caralluma retrospiciens leaves. The compounds were identified as 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-]-beta-D-cymaropyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], 12beta-benzoyloxy-11alpha-isovaleroyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], and 12beta-benzoyloxy-11alpha-isovaleroyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl (1 --> 4)-3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside]. The structures were determined by detailed analysis of one- and two-dimensional NMR spectra as well as by chemical means. The compounds showed cytotoxic activities towards brine shrimp having IC50 values of 1.19 x 10(-4), 8.83 x 10(-5), 2.64 x 10(-4), 2.26 x 10(-4), 2.39 x 10(-4) and 1.70 x 10(-4) M, respectively. This is the first report of the isolation of these compounds from a natural source.     

Saponins from the seeds of Mimusops laurifolia

Nine saponins were isolated from the seeds of Mimusops laurifolia. Their structures were established using one- and two-dimensional NMR spectroscopy and mass spectrometry. Three of them are identified as: 3-O-(beta-d-apiofuranosyl-(1-->3)-beta-d-glucuronopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, 3-O-(beta-d-glucopyranosyl-(1-->3)-beta-d-glucopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid and 3-O-(beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid.     

Triterpenoid saponins from Oreopanax guatemalensis

Seven oleanane-type saponins were isolated from the leaves and stems of Oreopanax guatemalensis, together with ten known saponins of lupane and oleanane types. The new saponins were respectively characterized as 3-O-alpha-L-arabinopyranosyl echinocystic acid 28-O-[alpha- L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester, 3-O-beta-D-glucopyranosyl 3beta-hydroxy olean-11,13(18)-dien-28-oic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta- D-glucopyranosyl]ester, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl]3beta-hydroxy olean-11,13(18)-dien-28-oic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]3beta, 23 dihydroxy olean-18-en-28-oic acid 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-6-O-acetyl glucopyranosyl-(1-->6)-beta-D-glucopyranosyl]ester, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl] hederagenin 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-[beta-D-xylopyranosyl-(1-->2 )-]beta-D-glucopyranosyl]ester, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]hederagenin 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-[beta-D-glucopyranosyl-(1-->2)-]beta-D-glucopyranosyl] ester and 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl] hederagenin 28-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-[alpha-L-arabinofuranosyl-(1-->2)]-beta-D-glucopyranosyl] ester. The structures were determined by spectral analyses. The NMR assignments were made by means of HOHAHA, 1H-1H COSY, HMQC, HMBC spectra and NOE difference studies.     

Polymer-supported and chemoenzymatic synthesis of the Neisseria meningitidis pentasaccharide: a methodological comparison

Neisseria meningitidis trisaccharide [GlcNAc[(1-->3)Galbeta(1-->4)Glc-R], tetrasaccharide [Galbeta(1-->4)GlcNAcbeta(1--> 3)Galbeta(1-->4)Glc-R], and a pentasaccharide [Neu5Acalpha(2-->3)Galbeta(1-->4)GlcNAcbeta(1-->3)G albeta(1-->4)Glc-SPh] were prepared via conventional chemical synthesis, polymer-supported synthesis, and chemoenzymatic methods, starting from D-lactose. The polymer polyethyleneglycol monomethylether (MPEG) and the linker dioxyxylene (DOX) were used with a lactose-bound acceptor to improve the purification process. Several enzymes (LgtA, GalE-LgtB fusion, and CMP-Neu5Ac synthetase/sialyltransferase fusion) were used for syntheses of these oligosaccharides. Excellent stereo- and regioselectivities as well as high yield (> 90% from Gal(1-->4)Glc-SPh) of the pentasaccharide were obtained. Both of the convenient processes are suitable for efficient preparation of target oligosaccharides.     

Carbohydrates from Cynanchum otophyllum

Four new carbohydrates were isolated from the acidic hydrolysis part of the ethyl acetate extract of Cynanchum otophyllum Schneid (Asclepiadaceae). Their structures were determined as methyl 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-beta-D-ribo-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-alpha-L-ribo-hexopyranoside (1), methyl 6-deoxy-1,3-di-O-methyl-beta-D-ribo-hexosyl-(1-->4)-2,6-dideoxy-3-O-methyl-alpha-D-arabino-hexopyranoside (2), methyl 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-alpha-L-ribo-hexopyranoside (3), and 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-2,6-dideoxy-3-O-methyl-alpha-D-arabino-hexopyranosyl-(1-->4)-2,6-dideoxy-3-O-methyl-beta-D-lyxo-hexopyranose (4), respectively, by spectral methods.