Triterpenoid saponins from Triplostegia grandiflora.

Four new oleanane triterpenoid saponins named triplosides D-G were isolated from the roots of Triplostegia grandiflora. Their structures were elucidated on the basis of chemical degradation and spectral evidence. The saponins investigated were: oleanolic acid 3-O-beta-D-xylopyranosyl(1----4)-beta-D-xylopyranosyl(1----3)-beta-D- xylopyranosyl(1----4)-alpha-L-rhamnopyranosyl(1----3)-beta-D- xylopyranosyl(1----3)-alpha-L-rhamnopyranosyl(1----2)-beta-D-xylopyranos ide, oleanolic acid 3-O-beta-D-glucopyranosyl(1----6)-[beta-D- xylopyranosyl(1----4)]-beta-D-glucopyranosyl(1----3)-beta-D- xylopyranosyl(1----4)-alpha-L-rhamnopyranosyl(1----3)-beta-D- xylopyranosyl(1----3)-alpha-L-rhamnopyranosyl(1----2)-beta-D-xylopyranos ide, oleanolic acid 3-O-beta-D-xylopyranosyl(1----3)-beta-D-xylopyranosyl(1----4)- alpha-L-rhamnopyranosyl(1----3)-beta-D-xylopyranosyl(1----3)-alpha-L- rhamnopyranosyl(1----2)-beta-D-xylopyranoside and oleanolic acid 3-O-alpha-L-rhamnopyranosyl(1----3)-beta-D-xylopyranosyl(1---3)-alpha-L- rhamnopyranosyl(1----2)-beta-D-xylopyranoside, respectively. All of them have a common aglycone and are monodesmosides.     

Biologically active labdane-type diterpene glycosides from the root-stalks of Gleichenia japonica.

A glycoside showing a strong growth inhibition of lettuce was isolated from the root-stalks of Gleichenia japonica and its structure was established to be the 3-O-alpha-rhamnopyranosyl-(1----2)-beta-glucopyranoside of 13-O-alpha-rhamnopyranosyl-(+)-3 beta-hydroxymanool. In addition, two related glycosides were also isolated and they were characterized as the 3-O-beta-fucopyranosyl-(1----3)-alpha-rhamnopyranosyl-(1----2)-beta- glucopyranoside of 13-O-alpha-rhamnopyranosyl-(+)-3 beta-hydroxymanool and the 13-O-rhamnopyranoside of the same diterpene alcohol. The diterpene alcohol accelerated the growth of lettuce.     

Feruloylated xyloglucan and p-coumaroyl arabinoxylan oligosaccharides from bamboo shoot cell-walls.

A novel feruloylated xyloglucan disaccharide and p-coumaroylated arabinoxylan trisaccharide were isolated from cell walls of growing bamboo (Phyllostachys edulis) shoots. On the basis of chemical and spectral data, their structures were determined to be O-(4-O-trans-feruloyl-alpha-D- xylopyranosyl)-(1----6)-D-glucopyranose and O-[5-O-(trans-p-coumaroyl)- alpha-L-arabinofuranosyl]-(1----3)-O-beta-D-xylopyranosyl-(1----4)-D- xylopyranose, respectively. This is the first reported evidence of a phenolic acid covalently associated with the cell wall hemicellulose, xyloglucan.     

Antioxidant activity of flavonoids from Sideritis javalambrensis.

Five flavonoid glycosides, 4'-O-methylisoscutellarein 7-O-[6"'-acetylallopyranosyl(1----2)glucopyranoside], 4'-O-methylisoscutellarein 7-O-allopyranosyl(1----2)glucopyranoside, 3'-hydroxy-4'-O-methylisoscutellarein 7-O-[6"'-acetylallopyranosyl(1----2) glucopyranoside], and hypolaetin-8-glucoside have been isolated from Sideritis javalambrensis aerial parts and identified by standard methods. These glycosides have been tested for their antioxidant properties alongside other 7,8-substituted flavonoids using FeSO4/cysteine-induced microsomal lipid peroxidation. Superoxide scavenging activity was assessed in the nitroblue tetrazolium test. Among this series of flavonoids, hypolaetin-8-glucoside is the most potent inhibitor of nonenzymic lipid peroxidation. The antiperoxidative activity of these flavonoids may be related to their superoxide scavenging ability.     

Bayogenin and asterogenic acid glycosides from Bellis perennis.

Four novel triterpenoid saponins were isolated from the underground parts of Bellis perennis. The structures were elucidated as 3-O-beta-D-glucopyranosides of 2 beta,3 beta,16 alpha-trihydroxyolean-12-ene-28-oic acid-28-alpha-L- rhamnopyranosyl(1----2)-[beta-D-glucopyranosyl(1----6)]-beta-D- glucopyranoside, 2 beta,3 beta,23-trihydroxyolean-12-ene-28-oic acid-28-O-beta-D-xylopyranosyl (1----2)-[beta-D-glucopyranosyl (1----6)]- beta-D-glucopyranoside and 2 beta,3 beta,23-trihydroxyolean-12-ene-28-oic acid-28-O-alpha-L-rhamnopyranosyl(1----2)-[beta-D-glucopyranosyl(1----6) ]- beta-D-glucopyranoside and as 3-O-alpha-L-rhamnopyranosyl-2 beta,3 beta,23-trihydroxyolean-12-ene-28-oic acid-28-O-beta-D-glucopyranosyl(1----2)-[beta-D-glucopyranosyl(1----6)]- beta-D-glucopyranoside by means of high field 1D and 2D NMR spectroscopic methods without recourse to derivatization or comparison with previous data.     

Measurement of cyclomaltodextrin glucanotransferase activity by high-performance liquid chromatography using a fluorogenic substrate

A mixture of p-nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranoside (FG5P) and p-nitrophenyl alpha-D-glucoside (GP) was incubated with cyclomaltodextrin glucanotransferase (CGTase) [EC 2.4.1.19]. Analysis of the digest by HPLC showed that the products were p-nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-alpha-D-glucopyranoside (FG4P) and p-nitrophenyl alpha-D-maltoside (G2P), and no other product could be detected. Based on the reaction, a sensitive method to assay for CGTase was developed.     

Withanolide glycosides from Dunalia australis.

Four new withanolide glycosides, (20R,22R)-O-(3)-[beta-D- xylopyranosyl(1----3), beta-D-xylopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D-xylopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D- glucopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl- 3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide and (20R,22R)-O-(3)-[beta-D-glucopyranosyl(1----3), beta-D- glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta, 12 beta,20-trihydroxy- 1 alpha,acetoxy-witha-5,24-dienolide, named dunawithanines C, D, E and F, respectively, were isolated from Dunalia australis. Their structures were elucidated on the basis of spectral and chemical evidence, especially NMR data of the peracetates.     

Total synthesis of the mollu-series glycosyl ceramides alpha-D-Manp-(1----3)-beta-D-Manp-(1----4)-beta-D-Glcp-(1----1)-Cer and alpha-D-Manp-(1----3)-[beta-D-Xylp-(1----2)]-beta-D-Manp-(1----4)-beta- D-Glcp-(1----1)-Cer

The mollu-series glycosphingolipids, O-alpha-D-mannopyranosyl-(1----3)-O-beta-D-mannopyranosyl-(1----4)-O-bet a-D-glucopyranosyl-(1----1)-2-N-tetracosanoyl-(4E)-sphingeni ne and O-alpha-D-mannopyranosyl-(1----3)-O-[beta-D-xylopyranosyl-(1----2])-O- beta-D-mannopyranosyl-(1----4)-O-beta-D-glucopyranosyl-(1----1)-2-N- tetracosanoyl-(4E)-sphingenine, were synthesized for the first time by using 2,3,4-tri-O-acetyl-D-xylopyranosyl trichloroacetimidate, methyl 2,3,4,6-tetra-O-acetyl-1-thio-alpha-D-mannopyranoside, benzyl O-(4,6-di-O-benzyl-beta-D-mannopyranosyl)-(1----4)-2,3,6-tri-O-benzyl-be ta-D- glucopyranoside 9, and (2S,3R,4E)-2-azido-3-O-(tert-butyldiphenylsilyl)-4-octade cene-1,3-diol 6 as the key intermediates. The hexa-O-benzyl disaccharide 9 was prepared by coupling two monosaccharide synthons, namely, 2,3-di-O-allyl-4,6-di-O-benzyl-alpha-D-mannopyranosyl bromide and benzyl 2,3,6-tri-O-benzyl-beta-D-glucopyranoside. It was demonstrated that azide 6 was highly efficient as a synthon for the ceramide part in the coupling with both glycotriaosyl and glycotetraosyl donors, particularly in the presence of trimethylsilyl triflate.     

Hydrolysis of (1----3)- and (1----2)-beta-D-xylosidic linkages by an endo-(1----4)-beta-D-xylanase of Cryptococcus albidus

The substrate specificity of an endo-(1----4)-beta-D-xylanase of the yeast Cryptococcus albidus was investigated using a series of methyl beta-D-xylotriosides. In addition to (1----4) linkages, the enzyme could cleave (1----3) and (1----2) linkages adjacent to a (1----4) linkage and further from the non-reducing end of the substrate. The enzyme could hydrolyse a (1----3) linkage that attached a terminal xylopyranosyl group to a (1----4)-linked xylobiosyl moiety. The enzyme did not attack alpha-D-xylosidic linkages. The rate of cleavage of (1----4) linkages was much higher than those of other linkages at 0.5mM substrate, but the rates were comparable at 20mM substrate when transglycosylation reactions also occurred that facilitated degradation of the substrates.     

Synthesis of a tetrasaccharide unit of the capsular polysaccharide of Streptococcus pneumoniae type 9V

In the synthesis of 8-methoxycarbonyloctyl O-(alpha-D-galactopyranosyl)-(1----3)-O-(2-acetamido-2-deoxy-beta-D- mannopyranosyl)-(1----4)-O-(beta-D-glucopyranosyl)-(1----4)-alpha-D- glucopyranoside, which represents a component of the capsular polysaccharide of Streptococcus pneumoniae type 9V, the key step was the coupling of alpha-D-Galp-(1----3)-beta-D-ManpNAc-(1----4)-D-Glc as glycosyl donor with 8-ethoxy-carbonyloctyl 6-O-acetyl-2,3-di-O-benzyl-alpha-D-glucopyranoside as glycosyl acceptor by use of the imidate method. Only the beta-imidate of the trisaccharide could be employed in this glycosidation reaction to give stereoselectively the tetrasaccharide in high yield. The alpha-imidate of the trisaccharide led to hydrolysis of the imidate group.     

A saponin from callus tissue of Stauntonia hexaphylla.

A new 30-nortriterpenoid saponin was isolated from the callus tissues of Stauntonia hexaphylla. The structure of the saponin (tentatively named mubenoside A) was elucidated as 3 beta,20 alpha-dihydroxy-30-nor-olean-12-en-28-oic acid 3-O-[beta-D-xylopyranosyl(1----2)-alpha-L-arabinopyranosyl(1----3) ]-beta-D- glucopyranoside by means of spectral experiments.     

Synthesis of methyl glycoside derivatives of tri- and penta-saccharides related to the antithrombin III-binding sequence of heparin, employing cellobiose as a key starting-material

Two key synthons for the title pentasaccharide derivative, methyl O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L-idopyranosyluronate)-(1----4)-6-O-acetyl- 2-azido - 3-O- benzyl-2-deoxy-beta-D-glucopyranoside and O-(methyl 2,3-di-O-benzyl-4-O- chloroacetyl-beta-D-glucopyranosyluronate)-(1----4)-3,6-di-O-acetyl-2-az ido-2- deoxy-alpha-D- glucopyranosyl bromide, were prepared from a common starting material, cellobiose. They were coupled to give a tetrasaccharide derivative that underwent O-dechloroacetylation to the corresponding glycosyl acceptor. Its condensation with the known 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide afforded a 77% yield of suitably protected pentasaccharide, methyl O-(6-O- acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)- O- (methyl 2,3- di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-O-(3,6-di-O-acetyl-2- azido-2 - deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L- idopyranosyluronate)- (1----4)-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-beta-D-glucopyranoside. Sequential deprotection and sulfation gave the decasodium salt of methyl O-(2- deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)-O-(be ta-D- glucopyranosyl-uronic acid)-(1----4)-O-(2-deoxy-2-sulfamido-3,6-di-O-sulfo-alpha-D-gluco pyranosyl)- (1----4)-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-(1----4)-2-deoxy-2- sulfamido-6-O- sulfo-beta-D-glucopyranoside (3). In a similar way, the trisaccharide derivative, the hexasodium salt of methyl O-(2-deoxy-2-sulfamido-6-O-sulfo-alpha-D- glucopyranosyl)- (1----4)-O-(beta-D-glucopyranosyluronic acid)-(1----4)-2-deoxy-2-sulfamido-3,6- di-O- sulfo-alpha-D-glucopyranoside (4) was synthesized from methyl O-(6-O-acetyl-2- azido- 3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2,3-di-O- benzyl-beta- D-glucopyranosyluronate)-3,6-di-O-acetyl-2-azido-2-deoxy-alpha-D- glucopyranoside. The pentasaccharide 3 binds strongly to antithrombin III with an association constant almost equivalent to that of high-affinity heparin, but the trisaccharide 4 appears not to bind.     

Studies on the active site of Taka-amylase A: its action on phenyl maltooligosides with a charge at their non-reducing-ends

Five modified moltooligosaccharides, phenyl O-6-amino-6-deoxy-alpha-D- glucopyranosyl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1-- --4)- alpha-D-glucopyransoide (AG4P), phenyl O-(alpha-D-glucopyranosyluronic acid)-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-d-glucopyran osy l- (1----4)-alpha-D-glucopyranoside (CG4P), phenyl O-6-amino-6-deoxy-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyra nos yl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1-- --4)- alpha-D-glucopyranoside (AG5P), phenyl O-(alpha-D-glucopyranosyluronic acid)-(1----4)-O-alpha-D-glucopyranosyl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1-- --4)- alpha-D-glucopyranoside (CG5P), and phenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)- O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-a lph a-D- glucopyranoside (FG4P), were prepared to examine the active site of Taka-amylase A (TAA) [EC 3.2.1.1, Aspergillus oryzae]. Phenyl alpha-maltotetraoside (G4P) was predominantly hydrolyzed by TAA to maltose and phenyl alpha-maltoside (G2P). While G2P, phenyl alpha-glucoside (GP), and phenol were liberated from AG4P in the ratio of 7:63:30. G4P, phenyl alpha-maltotrioside (G3P), G2P, and GP were liberated from G5P in the ratio of 1:20:73:6, but AG5P was almost completely hydrolyzed to modified maltotriose and G2P. On the hydrolysis of CG4P and CG5P, no remarkable change was observed except for a decrease in the relative reaction rates compared with G4P and G5P, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis of a dimeric Lewis X hexasaccharide derivative corresponding to a tumor-associated glycolipid

The dimeric Lewis X hexasaccharide p-trifluoroacetamidophenylethyl O-beta-D-galactopyranosyl-(1----4)-O-[alpha-L-fucopyranosyl-(1----3)]-O- (2- acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----3)-O-beta-D-galactopyrano syl- (1----4)-O-[alpha-L-fucopyranosyl-(1----3)]-2-acetamido-2-deoxy-beta-D- glucopyranoside (14), which is a derivative of a tumor-associated glycolipid, was synthesized from thioglycoside intermediates. A protected disaccharide was used as a key-intermediate for synthesis of the p-nitrophenylethyl glycoside of suitably protected O-beta-D-Galp-(1----4)-O-beta-D-GlcpN-(1----3)-O-beta-D-Galp-(1--- -4)-beta-D- GlcpN, which, after selective deblocking, was di-L-fucosylated and deprotected to give 14.     

A triterpenoid saponin from Phytolacca esculenta.

A new triterpenoid saponin, 3-O-[beta-D-glucopyranosyl(1----4)-beta-D- xylopyranosyl]-28-O-beta-D-glucopyranosyl-30-methyloleanate-9(11), 12-dien- 2,3,23-trihydroxyl-28-oic acid, was isolated from the roots of Phytolacca esculenta. The structure was assigned by chemical methods and spectral analysis (1H, 13C, DEPT NMR, EIMS and FABMS) including 1H-1H COSY, 1H-13C COSY and 1H-1H NOESY.     

Synthesis of O-alpha-D-glucopyranosyl-(1----4)-O-alpha -D-xylopyranosyl-(1----4)-O-alpha -D-xylopyranosyl-(1----4)-D-glucopyranose as a substrate analogue of alpha amylase

The tetrasaccharide a-D-Glcp-(1----4)-a-D-Xylp-(1----4)-a-D-Xylp-(1----4)-D- Glcp (1) has been synthesized, as a substrate analogue of alpha amylase, by silver perchlorate-catalyzed glycosylation of benzyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-a-D-xylopyranosyl)-beta-D- glucopyranoside (30) with 2,3-di-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-a-D- glucopyranosyl)-a-D-xylopyranosyl chloride or by methyl triflate-promoted condensation of 30 with methyl 2,3-di-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-a-D-glucopyranosyl)-1-thio- beta-D-xylopyranoside, followed by removal of protecting groups of the resulting tetrasaccharide derivative 40.     

Phenethyl alcohol glycosides and isopentenol glycoside from fruit of Bupleurum falcatum.

Investigation on the constituents of the fruit of Bupleurum falcatum L. resulted in the isolation of the three new glycosides, phenethyl alcohol 8-O-beta-D-glucopyranosyl-(1-->2)-O-beta-D-apiofuranosyl-(1-->6)-b eta-D- glucopyranoside, phenethyl alcohol 8-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside and isopentenol 1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside along with five known glycosides, icariside D1, icariside F2, saikosaponin a, saikosaponin c and saikosaponin d. The structures of these compounds were elucidated on the basis of interpretation of chemical and spectral data.     

女贞小蜡树的酚性配糖体成分研究

从女贞小蜡树 (LigustrumsinenseLour.)茎叶甲醇提取物的水溶性部分得到 1个新的和 6个已知酚性配糖体成分。它们是两个已知的裂环环烯醚萜类化合物 :1 0 hydroxyoleuropein( 1 )和specneuzhenide( 2 ) ,五个苯乙醇类化合物 :3 ,4 二羟基苯乙醇 ( 3 ) ,3 ,4 二羟基苯乙醇 2′ O β D 吡喃葡萄糖甙 ( 4 ) ,3 甲氧基 苯乙醇 4 O β D 吡喃葡萄糖甙 ( 5 ) ,4 羟基苯乙醇 ( 6) ,4 羟基苯乙醇 2′ O β D 吡喃葡萄糖甙 ( 7) ,化合物 5为新化合物 ,命名为小蜡甙A(sinenosideA) ,经理化和波谱分析鉴定了论文中的所有化合物的结构     

Complete 1H- and 13C-n.m.r. assignments for two sulphated oligosaccharide alditols of hen ovomucin

The complete 1H- and 13C-n.m.r. assignments for beta-D-Galp-(1----4)-beta-D-GlcpNAc-6-SO3H-(1----6)-[beta-D-Galp-(1----3 )]- D-GalNAcol and alpha-NeuAcp-(2----3)-beta-D-Galp-(1----3)-[beta-D-Galp-(1----4)-b eta-D- GlcpNAc-6-SO3H-(1----6)]-D-GalNAcol were made by a combination of 2-D correlation experiments (Relayed-Cosy; and 13C,1H Correlation-shift n.m.r. spectroscopy), and 1-D n.m.r. spectroscopy. The results illustrate the ability of these methods to locate sulphate and NeuAc groups in anionic mucinous glycoproteins.     

Steroidal saponins from the bulbs of Camassia cusickii.

Six new steroidal saponins have been isolated from the fresh bulbs of Camassia cusickii. Their structures were determined by spectroscopic analysis and some chemical transformations to be (25R)-5 alpha-spirostan-3 beta,6 alpha-diol (chlorogenin) 6-O-beta-D-glucopyranoside, chlorogenin 6-O-beta-D-glucopyranosyl-(1----2)-beta-D-glucopyranoside, chlorogenin 6-O-beta-D-glucopyranosyl-(1----3)-beta-D-glucopyranoside, chlorogenin 6-O-beta-D-glucopyranosyl-(1----2)-O-[beta-D-glucopyranosyl-(1----3)]-beta- D-glucopyranoside, (25R)-6 alpha-hydroxy-5 alpha-spirostan-3-one 6-O-beta-D-glucopyranosyl- (1----3)-beta-D-glucopyranoside and (25R)-3,3-dimethoxy-5 alpha-spirostan-6 alpha-ol 6-O-beta-D-glucopyranosyl-(1----3)-beta-D-glucopyranoside. The saponins isolated were shown to contribute to the bitter taste of the bulbs.