Oleanane-type glycosides from Weigela x Styriaca and two cultivars of W. florida: “Minor black” and “Brigela”

Sixteen oleanane-type glycosides were extracted from three Weigela hybrids and cultivars: W. x Styriaca, W. florida “Minor black” and W. florida “Brigela”, and four of them were previously undescribed ones: 3-O-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyloleanolic acid, 3-O-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid, 3-O-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid, and 3-O-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid. Their full structural elucidation required extensive 1D and 2D NMR experiments, as well as mass spectrometry analysis. Six compounds among the known ones were in sufficient amount to be tested for their antifungal activity against Candida albicans, and their antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa.     

New steroidal saponins of Agave americana

Two new saponins, agavasaponin E and agavasaponin H have been isolated from the methanolic extract of Agave americana leaves and their structures elucidated. Agavasaponin E is 3-O-[β-d-xylopyranosyl-(1→2glc1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-α-d-galactopyranosyl]-(25R)-5α-spirostan-12-on-3β-ol, whereas agavasaponin H is 3-O-[β-d-xylopyranosyl-(1→2 glc 1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3 glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl]-26-O-[β-d-glucopyranosyl]-(25R)-5α-furostan-12-on-3β,22α,26-triol.     

Synthesis of the tri- and tetra-saccharides related to the fine structures of lichenan and cereal β-d-glucans

Syntheses, based on silver trifluoromethanesulfonate-promoted Koenigs-Knorr type condensations, are described of the d-glucotrioses, β-d-Glcp-(1→3)-β-d-Glcp-(1→4)-d-Glcp and β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glcp, and the d-Glucotetraoses, β-d-Glcp-(1→3)-β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-d-Glcp, β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-β-d-Glcp-(1→4)-d-Glcp, and β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glcp, corresponding to the tri- and tetra-saccharide units in the linear chains of (1→4)- and (1→3)-linked β-d-glucopyranosyl residues of lichenan, and of oat and barley β-d-glucans.     

Two-dimensional, 1H-n.m.r. study of peracetylated, reduced derivatives of three oligosaccharides isolated from human milk

The structures of the peracetylated derivatives of the following alditols obtained from oligosaccharides of human milk have been established by two-dimensional, J-resolved and J-correlated, ¹H-n.m.r. spectroscopy at 360 MHz: β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-β- d-Galp-(1→4)- d-Glc-ol, α- l-Fucp-(1→2)-β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-β- d-Galp-(1→4)- d-Glc-ol, and β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-[β- d-Galp-(1→4)-β- d-GlcpNAc-(1→6)]-β- d-Galp-(1→4)- d-Glc-ol.     

Structure of desacylsaponins obtained from the bark of Quillaja saponaria

A triterpenoid saponin mixture (so-called quillajasaponin) obtained from the bark of Quillaja saponaria was treated with weak alkali and two major desacylsaponins were isolated. On the basis of chemical and spectral evidence, they were determined as 3-O-β-D-galactopyranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl quillaic acid 28-O-β-D-apiofuranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside and 28-O-β-D-apiofuranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-[β-D-glucopyranosyl-(1 → 3)]-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside. Diazomethane degradation providing selectively the 28-O-glycoside from the 3,28-O-bisglycoside was a useful method for the structure elucidation.     

Five glycosides from the chinese drug ‘tong-guang-san’: The stems of marsdenia tenacissima

Five new glycosides were isolated from the Chinese crude drug ‘Tong-guang-san’: the stems of Marsdenia tenacissima (Roth.) Wight et Arn. (Asclepiadaceae). The structures of tenacissosides A-E were deduced on the basis of chemical and spectral evidence as tenacigenin B-I 3-O-β-D-glucopyranosyl-(1→4)-3-O-methyl-6-deoxy-β-D- allopyranosyl-(1→4)-β-D-oleandropyranoside, tenacigenin B-II 3-O-β-D-glucopyranosyl-(1 →4)-3-O-methyl-6-deoxy- β-Dallopyranosyl-(1 →4)-β-D-oleandropyranoside, tenacigenin B-III 3-O-β-Dglucopyranosyl-(1→4)-3-O-methyl-6- deoxy-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranoside, tenacigenin B-IV 3-O-β-D-glucopyranosyl-(1 →4)-3-O- methyl-6-deoxy-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranoside and tenacigenin B-V 3-O-β-D-glucopyranosyl- (1 → 4)-3-O-methyl-6-deoxy-allopyranosyl-(1 → 4)-β-D-oleandropyranoside, respectively.     

Beshornin and beshornoside,steroidal saponins of Beshorneria yuccoides

Two new saponins beshornin and beshornoside have been isolated from the methanolic extract of Beshorneria yuccoides leaves and their structures elucidated. Beshornin is 3-O-[α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl- (1 → 2)-[α-l-rhamnopyranosyl-(1 -+ 4)-P-D-glucopyranosyl-(1 → 3)]-β-d-glucopyranosyl-(1 → 4)-β-d- galactopyranosyl-(25R)-5α-spirostan-3β-ol, whereas beshornoside is 3-O-[α-l-rhamnopyranosyl-(1 → 4)- β-d)-glycopyranosyl-(1 → 2)]-[α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 3)]-β-d-glucopyranosyl- (1 → 4)-β-d-galactopyranosyl 26-O-[β-d]-glucopyranosyl-(25R)-5α-furostan-3β,22α,26-triol.     

Structure identification of the complex-type,asparagine-linked sugar chains of β-d-galactosyl-transferase purified from human milk

The asparagine-linked sugar chains of human milk galactosyltansferase were quantitatively released as oligosaccharides from the polypeptide backbone by hydrazinolysis. They were converted into radioactive oligosaccharides by sodium borotritiate reduction after N-acetylation, and fractionated by paper electrophoresis and by Bio-Gel P-4 column chromatography after sialidase treatment. Structural studies of each oligosaccharides by sequential exoglycosidase digestion and methylation analysis indicated that the galactosyltransferase contains bi, tri-, and probably tetra-antennary, complex-type oligosaccharides having α-d-Manp-(1→3)-[α-d-Manp-(1→6)]-β-d-Manp-(1→4)-β-d-GlcpNAc-(1→4)-α-d-[Fucp-(1→6)]-d- GlcNAc as their common core. Variation is produced by the different locations and numbers of the five different outer chains: β-d-Galp-(1→4)-d-GlcNAc, α-l-Fucp-(1→3)-[β-d-Galp-(1→4)]-d-GlcNAc, α-NeuAc-(2→6)-β-d-Galp-(1→4)-d-GlcNAc, α-l-Fucp-(1→3)-[β-d-Galp-(1→4)]-β-d-GlcpNAc-(1→3)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-d- GlcNAc, and α-NeuAc-(2→6)-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→3)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)-β-d-GlcNAc.     

Steroidal saponins of Asparagus curillus

Three spirostanol and two furostanol glycosides were isolated from a methanol extract of the roots of Asparagus curillus and characterized as 3-O-[α-l-arabinopyranosyl (1→4)- β-d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, 3-O-[{α-l-rhamnopyranosyl (1→2)} {α-l-arabinopyranosyl (1→4)}-β-d-glucopyranosyl]-(25S)-5β-spirostan- 3β-ol, 3-O-[{β-d-glucopyranosyl (1→2)} {α-l-arabinopyranosyl (1→4)}-β- d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, 3-O-[{β-d-glucopyranosyl (1→2)} {α-l-arabinopyranosyl (1→4)}-β-d-glucopyranosyl]-26-O-[β-d-glucopyranosyl]- 22α-methoxy-(25S)-5β-furostan-3β, 26-diol and 3-O-[{β-d-glucopyranosyl (1→2)} {α-l-arabinopyranosyl (1→4)}-β-d-glucopyranosyl]-26-O-[β-d-glucopyranosyl]- (25S)-5β-furostan-3β, 22α, 26-triol respectively.     

Nebulosides A–B,novel triterpene saponins from under-ground parts of Gypsophila arrostii Guss. var. nebulosa

A bioassay-guided phytochemical analysis of the triterpene saponins from under ground parts of Gypsophila arrostii var. nebulosa allowed the isolation of two triterpene saponins; nebuloside A, B based on gypsogenin and quillaic acid aglycone. Two new oleanane type triterpenoid saponins (nebuloside A, B) and three known saponins (1–3) were isolated from the root bark of Gypsophila arrostii var. nebulosa. The structures of the two new compounds were elucidated as 3-O-β-d-galactopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→3)]-β-d-glucuronopyranosyl quillaic acid 28-O-β-d-glucopyranosyl-(1→3)-[β-d-xylopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)]-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranosyl ester (nebuloside A) and 3-O-β-d-xylopyranosyl-(1→3)-[β-d-galactopyranosyl(1→3)-β-d-galactopyranosyl-(1→2)]-β-d-glucuronopyranosyl gypsogenin 28-O-β-d-glucopyranosyl-(1→3)-[β-d-xylopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)]-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranosyl ester (nebuloside B), on the basis of extensive spectral analysis and chemical evidence. Nebuloside A and B showed toxicity enhancing properties on saporin a type-I RIP without causing toxicity by themselves at 15 μg/mL.     

Synthesis of the repeating units of Schizophyllan

The tetrasaccharides β-d-Glcp-(1→3)-β-d-Glcp-(1→3)-[β-d-Glcp-(1→6)]-d-Glcp, β-d-Glcp-(1→3)-[β-d-Glcp-(1→6)]-β-d-Glcp-(1→3)-d-Glcp, and β-d-Glcp-(1→6)-β-d-Glcp-(1→3)-β-d-Glcp-(1→3)-d-Glcp, corresponding to the three possible repeating-units of Schizophyllan, have been synthesised by silver trifluoromethanesulfonate-promoted Koenigs-Knorr type condensations, using 2,4,6-tri-O-acetyl-3-O-allyl-α-d-glucopyranosyl bromide as the key intermediate.     

Steroidal saponins of Asparagus adscendens

From the methanol extract of the fruits of Asparagus adscendens sitosterol-β-d-glucoside, two spirostanol glycosides (asparanin A and B) and two furostanol glycosides (asparoside A and B) were isolated and characterized as 3-O-[β-d-glucopyranosyl (1→2)-β-d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, 3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl}-(25S)-5β-spirostan-3β-ol,3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl|} -26-O-(β- d-glucopyranosyl)-22α-methoxy-(25S)-5β-furostan-3β,26-diol and 3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl}-26-O-(β-d-glucopyranosyl)- 25S)-5β-furostan-3β,22α, 26-triol, respectively.     

The carbohydrate units of ovalbumin: Complete structures of three glycopeptides

Three glycopeptides, obtained in quantity from ovalbumin by exhaustive digestion with Pronase and purified by ion-exchange chromatography and gel filtration, had mannose-2-acetamido-2-deoxyglucose-aspartic acid ratios of 5:4:1, 6:2:1, and 5:2:1. The structures of the glycopeptides have been investigated by sequential digestion with purified exo-glycosidases, Smith degradation, and selective acetolysis, and by methylation analysis of the glycopeptides and their degradation products. The resulting data indicated the structures to be α-d-Manp-(1→6)-[α-d- Manp-(1→3)]-α-d-Manp-(1→6)-[β-d-GlcNAcp-(1→4)]-[β-d-GlcNAcp-(1→2)-α-d- Manp-(1→3)]-β-d-Manp-(1→4)-β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn, α-d- Manp-(1→6)-[α-d-Manp-(1→3)]-α-d-Manp-(1→6)-[α-d-Manp-(1→2)-α-d-Manp- (1→3)]-β-d-Manp-(1→4)-β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn, and α-d-Manp- (1→6)-[α-d-Manp-(1→3)]-α-d-Manp-(1→6)-[α-d-Manp-(1→3)]-β-d-Manp-(1→4)- β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn. The glycopeptides had a common-core structure consisting of five mannose and two hexosamine residues, but the two larger glycopeptides were not homologous.     

Spirostanosides of Asparagus sprengeri

Four new spirostanosides were isolated from the methanol extract of Asparagus sprengeri roots and characterized as 3-O-[β-D-xylo-(1 → 4)-β-D-gluco]-(25R)-spirost-5-en-3β-ol; 3-O-[α-L-rhamno-(1 → 6)-β-D-gluco]-(25R)-spirost-5-en-3β-ol; 3-O-{[α-L-rhamno-(1 → 2)] [β-D-xylo-(1 → 4)]-β-D-gluco}-(25R)-spirost-5-en-3β-ol and 3- O-{[α-L-rhamno-(1 → 2)] [α-L-rhamno-(1 → 6)]-β-D-gluco}-(25R)-spirost-5-en-3β-ol respectively.     

Substrate specificities and kinetic properties of two (1→3), (1→4)-β-d-glucan endo-hydrolases from germinating barley (Hordeum vulgare)

Two β-d-glucan endo-hydrolases purified from germinating barley (Hordeum vulgare) hydrolyse (1→4)-β linkages in (1→3),(1→4)-β-d-glucans where the d-glucosyl residue is substituted at O-3, but will not hydrolyse (1→3)-β-d-glucans or (1→4)-β-d-glucans. Methylation analysis of hydrolytic products released from barley (1→3),(1→4)-β-d-glucan indicates that 3-O-β-cellobiosyl-d-glucose and 3-O-β-cellotriosyl-d-glucose are the major oligomers formed. The enzymes exhibit characteristic endo-hydrolase action-patterns on this substrate. Both enzyme can therefore be classified as (1→3),(1→4)-β-d-glucan 4-glucanohydrolases (EC 3.2.1.73). The reduced, pneumococcal polysaccharide RS III, which consists of alternating (1→3)- and (1→4)-linked β-d-glucosyl residues, is hydrolysed by the enzymes to release laminaribiose as a major oligomeric product. Although the kinetic parameters of the two enzymes are similar, one hydrolyses barley (1→3),(1→4)-β-d-glucan at a significantly higher rate than the other and is more stable at elevated temperatures.     

Spirostanol saponins from Paris polyphylla,structures of polyphyllin C,D, E and F

The structures of four new saponins, polyphyllin C, D, E and F, isolated from the tubers of Paris polyphylla have been elucidated as diosgenin-3-O-α-l-rhamnopyranosyl(1→3)-β-d-glucopyranoside, diosgenin-3-O-α-l-rhamnopyranosyl(1→3)- [α-l-arabinofuranosyl(1→4)]-β-d-glucopyranoside, diosgenin-3-O-α-l-rhamnopyranosyl(1→2)-α-l-rhamnopyranosyl (1→4)[α-l-rhamnopyranosyl(1→3)]-β-d-glucopyranoside and diosgenin-3-O-α-l-rhamnopyranosyl(1→4)[α-l- rhamnopyranosyl(1→3)][β-d-glucopyranosyl(1→2)]-α-l-rhamnopyranoside, respectively, on the basis of chemical and spectral data.     

Entada saponin-III,a saponin isolated from the bark of Entada phaseoloides

The structure of Entada saponin (ES)-III, one of the main saponins of Entada phaseoloides bark, was established to be 3-O-[β-d-xylopyranosyl (1 → 2)-α-l-arabinopyranosyl (1 → 6)] [β-l-glucopyranosyl (1 → 4)]-2-acetamido-2-deoxy-β-l-glucopyranosyl-28-O-[β-l-apiofuranosyl (1 → 3)-β-d-xylopyranosyl (1 → 2)] [(2-O-acetoxyl)-β-d-glucopyranosyl-(1 → 4)] (6 − O(R) (−)2,6-dimethyl-2-trans-2,7-octadienoyl)-β-d-glucopyranosyl echinocystic acid.     

Steroidal saponins of Yucca filamentosa: Yuccoside C and protoyuccoside C

Two new saponins, yuccoside C and protoyuccoside C, have been isolated from the methanolic extract of Yucca filamentosa root and their structures elucidated. Yuccoside C is 3-O-[α-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, whereas protoyuccoside C is 3-O-[α-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl]-26-O-[β-d-glucopyranosy]-(25S)-5β-furostan-3β,22α,26-triol.     

Structural investigations of the galactan of the snail Lymnaea stagnalis

A galactan, isolated from the spawn of the snail Lymnaea stagnalis, contained d-galactose and 0.9% of nitrogen, but neither l-galactose nor phosphate groups. The [α]_D²⁰ values of the galactan and its first Smith-degradation product were +19.5° and +20°, respectively. During each of two consecutive Smith-degradations of the galactan, 1 mol of periodate was consumed and 0.45 mol of formic acid was liberated per mol of “anhydrogalactose” unit. Methylation analyses of the galactan and its first Smith-degradation product yielded equal proportions of 2,3,4,6-tetra-O-methyl- and 2,4-di-O-methyl-galactose. Only small quantities of 2,4,6- (4.9 mol%) and 2,3,4-tri-O-methylgalactose (0.7 mol%) were formed from the galactan, whereas the first Smith-degraded product gave 15.6 and 20.4 mol%, respectively. The product of the second Smith-degradation disintegrated and the following oligosaccharides were identified: β-d-Gal-(1→1)-l-Gro, β-d-Gal-(1→3)-β-d-Gal-(1→1)-l-Gro, β-d-Gal-(1→6)-β-d-Gal-(1→1)-l-Gro, β-d-Gal-(1→6)-d-Gal-β-d-Gal-(1→3)-β-d-Gal-(1→1)-l-Gro, β-d-Gal-(1→3)-[β-d-Gal-(1→6)]-β-d-Gal-(1→1)-l-Gro, β-d-Gal-(1→3)-β-d-Gal-(1→6)-β-d-Gal-(1→1)-l-Gro, and β-d-Gal-(1→3)-β-d-Gal-(1→3)-β-d-Gal-(1→1)-l-Gro. Thus, the galactan is highly branched with the backbone containing sequences of either exclusively (1→6)-linked or of more or less regularly alternating (1→3)- and (1→6)-linked units. The side chains vary in length and in the degree of branching. In immunoprecipitin studies, a high degree of species-specificity was seen when various snail galactans were tested with the antiserum to the Lymnaea stagnalis galactan.     

Flavonol triglycosides from Magnolia utilis

Three undescribed flavonol triglycosides, rhamnetin-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→6)]-β-d-glucopyranoside (champaluangoside A), rhamnetin-3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)]-β-d-galactopyranoside (champaluangoside B) and rhamnocitrin-3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)]-β-d-glucopyranoside (champaluangoside C), were isolated from Magnolia utilis in addition to eleven known compounds; quercetrin-3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)]-β-d-glucopyranoside, oxytroflavoside G, magnoloside A, magnoloside M, magnoloside D, manglieside A, manglieside B, 1,2-di-O-β-d-glucopyranosyl-4-allylbebzene, syringrin, benzyl β-d-allopyranoside and (+)-syringaresinol-O-β-d-glucopyranoside. The structure elucidation of these compounds was based on analyses of physical and spectroscopic data.