Isolation and structural characterization of a low-molecular-weight pectic polysaccharide SHPPB-1 isolated from sunflower heads

A novel low-molecular-weight pectic polysaccharide was isolated from sunflower heads that are a useless side product produced from sunflower oil processing. The low-molecular-weight pectic polysaccharide was purified by using an optimized four-step procedure and named as SHPPB-1. The molecular weight of SHPPB-1 is about 1.69× 10⁴ Da. Structure characterizations of SHPPB-1 by monosaccharide composition, methylation analysis, and Fourier transform infrared (FT-IR) spectroscopy showed that SHPPB-1 is consisted of 1,4-linked α-D-GalpA and 1,4-linked 2-OAc-5-COOMe-α-D-GalpA with rare α/β-D-Rhap, α/β-D-Manp, and α/β-D-GalpA. This was combined with NMR spectroscopic analysis to propose a structure of SHPPB-1 as: →4)-[α/β-D-monosaccharide-(1→3)]-α-D-GalpA-(1→4)-2-OAc-5-COOMe-α-D-GalpA-(1→ .     

Structure analysis and anti-fatigue activity of a polysaccharide from Lepidium meyenii Walp

A polysaccharide was obtained from Lepidium meyenii Walp by hot water extraction and purification by Millipore (100 kD) and Sephadex G-200. The content of polysaccharide was examined to be 89.9% with phenol-sulfuric acid method. Its average molecular weight was estimated to be 2.213 × 10⁶ Da by High Performance Gel Permeation Chromatography (HPGPC). Monosaccharide analysis showed that the polysaccharide was composed of arabinose, mannose, glucose and galactose with the molar ratio of 2.134: 1: 2.78: 2.82. After Smith degradation, methylation, infrared spectroscopy and NMR, the primary structure of the polysaccharide was identified. The backbone of the polysaccharide was composed of →4)-β-D-Galp-(1→ and →4)-α-D-Galp-(1→, while the branches were comprised of →6)-β-D-Glup-(1→, →5)- β-D-Araf-(1→, →3,6)-α-D-Manp-(1→, →3)-α-D-Galp-(1→, and α-D-Glup-(1→. The anti-fatigue effect of the polysaccharide was evaluated using exhaustive swimming test and biochemical indexes. The results indicated the polysaccharide has anti-fatigue effect.     

Structural Characterization and In Vitro Antitumor Activity of a Novel Exopolysaccharide from <Emphasis Type="Italic">Lachnum</Emphasis> YM130

Exopolysaccharide of Lachnum YM130 (LEP) was purified by diethylaminoethyl cellulose 52 and Sepharose CL-6B column chromatography. LEP-2a was identified to be a homogeneous component with an average molecular weight of 1.31?×?10⁶ Da, which was consisted of mannose and galactose in a molar ratio of 3.8:1.0. The structure of LEP-2a was characterized by methylation analysis, FT-IR analysis, and NMR analysis. Results indicated that LEP-2a was a galactomannan with a backbone, composed of 1,2-linked-α-D-Manp, 1,2,6-linked-α-D-Manp, 1,3,4-linked-α-D-Manp, and 1,3-linked-β-D-Galp, which was substituted at O-2, O-3, O-4, and O-6 by branches. In vitro antitumor activity assay proved that LEP-2a could significantly enhance the inhibitory effectiveness of 5-FU on Hela cells at the concentrations of 100, 200, 300, and 400 μg/mL. The above results suggested that LEP-2a could be seen as a potential source for developing novel antineoplastic agents.     

Structural features of an acidic polysaccharide with the potential of promoting osteoblast differentiation from Lycium ruthenicum Murr.

Abstract

The enhanced osteoblast differentiation is beneficial to the prevention of osteoporosis. In this study, a homogeneous polysaccharide (LRP-S2A) with the potential of promoting osteoblast differentiation was obtained from the fruits of Lycium ruthenicum, a traditional herb for treatment of postmenopausal metabolic disorders. Structural identification indicated that LRP-S2A, with a relative molecular weight of 2.65 × 10⁶ Da and an uronic acid content of 41.8%, contained Rha, Ara, Gal, Glc and GlcA in a molar ratio of 1.00 : 2.07 : 0.57 : 2.59 : 4.33 and was composed of a backbone consisting of 6-O-Me-α-(1→4)-D-GlcpA, 2-O-acetyl-α-(1→4)-D-Glcp, α-(1→2,4)-L-Rhap, β-(1→3)-D-Galp andα-(1→3,5)-L-Araf, and some branches consisting of 6-O-Me-α-(1→4)-D-GlcpA and terminal α-L-Araf. These results suggested that LRP-S2A with the potential of promoting osteoblast differentiation was a new acidic polysaccharide.     

Structural study on a bioactive fructan from the root of Achyranthes bidentata Blume

The structure of a saccharide component (Abs),with pronounced activity of improving immunity system,isolated from the root of Achyranthes bidentata Blume,a traditional Chinese herbal medicine,was studied.Based on 13C NMR,HPLC,and methylation analyses,Abs was shown to be a mixture of short-chain fructans with an average dp of 8,containing more (2→6) than (2→1) linked β-D-fructofuranosyl residues,with branching at O-6 or O-1 of 18% of the D-fructofuranoeyl residues.     

Structure Studies of the Extracellular Polysaccharide from <Emphasis Type="Italic">Trichoderma</Emphasis> sp. KK19L1 and Its Antitumor Effect via Cell Cycle Arrest and Apoptosis

An extracellular polysaccharide TP1A was purified from the fermented broth of Trichoderma sp. KK19L1 by combination of Q Sepharose fast flow and Sephacryl S-300 chromatography. TP1A was composed of Man, Gal, and Glc in a molar ratio of about 3.0:5.1:8.1. The molar mass of TP1A was about 40.0 kDa. Methylation and NMR analysis indicated that the probable structure of TP1A was [→4,6)-α-D-Glcp(1→6)-β-D-Galf(1→6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-α-D-Manp(1→2,6)-α-D-Manp(1→] with [α-D-Glcp(1→] and [α-D-Manp(1→6)-α-D-Glcp(1→6)-α-D-Glcp(1→] as branches. The antitumor study showed that TP1A was able to inhibit the cell viability of HeLa and MCF-7 cells. TP1A could arrest HeLa cells in G2/M phase and induce HeLa cell apoptosis. These findings suggest that fungal polysaccharides could be a potential source for antitumor agents.     

Synthesis of Ether Linked Pseudo-Oligosaccharides Via 5,6-Cyclic Sulfate Derivatives of Protected Manno and Glucofuranose

Abstract

C-6 ring opening of 5,6-cyclic sulfate derivatives of protected manno and glucofuranose with carbohydrate alkoxides gave ether linked pseudo-di or trisaccharides. Use of methyl 2,3-O-isopropylidene-5,6-O-sulfuryl-α-D-mannofuranoside 1 led to protected pseudo-disaccharide D-Glcf-(3→6)-D-Manf-(5→6)-D-Manf 4 and protected pseudo-trisaccharide D-Manf-(6→3)-D-Glcf-(6→3)-D-Glcf 11 derivatives in 66% and 41% overall yields, respectively.     

Carbon-13 NMR Spectra of Peracetylated Derivatives of Methyl L-Arabinofuranoside and Oligosaccharides Related to Arabinoxylan

Abstract

The ¹³C NMR signals of methyl tri-O-acetyl-l-arabinofuranosides were assigned on the basis of heteronuclear shift correlated NMR spectra. From the enzymic digest of barley-hull arabinoxylan two oligosaccharides, i.e., α-l-Araf-(1→3)-β-d-xylp-(1→4)-d-xylp and α-l-Araf-(1→3)-β-d-xylp-(1→4)-β-d-xylp-(1→4)-d-xylp were obtained. The NMR spectra of their per-O-acetylated derivatives were assigned, and discussed.     

Triterpene glycosides of Hedera taurica

From the leaves of Crimean ivy we have isolated the previously known glycosides 3-O-α-L-Ara_p-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]hederagenin, 3-O-[O-α-L-Rha_p-(1→2)-α-L-Ara_p]-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]oleanic acid and -hederagenin, and 3-O-[O-α-L-Rha_p-(1→2)-α-L-Ara_p]-28-O-[O-β-D-Glc_p-(1→6)-β-D-Glc_p]hederagenin and a new one: tauroside H₁ — 3-O-[O-α-L-Rha_p-(1→2)-O-α-L-Ara_p]-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]echinocystic acid.     

Synthesis of Rhamnogalacturonan I Fragments

ABSTRACT

The partially deprotected trisaccharide 17 has been synthesized as an analogue of the repeating unit of the backbone of rhamnogalacturonan I. The trisaccharide 17 was obtained after prior selective derivatization of HO-3 and HO-4 of a rhamnopyranose cyanoethylidene glycosyl donor, followed by coupling with a tritylated galactopyranosyluronic acceptor (11), selective removal of the acetyl group at the O-2' position of the formed disaccharide 12, and glycosylation of the HO-2' position with methyl (ethyl 2,3-di-O-benzyl-4-O-p-methoxybenzyl-1-thio-β-D-galactopyranosid)uronate (14) providing methyl (methyl 2,3-di-O-benzyl-4-O-p-methoxybenzyl-α-D-galactopyranosyluronate)-(1→2)-(4-O-benzoyl-3-O-benzyl-α-L-rhamnopyranosyl)-(1→4)-(allyl 2,3-di-O-benzyl-β-D-galactopyranosid)uronate (15). Finally, palladium chloride catalyzed deallylation (16) and hydrogenolysis over Pd-C resulted in methyl (methyl α-D-galactopyranosyluronate)-(1→2)-(4-O-benzoyl-α-L-rhamnopyranosyl)-(1→4)-α/β D-galactopyranuronate (17).     

Synthesis of p-Trifluoroacetamidophenylethyl O-(2-Acetamido-2-Deoxy-β-D-Galactopyranosyl)-(1→4)-O-β-D- Galactopyanosyl-(1→4)-O-β-D-Glucopyranoside,Containing the Trisaccharide Portion of the Asialo-GM2 Glycolipid

ABSTRACT

The p-trifluoroacetamidophenylethyl β-glycoside 9 of the trisaccharide O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-(1→4)-O-β-D-galactopyranosyl-(1→4)-D-glucopyranose (gangliotriose, asialo-GM2) was synthesised. The key step was coupling of a suitably protected lactose derivative with a galactosamine thioglycoside derivative using sulfuryl chloride/trifluoromethanesulfonic acid activation.     

Synthetic Studies on Sialoglycoconjugates 23: Total Synthesis of Sialyl-α(2↠6)-Lactotetraosylceramide and Sialyl-α(2↠6)-Neolactotetraosylceramide

ABSTRACT

The first total syntheses of sialyl-α(2→6)-lactotetraosylceramide (29, IV⁶NeuAcLc₄Cer) and sialyl-α(2→6)-neolatotetraosylceramide (33, IV⁶NeuAcnLc₄Cer) are described. Methyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→6)-2,4-di-O-benzoyl-3-O-benzyl-1-thio-ß-D-galactopyranoside (11), the key glycosyl donor was prepared, via glycosylation of 2-(trimethylsilyl)ethyl 3-O-benzyl-ß-D-galactopyranoside (2) with the methyl α-thioglycoside 3 of N-acetylneuraminic acid, benzoylation, replacement of the 2-(trimethylsilyl)ethyl group by acetyl, and introduction of the methylthio group with (methylthio)trimethylsilane. Each coupling of 2-(trimethylsilyl)ethyl O-(2-acetamido-4,6-O-benzylidene-2-deoxy-ß-D-glucopyranosyl)-(1→3′)-per-O-benzyl-ß-lactoside (12) or 2-(trimethylsilyl)ethyl O-(2-acetamido-3-O-acetyl-6-O-benzyl-2-deozy-ß-D-glucopyranosyl)-(1→3′)-per-O-benzyl-ß-D-lactoside (14) prepared from 12 by O-acetylation and reductive opening of the benzylidene acetal, with 11 gave the pentasaccharides 16 and 20 in good yields. Compounds 16 and 20 were converted into the corresponding α-trichloroacetimidates 19 and 24 which, on coupling with (2S, 3R, 4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (25), gave the ß-glycosides 26 and 30, respectively. Finally, 26 and 30 were transformed, via selective reduction of the azide group, condensation with octadecanoic acid, O-deacylation, and hydrolysis of the methyl ester group, into 29 and 33, respectively.     

Synthesis of Neu5Ac α-(2→ 8)Neu5Ac α-(2→ 3)Galβ1→ Och2Ch2Ch3, A Determinant Epitope of Gd3 Ganglioside

ABSTRACT

Synthesis of the terminal trisaccharide sequence of the ganglioside GD₃, α-D-Neup5Ac-(2→8)-α-D-Neup5Ac-(2→3)-β-D-Galp-(1→4)-β-D-Glcp-(1→1)-Cer (2) was achieved by employing an α-(2→8) disialyl glycosyl donor (1). Condensation of 1 with the glycosyl acceptor 6, propyl 4,6-O-benzylidene-β-D-galactopyranoside, gave the desired protected trisaccharide 10 (14%) as well as the elimination and hydrolysis products of 6, compounds 8 and 9 respectively. O-Deacetylation and debenzylation of 10 gave the final trisaccharide 11, as its propyl glycoside.     

Sulfated Galactans of Champia indica and Champia parvula (Rhodymeniales,Rhodophyta) of Indian Waters

Sulfated galactans of the red seaweed species Champia indica and Champia parvula of Indian waters were extracted and purified by ion exchange chromatography. These were characterized by infrared and ¹³C NMR spectroscopy as well as by GC-MS analysis of alditol acetate derivatives produced by reductive hydrolysis/acetylation of sulfated and desulfated and their methylated samples. The sulfated galactans of these Champia species contained alternating β-(1→3)-linked galactopyranosyl units with sulfation at the 2-position and α-(1→4)-linked galactopyranosyl units having sulfation at both the 2- and 3-positions. Other minor substitutions included 6-O-methyl ether of the β-(1→3)-linked galactose residues only in Champia parvula.     

Structural Features of Fructans from the Root of Cyathula officinalis Kuan

Three fructans (CoPS1, CoPS2 and CoPS3) were isolated from the root of Cyathula officinalis Kuan, a traditional Chinese medicine. The structures of the fructans were determined by methylation, reductive-deavage method combined with GC-MS analysis, and 13C NMR spectroscopy. These results show that the fructans (CoPS1, CoPS2 and CoPS3) are graminan type fructans, and comprised of (2→t)- and (2→6)-linked β-D-fructofuranosyl backbone residues containing high branches.     

AN EXTRACELLULAR GALACTOGLUCOXYLOMANNAN PROTEIN FROM THE YEAST Cryptococcus laurentii VAR. laurentii

An extracellular galactoglucoxylomannan protein composed of d-galactose, d-glucose, d-xylose and d-mannose in a 2.9:1.0:1.1:10.2 mole proportion has been isolated from culture medium of Cryptococcus laurentii var. laurentii. The polymer of number average molecular mass 19,000 contained 86% carbohydrates, 6.5% protein and 0.7% phosphorus. Results of structural analyses suggested a highly branched comb-like structure of the polysaccharide with a backbone composed of 6-linked α-d-Man residues. Mannose units of the backbone are highly branched at O-2, O-3, and O-4 by side chains composed mainly of 2-linked α-d-Man mostly in the form of dimers and trimers, and to a lesser amount as tetra- and pentamers. Galactosyl units were found to be mostly 6-linked with a very low degree of substitution. Mannose side chains are further branched with d-Xyl, d-Glc, and d-Gal residues preferably in β their forms. The protein part of the glycoprotein was O-glycosylated by mannose, mannobiose, and mannotetrose.     

Efficient purification and complete NMR characterization of galactinol,sucrose, raffinose,and stachyose isolated from Pinus halepensis (Aleppo pine) seeds using acetylation procedure

The use of precipitation followed by acetylation procedures and preparative TLC purification allowed a facile isolation of four carbohydrates from the methanol extract of Pinus halepensis seeds. The isolated oligosaccharides exhibited high degree of purity. They were identified as α-D-galactosyl-(1→1)-myo-inositol nonaacetate (1), α-D-glucosyl-(1→2)-β-D-fructosyl octaacetate (2), α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl undecaacetate (3), and α-D-galactosyl-(1→6)-α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl tetradecaacetate (4) and were isolated for the first time from this plant. The ¹H and ¹³C NMR assignments for compounds 2, 3, and 4 were detailed herein for the first time.     

N7-DNA: Synthesis and Base Pairing of Oligonucleotides Containing N7-(2-Deoxy-β-D-erythro-pentofuranosyl)guanine (N7Gd)

The synthesis of oligonucleotides containing N⁷-(2-deoxy-β-D -erythro-pentofuranosyl)guanine (N⁷G_d; 1 ) is described. Compound 1 was prepared by nucleobase-anion glycosylation of 2-amino-6-methoxypurine ( 5 ) with 2-deoxy-3,5-di-O-(4-toluoyl)-α-D -erythro-pentofuranosyl chloride ( 6 ) followed by detoluoylation and displacement of the MeO group ( 8→10→1 ). Upon base protection with the (dimethylamino)methylidene residue (→ 11 ) the 4,4-dimethoxytrityl group was introduced at OH? C(5′) (→ 12 ). The phosphonate 3 and the phosphoramidite 4 were prepared and used in solid-phase oligonucleotide synthesis. The self-complementary dodecamer d(N⁷G? C)₆ shows sigmoidal melting. The T_m of the duplex is 40°. This demonstrates that guanine residues linked via N(7) of purine to the phosphodiester backbone are able to undergo base pairing with cytosine.     

Investigation by NMR Spectroscopy and Molecular Modeling of the Conformations of Some Modified Disaccharide Antigens for Shigella Dysenteriae Type 1

Abstract

The O-polysaccharide of Shigella dysenteriae type 1 is made up of multiple repeats of the linear tetrasaccharide 3)-α-L-Rhap-(1→2)-α-D-Galp-(1→3)-α-D-GlcpNAc-(1→3)-α-L-Rhap-(1→, for which the antigenic determinant for a murine monoclonal IgM antibody is the disaccharide α-L-Rhap-(1→2)-α-D-Galp. This disaccharide and various analogs have been studied by 2D NOESY, ROESY, and TOCSY NMR spectroscopy, in conjunction with proton spin-lattice relaxation rate measurements, restrained molecular mechanics, and restrained molecular dynamics with simulated annealing. It has been found that replacement of any single hydroxyl group in the determinant by a hydrogen atom, or replacement of any single hydroxyl group in the Gal residue by a fluorine atom has little if any influence on the conformation of the resulting derivatives.