A protein-bound polysaccharide from the stem bark of Eucommia ulmoides and its anti-complementary effect

Bioactivity-guided fractionation of a hot-water extract from the stem bark of Eucommia ulmoides led to the isolation of a homogeneous polysaccharide EWDS-2, which was identified as a highly branched protein-bound polysaccharide with average molecular weight between 1000 and 2000 kDa, composed of Glc, Gal, Ara, and Rha in the ratio of 2.2:1.0:0.4:0.2, along with traces of Man and 6.55% of protein. The main linkages of the residues of EWDS-2 include terminal, 1,3-linked, 1,4-linked, 1,2,6-linked, 1,3,6-linked Glc; 1,6-linked, 1,2,6-linked, 1,3,4-linked, 1,4,6-linked Gal; 1,5-linked, 1,3,5-linked Ara; terminal and 1,2,5-linked Rha. The bioassay revealed that EWDS-2 inhibits complement activation on both the classic and alternative pathways with CH₅₀ and AP₅₀ values of 282 ± 11 μg/mL and 144 ± 17 μg/mL, respectively. Preliminary mechanism studies indicate that EWDS-2 inhibits the activation of the complement system by interacting with C1q, C1r, C1s, C2, C3, C4, C5, and C9. The results suggested that EWDS-2 could be valuable for the treatment of diseases associated with the excessive activation of the complement system.     

Structural characterization of a highly branched polysaccharide from the seeds of Plantago asiatica L.

In this paper, polysaccharides were extracted from the seeds of Plantago asiatica L. with hot water and separated into three fractions PLP-1 (18.9%), PLP-2 (52.6%) and PLP-3 (28.5%) by Sephacryl™ S-400 HR column chomatography. The main fraction PLP-2's structure was elucidated using oxalic acid hydrolysis, partial acid hydrolysis, methylation, GC, GC-MS, 1D and 2D NMR. PLP-2 was composed of Rha, Ara, Xyl, Man, Glc and Gal, in a molar ratio of 0.05:1.00:1.90:0.05:0.06:0.10. Its uronic acid was GlcA. PLP-2 was highly branched heteroxylan which consisted of a β-1,4-linked Xylp backbone with side chains attached to O-2 or O-3. The side chains consisted of β-T-linked Xylp, α-T-linked Araf, α-T-linked GlcAp, β-Xylp-(1 → 3)-α-Araf and α-Araf-(1 → 3)-β-Xylp, etc. Based on these results, the structure of PLP-2 was proposed.     

Structural characterization and protective effect against murine sepsis of fucogalactans from Agaricus bisporus and Lactarius rufus

Fucogalactans from edible Agaricus bisporus (RFP-Ab) and wild Lactarius rufus (RFP-Lr) mushrooms were obtained on aqueous extraction followed by purification. RFP-Ab had M_w 43.8 × 10⁴ g mol⁻¹ and RFP-Lr M_w 1.4 × 10⁴ g mol⁻¹. RFP-Lr had a (1 → 6)-linked α-d-Galp main-chain partially substituted at O-2 by nonreducing end-units of α-l-Fucp (29%). While RFP-Ab had a similar main chain, it was partially substituted at O-2 by nonreducing end-units of α-l-Fucp (2.8%) and β-d-Galp (14.5%), and partially methylated at HO-3. Both RFP-Lr and RFP-Ab were tested in mice against polymicrobial sepsis. Lethality rate, myeloperoxidase (MPO) activity and cytokine levels were determined. It was observed a reduction in late mortality rate by 62.5% and 50%, respectively, prevention of neutrophil accumulation in ileum and decreasing in TNF-α and IL-1β serum levels.     

Isolation and characterization of poly- and oligosaccharides from the red microalga Porphyridium sp.

The current study forms part of an ongoing research effort focusing on the elucidation of the chemical structure of the sulfated extracellular polysaccharide of the red microalga Porphyridium sp. (UTEX 637). We report here on the chemical structure of a fraction separated from an acidic crude extract of the polysaccharide, as investigated by methylation analysis, carboxyl reduction-methylation analysis, desulfation-methylation analysis, partial acid hydrolysis, Smith degradation, together with 1D and 2D ¹H and ¹³C NMR spectroscopy. This fraction with a molar mass of 2.39 × 10⁵ g mol⁻¹ comprised d- and l-Gal, d-Glc, d-Xyl, d-GlcA, and sulfate groups in a molar ratio of 1.0:1.1:2.1:0.2:0.7. The almost linear backbone of the fraction is composed of (1→2)- or (1→4)-linked d-xylopyranosyl, (1→3)-linked l-galactopyranosyl, (1→3)-linked d-glucopyranosyl, and (1→3)-linked d-glucopyranosyluronic acid and comprises a possible acidic building unit:

[(2 or 4)-β-d-Xylp-(l→3)]_m-α-d-Glcp-(1→3)-α-d-GlcpA-(1→3)-l-Galp(l→

Attached to the backbone are sulfate groups and nonreducing terminal d-xylopyranosyl and galactopyranosyl residues, which occur at the O-6 positions of Glc-derived moieties in the main chain.     

Separation, structure characterization, conformation and immunomodulating effect of a hyperbranched heteroglycan from Radix Astragali

A water soluble polysaccharide (RAP) was isolated and purified from Radix Astragali and its structure was elucidated by monosaccharide composition, partial acid hydrolysis and methylation analysis, and further supported by FT-IR, GC-MS and ¹H and ¹³C NMR spectra, SEM and AFM microscopy. Its average molecular weight was 1334 kDa. It was composed of Rha, Ara, Glc, Gal and GalA in a molar ratio of 0.03:1.00:0.27:0.36:0.30. The backbone consisted of 1,2,4-linked Rhap, α-1,4-linked Glcp, α-1,4-linked GalAp6Me, β-1,3,6-linked Galp, with branched at O-4 of the 1,2,4-linked Rhap and O-3 or O-4 of β-1,3,6-linked Galp. The side chains mainly consisted of α-T-Araf and α-1,5-linked Araf with O-3 as branching points, having trace Glc and Gal. The terminal residues were T-linked Araf, T-linked Glcp and T-linked Galp. Morphology analysis showed that RAP took random coil feature. RAP exhibited significant immunomodulating effects by stimulating the proliferation of human peripheral blood mononuclear cells and enhancing its interleukin production.     

Water-soluble polysaccharide from Bupleurum chinense DC: Isolation, structural features and antioxidant activity

The water-soluble polysaccharide (BCPS-1) was isolated from Bupleurum chinense DC. BCPS-1 (M_w = 29 kDa) was composed of Ara; Gal; Glc with a molar ratio of 2.1:2.5:1. According to FT-IR, partial acid hydrolysis, periodate oxidation and Smith degradation, methylation and GC-MS analysis, the results indicate BCPS-1 had a backbone of (1→5)-linked Ara, (1→4)-linked Gal and (1→3)-linked Gal residues with occasionally branches at O-6. The branches were composed of (1→4)-linked Glc, and terminated with Gal residues. The in vitro antioxidant activity evaluated by DPPH radical scavenging method showed that BCPS-1 had a significant antioxidant effect in a concentration-dependent manner.     

Occurrence of cellobiose residues directly linked to galacturonic acid in pectic polysaccharides

The study carried out in this work concerns the structural characterization of pectic polysaccharides from plum (Prunus domestica L.) and pear (Pyrus communis L.) cell walls and commercial pectic polysaccharides, obtained from Citrus. The α-(1 → 4)-d-galacturonic acid backbone was submitted to a selective hydrolysis with endo-polygalacturonase (EPG) and the fractions with low molecular weight (<1 kDa) obtained by size-exclusion chromatography were analysed by mass spectrometry using electrospray ionisation (ESI-MS). The ESI-MS spectra obtained revealed the presence of several [M+Na]⁺ ions of pectic oligosaccharides identified as belonging to different series, including oligosaccharides constituted only by galacturonic acid residues (GalA_n, n = 1-5) and galacturonic acid residues substituted by pentose residues (GalA₃Pent_n, n = 1-2). Surprisingly, it was also observed the occurrence of galacturonic acid residues substituted by hexose residues (GalA_nHex_m, n = 2-4, m = 1-2). The fragmentation of the observed [M+Na]⁺ ions, obtained under ESI-MS/MS and MSⁿ allowed to confirm the proposed structures constituent of these pectic oligosaccharides. Furthermore, the ESI-MSⁿ spectra of the ions that could be identified as GalA_nHex_m (n = 2-4, m = 1-2) confirmed the presence of Hex or Hex₂ residues linked to a GalA residue. Methylation analysis showed the presence, in all EPG treated samples, of terminally linked arabinose, terminally and 4-linked xylose, and terminally and 4-linked glucose. The occurrence of GalA substituted by Glc, and Glc-β-(1 → 4)-Glc are structural features that, as far as we know, have never been reported to occur in pectic polysaccharides.     

Structural analysis of water-soluble polysaccharides in the fruiting body of Dictyophora indusiata and their in vivo antioxidant activities

The water-soluble Dictyophora indusiata polysaccharides (DIP) were extracted from the fruiting body of D. indusiata. The structural features of purified DIPs I and II were investigated. The results indicated that DIP I was composed of glucose (Glc) and mannose (Man) with molecular weight of 2100 kDa, while DIP II comprised of xylose (Xyl), galactose (Gal), glucose (Glc) and Man with molecular weight of 18.16 kDa. The glycosidic linkage of DIP I was composed of →1)-Glc-(6→: →1)-Man-(3,6→ with the ratio of 5.6:1.0, while DIP II was composed of →1)-Glc-(6→: →1)-Man-(3,6→: →1)-Xyl-(5→: →1)-Gal-(3→: →1)-Gal-(6→: with the ratio of 4.9: 15.5: 7.8: 1.0: 5.7. DIP significantly (P < 0.05) decreased the malondialdehyde (MDA), lipofuscin levels and increased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities of mice. The strong in vivo antioxidant activity indicated DIP had great potential as functional food.     

Structure and antioxidant activity of an extracellular polysaccharide from coral-associated fungus, Aspergillus versicolor LCJ-5-4

An extracellular polysaccharide AVP was isolated from the fermented broth of coral-associated fungus Aspergillus versicolor LCJ-5-4. AVP was a mannoglucan with molecular weight of about 7 kDa, and the molar ratio of glucose and mannose was 1.7:1.0. On the basis of detailed one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopic analyses, the backbone of AVP was characterized to be composed of (1 → 6)-linked α-d-glucopyranose and (1 → 2)-linked α-d-mannopyranose units. The mannopyranose residues in the backbone were substituted mainly at C-6 by the side chain of (1 → 2)-linked α-d-mannopyranose trisaccharides units. The antioxidant activity of AVP was evaluated with the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in vitro, and the results indicated that AVP had good antioxidant activity, especially scavenging ability on superoxide radicals. AVP was a novel extracellular polysaccharide with different structural characteristics from other extracellular polysaccharides and could be a potential source of antioxidant.     

An acetylated galactomannoglucan from the stems of Dendrobium nobile Lindl

A water-soluble polysaccharide DNP-W2 composed of glucose, mannose, and galactose in the molar ratio of 6.1:2.9:2.0 had been isolated from the stems of Dendrobium nobile. Its molecular weight was 1.8 × 10⁴ Da determined by HPGPC. Structural features of DNP-W2 were investigated by a combination of chemical and instrumental analysis, including FTIR, GC, GC-MS, periodate oxidation-Smith degradation, methylation analysis, partial acid hydrolysis, and NMR spectroscopy. The results showed that DNP-W2 is a 2-O-acetylgalactomannoglucan and has a backbone consisting of (1→4)-linked β-d-Glcp, (1→6)-linked β-d-Glcp, and (1→4)-linked β-d-Manp, with branches at O-6 of (1→4)-linked β-d-Glcp and β-d-Manp. The branches are composed of α-d-Galp. The acetyl groups are substituted at O-2 of (1→4)-linked Manp. Preliminary tests in vitro reveals that DNP-W2 can stimulate ConA- and LPS-induced T and B lymphocyte proliferation.     

Structural characterization and antioxidant properties of an exopolysaccharide produced by the mangrove endophytic fungus Aspergillus sp. Y16

A homogeneous exopolysaccharide, designated As1-1, was obtained from the culture medium of the mangrove endophytic fungus Aspergillus sp. Y16 and purified by anion-exchange and gel-permeation chromatography. Results of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy showed that As1-1 was mainly composed of mannose with small amounts of galactose, and that its molecular weight was about 15 kDa. The backbone of As1-1 mainly consists of (1 → 2)-linked α-d-mannopyranose units, substituted at C-6 by the (1 → 6)-linked α-d-mannopyranose, (1→)-linked β-d-galactofuranose and (1→)-linked β-d-mannopyranose units. As1-1 possessed good in vitro antioxidant activity as evaluated by scavenging assays involving 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals. The investigation demonstrated that As1-1 is an exopolysaccharide different from those of other marine microorganisms, and could be a potential antioxidant and food supplement.     

α,β-dicarbonyl reduction by Saccharomycesd-arabinose dehydrogenase

An α,β-dicarbonyl reductase activity was purified from Saccharomyces cerevisiae and identified as the cytosolic enzyme d-Arabinose dehydrogenase (ARA1) by MALDI-TOF/TOF. Size exclusion chromatography analysis of recombinant Ara1p revealed that this protein formed a homodimer. Ara1p catalyzed the reduction of the reactive α,β-dicarbonyl compounds methylglyoxal, diacetyl, and pentanedione in a NADPH dependant manner. Ara1p had apparent K_m values of ∼ 14 mM, 7 mM and 4 mM for methylglyoxal, diacetyl and pentanedione respectively, with corresponding turnover rates of 4.4, 6.9 and 5.9 s^− 1 at pH 7.0. pH profiling showed that Ara1p had a pH optimum of 4.5 for the diacetyl reduction reaction. Ara1p also catalyzed the NADP⁺ dependant oxidation of acetoin; however this back reaction only occurred at alkaline pH values. That Ara1p was important for degradation of α,β-dicarbonyl substrates was further supported by the observation that ara1-Δ knockout yeast mutants exhibited a decreased growth rate phenotype in media containing diacetyl.     

Galactan sulfate of Grateloupia indica: Isolation, structural features and antiviral activity

Natural compounds offer interesting pharmacological perspectives for antiviral drug development with regard to broad-spectrum antiviral properties and novel modes of action. In this study, we have analyzed polysaccharide fractions isolated from Grateloupia indica. The crude water extract (GiWE) as well as one fraction (F3) obtained by anion exchange chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC₅₀) values (0.12-1.06 μg/ml) were much lower than cytotoxic concentration 50% values (>850 μg/ml). These fractions, which were effective antiviral inhibitors if added only during the adsorption period, had very low anticoagulant activity. Furthermore, they had no direct inactivating effect on virions in a virucidal assay. Chemical, chromatographic and spectroscopic methods showed that the active polysaccharide, which has an apparent molecular mass of 60 kDa and negative specific rotation −16° (c 0.2, H₂O), contains α-(1 → 4)- and α-(1 → 3)-linked galactopyranose residues. Sulfate groups, if present, are located mostly at C-2/6 of (1 → 4)- and C-4/6 of (1 → 3)-linked galactopyranosyl units, and are essential for the anti herpetic activity of this polymer.     

Structural characterization of a sulfated glucan isolated from the aqueous extract of Hedysarum polybotrys Hand.-Mazz

A water-soluble sulfated glucan, SHG, was isolated from Hedysarum polybotrys Hand.-Mazz using anion-exchange and gel-permeation chromatography. Elemental analysis indicated that SHG was a sulfated polysaccharide containing small amount of sulfate groups (1.47 mass%). The molecular weight was estimated to be 1.72 × 10⁵ Da by high-performance gel permeation chromatography (HPGPC) and size exclusion chromatography-multi angle laser light scattering (SEC-MALLS). SHG took random coil compact conformation in 0.1 M NaNO₃. Compositional analysis revealed that SHG was composed of glucose only. On the base of partial acid hydrolysis, methylation analysis, gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FT-IR) spectra, nuclear magnetic resonance (NMR) spectroscopy of ¹H, ¹³C, β-correlation spectroscopy (β-COSY), total correlation spectroscopy (TOCSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC), the results showed that SHG was composed of α-d-(1 → 4)-linked glucopyranosyl residues, with branches at C-6 consisting of non-reducing terminal approximately every eight residues. Sulfate groups may attach to the backbone at O-6, occasionally occurring per thirty-eight anhydrous glucose units.     

Introducing transglycosylation activity in Bacillus licheniformis α-amylase by replacement of His235 with Glu

To understand the role of His and Glu in the catalytic activity of Bacillus licheniformis α-amylase (BLA), His235 was replaced with Glu. The mutant enzyme, H235E, was characterized in terms of its mode of action using labeled and unlabeled maltooctaose (Glc8). H235E predominantly produced maltotridecaose (Glc13) from Glc8, exhibiting high substrate transglycosylation activity, with K_m = 0.38 mM and k_cat/K_m = 20.58 mM⁻¹ s⁻¹ for hydrolysis, and K_m2 = 18.38 mM and k_cat2/K_m2 = 2.57 mM⁻¹ s⁻¹ for transglycosylation, while the wild-type BLA exhibited high hydrolysis activity exclusively. Glu235—located on a wide open groove near subsite +1—is likely involved in transglycosylation via formation of an α-1,4-glycosidic linkage and may recognize and stabilize the non-reducing end glucose of the acceptor molecule.     

Structural characterization of trace stilbene glycosides in Lysidice brevicalyx Wei using liquid chromatography/diode-array detection/electrospray ionization tandem mass spectrometry

The mass fragmentation patterns of stilbene glycosides isolated from the genus Lysidice were investigated by negative ion electrospray ionization tandem mass spectrometry, and the influence of collision energy on their fragmentation behavior is discussed. It is found that the presence of the Y₀⁻ and B₀⁻ ions in the MS² spectra is characteristic for 1 → 6 linked diglycosyl stilbenes, while the Y₀⁻, Y₁⁻, and Z₁⁻ ions are representative ions of 1 → 2 linked diglycosyl stilbenes. These results indicate that ESI-MSⁿ in the negative ion mode can be used to differentiate 1 → 6 and 1 → 2 linked diglycosyl stilbenes. Based on the fragmentation rules, 9 new trace constituents were identified or tentatively characterized in a fraction of Lysidice brevicalyx by using HPLC/HRMS and HPLC-DAD/ESI-MSⁿ. The results of the present study can assist in on-line structural identification of analogous constituents and targeted isolation of novel compounds from crude plant extracts.     

Ultrasonic degradation, purification and analysis of structure and antioxidant activity of polysaccharide from Porphyra yezoensis Udea

The chemical structure and antioxidant of natural and ultrasonic degraded polysaccharides from Porphyra yezoensis Udea was investigated. The degraded polysaccharide (PYPS_UD) was purified, and F2 (a homogeneous fraction) was obtained. FT-IR, ¹H and ¹³C NMR spectral analysis revealed that F2 have typical porphyran structure. It has a backbone of alternating (1 → 4)-3,6-anhydro-α-l-galactopyranose) units and (1 → 3)-linked β-d-galactose or (1 → 4)-linked α-l-galactose 6-sulfate units. The result ascertained ultrasound degradation did not change the main structure of polysaccharides in the test conditions. Antioxidant proved that the activity of scavenging superoxide and hydroxyl radical is F₂ > V_C > PSPY_UD > PSPY. It was possible that ultrasonic treatment is an effective way for enhancing PSPY's antioxidant activity ascribing to decreasing molecular weight of polysaccharides.     

Galactans from Cryptonemia species. Part II: Studies on the system of galactans of Cryptonemia seminervis (Halymeniales) and on the structure of major fractions

Cryptonemia seminervis biosynthesizes a family of d,l-hybrid galactans based on the classical 3-linked β-d-galactopyranosyl→4-linked α-d- and α-l-galactopyranosyl alternating sequence (A-units→B-units) with major amounts of α-d- and α-l-galactose and 3,6-anhydro-d- and l-galactose and lesser percentages of 3,6-anhydro-2-O-methyl-l-galactose, 2-O-methyl-, 4-O-methyl- and 6-O-methylgalactoses. The dispersion of structures in this family is based on five structural factors, namely: (a) the amount and position of substituent groups as sulfate (major), pyruvic acid ketals, methoxyl and glycosyl side-chain (4-O-methyl galactopyranosyl and/or xylosyl); (b) the ratio galactose/3,6-anhydrogalactose in the B-units; (c) the ratio d,l-galactoses and d,l-3,6-anhydrogalactoses also in the B-units, (d) the formation of diads and (e) the sequence of the diads in the linear backbone. Considering these variables it is not unexpected to find in the fractions studied at least 18 structural units producing highly complex structures. Structural studies carried out in two major fractions (S2S-3 and S2S-4) showed that these galactans were formed mainly by β-d-galactopyranosyl 2-sulfate (20 and 11.9 mol %), β-d-galactopyranosyl 2-sulfate 4,6-O-(1′-carboxyethylidene) (8.9 and 6.0 mol %) and β-d-galactopyranosyl 2,6-sulfate (5.4 and 18.6 mol %), together with 3,6-anhydro-α-l-galactopyranosyl (11.4 and 7.3 mol %) and 3,6-anhydro-α-l-galactopyranosyl 2-sulfate (4.9 and 15.4 mol %) and minor quantities of 12-15 other structural units.Preparative alkaline treatment carried out on fraction (S2S-3) produced a quantitative formation of 3,6-anhydro α-l-galactopyranosyl units from precursor units (α-l-galactose 6-sulfate and α-l-galactose 2,6-sulfate). Kinetic studies on this 3,6-anhydro cyclization show a rate constant of 5.2 × 10⁴ s⁻¹ indicating diads of the type G→L6S/2,6S. Data from chemical, spectroscopic and kinetic studies suggest that, in S2S-3, the agaran block in the d,l-hybrid galactan is composed of the following diads: G(6R)→L6S/2,6S and G2S(P)(2,6S)→LA(2S)(2R)(2M) and the carrageenan block of G2S(P)→D(2S)(2,3S)(3S)(3,6S) in a molar ratio of agaran to carrageenan structures of ∼2:1.     

Characterization of a neutral polysaccharide with antioxidant capacity from red wine

A neutral fraction (PS-SI) (0.3 g/L) with MW of 74 kDa, which contained galactose, arabinose, mannose, and glucose in the molar ratio of 1.0:0.6:0.4:0.2 was obtained by treatment of the whole polysaccharide extracted from red wine with cetrimide, followed by gel permeation chromatography. Spectroscopic and methylation analyses indicated that PS-SI is a mixture of neutral polysaccharides, consisting mainly of β (1→3)-linked galactopyranosyl residues, with side chains of galactopyranosyl residues at positions O-6. Arabinofuranosyl residues linked α (1→5), α-mannopyranosyl and glucosyl residues appear to be components of different polysaccharides. The in vitro antioxidant capacity of fractions of wine polysaccharide was studied by hydroxyl radical scavenging and ORAC assays. Fraction PS-SI presented the strongest effect on hydroxyl radicals (IC₅₀ = 0.21).     

Synthesis of LeLe oligosaccharide fragments and efficient one-step deprotection

We describe here the synthesis of two oligosaccharide fragments of the tumor associated carbohydrate antigen Le^aLe^x. While the linear lacto-N-triose I: β-d-Galp-(1→4)-β-d-GlcNAcp-(1→3)-β-d-Galp-OMe is a known compound, this is the first reported preparation of the branched tetrasaccharide β-d-GlcNAcp-(1→3)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-β-d-GlcNAcp-OMe. Our synthetic schemes involved using an N-trichloroacetylated trichloroacetimidate glucosaminyl donor activated with excess TMSOTf at 0 °C for glycosylation at O-3 of galactosyl residues and that of trichloroacetimidate galactosyl donors activated with excess BF₃·OEt₂ to glycosylate either O-3 or O-4 of glucosamine residues. The fucosylation at O-3 of the glucosamine acceptor was accomplished using a thiofucoside donor activated with copper(II) bromide and tetrabutylammonium bromide. Thus, syntheses of the protected tri- and tetrasaccharides were achieved easily and efficiently using known building blocks. Of particular interest, we also report that these protected oligosaccharides were submitted to dissolving metal conditions (Na-NH₃) to provide in one single step the corresponding deprotected compounds. Under these conditions all protecting groups (O-acyl, benzylidene, benzyl, and N-trichloroacetyl) were efficiently cleaved. The work-up procedure for such reactions usually involves quenching with excess methanol and then neutralization with acetic acid. In our work the neutralization was carried out using acetic anhydride rather than acetic acid to ensure N-acetylation of the glucosamine residue. Both fully deprotected compounds were then simply purified and desalted by gel permeation chromatography on a Biogel P2 column eluted with water.