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PubMed1987

Amino-sugars inhibit the in vitro cytoadherence of Plasmodium falciparum-infected erythrocytes to melanoma cells.

Twenty-two sugars and related compounds, nine neoglycoproteins, dopamine, four polyamines and oligomers of glucosamine were examined for their effect on the cytoadherence of Plasmodium falciparum-infected erythrocytes to melanoma cells. Inhibition of cytoadherence was high in the presence of the amino-sugars, glucosamine, galactosamine and mannosamine, and dopamine, and significant, although lower, in the presence of the polyamines, spermine, spermidine and putrescine. N-acetylated amino-sugars and the other compounds were not significant inhibitors of cytoadherence.

Amino Sugars↗
PubMed1995

Co-ordinated regulation of amino sugar biosynthesis and degradation: the NagC repressor acts as both an activator and a repressor for the transcription of the glmUS operon and requires two separated NagC binding sites.

The NagC repressor controls the expression of the divergently transcribed nagE-nagBACD operons involved in the uptake and degradation of the amino sugars, N-acetyl-D-glucosamine (GlcNAc) and glucosamine (GlcN). The glmUS operon, encoding proteins necessary for the synthesis of GlcN (glmS) and the formation of UDP-GlcNAc (glmU), is transcribed from two promoters located upstream of glmU. In the absence of amino sugars both promoters are active. However, in the presence of GlcNAc, the glmU proximal promoter, P1, is inactive while the upstream promoter, P2, is subject to weak induction. Two binding sites for the NagC repressor are located at -200 and -47 bp upstream of P1. Mutations which prevent NagC binding to either of these sites eliminate expression from the P1 promoter. This shows that binding of NagC is necessary for expression of the glmU P1 promoter and implies that NagC is playing the role of activator for this promoter. Moreover, the location of the distal NagC site suggests that this site is behaving like an upstream activating sequence (UAS).

Acetylglucosamine↗
PubMed2006

Beta-turn modified gramicidin S analogues containing arylated sugar amino acids display antimicrobial and hemolytic activity comparable to the natural product.

This paper describes the design and synthesis of gramicidin S (GS) analogues 10a-c containing arylated sugar amino acids (SAAs) as a replacement of one of the two (D)Phe-Pro beta-turn regions. The cyclic, amphiphilic peptides adopt a beta-sheet conformation featuring an unusual reverse turn induced by the SAAs. The altered turn region induces a slight distortion of the antiparallel beta-sheet, as compared to GS; the overall geometry however closely resembles that of the nonarylated GS analogue 1. GS analogues 10a-c proved to be as active as the parent GS itself as antibacterial agents and are equally efficient in lysing red blood cells. These properties are in sharp contrast to the diminished biological activity displayed by 1. We conclude that the presence of aromaticity in the turn regions of GS derivatives is required for biological activity, whereas the native conformation of the beta-hairpin is not. Our findings may guide future research toward efficient and nonhemolytic GS analogues for combating bacterial infections.

Acrylates↗
PubMed1999

Enhanced binding to DNA and topoisomerase I inhibition by an analog of the antitumor antibiotic rebeccamycin containing an amino sugar residue.

Many antitumor agents contain a carbohydrate side chain appended to a DNA-intercalating chromophore. This is the case with anthracyclines such as daunomycin and also with indolocarbazoles including the antibiotic rebeccamycin and its tumor active analog, NB506. In each case, the glycoside residue plays a significant role in the interaction of the drug with the DNA double helix. In this study we show that the DNA-binding affinity and sequence selectivity of a rebeccamycin derivative can be enhanced by replacing the glucose residue with a 2'-aminoglucose moiety. The drug-DNA interactions were studied by thermal denaturation, fluorescence, and footprinting experiments. The thermodynamic parameters indicate that the newly introduced amino group on the glycoside residue significantly enhanced binding to DNA by increasing the contribution of the polyelectrolyte effect to the binding free energy, but does not appear to participate in any specific molecular contacts. The energetic contribution of the amino group of the rebeccamycin analog was found to be weaker than that of the sugar amino group of daunomycin, possibly because the indolocarbazole derivative is only partially charged at neutral pH. Topoisomerase I-mediated DNA cleavage studies reveal that the OH-->NH2 substitution does not affect the capacity of the drug to stabilize enzyme-DNA covalent complexes. Cytotoxicity studies with P388 leukemia cells sensitive or resistant to camptothecin suggest that topoisomerase I represents a privileged intracellular target for the studied compounds. The role of the sugar amino group is discussed. The study provides useful guidelines for the development of a new generation of indolocarbazole-based antitumor agents.

Amino Sugars↗
PubMed2006

Synthesis, glycosidase activity and X-ray crystallography of 3-amino-sugars.

The cleavage of two sugar epoxides, methyl 2,3-anhydro-alpha-D-mannopyranoside and 2,3-anhydro-alpha-D-allopyranoside, with amines is presented as a method for preparing a library of 3-amino-sugars (methyl 3-amino-3-deoxy-alpha-D-altropyranosides and methyl 3-amino-3-deoxy-alpha-D-glucopyranosides) as potential glycosidase inhibitors. Several of the altropyranosides were micromolar inhibitors of bovine liver beta-galactosidase and almond beta-glucosidase. X-ray crystal structures were determined for one of the methyl 3-amino-3-deoxy-alpha-D-altropyranosides, 4t, and one of the methyl 3-amino-3-deoxy-alpha-D-glucopyranosides, 6d.

Amino Sugars↗
PubMed1988

Ganglioside biosynthesis in rat liver: effect of UDP-amino sugars on individual transfer reactions.

Several glycosyltransferases participating in ganglioside biosynthesis were measured in Golgi-rich fractions from rat liver. Addition of those UDP-amino sugars to the enzyme assays which accumulate in liver after treatment of rats with D-galactosamine inhibited the transferases to different degrees. The simultaneous presence of UDP-GalN, UDP-GalNAc, UDP-GlcN, and UDP-GlcNAc in concentrations resembling their overall content in livers 6 h after D-galactosamine administration led to an inhibition of the glycolipid galactosyltransferases, GL2 and GM1 synthases of 44 and 64%, respectively. GM2 synthase was moderately inhibited whereas the sialyltransferases (GM3, GD3, and GD1a synthases) were almost unimpaired. Induction of liver cell damage by D-galactosamine did not cause any change of glycosyltransferase activities as determined in rat liver homogenates and Golgi-rich fractions. These results indicate a possible role for UDP-amino sugars in the depression of ganglioside biosynthesis observed in vivo after GalN administration.

Animals↗
PubMed1992

Complexes of Fe(III) with amino sugars and small glycopeptides.

The complexes of Fe(III) with small molecules (glycopeptides, amino sugars) related to peptidoglycan monomer (PGM) structure were prepared and characterized by chemical and physicochemical methods. A simple method for preparation using separation of the reaction products on a molecular sieve was introduced. Using this method, monomeric complexes of small molecular weight were obtained. The likely structures were proposed on the basis of analytical results.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1994

Structure-activity relationships in the induction of single-strand breakage in plasmid pBR322 DNA by amino sugars and derivatives.

Structure-activity relationships in the induction of strand breakage in plasmid pBR322 DNA by amino sugars and their derivatives were investigated using agarose gel electrophoresis. The coexistence of a potential free aldehyde group at the C-1 position and a free amino group at the C-2 position in the molecules was indispensable for the display of DNA strand-breaking activity in both mono- and oligo-aminosaccharides. The activity was increased by the introduction of an acidic group, especially a phosphate group, at the C-6 position. The activity was also increased by the addition of Cu2+. The order of activity of the amino monosaccharides tested was D-isoglucosamine > D-mannosamine > D-galactosamine > D-glucosamine, and it is suggested that this order is correlated with the portion of acyclic (aldehydo) form in the solution of each sugar. The possible chemical basis for DNA strand breakage by amino sugars is discussed.

Carbohydrate Conformation↗
PubMed2005

Sugar amino acids in designing new molecules.

Emulating the basic principles followed by nature to build its vast repertoire of biomolecules, organic chemists are developing many novel multifunctional building blocks and using them to create 'nature-like' and yet unnatural organic molecules. Sugar amino acids constitute an important class of such polyfunctional scaffolds where the carboxyl, amino and hydroxyl termini provide an excellent opportunity to organic chemists to create structural diversities akin to Nature's molecular arsenal. This article describes some of our works on various sugar amino acids and many other related building blocks, like furan amino acids, pyrrole amino acids etc. used in wide-ranging peptidomimetic studies.

Amino Acids↗
PubMed2003

Simultaneous analyses of neutral carbohydrates and amino sugars in freshwaters with HPLC-PAD.

In this study, we determine concentrations of neutral and amino sugars and a sugar alcohol in freshwaters using high-performance liquid chromatography and pulsed amperometric detection with a single isocratic analysis. Coeluting arabinose, galactosamine, and mannosamine are separated with a mobile phase of 22.8 mM NaOH-KOH at a temperature of 17 degrees C. The resolutions are 0.73 and 0.64, respectively. The method separates closely eluting glucose-mannose and mannose-xylose peaks with resolutions of 0.85 and 0.71. Other sugars, fucose, rhamnose, galactose, fructose, ribose, glucosamine, and mannitol are resolved completely. Arabinose and galactosamine are measured in stream, ground, and soil waters that contain dissolved total saccharide (DTS) concentrations of 527 to 1555 nM. Failure to distinguish galactosamine from arabinose in those samples results in a 53-82% overestimation of arabinose concentrations and a 1.8-6.5% overestimation of DTS concentrations. The near unity of glucosamine and galactosamine concentrations in stream water samples allows us to suggest a correction factor for historical samples that had been analyzed without resolving galactosamine and arabinose.

Amino Sugars↗
PubMed1990

Simultaneous determination of neutral and amino sugars in biological materials.

A method is described for the simultaneous analysis of nine neutral and three amino sugars. Mixtures of standard sugars and biological samples were acid hydrolyzed with a two step Saeman procedure, neutralized with BaCO3, reduced with sodium borohydride, acidified, evaporated and alditol acetates prepared. Baseline resolution was achieved on a glass-capillary SP-2340 column in ca. 52 min. Reproducibility, response factors and hydrolysis losses were determined. Quantitation was linear over the range of 10-20 micrograms/ml to 2000 micrograms/ml. Conditions were defined for the reproducible quantitation of muramic acid.

Amino Sugars↗
PubMed1985

Microquantitative analysis of neutral and amino sugars as fluorescent pyridylamino derivatives by high-performance liquid chromatography.

A method for the quantitation of picomole amounts of neutral and amino sugars in glycoconjugates was developed. Glycoconjugates were hydrolyzed with a mixture of equal amounts of 4 M trifluoroacetic acid and 4 M hydrochloric acid, and the free amino groups were acetylated. Sugars were coupled with 2-aminopyridine. After the excess reagents were removed by gel-permeation high-performance liquid chromatography, the fluorescent pyridylamino derivatives of sugars were separated and quantified by high-performance liquid chromatography on a reversed-phase column. This method allowed the determination of 0.01-10 nmol of sugars. About 100 pmol of several glycoconjugates were analyzed by the present method, with satisfactory results.

Amino Sugars↗