Kegg Pathway: Aminosugars metabolism

Zh Mikrobiol Epidemiol Immunobiol. 2007 Nov-Dec; 68-72
Lomov IuM, Telesmanich NR, Koliakina AV

Spectrum of carbohydrate specificity of lectin receptors of epidemically significant cholera vibrios (ctx(+) tcp(+) Hly(-)) as well as non epidemic hemolytic variants with or without tcp A gene (ctx(-) tcp(-) Hly(+), ctx(-) tcp(+) Hly(+)) was studied under the carbohydrates-mediated inhibition of hemagglutination between human erythrocytes of four blood groups and sheep erythrocytes. It was demonstrated that in toxigenic cultures lectin receptors specific for glucose, mannose, sacharose, lactose dominate whereas receptors specific for Aminosugars are virtually absent. The latter are detected in hemolytic vibrios that can explain their ecologic flexibility.

Protein Sci. 2008 Mar; 17(3): 577-82
Mochalkin I, Lightle S, Narasimhan L, Bornemeier D, Melnick M, Vanderroest S, McDowell L

N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU) is an essential enzyme in Aminosugars metabolism and an attractive target for antibiotic drug discovery. GlmU catalyzes the formation of uridine-diphospho-N-acetylglucosamine (UDP-GlcNAc), an important precursor in the peptidoglycan and lipopolisaccharide biosynthesis in both Gram-negative and Gram-positive bacteria. Here we disclose a 1.9 A resolution crystal structure of a synthetic small-molecule inhibitor of GlmU from Haemophilus influenzae (hiGlmU). The compound was identified through a high-throughput screening (HTS) configured to detect inhibitors that target the uridyltransferase active site of hiGlmU. The original HTS hit exhibited a modest micromolar potency (IC(50) approximately 18 microM in a racemic mixture) against hiGlmU and no activity against Staphylococcus aureus GlmU (saGlmU). The determined crystal structure indicated that the inhibitor occupies an allosteric site adjacent to the GlcNAc-1-P substrate-binding region. Analysis of the mechanistic model of the uridyltransferase reaction suggests that the binding of this allosteric inhibitor prevents structural rearrangements that are required for the enzymatic reaction, thus providing a basis for structure-guided design of a new class of mechanism-based inhibitors of GlmU.

Org Lett. 2007 Aug 30; 9(18): 3547-50
Fei Z, McDonald FE

In explorations toward the total synthesis of the antitumor anthrapyran natural product kidamycin, the regioselective introduction of Aminosugars angolosamine and vancosamine as C-arylglycosides has been accomplished onto hydroxylated anthrapyran aglycones. Specifically, the 9,11-dihydroxylated anthrapyran A undergoes sequential glycosylations with angolosamine synthon B and vancosamine synthon C to regio- and stereoselectively afford bis-C-glycoside D corresponding to the C-glycoside pattern of kidamycin.

J Neural Transm. 2007; 114(6): 751-6
O'Sullivan J, Davey G, O'Sullivan M, Tipton KF

Semicarbazide-sensitive amine oxidase (SSAO) also functions as a vascular-adhesion protein (VAP-1). The nature of the target site on lymphocytes to which endothelial-cell SSAO/VAP-1 binds is unknown. We have shown that amino sugars (galactosamine, glucosamine and mannosamine), which are not SSAO substrates, can bind to the enzyme as reversible inhibitors. Thus, they serve as a model system in which to study the interaction process. Binding occurred during substrate (benzylamine) oxidation but not when the amino sugar was incubated, for extended periods, with SSAO alone. These results suggest that one, or more of the products of the SSAO-catalysed amine oxidation might be necessary for the inhibitory process to occur. Two of the reaction products of benzylamine oxidation, benzaldehyde and ammonia were found to have no effect on the inhibition of SSAO by galactosamine. Preincubation of the enzyme with galactosamine plus H(2)O(2) was, however, found to result in time-dependent inhibition. This is not a result of the non-enzymic reaction between H(2)O(2) and the amino sugar, since preincubation of galactosamine with H(2)O(2) alone, for extended periods, did not give rise to an inhibitory species. The amount of exogenously added H(2)O(2) necessary for inhibition was very much greater than that formed during substrate oxidation. These results suggest that the H(2)O(2) formed as a product of the SSAO-catalysed oxidation reaction is more efective in promoting the binding of amino sugars.

Postepy Hig Med Dosw (Online). 2007; 61: 106-21
Lodowska J, Wolny D, Weglarz L, Dzierzewicz Z

The majority of Gram-negative bacteria are pathogenic to humans and animals. Lipopolysaccharide (LPS) is the most biologically active component of these microorganisms. This compound is also called endotoxin to emphasize its negative impact on a macroorganism. Lipid A, one of the three structural components of the LPS molecule, is responsible for the pathophysiological effects associated with Gram-negative bacteria infections. Although lipid A is considered the conservative component of endotoxin, differences in its structure among species and even strains may occur. These differences concern the type of Aminosugars, the degree of substitution of the disaccharide core by fatty acids, phosphate, and/or ethanolamine, and also the type, quantity, and distribution of fatty acids. The lipid A saccharide backbone of the majority of Gram-negative bacteria consists of two glucosamine units in beta (1-->6) glycosidic linkage. Amino groups (at positions 2 and 2') and hydroxy groups (at positions 3 and 3') of glucosamines are commonly substituted by 3-hydroxyfatty acids, most often by 3-hydroxytetradecanoic acid. Other fatty acids (usually saturated, unbranched) are ester-linked to hydroxyacids by their hydroxy group. In lipid A of different microorganisms there is a high diversity of fatty acids, from mirystic (tetradecanoic, 14:0) and lauric (dodecanoic, 12:0) acids and their hydroxylated derivatives to such unique structures as cis-11-octadecenoic acid (Rhodospirillum salinarum 40), 3-hydroxy-5-dodecenoic acid (Phenylobacterium immobile), and iso-2,3-dihydroxytetradecanoic acid (Legionella pneumophila). The saccharide core of some bacterial lipid A may consist of sugars different from glucosamine, e.g., 2,3-diamino-2,3-dideoxy-D-glucose. Other substituents of this part of LPS, besides phosphate groups and ethanolamine, are beta -mannopyranose, 4-aminoarabinose, galacturonic acid, and glycine. Therefore, lipid A, though considered the relatively conservative component of endotoxin, reveals relatively large structural diversity, which influences the variety of LPS biological activity.

Org Lett. 2006 Mar 30; 8(7): 1303-6
Das I, Pathak T

[reaction: see text] A catalytic amount of NiBr(2) with Mg-MeOH increases the efficiency of reductive desulfonylation of the beta-sulfonylated Aminosugars. The Mg-MeOH-NiBr(2) system has been utilized in the synthesis of 2-amino-2,3-dideoxypentofuranosides and 2-amino-2,3-dideoxyhexofuranosides. The yield of the desulfonylation improved dramatically from 0% with the known reagents to 44-75% with Mg-MeOH-NiBr(2).

Org Lett. 2005 Mar 31; 7(7): 1383-5
Suri JT, Ramachary DB, Barbas CF

[reaction: see text] A practical and environmentally friendly organocatalytic strategy designed to mimic the DHAP aldolases has been developed and shown to be effective in the preparation of carbohydrates and Aminosugars. (S)-Proline and (S)-2-pyrrolidine-tetrazole catalyzed the aldol reaction between dihydroxy acetone variants such as 1,3-dioxan-5-one and 2,2-dimethyl-1,3-dioxan-5-one with aldehydes to give the corresponding polyols in good yields with very high ees.

J Am Chem Soc. 2005 Feb 16; 127(6): 1711-8
Kudo F, Kawabe K, Kuriki H, Eguchi T, Kakinuma K

Aminoglycoside antibiotics are composed of Aminosugars and a unique aminocyclitol aglycon including 2-deoxystreptamine (DOS), streptidine, actinamine, etc., and nucleotidylyltransferases, sugar modifying enzymes, and glycosyltransferases appear to be essential for their biosynthesis. However, the genes encoding those enzymes were unable to be identified by a standard homology search in the butirosin biosynthetic btr gene cluster, except that the btrM gene appeared to be a glycosyltransfease. Disruption studies of the btrD gene indicated that BtrD was involved in the supply of a glycosyl donor immediately prior to the glycosylation of DOS giving paromamine. As anticipated, BtrD expressed in Escherichia coli was able to catalyze UDP-D-glucosamine formation from D-glucosamine-1-phosphate and UTP. Both dTTP and UTP were good NTP substrates, and D-glucose-1-phosphate and D-glucosamine-1-phosphate were good sugar phosphates for the enzyme reaction. This finding is the first to identify an enzyme which activates a sugar donor in the DOS-containing antibiotics. Interestingly, BtrD homologues have been reported as functionally unknown open reading frames (ORFs) in the biosynthetic gene clusters for several antibiotics including teicoplanin, balhimycin, chloroeremomycin, and mitomycin C. It appears therefore that gene clusters for antibiotic biosynthesis provide their own nucleotidylyltransferases, and the BtrD homologues are among the secondary metabolism specific enzymes.

Inflamm Res. 2004 Dec; 53(12): 680-8
Hua J, Suguro S, Iwabuchi K, Tsutsumi-Ishii Y, Sakamoto K, Nagaoka I

OBJECTIVE: To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined. MATERIALS AND METHODS: Human platelet-rich plasma was stimulated with 2.5 microM ADP in the presence of glucosamine (0.01 approximately 1 mM) or other Aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet aggregation was monitored. Furthermore, the effects of glucosamine on the thromboxane A2 production, release of granule contents, intracellular calcium mobilization and phosphorylation of Syk (a 72 kD protein tyrosine kinase) were evaluated following ADP-stimulation. In addition, the binding of [3H] ADP to its receptors was examined. RESULTS: Glucosamine (>0.01 mM) dose-dependently suppressed platelet aggregation in response to ADP (p < 0.05), whereas N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine (1 mM) did not affect the ADP-induced platelet aggregation. Furthermore, glucosamine (>0.1 mM) inhibited the extracellular release of granule contents (ATP and platelet factor 4) and production of thromboxane A2 from ADP-stimulated platelets (p < 0.05). Moreover, glucosamine significantly repressed the intracellular calcium mobilization at >0.1 mM and phosphorylation of Syk at >0.01 mM upon ADP-stimulation (p < 0.05). In addition, glucosamine (>0.1 mM) inhibited the binding of ADP to its receptors (p < 0.05). CONCLUSION: Glucosamine is able to suppress platelet aggregation, release of granule constituents, thromboxane A2 production, calcium mobilization and phosphorylation of Syk possibly via the inhibition of ADP-binding to the receptors. Glucosamine could be expected as a novel anti-platelet agent for thrombotic disorders due to its suppressive actions on platelets.

J Org Chem. 2004 Mar 5; 69(5): 1513-23
Elchert B, Li J, Wang J, Hui Y, Rai R, Ptak R, Ward P, Takemoto JY, Bensaci M, Chang CW

A divergent approach was employed for the synthesis of Aminosugars, from which a novel library of aminoglycoside antibiotics (pyranmycins) was synthesized. Pyranmycins have comparable antibacterial activity as neomycin, a clinically used aminoglycoside antibiotic, against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Mycobacterium smegmatis. In addition, pyranmycins, like streptomycin, are bacteriocidal while isoniazid (INH) is bacteriostatic. Therefore, pyranmycins may provide new therapeutic options in the treatment against tuberculosis. Several members of pyranmycins also manifest modest anti-Tat and anti-Rev activities, which may aid in the development of new anti-HIV agents. Although the antibacterial activity of pyranmycins against aminoglycoside resistant bacteria is less than expected, the synthetic methodologies of utilizing a library of Aminosugars can be a model for future studies of glycodiversification or glycorandomization.

J Am Chem Soc. 2003 Jun 25; 125(25): 7482-3
Trost BM, Rhee YH

The ability to form rhodium-vinylidene complexes in situ from terminal alkynes has led to the development of a catalytic process, the cycloisomerization of homopropargylic and bis-homopropargylic alcohols to dihydrofurans and dihydropyrans. Among the transition metals that perform similar reactions, rhodium catalysts demonstrate the best chemoselectivity and turnover numbers to date. Both secondary and tertiary alcohols participate equally well. The presence of proparylic oxygen and nitrogen functionality, which potentially can be induced to ionize via formation of allenylidene metal complexes, is compatible with this catalyst. The formation of a 5-amino-dihydropyran which is not compatible with some of the previous catalysts proceeds in good yield with the rhodium catalysts. A substrate bearing a benzylic hydroxyl group adjacent to an electron-rich aromatic ring also participates without complications of ionization. The method provides access to useful Aminosugars. A mechanism to account for the different selectivity of this catalyst as compared to others is proposed.

J Environ Qual. 2002 Nov-Dec; 31(6): 1885-92
Kaschl A, Römheld V, Chen Y

The agricultural practice of amending soils with composted municipal solid waste (MSW) adds significant amounts of organic matter and trace metals, including Cd. Under these conditions, soluble organic complexes of Cd formed in the compost may be more significant than previously thought, due to Cd bioavailability and mobility in the soil environment. To study the relative importance of different types of organic ligands in MSW compost for the binding of Cd, six fractions of the dissolved organic matter (DOM) in addition to humic acid (HA) and fulvic acid (FA) were extracted and their complexation of Cd quantified at pH 7 using an ion-selective electrode (ISE). The highest complexing capacities (CC) for Cd were found for the most humified ligands: HA (2386 micromol Cd g(-1) C of ligand), predialyzed FA (2468 micromol Cd g(-1) C), and HoA, a fulvic-type, easily soluble fraction (1042 micromol Cd g(-1) C). The differences in CC for Cd of the various organic ligands were not directly related to total acid-titratable or carboxylic groups, indicating the importance of sterical issues and other functional groups. The strength of association between Cd and the organic ligands was characterized by calculating stability constants for binding at the strongest sites (pK(int)) and modeling the distribution of binding site strengths. The pK(int) values of the DOM fractions ranged between 6.93 (HiN: polysaccharides) and 8.11 (HiB: proteins and Aminosugars), compared with 10.05 for HA and 7.98 for FA. Hence, the highly complex and only partially soluble organic molecules from compost such as HA and FA demonstrated the highest capacity to sequester Cd. However, strong Cd binding of organic ligands containing N-functional groups (HiB) in addition to a high CC of soluble, humified ligands like HoA indicated the relevance of these fractions for the organic complexation of Cd in solution.

Mikrobiologiia. 2002 Sep-Oct; 71(5): 596-603
Eshinimaev BTs, Khmelenina VN, Sakharovskiĭ VG, Suzina NE, Trotsenko IuA

The halotolerant alkaliphilic methanotroph Methylomicrobium buryatense 5B is capable of growth at high methanol concentrations (up to 1.75 M). At optimal values of pH and salinity (pH 9.5 and 0.75% NaCl), the maximum growth rate on 0.25 M methanol (0.2 h-1) was twice as high as on methane (0.1 h-1). The maximum growth rate increased with increasing medium salinity and was lower at neutral than at alkaline pH. The growth of the bacterium on methanol was accompanied by a reduction in the degree of development of intracytoplasmic membranes, the appearance of glycogen granules in cells, and the accumulation of formaldehyde, formate, and an extracellular glycoprotein at concentrations of 1.2 mM, 8 mM, and 2.63 g/l, respectively. The glycoprotein was found to contain 23% protein and 77% carbohydrates, the latter being dominated by glucose, mannose, and Aminosugars. The major amino acids were glutamate, aspartate, glycine, valine, and isoleucine. The glycoprotein content rose to 5 g/l when the concentration of potassium nitrate in the medium was augmented tenfold. The activities of sucrose-6-phosphate synthase, glycogen synthase, and NADH dehydrogenase in methanol-grown cells were higher than in methane-grown cells. The data obtained suggest that the high methanol tolerance of M. buryatense 5B is due to the utilization of formaldehyde for the synthesis of sucrose, glycogen, and the glycoprotein and to the oxidation of excess reducing equivalents through the respiratory chain.

Microbiology. 2002 Nov; 148(Pt 11): 3375-84
Räty K, Hautala A, Torkkell S, Kantola J, Mäntsälä P, Hakala J, Ylihonko K

In this study a set of Streptomyces galilaeus ATCC 31615 mutants was characterized, which are incapable of synthesizing some or all of the deoxyhexose sugars of aclacinomycin A. Complementation experiments with the the mutant strains H026, H038, H039, H054, H063, H065 and H075 were carried out with glycosylation genes previously derived from the wild-type S. galilaeus. Mutations in strains H038, H063 and H075 were complemented with single PCR-amplified genes. Furthermore, amplification and sequencing of the corresponding genes from the mutant strains revealed single point mutations in the sequences. First, in H038 a transition mutation in aknQ, encoding a putative dTDP-hexose 3-ketoreductase, causes an amino acid substitution from glycine to aspartate, suppressing the biosynthesis of both 2-deoxyfucose and rhodinose and thus leading to the accumulation of aclacinomycin T with rhodosamine as its only sugar. Second, in H063, which accumulates aklavinone without a sugar moiety, amino acid substitution occurs, with threonine being substituted by isoleucine in dTDP-glucose synthase, the first enzyme participating in deoxyhexose biosynthesis, encoded by aknY. Third, a nonsense mutation in aknP leads to truncated dTDP-hexose 3-dehydratase in H075, which is incapable of synthesizing rhodinose. In addition, mutants H054 and H065, which accumulate aclacinomycins without Aminosugars, were complemented by a gene for an aminotransferase, aknZ. Characterization of the nature of the mutations adds to the usefulness and value of the mutants in the analysis of gene function and in the creation of novel compounds by combinatorial biosynthesis. Furthermore, these results strengthen the assignments of akn gene products and enlighten the biosynthetic pathway for deoxyhexoses.

J Chromatogr B Biomed Sci Appl. 2001 Dec 25; 765(2): 151-60
Campo GM, Campo S, Ferlazzo AM, Vinci R, Calatroni A

An improved isocratic high-performance liquid chromatography (HPLC) method for the analysis of L-(-)-fucose. D-(+)-galactosamine, D-(+)-glucosamine, D-(+)-galactose, obtained by hydrolysis of glycosaminoglycans (GAGs) and D-(+)-glucose and D-(+)-mannose is described. The presence in circulation of GAGs, acid polysaccharide sequences of alternate monosaccharide units, aminosugar and uronic acid (galactose in keratan sulfate), has been measured in terms of their sugar components. To evaluate concentration of these circulating sugars we considered blood samples obtained from healthy humans. Plasma or serum was filtered through weak anion-exchange Ecteola-cellulose either untreated or after mild alkaline treatment. GAGs adhering to resin were recovered by salt elution, and desalted on Bio-Gel P-2 resin. GAG fractionation by charge was carried out on a strong anion exchanger. GAG composition was evaluated in terms of galactose and Aminosugars, measured in HPLC by the proposed procedure using anion-exchange resin and pulsed amperometric detection. The mobile phase consisted of 0.02 M NaOH and elution was carried out at flow-rate of 1.0 ml/min. The amperometric detector was set as follows: t1 (0.5 s), E1 (+0.1 V); t2 (0.09 s), E2 (+0.6 V); t3 (0.05 s), E3 (-0.6 V). The analysis required 14 min. Calibration standard curves for the six analytes were linear from 0.25 to 40 microM. RSD values for intra- and inter-day variabilities were < or = 5.3% at concentrations between 0.25 and 40 microM. Accuracy, expressed as percentage error, ranged from - 16 to 14%. The method was specific and sensitive with quantitation limits of 1 pmol for L-(-)-fucose, D-galactosamine and D-glucosamine, 3 pmol for D-(+)-galactose and D-(+)-glucose and 5 pmol for D-(+)-mannose. The results of the assay showed higher GAG concentrations in serum than in plasma.

Biochem Biophys Res Commun. 2001 Sep 14; 287(1): 11-20
Krist P, Herkommerová-Rajnochová E, Rauvolfová J, Semenuk T, Vavrusková P, Pavlícek J, Bezouska K, Petrus L, Kren V

Aminosugars have a good affinity for the NKR-P1A protein, the major activating receptor at the surface of rat natural killer cells. We have systematically investigated the structural requirements of the recombinant soluble dimeric form of the receptor for its optimal carbohydrate ligands. While N-acetylD-mannosamine was the best neutral monosaccharide ligand, its participation in the context of an extended oligosaccharide sequence was equally important. The IC(50) value for the GalNAcbeta1 --> ManNAc disaccharide was nearly 10(-10) M with a further possible increase depending on the type of the glycosidic linkage and the aglycon nature. From the point of view of its availability, stability, and affinity for the receptor and a potential in vivo use, these studies are pivotal for the design of an oligosaccharide or glycomimetics suitable for further clustering into the multivalent glycodendrimers.

Med Vet Entomol. 2000 Sep; 14(3): 251-6
Volf P, Tesarová P, Nohýnkova EN

Salivary gland proteins were studied in sandflies (Diptera: Psychodidae: Phlebotominae) by electrophoretic techniques. In Phlebotomus duboscqi Neveu-Lemaire the protein concentration was about 30 times higher in females than in males. SDS PAGE revealed eight major bands of 29-62 kDa in salivary gland extracts (SGE) from females, whereas only one band of 57kDa was detected in males. The number of protein components in SGE gradually increased with the age of females. In P. papatasi (Scopoli) the typical electrophoretic pattern was reached in 3-5 days after imago emergence, depending on the temperature at which females were maintained. All major protein components of the female SGE were present in the content of glands. Female SGE were compared in seven colonies of five Phlebotomus and Lutzomyia species; electrophoretic profiles distinguished between species and even between colonies of different geographical origin. In general, the highest variability of major protein components was observed in the 38-48kDa region. Four colonies of the subgenus Phlebotomus (P. duboscqi and P. papatasi) possessed common mobility polypeptides, the highest similarity was found between two colonies of P. papatasi. Other species tested significantly differed, specific prominent bands of 33, 35 and 38kDa were found in P. halepensis Theodor, P. perniciosus Newstead and Lutzomyia longipalpis (Lutz & Neiva), respectively. Glycoproteins in SGE of Lu. longipalpis and P. duboscqi females were identified and analysed using blotting with five lectin conjugates. Specific reaction of lectins ConA and WGA revealed the complex type of N-glycans in the 48 and 53-54kDa glycoproteins present in both species. Similar glycosylation was detected in species-specific bands of the 57-60 and 65-67 kDa in P. duboscqi and Lu. longipalpis, respectively. The high mannose type of glycosylation was found in the 20 and 39 kDa polypeptides of Lu. longipalpis and the 40-42 kDa polypeptides of P. duboscqi. Innate lectin activity specific for Aminosugars was detected in SGE of P. duboscqi females using haemagglutination tests with rabbit erythrocytes.

J Agric Food Chem. 2000 Apr; 48(4): 1204-9
Shimamura T, Takamori A, Ukeda H, Nagata S, Sawamura M

Dihydropyrazine derivatives formed by the self-condensation reaction of D-glucosamine have the DNA breaking activity. To establish the monitoring method of the biological active dihydropyrazines, we investigated the relationship between the XTT (3'-[1-[(phenylamino)-carbonyl]-3, 4-tetrazolium]bis(4-methoxy-6-nitro)benzensulfonic acid hydrate) reducibility and the DNA breaking activity of Aminosugars. Aminosugar in 50 mM sodium phosphate buffer (pH 7.4) was incubated at 37 degrees C. At a given time, the XTT reducibility and the DNA breaking activity of the incubated aminosugar were measured. Both XTT reducibility and DNA breaking activity showed a maximum value within 1-4 h after the incubation and then gradually decreased with the incubation time. Superoxide anion was suggested to involve in both of the DNA breaking activity and the XTT reducibility by the addition of the radical scavengers into those assay mixtures. The quantity of remaining covalently closed circular DNA and the XTT reducibility of all Aminosugars showed a good correlation (r = 0.825, n = 26). This means that the XTT assay is applicable for the monitoring of those biologically active products derived from Aminosugars when the participation of superoxide anion in DNA scission is recognized.

Free Radic Res. 1999 Nov; 31(5): 389-403
Hiraku Y, Kawanishi S

We investigated the mechanisms of apoptosis and DNA damage induced by Aminosugars in relation to their antitumor actions. The order of cytotoxic effects of Aminosugars was D-mannosamine (ManN) >> D-galactosamine (GalN) > D-glucosamine (GlcN). A comparison of the frequency of apoptotic cells showed the same order. DNA ladders were formed by only ManN and the formation of DNA ladders was inhibited by a caspase inhibitor. Pulsed-field gel electrophoresis showed that ManN caused cellular DNA cleavage at a lower concentration than those causing apoptosis. Cellular DNA cleavage was inhibited by catalase and enhanced by a catalase inhibitor. Flow cytometry showed that ManN enhanced the production of intracellular peroxides. These results suggest that ManN-induced apoptosis is preceded by H2O2-mediated DNA damage. The order of the extent of damage to 32P-labeled DNA fragments by Aminosugars plus Cu(II) was ManN >> GalN > GlcN. The DNA damage was inhibited by catalase and bathocuproine, suggesting that H2O2 reacts with Cu(I) to form the metal-peroxide complex capable of causing DNA damage. Two mechanisms of H2O2 generation from Aminosugars were proposed: one is the major pathway to form a dioxo compound and NH4+; the other is the minor pathway to form a pyrazine derivative through the condensation of two molecules of an aminosugar. The order of reactivity to generate these products was ManN >> GalN > GlcN. On the basis of these results, it is concluded that Aminosugars, especially ManN, produce H2O2 to cause DNA damage, which mediates apoptosis resulting in tumor growth inhibition.

Eur J Pharmacol. 1998 Apr 24; 347(2-3): 311-7
Segal JA, Skolnick P

Recent pharmacological studies indicate that aminoglycoside-induced hearing loss may be an excitotoxic process modulated by a polyamine-like activation of cochlear NMDA receptors. Aminoglycoside antibiotics are constituted by a series of glycosidically linked aminocyclitols and Aminosugars. We report here on the actions of these individual aminocyclitols and Aminosugars on wild type NMDA receptors from rat brain. Compared to the parent molecules, neither aminocyclitols (e.g., 2-deoxystreptamine, streptamine, and streptidine) nor Aminosugars (e.g., D-glucosamine and kanosamine) were effective at enhancing [3H]dizocilpine ([3H]MK-801) binding or inhibiting [3H]ifenprodil at NMDA receptors. Moreover, the appropriate combinations of Aminosugars and aminocyclitols did not reconstitute the activity of the parent aminoglycoside at NMDA receptors. These data indicate that the polyamine-like actions of aminoglycosides are attributable to the conformation of the parent molecule rather than a particular amine containing constituent. Thus, it may be possible to synthesize or isolate aminoglycoside antibiotics devoid of ototoxicity.