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PubMed1987

High-performance liquid chromatographic analysis of galactosamine, glucosamine, glucosaminitol, and galactosaminitol.

Both N-acetylgalactosamine and N-acetylglucosamine covalently link oligosaccharides to peptide in glycoproteins. In order to identify the N-acetylhexosamine involved in this linkage, the corresponding hexosaminitol generated by alkaline borohydride treatment must be determined. An HPLC method modified from the Waters PICO-TAG amino acid analysis procedure is described. Phenylisothiocarbamyl derivatives of galactosamine, glucosamine, glucosaminitol, galactosaminitol, and the internal standard, p-aminophenyl-beta-D-galactoside, are eluted from the Waters PICO-TAG column at 3.9, 4.3, 6.9, 8.1, and 10.1 min, respectively. The standard curves for the hexosamines and hexosaminitols are linear between 1 and 75 nmol. In addition to p-aminophenyl-beta-D-galactoside, several synthetic hexosamines and hexosaminitols can be employed as internal standard. These include 3-allosamine, 3-glucosamine, allosamine, 3-allosaminitol, mannosaminitol, and allosaminitol, which are eluted at 3.1, 3.4, 4.8, 6.4, 7.4, and 7.8 min, respectively. The analysis time is 15 min but can be shortened to 10 min if only hexosamines are to be analyzed and either 3-glucosamine or 3-allosamine is used as the internal standard. This rapid method is superior to previous methods for the analysis of hexosamines in glycoconjugates and hexosaminitols generated from glycoconjugates following alkaline borohydride treatment.

Chromatography, High Pressure Liquid↗

PubMed1989

Production of [3H]hexosamine-labeled proteoglycans by cultures of normal and diabetic skin fibroblasts: dilution of exogenous [3H]glucosamine by endogenous hexosamine from glucose and other sources.

Human skin fibroblast monolayer cultures from two normal men, three Type I diabetic men, and one Type I diabetic woman were incubated with [3H]glucosamine and [35S]-sulfate for varying periods of time. Incorporation of 3H into macromolecules appearing in the medium was linear after approximately 45 min, and incorporation of 35S was linear after approximately 30 min. The amounts of 35S-proteoglycan formed by each of the cultures during 5-h incubations were compared and were found to be fairly similar for the six lines, varying from 0.08 to 0.14 nmol sulfate/microgram DNA. Isolated 3H,35S-glycosaminoglycans were then treated with chondroitin ABC lyase to characterize the location and degree of sulfation. Results indicated a considerable variation in completeness of chondroitin/dermatan sulfation and in proportions of 6-sulfation to 4-sulfation among the various lines. However these variations did not seem to be related to whether the cells were from normals or diabetics. 3H,35S-Labeled disaccharides were isolated and ratios of 3H to 35S determined in order to calculate the [3H]glucosamine dilution by endogenous glucosamine derived from glucose or other sources during the period of incubation. Dilutions varied widely from 160- to 635-fold among the different cell lines, but the variations did not seem to be related to whether the cells were from normals or diabetics.

Adult↗

PubMed1982

Transport of glucosamine (aldohexoses) by preimplantation mouse blastocysts.

A carrier-mediated system for uptake of glucosamine (and other aldohexoses) was identified in preimplantation mouse blastocysts. With early and late blastocysts, the values for Km (525 +/- 82 and 651 +/- 137 microM, respectively) and V (0.29 +/- 0.02 and 0.29 +/- 0.04 pmol/h per ng protein, respectively) for glucosamine are statistically indistinguishable. The same carrier system, therefore, is operative at the two developmental stages. Glucosamine uptake was temperature sensitive and inhibited by structural analogues and phloretin.

Animals↗

PubMed1983

Autoradiographic localizations of [35S]-sulfate and [3H]-glucosamine in the hamster ciliary epithelium.

The localization of [35S]-sulfate and [3H]-glucosamine in the hamster non-pigmented ciliary epithelium was studied by light and electron microscopic autoradiography. The radioactivity was concentrated in the Golgi complex of the non-pigmented ciliary epithelium 10 mins after injections of [35S]-sulfate or [3H]-glucosamine. Silver grains of both isotopes covered the cytoplasm 60 mins after the administration and were then associated with the basal infoldings. Radioactivity of [3H]-glucosamine was observed in the basal lamina of the non-pigmented ciliary epithelium and the ciliary zonule; however, the localization of [35S]-sulfate in the basal lamina and the ciliary zonule was not demonstrated. These data lend support to the idea that the non-pigmented ciliary epithelium may synthesize glycosaminoglycans (GAG) and secrete non-sulfated glycosaminoglycans into the posterior chamber.

Animals↗

PubMed1985

The influence of prostaglandin E2 and oxytocin on the incorporation of [3H]proline and [3H]glucosamine in the human amnion.

Fetal membranes were obtained in connection with 1st-trimester abortion and vaginal delivery or elective caesarean section at term. Pieces of the isolated amnion membrane were incubated in vitro with [3H]proline or [3H]glucosamine in the presence of prostaglandin (PG) E2 or oxytocin. PGE2 reduced the labelling with [3H]proline in the 1st trimester and in membranes obtained at vaginal delivery, whereas an increase of incorporation was observed before start of labour. Oxytocin reduced [3H]proline labelling at any stage. In membranes from vaginally delivered women both oxytocin and PGE2 stimulated the incorporation of [3H]glucosamine, whereas oxytocin diminished radiolabelling in the other experimental groups. Regarding the radiolabelling with [3H]proline and [3H]glucosamine as reflecting the de novo formation of collagen and proteoglycans, respectively, it is suggested that both PGE2 and oxytocin, by their influence on connective tissue metabolism, may regulate the tensile properties of the fetal membranes.

5,8,11,14-Eicosatetraynoic Acid↗

PubMed1985

1-Deoxy-glucosamine initiates, then effectively suppresses feeding in the rat.

The deoxy analogues of D-glucose, 1-deoxy-D-glucosamine and D-glucosamine, are biochemically and structurally similar to 1-deoxy-D-glucose, so their direct effects on food intake were studied. Both 12 and 24 mumol 1-deoxy-glucosamine potently decreased feeding and body weight after an initial transient elicitation of food intake. The suppression included decreased meal size and prolonged postprandial intermeal interval which persisted for at least 3 days after injection. Ambulatory activity was unaffected. The initial elicitation of feeding was not accompanied by drinking episodes, and subsequent drinking suppression was persisted. These findings, plus other biochemical evidence, suggest that inversion with an amino group or removal of a hydroxyl group from C-2 and/or C-1 may affect feeding.

Animals↗

PubMed1977

Biosynthesis of N-methyl-L-glucosamine from D-glucose by Streptomyces griseus.

Biosynthesis of N-methyl-L-glucosamine moiety of streptomycin from D-glucose by Streptomyces griseus was studied. A mixture of D-[1-(14) C] glucose and D-[6(-3)H]glucose was given to the culture of S. griseus. The 3H/14C ratio found in N-methyl-L-glucosamine further supports a mechanism that the conversion of D-glucose to L-hexose is carried out without scission of carbon skeleton. When D-[1-14C]glucose and D-[3-3H]glucose were used, the fall of 3H/14C ratio in N-metyl-L-glucosamine showed that the hydrogen atom at C-3 plays a rôle in such a transformation.

Glucosamine↗

PubMed1981

Incorporation of [3H]glucosamine into glycosaminoglycans in different cell culture conditions by rabbit aortic smooth muscle cells.

This study sought to elucidate the optimal cell culture conditions for studies concerned with the incorporation of [3H]glucosamine into glycosaminoglycans by rabbit aortic smooth muscle cells. The incorporation of radioactivity into extracellular sulphated glycosaminoglycans was linear for at least 72 h and that into pericellular sulphated glycosaminoglycans for up to 24 h. The incorporation of radiolabel into hyaluronic acid was linear only up to 12 h. In the exponential growth phase the incorporation of [3H]glucosamine into sulphated glycosaminoglycans and hyaluronic acid proved to be less marked than in the stationary growth phase, but the highest values were nevertheless obtained immediately after trypsinisation. When studied in the stationary growth phase, cell density and incorporation of [3H]glucosamine were positively correlated in the case of hyaluronic acid, but in the case of sulphated glycosaminoglycans there was a negative correlation. The serum concentration of the incubation medium and the incorporation of radioactivity into hyaluronic acid were positively related. With sulphated glycosaminoglycans this was the case only after a 7-day preincubation in the different serum concentrations. When incorporation was studied without preincubation, the incorporation of radioactivity into sulphated glycosaminoglycans proved to be negatively associated with the serum concentration of the medium. The environmental pH of the cells was associated with the incorporation of radioactivity into hyaluronic acid and sulphated glycosaminoglycans in that between pH values 6.8 and 7.9 the incorporation of radioactivity increased when the pH of the medium was raised.

Animals↗

PubMed1987

Regional differences in protein and glycoprotein synthesis and their processing in the mouse brain as revealed by the incorporation of [3H]proline, N-6-[3H]acetyl-D-glucosamine and [3H]fucose.

The incorporation rate of [3H]fucose, N-6-[3H]acetyl-D-glucosamine and [3H]proline has been compared in five regions of the mouse brain on postnatal day 6. The olfactory bulbs and the cerebellum showed a prevalence of incorporation of [3H]fucose over other brain regions. Less expressed, but still well evident regional differences were observed in [3H]proline incorporation while the incorporation of N-6-[3H]acetyl-D-glucosamine was almost equal in all brain regions. The regional differences were also apparent after considering an actual pool of free isotopes in the individual regions. Gel electrophoresis of [3H]fucose-labelled membrane fraction showed that the higher incorporation of [3H]fucose in the olfactory bulbs is partly due to higher synthesis of low molecular weight glycoproteins, especially in the molecular range of 30,000. The data showed that the protein synthesis and fucosylation, and/or a fast transport of the corresponding molecules, varies more within the brain than the incorporation of N-6-[3H]acetyl-D-glucosamine and possibly also than the "core" part of glycan molecule synthesis.

Acetylglucosamine↗

PubMed1991

Incorporation of D-[3H]-glucosamine and L-[3H]-fucose into the developing rat cochlea.

The uptake of two tritiated carbohydrates, D-[3H]-glucosamine and L-[3H]-fucose, to the developing rat cochlea was examined using light and electron microscopic radioautography. Both carbohydrates, administered to in vitro developing rat cochleas, shared a similar ultrastructural labeling pattern on the microvilli and apical cell region and on the tectorial membrane (TM) fibrils. On embryonic day 18, the radiolabeling appeared on the apical surface of the undifferentiated epithelium that will develop into both spiral limbus and Kölliker's organ (KO), while on postnatal day (PD) 1, it was only located on the apical surface of the KO. When D-[3H]-glucosamine was administered in vivo to newborn rats, the radiolabeling was observed in the TM covering the KO at PD 3. Lastly, D-[3H]-glucosamine administered in vivo to PD 7 rats, appeared at PD 9 in the TM region lying just above the organ of Corti. The present findings support the previously suggested leading role of the spiral limbus and KO in the secretion of the TM during cochlear development. The secretion of carbohydrates, and probably of other matrix components, starts on the spiral limbus and KO region and progressively extends to the organ of Corti.

Animals↗

PubMed2005

Determination of glucosamine in impure chitin samples by high-performance liquid chromatography.

A simple, rapid, selective, and specific high-performance liquid chromatography (HPLC) method was developed to quantitate glucosamine, and its application for estimating purity of chitin was investigated. The chromatographic separation was achieved using a reversed-phase C8 column, pre-column derivatization with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) and ultraviolet detection (lambda=254 nm). The mobile phase consisted of CH3CN and H2O. The optimum conditions of acid hydrolysis of chitin (concentration of HCl, temperature, and heating time) was obtained by performing the orthogonal array design (OAD) procedure and the released glucosamine was determined by the above HPLC method. The accuracy of the method was checked by the standard addition technique. The method was found to be specific with good linearity, accuracy, precision, and well suited for quantitation of glucosamine and determination of the purity of chitin in biological materials and food products.

Alcohols↗

PubMed2005

Mosquito glucosamine-6-phosphate N-acetyltransferase: cDNA, gene structure and enzyme kinetics.

Mosquito midgut epithelial cells secrete digestive enzymes as well as components of the peritrophic matrix in response to blood-feeding. The peritrophic matrix is composed of proteins, glycoproteins and chitin fibrils in a proteoglycan matrix and may function to protect the midgut epithelium from mechanical damage and insult from pathogens and toxins. Chitin biosynthesis takes place via the hexosamine pathway converting fructose-6-phosphate to UDP-N-acetylglucosamine, which is then polymerized to chitin by chitin synthase. Glucosamine-6-phosphate N-acetyltransferase (GNA) is one of the hexosamine pathway enzymes and catalyzes the transfer of the acetyl group from acetyl-CoA to the primary amine of glucosamine-6-phosphate. We cloned and sequenced the GNA cDNA, gene (AeGna) and its putative promoter regions from Aedes aegypti. AeGna consists of five exons and four introns and lacks a TATA box near the transcription start site. The AeGna cDNA is 1.3 kb in length and the predicted protein is approximately 23.6 kDa. The amino acid sequence of AeGna has high homology to its orthologues. AeGna mRNA is constitutively expressed in all developmental stages and blood-feeding causes no obvious effect on levels of AeGna transcript in the midgut. The Km value of recombinant GNA for glucosamine-6-phosphate was 330 microM and the Km for acetyl-CoA was 500 microM.

Acetyltransferases↗

PubMed2004

Comparative evaluation of cytotoxicity of a glucosamine-TBA conjugate and a chitosan-TBA conjugate.

D-glucosamine and chitosan were modified by the immobilization of thiol groups utilizing 2-iminothiolane. The toxicity profile of the resulting D-glucosamine-TBA (4-thiobutylamidine) conjugate, of chitosan-TBA conjugate and of the corresponding unmodified controls was evaluated in vitro. On the one hand, the cell membrane damaging effect of 0.025% solutions of the test compounds was investigated via red blood cell lysis test. On the other hand, the cytotoxity of 0.025, 0.25 and 0.5% solutions of the test compounds was evaluated on L-929 mouse fibroblast cells utilizing two different bioassays: the MTT assay (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide), which assess the mitochondrial metabolic activity of the cells, and the BrdU-based enzyme-linked immunosorbent assay, which measures the incorporation in the DNA of 5-bromo-2'-deoxyuridine and consequently the cell proliferation. Results of the red blood cell lysis test showed that both thiolated compounds displayed a lower membrane damaging effect causing a significantly lower haemoglobine release than the unmodified compounds. Data obtained by the MTT assay and the BrdU assay revealed a concentration dependent relative cytotoxicity for all tested compounds. The covalent linkage of the TBA-substructure to D-glucosamine did not cause a significant increase in cytotoxicity, whereas at higher concentrations a slightly enhanced cytotoxic effect was caused by the derivatisation of chitosan. In conclusion, the -TBA derivatives show a comparable toxicity profile to the corresponding unmodified compounds, which should not compromise their future use as save pharmaceutical excipients.

Animals↗

PubMed2004

Oral glucosamine and the management of feline idiopathic cystitis.

Oral glucosamine was compared to a placebo for the management of cats with feline idiopathic cystitis (FIC) in a randomised, double-blinded, placebo-controlled, study. Forty cats with a history of recurrent cystitis due to FIC were divided into two groups and treated daily per os with either 125 mg N-acetyl glucosamine or a placebo for six months. Owners graded their cats' clinical signs at the beginning and end of the study, and kept daily diaries documenting signs of cystitis using visual analogue scales. Further episodes of cystitis were seen in 26 (65%) of the cats during the study. Affected cats experienced a mean of five recurrences (range 1-19) with each recurrence lasting a mean of four days (range 1-64 days). There were no significant differences between the two groups when considering the owners assessments of the mean health score (P>0.5), the average monthly clinical score (P=0.22) or the average number of days with clinical signs (P=0.28). Two cats suffered from such severe recurrent urethral obstruction that they were euthanased; they were both in the placebo group. Compared to the start of the study the majority of cats in both groups improved significantly (P<0.001) (mean health score of each group at the start was 0.5+/-SD 0.5, compared to glucosamine 4.4+/-0.7 and placebo 3.9+/-1.6 at the end). This is believed to have occurred because the owners of 36 of the 40 cats (90%) started feeding more canned cat food. The urine specific gravity at the start of the trial was significantly higher (mean 1.050+/-SD 1.007) than when reassessed one month later (1.036+/-1.010, P<0.01).

Administration, Oral↗

PubMed2005

Glucosamine decreases expression of anabolic and catabolic genes in human osteoarthritic cartilage explants.

OBJECTIVE: To investigate the effect of glucosamine (GlcN) in a human osteoarthritic explant model on expression of genes involved in anabolic and catabolic activities of chondrocytes. METHODS: Human osteoarthritic explants, obtained during knee arthroplasty surgery, were pre-cultured (3 days) and treated with glucosamine-hydrochloride (GlcN-HCl) or glucosamine-3-sulphate (GlcN-S) at 0.5mM and 5mM (4 days). RNA was isolated from the explants and real time RT-PCR was performed. Additionally, total matrix metalloproteinase (MMP) activity was measured in culture medium. RESULTS: Addition of 5mM GlcN led to significant down-regulation of aggrecan (2.65-7.73-fold) and collagen type II (7.75-22.17-fold) gene expression, indicating inhibited anabolic activity. Considering catabolic activities, 5mM GlcN significantly down-regulated aggrecanase-1 and MMP3 and 5mM GlcN-S additionally down-regulated aggrecanase-2 and tissue inhibitor of MMP gene expression significantly. Gene expression was not significantly altered by 0.5mM GlcN. Total MMP activity in culture medium was only significantly reduced after addition of 5mM GlcN-HCl. CONCLUSION: The effects of GlcN on gene expression in a human osteoarthritic explant model suggest that enzymatic breakdown of the extra-cellular matrix might be reduced by the addition of 5mM GlcN. Additionally, restoration of already damaged cartilage is not to be expected, because gene expression of anabolic genes is also down-regulated. We suggest that chondroprotective properties of GlcN in vivo may be based on inhibiting further degradation due to catabolic activities, rather than on the ability to rebuild cartilage.

Aged↗

PubMed2004

A stability-indicating HPLC method for the determination of glucosamine in pharmaceutical formulations.

A stability-indicating high performance liquid chromatographic (HPLC) method was developed for the assay of glucosamine in bulk forms and solid dosage formulations. The HPLC separation was achieved on a Phenomenex Luna amino column (150 mm x 4.6 mm, i.d., 5 microm particle size) using a mobile phase of acetonitrile-phosphate buffer (75:25, v/v, pH 7.50) at a flow rate of 1.5 ml min(-1) and UV detection at 195 nm. The method was validated for specificity, linearity, solution stability, accuracy, precision, limit of detection, and limit of quantitation. The detector response for glucosamine hydrochloride was linear over the selected concentration range from 1.88 to 5.62 mg ml(-1) with a correlation coefficient 0.9998. The accuracy was between 98.9 and 100.5%. The precision (R.S.D.) amongst six sample preparations was 1.1%. The limit of detection and the limit of quantitation are 0.037 and 0.149 mg ml(-1), respectively. The sample and standard solutions were stable for 1 week. The method was successfully used for analysis of active-excipient compatibility samples used for development of a solid dosage formulation in our laboratory and subsequent stability studies. The method was also used for the analysis of glucosamine in several commercially available solid dosage forms.

Chemistry, Pharmaceutical↗

PubMed2005

Mannosamine can replace glucosamine in glycosylphosphatidylinositols of Plasmodium falciparum in vitro.

Mannosamine (2-deoxy-2-amino-D-mannose) is unable to block GPI biosynthesis in Plasmodium falciparum: neither parasite development nor GPI biosynthesis were blocked by mannosamine treatment in P. falciparum cultures. Further, it was shown by metabolic labeling with [3H]mannosamine and subsequent monosaccharide analysis by high pH anion exchange chromatography that mannosamine is converted at a high rate into glucosamine. Both mannosamine and glucosamine are incorporated into P. falciparum glycolipids, but the characterization of mannosamine-labeled glycolipids synthesized in vivo proved difficult. Therefore, a cell-free system was developed to investigate the incorporation of [3H]mannosamine into glycolipids in P. falciparum. It was observed that mannosamine is incorporated in vitro into P. falciparum glycolipids, which possess a phosphate group. Chemical (nitrous acid deamination, mild acid hydrolysis and alkaline hydrolysis) and enzymatic (PI-PLC) treatments of [3H]mannosamine-labeled glycolipids synthesized in vitro showed the presence of GPIs. Further analyses by Bio-Gel P4 size-exclusion chromatography and HPAEC demonstrated the presence of a mannosamine-containing GPI-like structures, where mannosamine is incorporated instead of glucosamine, i.e. Man3-ManN-PI. This utilization of mannosamine is novel and not been described for any other cellular or parasitic system.

Animals↗

PubMed1976

An assay for total hexosamine and a differential assay for glucosamine and galactosamine.

Two new procedures are presented for quantitative determination of glucosamine and galactosamine. One, which is proposed for total hexosamine, yields chromogens of equal intensity with equal concentration of glucosamine and galactosamine. There is addition of the correspondent chromogens when they are present in mixtures. The procedure is presented as a manual as well as an automated assay. The other procedure is a differential assay which allows the detection of galactosamine without interference by glucosamine. By the two procedures, the hexosamines present in acid mucopolysaccharides and/or glycoproteins can be determined.

Acetylgalactosamine↗