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At least 613 records · Page 34Linked to original sources
PubMed1991

Preparation of glycyrrhetic acid glycosides having various beta(1----2)-linked disaccharides and their cytoprotective effects on carbon tetrachloride-induced hepatic injury.

Glycyrrhetic acid glycosides (1-7) having beta(1----2)-linked disaccharides such as 2-O-beta-D-glucopyranosyl-beta-D-galactopyranose, 2-O-beta-D-galactopyranosyl-beta-D-galactopyranose, 2-O-beta-D-glucuronopyranosyl-beta-D-galactopyranose, 2-O-beta-D-glucopyranosyl-beta-D-glucuronopyranose, 2-O-beta-D-galactopyranosyl-beta-D-glucuronopyranose, 2-O-beta-D-galactopyranosyl-beta-D-glucopyranose, 2-O-beta-D-glucuronopyranosyl-beta-D-glucopyranose, respectively, were synthesized by stepwise construction; from glycyrrhetic acid monoglycosides to the diglycosides. The cytoprotective activities of the glycosides 1-7 and 2-O-(beta-D-glucopyranosyl)-beta-D-glucopyranosyl-11-oxoolean-12-e n-30-oate (8) were compared with natural occurring glycyrrhizin (9). Among these glycosides 1-8, glycosides 3 and 7 having beta-D-glucuronopyranose (glcUA) as the only terminal sugar component were more effective materials against hepatic injury than glycyrrhizin 9.

Animals↗
PubMed1996

Compositional analysis of hyaluronan, chondroitin sulfate and dermatan sulfate: HPLC of disaccharides produced from the glycosaminoglycans by solvolysis.

An ion-exchange high-performance liquid chromatography procedure was developed for analysis of mixtures of N-acetyldermosine, N-acetylchondrosine and N-acetylhyalobiuronic acid produced quantitatively by heating dermatan sulfate, chondroitin sulfate and hyaluronan in dimethyl sulfoxide (DMSO) containing 0.1% (v/v) H20 at 80 degrees C for 48 h. These disaccharides were eluted from a TSK gel SAX column using 0.1 M acetic acid containing KCl, and detected fluorometrically by post column derivatization. The eluate was mixed with 2-cyanoacetamide solution and alkaline solution, and heated at 110 degrees C for 4 min. The resultant compounds were detected fluorometrically (Ex. 335 nm and Em. 390 nm). The usefulness and practicality of the present method were verified by applications to the determination of glycosaminoglycans in tissues.

Animals↗
PubMed1993

Synthesis of alpha-L-mannopyranosyl-containing disaccharides and phenols as substrates for the alpha-L-mannosidase activity of commercial naringinase.

In order to clarify the substrate specificity of the alpha-L-mannosidase activity of naringinase (Sigma), the following disaccharides and phenol glycosides were freshly prepared: methyl 2-O-(alpha-L-mannopyranosyl)-beta-D-glucoside (1), methyl 3-O-(alpha-L-mannopyranosyl)-alpha-D-glucoside (2), methyl 4-O-(alpha-L-mannopyranosyl)-alpha-D-glucoside (3), methyl 5-O-(alpha-L-mannopyranosyl)-beta-D-glucoside (4), methyl 6-O-(alpha-L-mannopyranosyl)-alpha-D-glucoside (5), 6-O-(alpha-L-mannopyranosyl)-D-galactose (6), p-nitrophenyl alpha-L-mannoside (7), and 4-methyl umbelliferone alpha-L-mannoside (8). These compounds, except for 3 and 5 were hydrolyzed with naringinase.

Carbohydrate Sequence↗
PubMed1997

Enzymatic synthesis of oligosaccharides containing Gal beta-->4Gal disaccharide at the non-reducing end using beta-galactanase from Penicillium citrinum.

The transglycosylation reaction was done with a beta-galactanase from Penicillium citrinum. The regioselectivity in the transglycosylation reaction was studied using soy bean arabinogalactan as a donor and mono- or disaccharide derivatives containing beta-galactosyl residue as acceptors. We also synthesized oligosaccharides containing Gal beta 1-->4Gal sequence such as Gal beta 1-->4Gal beta1-->4Glc, Gal beta 1-->4Gal beta 1-->3GlcNac, Gal beta 1-->4Gal beta 1-->4GlcNAc, Gal beta 1-->4Gal beta 1-->6GlcNAc, and Gal beta 1-->4Gal beta 1-->3GalNAc for use in the total synthesis of complex sugar chains.

Carbohydrate Sequence↗
PubMed2000

Practical synthesis of the disaccharide epitope, D-galactopyranosyl-alpha-1,3-D-galactopyranose, by using 1,2;5,6-di-O-cyclohexylidene-alpha-D-galactofuranose as the glycosyl acceptor.

D-Galactosyl-alpha-1,3-D-galactopyranose (1) was chemically prepared in a good yield by coupling phenyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-galactopyranoside (5) or 2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl bromide (8) with 1,2:5,6-di-O-cyclohexylidene-alpha-D-galactofuranose (3) with subsequent de-O-benzylation and de-O-cyclohexylidenation of the resulting protected alpha1,3-disaccharide.

Carbohydrate Conformation↗
PubMed2001

Effects of alpha-D-glucosylglycerol on the in vitro digestion of disaccharides by rat intestinal enzymes.

Alpha-D-glucosylglycerol (GG) is a mixture of 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG has been found to be slightly hydrolyzed in vitro only by rat intestinal enzymes, but hardly at all by other digestive juices. GG suppressed the hydrolysis of maltose, sucrose and isomaltose by rat intestinal enzymes because the amount of glucose in the digestion of a mixture of GG and disaccharide was less than the sum of that in each individual digestion. The consumption of GG was suppressed by isomaltose, but promoted by maltose, with the hydrolysis of GG being suppressed. Sucrose appeared to suppress only the consumption of S-GG-I, suggesting that S-GG-I was hydrolyzed by the active site of sucrase in a sucrase-isomaltase complex. Transglucosylation seems to have occurred more frequently in the individual digestion of maltose and isomaltose than in that of GG and sucrose. GG seemed to promote transglucosylation in the presence of maltose, to suppress it with sucrose, and to delay it with isomaltose.

Animals↗
PubMed2001

On the interaction of the vanadyl(IV) cation with lactose: inhibition effects of vanadyl(IV)/monosaccharide and disaccharide complexes upon alkaline phosphatase activity.

A new vanadyl(IV) complex of the disaccharide lactose was obtained in aqueous solution at pH = 13. The sodium salt of the complex, of composition Na4[VO(lactose)2].3H2O, has been characterized by elemental analysis and by ultraviolet-visible, diffuse reflectance, and infrared spectroscopies. Its magnetic susceptibility and thermal behavior were also investigated. The inhibitory effect on alkaline phosphatase activity was tested for this compound as well as for the vanadyl(IV) complexes with maltose, sucrose, glucose, fructose, and galactose. For comparative purposes, the free ligands and the vanadyl(IV) cation were also studied. The free sugars and the sucrose/VO complex exhibited the lowest inhibitory effect. Lactose-VO, maltose-VO, and the free VO2+ cation showed an intermediate inhibition potential, whereas the monosaccharide/VO complexes appeared as the most potent inhibitory agents.

Alkaline Phosphatase↗
PubMed1983

A reliable and quick radial thin layer chromatographic method for the diagnosis of mono- and disaccharide disorders.

The authors propose a radial thin layer chromatographic method for the separation of mono- and disaccharides, which shows better resolution, and is more sensitive (0.25 microgram for glucose) and less time-consuming (20 min) than the linear technique. Moreover, the procedures used for the detection of sugars and their dansyl-derivatives (staining with naphthoresorcinol and fluorescence of the dansyl-hydrazones) make the identification more specific and reliable. This simple method is quite suitable for the analysis of biological samples (urine, faeces) and the diagnosis of metabolic disorders in children.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1997

Lactulose, disaccharides and colonic flora. Clinical consequences.

Lactulose is one of the most frequently utilised agents in the treatment of constipation and hepatic encephalopathy because of its efficacy and good safety profile. The key to understanding the possible modes of action by which lactulose achieves its therapeutic effects in these disorders lies in certain pharmacological phenomena: (a) lactulose is a synthetic disaccharide that does not occur naturally; (b) there is no disaccharidase on the microvillus membrane of enterocytes in the human small intestine that hydrolyses lactulose; and (c) lactulose is not absorbed from the small intestine. Thus, the primary site of action is the colon in which lactulose is readily fermented by the colonic bacterial flora with the production of short-chain fatty acids and various gases. The purpose of this review is to focus on some pertinent basic aspects of the clinical pharmacology of lactulose and to discuss the possible mechanisms by which lactulose benefits patients with constipation and hepatic encephalopathy.

Animals↗
PubMed1992

Use of oral tolerance tests to investigate disaccharide digestion in neonatal foals.

Oral tolerance tests were performed on 13 neonatal foals to determine their ability to digest disaccharides on d 1, 3 and 5 postpartum. Foals were assigned randomly to treatments consisting of 20% (wt/vol) solutions of either maltose, lactose, or sucrose, dosed at 1 g/kg of BW, or glucose, dosed at .5 g/kg of BW. After a 2-h fast, an initial blood sample was collected via jugular catheter. Foals were administered the appropriate solution orally, and blood was collected every 15 min for 1 h and then every 30 min for 3 h. Plasma glucose increased after dosing with lactose or glucose but not with sucrose. Plasma glucose concentrations increased slightly on d 3 and 5 in foals dosed with maltose. These findings suggest that although lactose is well digested by neonatal foals, maltose is digested only slightly, and sucrose is not digested by d 5. Results of this experiment indicate that maltose and sucrose would not be suitable for inclusion in artificial diets for foals less than 1 wk old. Oral tolerance tests could be useful for determining the ability of premature or sick foals with lactose intolerance to digest alternate carbohydrate sources.

Animal Feed↗
PubMed1987

Synthetic antigens as immunogens: Part I. The combining site specificities of antibodies formed in rabbits to synthetic disaccharide alpha-L-Fuc-(1----3)-D-Gal.

Antibody to chemically synthesized Fuc alpha 1----3 Gal-1----OC6H4N = N bovine serum albumin was developed. Specificity analysis using related synthetic saccharides was performed. The antisera were shown to be specific for both sugars in the disaccharide, to the 1----3 positional linkage and to the alpha anomeric configuration. Immunohistochemical staining was performed on benign disease and adenocarcinoma tissue of the colon. 5/8 of the benign colon polyp tissue and 4/6 of the colonic adenocarcinoma tissue showed strong granular cytoplasmic staining of the epithelia cells lining the ducts. None of the six normal colon tissues tested showed any reactivity. Immunohistochemical staining was also performed on tissue from benign disease and from carcinoma of the mammary gland. 2/5 of the tissue from benign disease of the breast and 3/6 of the tissue from breast carcinoma showed strong granular cytoplasmic staining of the ductal epithelial cells.

Adenocarcinoma↗
PubMed1989

Solution conformation of the disaccharide of avermectin B1a examined by NMR spectroscopy and nuclear Overhauser enhancement restrained hard-sphere exo-anomeric effect calculation.

The solution conformation of the disaccharide of avermectin B1a was examined by combining NMR data with theoretical conformational energy calculations. Carbon and proton resonances were assigned unambiguously using high-field, high-resolution 2D NMR correlation spectroscopy. 3JHH coupling constants were determined at 600 MHz. The minimum-energy conformation was attained through an extended hard-sphere exo-anomeric effect (HSEA) approach. The HSEA conformation was refined by considering the experimental nuclear Overhauser enhancement contacts. The resulting three-dimensional structure was confirmed by comparing its glycosidic dihedral angles to those calculated from experimental 3JCOCH coupling constants. Differences has been found in the glycosidic dihedral angles between the solution conformation and the X-ray structure.

Anthelmintics↗
PubMed2000

[Synthesis of disaccharide Neu5Gcalpha(2-6)GalNAcalpha as a spacer glycoside].

The first synthesis of the Neu5Gc analogue of SiaTn disaccharide, which can be detected in breast tumors by immunochemical methods, is reported. The regioselective sialylation of (3-trifluoroacetamidopropyl)-2-azido-2-deoxy-alpha-D-galactopyranoside with peracetate of the methyl ester of N-acetoxyacetylneuraminic acid beta-ethylthioglycoside in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid (or its trimethylsilyl ester) resulted in the derivatives of alpha- and beta-sialyl(2-->6)galactosaminide in 39 and 32% yields, respectively. The catalytic hydrogenolysis of the azido group and subsquent N- and O-acetylation of the alpha-anomer gave the trifluoroacetamidopropyl glycoside peracetate. Removal of the protective groups led to glycoside Neu5Gc alpha(2-->6)GalNAc alpha-O(CH2)3NH2. Using the Neu5Gc derivative with acetoxyacetyl groups at positions O9 and O4 as a donor increases the alpha-selectivity of sialylation to afford the alpha- and beta-anomers in 69 and 8% yields, respectively.

Biomarkers, Tumor↗
PubMed1976

Augmentation of ethanol absorption by mono- and disaccharides.

Assessment of the influence of nutritional substrates on the disposition of ingested ethanol from the blood requires, first, an understanding of the influence that these may exert upon ethanol absorption from the gastrointestinal tract. In this report, the effects of various carbohydrates on the intestinal absorption of ethanol were studied. When carbohydrates (50 mM) were perfused simultaneously with ethanol (50 mM) in vivo in the rat small bowel, ethanol absorption increased up to 34% (P less than 0.005) above controls receiving ethanol alone. Of the monosaccharides, fructose, 3-O-methylglucose, glucose, or galactose added to an ethanol perfusate, only glucose or galactose increased ethanol absorption over control animals receiving ethanol alone. Of the disaccharides tested, sucrose and maltose, but not lactose, enhanced ethanol absorption. Addition of varying concentrations of maltose to an ethanol perfusate augmented ethanol absorption in a direct proportion to the quantity of glucose absorbed, rather than to the quantity of maltose hydrolyzed. Augmentation of ethanol absorption by carbohydrates appears to be dependent upon sugar-active transport. Ethanol, dissolved in intraluminal water, may cross the mucosa in water absorbed during sugar-active transport. This quantity of ethanol is absorbed in addition to that which normally crosses the mucosa by diffusion down its concentration gradient.

Animals↗
PubMed1990

Immunologic and toxicologic study of disaccharide tripeptide glycerol dipalmitoyl: a new lipophilic immunomodulator.

A new lipophilic immunomodulator, disaccharide tripeptide glycerol dipalmitoyl (DTP-GDP), has been synthesized and evaluated for its immunologic activity and toxicology. DTP-GDP alone or in liposomes is more effective as an adjuvant and in activating macrophages compared with muramyldipeptide (MDP). Preclinical studies demonstrate no evidence of toxicity, including vasculitis. DTP-GDP in liposomes has shown antitumor activity in phase I clinical trials.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Quantitation of IgM antibodies to the M. leprae synthetic disaccharide can predict early bacterial multiplication in leprosy.

Quantitative enzyme-linked immunosorbent assays detecting IgM to the soluble Mycobacterium leprae crude sonicate (CD75) and the synthetic disaccharide antigen coupled to bovine serum albumin (ND-BSA) were assessed for their ability to determine early infection in families/household contacts of leprosy patients and employees of a leprosy center working in close contact with leprosy patients. Although IgM to both antigens (CD75 and ND-BSA) correlated with the bacterial index (BI) assessed histologically on skin-biopsy samples, the level of IgM antibodies to ND-BSA was a much more sensitive indicator of low bacterial loads. A 4.4-fold difference in antibody levels was observed between the mean group levels of endemic controls (N = 116) and tuberculoid leprosy patients with a BI of 0 (N = 88), increasing to sevenfold in tuberculoid leprosy patients with a BI of 1 (N = 20). Using a statistical cut off with endemic controls (mean + 2 S.D.), household/family contacts showed 30% seropositivity (N = 180) as compared to staff contacts who showed 17% seropositivity (N = 55). Percent seropositivity in family contacts was not related to the type of leprosy of the index case (lepromatous vs. tuberculoid) or the duration of treatment of the index case. Age of the individual in the family contact group had a significant influence on seropositivity. These results support the hypothesis that, in this community, factors other than the viable bacterial load of the index case, such as genetic susceptibility, may be influencing the high rate of seropositivity in family contacts. IgM ND-BSA antibodies seem to provide a good indicator of low antigenic loads and could prove to be useful in detecting subclinical infection before the onset of disease. Follow-up studies of these seropositive individuals are in progress to understand the relationship between seropositivity and the progress of clinical disease.

Antibodies, Bacterial↗