Search results for "Nose"

N-Glycosylamines of 4,6-O-ethylidene-alpha-D-glucopyranose: synthesis, characterisation and structure of CO2H, Cl and F ortho-substituted phenyl deri…

2000

A saccharide based ligand suitable for metal binding (HLCOOH) has been synthesized using 4,6-O-ethylidene-alpha-D-glucopyranose (4,6-O-EGP) and anthranilic acid. A few analogous glycosylamines with chloro and fluoro ortho substitutions have also been synthesized and characterised. Complexes of HLCOOH with Na+, K+, Mg2+, Ca2+, Ba2+, Cd2+ and Hg2+ have been isolated and characterised fully. The crystal structures of 4,6-O-EGP, the chloro analogue of HLCOOH and the K+ complex of L-COOH are established. The anomeric nature, orientation of the binding core and the co-ordination aspects of K+ have been derived from these structures.

α-L-rhamnosidases: Old and New Insights

2007

L-Rhamnose is a component of plant cell wall pectic polysaccharides (Mutter et al., 1994; Ridley et al., 2001), glycoproteins (Haruko and Haruko, 1999) and secondary metabolites such as anthocyanins (Renault et al., 1997), flavonoids (Bar-Peled et al., 1991) and triterpenoids (Friedman and McDonald, 1997). It has also been found in bacterial heteropolysaccharides (Hashimoto and Murata, 1998), rhamnolipids (Ochsner et al., 1994) and in the repeating units of the O-antigen structure of the lipopolysaccharide component of bacterial outer membranes (Chua et al., 1999). Some rhamnosides are important bioactive compounds, e.g. cytotoxic saponins (Bader et al., 1998; Yu et al., 2002), antifungal p…

Flavanones in Citrus fruit: structure-antioxidant activity relationships

2005

Epidemiological surveys have shown an inverse relationship between the intake of fruit and the incidence of coronary heart disease and some type of cancer. Data found in the literature regarding the flavonoids in general while this study focuses on flavanones, a subclass of flavonoids which occurs in Citrus fruit. The aim of this work is to elucidate the antioxidant or pro-oxidant behaviours of some common flavanones and to determine their activity–structure relationships as antioxidant using the crocin bleaching inhibition assay. The compounds studied were regarding both the aglycon form and the glycoside form. Data evidence that the substitution of the 7th OH group of the flavanones by a …

Water-soluble polysaccharides from Opuntia stricta Haw. fruit peels: Recovery, identification and evaluation of their antioxidant activities

2015

Abstract Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical comp…

Improved synthesis and application of conjugation-amenable polyols from d-mannose

2019

A series of polyhydroxyl sulfides and triazoles was prepared by reacting allyl and propargyl d-mannose derivatives with selected thiols and azides in thiol-ene and Huisgen click reactions. Conformational analysis by NMR spectroscopy proved that the intrinsic rigidity and linear conformation of the mannose derived polyol backbone is retained in the final click products in solution. Single crystal X-ray structure determination of one of the compounds prepared further verified that the linear conformation of the polyol segment is also retained in the solid state. In addition, an improved method for direct Barbier-type propargylation of unprotected d-mannose is reported. The new reaction protoc…

Hemicellulose hydrolysis catalysed by solid acids

2013

Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reactions in water, under neutral pH and relatively mild temperature and pressure (120°C and 10 bar) conditions. Sulphonated resins are highly active, but they leach out sulphonic groups. Sulphonated silicas are less active, but more stable. They have weakly and strongly bound sites and the strongly bound ones do not leach. Zeolites are moderately active and stable. Among them, H-ferrierite especially, d…

Cover Feature: Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells (ChemBioChem 9/2018)

2018

Characterization of totally chlorine-free effluents from Kraft pulp bleaching

1999

A capillary zone electrophoresis (CZE) method for analyzing the total acid hydrolysis products (monosaccharides and their derivatives) of the dissolved carbohydrates from a totally chlorine-free bleaching plant was developed. Several borate buffer concentrations and other running conditions were tested. Neutral monosaccharides (arabinose, galactose, glucose, mannose, rhamnose and xylose) in hydrolysates were derivatized by means of 4-aminobenzonitrile and resolved by 500 mM borate buffer (pH 9.5, 16.0 kV). The detection level was less than 10 fmol. In addition, the separation of some uronic acids and oligosaccharides was studied.

Über die Verbreitung von Flavonoiden bei pleurokarpen Laubmoosen I. Apigenin-7-rhamnoglucosid bei Hylocomium splendens (Hedw.) Br. eur.

1977

Summary 15 species of pleurocarpous mosses have been investigated as to their content of flavonoids. Flavonoid tests on 14 species have given negative results. Only one species, Hylocomium splendens , contains one flavonoid. It was purified by means of paper chromatography and is by chromatography and absorption spectrum identical with rhoifolin (apigenin-7-neohesperidoside). Partial acid hydrolysis yields apigenin-7-monoglucoside and rhamnose, quantitative hydrolysis apigenin, rhamnose and glucose. They were identified by comparison with authentic samples.

O-linked mannose composition of secreted invertase of Saccharomyces cerevisiae

1989

The secreted invertase (EC 3.2.1.26) of Saccharomyces cerevisiae is a glycoenzyme that contains N- and O-linked mannoses in 40/1 proportion. The small amount of mannose chains O-linked to invertase is distributed as follows: mannose (20%), mannobiose (50%), mannotriose (6%), mannotetraose (7%) and mannopentaose (17%).