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At least 1,405 records · Page 78Linked to original sources
PubMed1985

Stimulation of the hexose monophosphate pathway in the human erythrocyte by Mn2+: evidence for a Mn2+-dependent NADPH peroxidase activity.

In human RBC hemolysates, Mn2+ was found to stimulate the HMP as determined by the release of 14CO2 from [1-14C]glucose, providing activities of 125, 200, and 300% of basal at Mn2+ concentrations of 1, 10, and 100 mM, respectively. To explore the possibility that this stimulatory effect upon the HMP is a result of redox recycling of NADPH, RBC hemolysates were used to study NADPH oxidation. Mn2+, alone or in combination with a free radical-generating system, did not enhance the ability of hemolysates to oxidize NADPH. However, hemolysates + 10 mM H2O2 brought about a 10-fold increase in NADPH oxidation (0.51 +/- 0.05 nmole/min to 5.67 +/- 0.84 nmole/min) and the addition of 10 mM Mn2+ to this system increased the rate of oxidation to 34.10 +/- 2.97 nmole/min. Boiled hemolysates, either in the presence or absence of Mn2+, had some residual catalytic activity.

Erythrocytes↗
PubMed1983

An automated Elson-Morgan assay for 2-amino-2-deoxy-hexoses, with increased sensitivity.

The Elson-Morgan assay for 2-amino-2-deoxyhexoses, despite its many modifications, can still give variable results because of slight variations in reaction conditions. An automated method is reported which uses microgram samples and provides greater sensitivity than hitherto possible. The use of sodium orthophosphate and optimisation of the concentrations of the reagents provide conditions that are more stable, and results that are more reliable, than any previously reported.

Autoanalysis↗
PubMed1988

Carbohydrate components for modified anthracyclines: synthesis of derivatives of 3-amino-3,4,6-trideoxy-L-lyxo- and -L-xylo-hexose, and attempts at fluorination of C-2.

Two new trideoxyglycosides, methyl 3,4,6-trideoxy-3-nitro-alpha-L-lyxo-hexopyranoside (7) and its alpha-L-arabino isomer, as well as the known alpha-L-xylo isomer (15), were synthesized from methyl 3,6-dideoxy-3-nitro-alpha-L-glucopyranoside (1) by methods involving elimination and reduction processes in mesylates prepared from 1. Catalytic hydrogenation of 7 and 15 gave the new and the known aminodeoxyglycosides, respectively, both of which were N-(trifluoroacetyl)ated and sub-subsequently O-(trifluoromethylsulfonyl)ated. Various attempts to effect displacement by fluoride ion in the N-protected 2-triflates so obtained, and also in a related 3-azido-2-triflate, were unsuccessful as far as fluorination at C-2 was concerned. Among other products, two new 2-enopyranosides resulting from elimination of triflic acid were obtained.

Deoxy Sugars↗
PubMed1990

Synthesis of L-gulose, L-galactose, and their acetylated aldehydo forms from 6-S-phenyl-6-thio-D-hexoses.

Methyl 6-S-phenyl-6-thio-a-D-glucopyranoside, prepared in high yield from methyl a-D-glucopyranoside by the action of diphenyl disulfide and tributylphosphine in pyridine, was converted into 6-S-phenyl-6-thio-D-glucitol pentaacetate (7) by sequential hydrolysis, borohydride reduction, and acetylation. Oxidation of 7 with 3-chloroperoxybenzoic acid gave the corresponding S-epimeric sulfoxides, which underwent Pummerer rearrangement to 1-epimeric L-gulose S-phenyl monothiohemiacetal hexaacetates. Boron trifluoride-catalyzed reaction of the latter with thiophenol gave the analogous diphenyl dithioacetal, whereas base-catalyzed methanolysis led to free L-gulose. Treatment of 7 with N-chlorosuccinimide afforded 1-epimeric 1-chloro-1-S-phenyl-1-thio-L-gulitol pentaacetates, which were hydrolyzed to provide aldehydo-L-gulose pentaacetate. The same reaction sequences were performed with 6-S-phenyl-6-thio-D-galactose, synthesized in two steps from 1,2:3,4-di-O-isopropylidene-a-D-galactopyranose, furnishing ultimately L-galactose, its diphenyl dithioacetal pentaacetate, and aldehydo-L-galactose pentaacetate. Similar reaction sequences for the chain-terminal interchange of oxidation state in other omega-S-phenyl-omega-thioaldoses may prove useful for the preparation of less-common sugar derivatives.

Acetylation↗