PubMed Health⌕ Search

Biomedical subjects

R L Whistler

Publications and source records attributed to R L Whistler.

At least 19 recordsLinked to original sources
PubMed1990

Formylation of primary hydroxyl groups in sugars.

Application of 99% formic acid at 25 degrees formylates primary hydroxyl groups as shown by the easy formation of 6-O-formyl-D-glucopyranose and 6-O-formyl-D-fructofuranose, isolated as their tetra-acetates in yields of 77% and 31%, respectively. Likewise, D-glucitol gave the 2,3,4,5-tetra-O-acetyl-1,6-di-O-formyl derivative (84%) and methyl alpha-D-glucopyranoside gave the 6-formate (74%) characterized as the crystalline triacetate. On storage of the triacetate in methanol at 25 degrees, the formyl group was lost and the 2,3,6-triacetate was formed, whereas the corresponding tribenzoate was deformylated in acidic methanol without migration of the benzoyl groups.

Carbohydrates↗
PubMed1990

Synthesis of sweet-tasting methylthio derivatives of D-fructose and sucrose.

1,6-Di-S-methyl-1,6-dithio-D-fructofuranose and its bis(S-oxide) and bis(S,S-dioxide) are described. On examination for sweetness, the oxygenated compounds were neutral but the parent compound was 15-20 times sweeter than sucrose, and 1',6'-di-S-methyl-1',6'-dithiosucrose was slightly less sweet than sucrose.

Carbohydrate Sequence↗
PubMed1986

Synthesis of some derivatives of 6-amino-1,5-anhydro-6-deoxy-D-glucitol and 2-amino-1,5-anhydro-2-deoxy-D-glucitol.

6-Amino-1,5-anhydro-6-deoxy-D-glucitol (11) was prepared from 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide (1) in six steps. Reduction of 1 with tributyltin hydride, followed by deacetylation, monomolar tosylation, and reacetylation, afforded 2,3,4-tri-O-acetyl-1,5-anhydro-6-O-toluene-p-sulfonyl-D-glucitol (9). Alternatively, tritylation of 1,5-anhydro-D-glucitol, followed by acetylation, detritylation, and tosylation, gave 9. Mesylation gave 8. Treatment of 8 or 9 with azide anion afforded the azide 10, reduction of which with tributyltin hydride gave 11, which was mesylated or tosylated, and then deacetylated to give the 6-methane-sulfonamido or 6-toluene-p-sulfonamido derivative. Similarly, mesylation or tosylation of 3,4,6-tri-O-acetyl-2-amino-1,5-anhydro-2-deoxy-D-glucitol (20) gave the 2-methanesulfonamido or 2-toluene-p-sulfonamido derivatives. Treatment of 11 and 20 with sulfur trioxide-pyridine afforded the sulfoamino derivatives, deacetylation of which gave sugar analogs of cyclamate-like compounds.

Glucosamine↗
PubMed1986

Synthesis of N-trifluoroacetyl-L-acosamine, N-trifluoroacetyl-L-daunosamine, and their 1-thio analogs.

A simple and efficient route to N-trifluoroacetyl-L-acosamine (13), N-trifluoroacetyl-L-daunosamine (12), and their 1-thio analogues (18 and 20) is described. Stereoselective reduction of oxime 5 with borane, followed by trifluoroacetylation resulted in the arabino methyl glycoside (8), which, on mild acid hydrolysis gave N-trifluoroacetyl-L-acosamine (13) in an overall yield of 33%, based on L-rhamnal (1). Upon oxidation of the C-4 hydroxyl group and stereoselective reduction of the resulting ketone 11, compound 8 of L-arabino configuration was converted into N-trifluoroacetyl-L-daunosamine (12) in a one-flask sequence with an overall yield of 28% calculated for 1. Benzyl 1-thio-N-trifluoroacetyl-alpha-L-acosaminide (18) was synthesized from enone 2 on Michael-type addition of phenylmethanethiol, followed by oximation, stereoselective reduction with borane and subsequent trifluoroacetylation. 4-O-Acetyl-1-S-acetyl-N-trifluoroacetyl-1-thio-beta-L-daunosamine 20 was prepared from 12 via the corresponding glycosyl chloride derivative.

Carbohydrate Conformation↗
PubMed1984

Synthesis of 3-C-(hydroxymethyl)erythritol and 3-C-methylerythritol.

3-C-(Hydroxymethyl)erythritol was prepared from 3-C-(hydroxymethyl)-2,3-O-isopropylidene-D-erythro-tetrofuranose (4) by hydrolysis followed by reduction, or by reduction followed by hydrolysis. Monotosylation of 4, followed by reduction with lithium aluminum hydride and hydrolysis, afforded 3-C-methylerythritol.

Erythritol↗
PubMed1977

Effect of 5-thio-D-glucose on food and water intakes and on the acquisition and performance of maze tasks in the rat.

A potent inhibitor of D-glucose transport across the membrane, 5-thio-D-glucose (5-TDG) was examined with respect to its effect on runway and maze performance as well as on food and water intakes and body weight. In an initial experiemnt, three groups of Sprague-Dawley rats were matched in terms of their performance to learn a runway taks with Noyes pellets serving as the reinforcement. After extinction, two groups of rats were given 5-TDG in their food for 14 days, in doses of 20 and 100 mg/kg/day, which exerts potent effects on other functions. Retesting in the runway task showed no significant differences in the time required for the controls and for the 5-TDG treated rats to reach the goal box. Nonfed controls and the same two groups were again fed 500 ant 100 mg/kg/day 5-TDG and were tested on the 12 problems of the Hebb-Williams maze. Again, no significant differences were found in the number of erros made on the 12 problems by the 5-TDG treated animals or by the controls. Thus, this sugar analogue, administered in doses that affect spermatogenesis and other processes, has no effect on the ability of the rats to perform these tasks. Similarly, the intakes of food and water were unaffected by the systemic administration of 5-TDG.

Animals↗
PubMed1976

Uridine 5'-(5-thio-alpha-D-glucopyranosyl pyrophosphate): chemical synthesis and activation of rat liver glycogen synthetase.

Uridine 5'-(5-thio-alpha-D-glucopyranosyl pyrophosphate), UDPTG, appears to be a potent activator of rat liver glycogen synthetase a even though it is not a substrate. At 1.0 mM, UDPTG causes over 400% activation of glycogen synthetase a activity. Activation by UDPTG is accompanied by normalization of the otherwise sigmoidal kinetics for UDPG with glycogen synthetase a and a decrease in the apparent Km for UDPG from approximately 2.0 to 0.62 mM. UDPTG inhibits catalytic activity at higher concentrations. At the concentrations examined, UDPTG has no effect on glycogen synthetase b activity. The use of glycogen synthetase free from glycogen synthetase b phosphatase and the selective inhibition of glycogen synthetase b phosphatase by 100 mM NaF-indicate that conversion of synthetase b to a is not responsible for the activation. Moreover, the use of the colorimetric assay for glycogen synthetase activity precludes effects of UDPTG on glycogen phosphorylase activity. UDPTG, chemically synthesized in 60% yield, is characterized by chromatographic and electrophoretic procedures, by its uv spectra, and by analysis of products after chemical and enzymatic hydrolysis.

Animals↗
PubMed1975

Synthesis and biological activity of 5-fluoro-4'-thiouridine and some related nucleosides.

The synthesis of a series of 4'-thio-5-halogenopyrimidine nucleosides, including the 5-fluoro, chloro, bromo and iodo derivatives, has been carried out by condensation of the 2,4-bis-O-trimethylsilyl derivatives of the corresponding pyrimidine bases with the protected 4-thio-D-ribofuranosyl chloride. Among these, the alpha and beta anomers of 4'-thio-5-fluorouridine inhibited the growth of leukemia L1210 cells at concentrations of 4 x 10(-7) and 2 x 10(-7) M, respectively, and that of S. faecium at 4 x 10(-9) and 6 x 10(-10) M, respectively. These compounds retained marked activity against strains of S. faecium resistant to 10(-3) M 5-fluorouracil or 5-fluorouridine. As determined in S. faecium cultures, 4'-thio-5-fluorouridine decreased the total protein content of the cells more markedly than it did their RNA or DNA content. X-Ray crystallography showed that substitution of sulfur for the oxygen in the carbohydrate ring markedly changes the conformation of that moiety.

Animals↗