P-D-xylopyranosides

Carboxyethyl 1 -seleno-p-D-xylopyranoside or 3-(P-D-xylopyranosylseleno)propanoic acid... 

T. versicolor >95% after 14 days 2,4-Dichlorophenol the conjugates 2-0-(2,4,4 -trichlorodiphenyl ether)-p-D-xylopyranoside and 2-0-(2,4,4 -trichlorodiphenyl ether)-p-D-glucopyranoside [49]... 

Xylan fragments induced xylanase also in non-cellulolytic microorganisms like Streptomyces sp. (71) and yeasts of the genus Cryptococcus and Trichosporon (72-74). In these strains xylanase could be efficiently induced also by methyl P-D-xylopyranoside, which is extremely slowly metabolized in the cells (72-74). TTie glycoside accelerated xylanase production in hyperproducing color variants of A. pullu-lans (75) and in several strains of Aspergillus (70). Low cost and easy preparation of methyl p-D-xylopyranoside favors its use for large-scale xylanase production. 

We briefly present here a conformational analysis of the disaccharide, methyl (4-0-P-D-xylopyranosyl-p-D-xylopyranoside)... 

Thio-p-D-xylopyranosides that contain aromatic aglycons, such as Beciparcil (246, Fig. 24), and related analogues have potent antithrombotic activity in... 

Y. Li, D. Horton, V. Barberousse, F. Bellamy, P. Renaut, and S. Samreth, Chemical interconversions of 4-cyanophenyl 1,5-dithio-P-D-xylopyranoside (Beciparcil) Structural modification at the C-4 position, Carbohydr. Res., 314 (1998) 161—167. 

The complex structure isolated from Scleranthus uncinatus, 5,7-dihydroxy-3 -meth-oxy-4 -acetoxyflavone-8-C-p-D-xylopyranoside-2 -0-glucoside, was determined by using ID NMR ( H, C, DEPT) and 2D NMR (H-COSY, TOCSY, HMQC, HMBC, NOESY) data sequence and linkage of the sugar chain and acylation site were confirmed by observation of inter-residue NOEs in the NOESY spectrum. 

Rhamnoside, a-L-rhamnopyranoside apioside, p-apiofuranoside glucoside, p-D-glucopyranoside galactoside, P-d-galactopyranoside xyloside, p-D-xylopyranoside glucuronide, p-D-glucuronopyranoside. Cinnamic acids are assumed to be in the -form. 

From methyl a-D-glucopyranoside, 55% of 2-O-benzyl and 18% of 3-O-benzyl derivatives could be obtained using 1,4-dioxane as a solvent. No monobenzyl derivative was observed under standard DMF solvent conditions [131]. Conformational equilibria 4Ct XC4 play a role in the results of alkylation of all-equatorial methyl P-D-xylopyranoside and methyl P-D-glucopyranoside [131]. 

Just as in the case of nucleosides, the older results were re-investigated with novel methods also for tritylation of pyranosides. All the monotrityl ethers of methyl p-D-xylopyranoside and methyl oc-D-xylopyranoside have been isolated recently [311] to complement the pioneering work by Hockett and Hudson [312], The monotrityl fraction obtained [313] from methyl a-L-fucopyranoside was now found [314] to consist of 2-0- and 3-0-trityl derivatives in the ratio of 3 2 (D-enantiomer has been actually studied). 

L. V. Backinowsky, N. E. Nifantiev, and N. K. Kochetkov, Loss of stereospecificity upon glycosylation of methyl 2,3-di-0-acetyl-4-0-trityl-P-D-xylopyranoside by 1,2-O-cyanoalkyli-dene derivatives of monosaccharides, Bioorg. Khim., 9 (1983) 1089-1096. 

Table 4 Relative Reactivities of Hydroxyl Groups in Methyl a- and P-o-Glucopyranosides (MG), Methyl-a-o-Mannopyranoside (MM), and Benzyl-4-O-Methyl p-D-Xylopyranoside (BX) Toward Methylation or Reaction with N.yV-diethylaziridinium Chloride (DAC)... 

P-Xylosidases are being used commonly in paper industry for complete degradation of xylans. The enzymes used in the synthesis of xylose-containing compounds have also been reported. For example, Eneyskaya et al. (50) have used />-nitrophenyl P-D-xylopyranosides (XyiPpNP) as a donor and a 3-xylosidase ixom Aspergillus sp. in the synthesis of several 31,4-D-xylooli-gosaccharides as P-xylanase substrates. 

HomoDMDP-7-O-p-D-xylopyranoside Hyacinthoides rum-scripta (Hyadnthaceae) fniits/stalks Scilla campanulata (Hyacinthaceae) bulb Muscari. armeniacum (Hyadnthaceae) bulbs "... 

HomoDMDP-7-O-P-D- xylopyranoside potent inhibitor of P-glucosidases and p-galactosidases (including lactase) and moderate inhibitor of amyloglucosidase and P-mannosidase ... 

Orally administered 4-cyanophenyl 1,5-dithio-p-D-xylopyranoside 53 was reported to exhibit powerful antithrombotic activity [106]. Consequently, syntheses of several related compounds... 

Bozo, E, Boros, S, Kuszmann, J, Synthesis of 4-cyanophenyl 2-azido-2-deoxy- and 3-azido-3-deoxy-1,5-dithio-p-D-xylopyranosides, Carbohydr. Res., 301, 23-32, 1997. 

P-hydroxy-25,26-didehydroponasterone A 20-hydroxyecdysone (5a-H)20-hydroxyecdysone 20-hydroxyecdysone 2-acetate 20-hydroxyecdysone 3-acetate 20-hydroxyecdysone 22-acetate 20-hydroxyecdysone 22-benzoate 20-hydroxyecdysone 6-carboxymethyloxime 20-hydroxyecdysone dimer 20-hydroxyecdysone 2-P-D-glucopyranoside 20-hydroxyecdysone 3-P-D-glucopyranoside 20-hydroxyecdysone 22-p-D-glucopyranoside 20-hydroxyecdysone 25-p-D-glucopyranoside 20-hydroxyecdysone 2-hemisuccinate 20-hydroxyecdysone 22-hemisuccinate 20-hydroxyecdysone 2,3,22-triacetate 20-hydroxyecdysone 3 p-D-xylopyranoside 6p-hydroxy-20-hydroxyecdysone 6a-hydroxy-20-hydroxyecdysone... 

Scheme 11 General procedure for the preparatirai of 6-hydroxynaphthyl-P-D-xylopyranosides...

Retention Volumes of 0-Trimethylsilyl Derivatives of D-Pentopyranoses Relative to Trimethylsilyl S,3,4-Tri-0- trimethylsilyl)-p-D-xylopyranoside ... 

Determination of Initial Rate Kinetics on />-nitrophenol P-D xylopyranoside... 

Initial rate kinetic assays were conducted at 37 C in 50 mM citrate buffer at pH 4.8 in 96-well microtiter plates using /)-nitrophenol P-D-xylopyranoside. For all assays, the XlnD was loaded at 1.5 p.g/ml of reaction, and initial substrate concentrations were varied from 0.1 to 3.2 mM. The release of pNP was monitored every 15 s for the initial 10 min of each reaction by measming the absorbance at 405 nm on a SpectraMax 190 UV/VIS microplate scanner from the Molecular Devices (Sunnyvale, CA). End product inhibition by D-xylose was confirmed by ranning identical assays to those described above with initial D-xylose concentrations ranging from 3.33 to 40 mM. Triplicate analyses of all assays were run at all conditions. All parameters estimated in this study were calculated using standard Michaelis-Menten kinetics as described previously [11]. 

Action on the following artificial aryl-glycoside substrates was tested /j-NP- 3-d-xylopyranoside (p-NP-XylP), o-NP-P-D-xylopyranoside (o-NP-XylP), p-NP-a-L-arabinofur-anoside (p-NP-AraF), p-NP-a-L-arabinopyranoside (p-NP-AraP), p-NP- P -D-glucopyranoside, p-NP-P-D-fucopyranoside, p-NP-P-D-galactopyranoside, and p-NP-p-D-mannopyranoside (all from Sigma or Research Products International Corporation). Reaction conditions were... 

P-Glucosidase, p-xylosidase, and a-arabinofiiranosidase activities were determined by following the release of 4-nitrophenol from 4-nitrophenyl-P-D-glucopyranoside, 4-nitrophenyl-P-D-xylopyranoside, and 4-nitrophenyl-a-L-arabinopyranoside (Sigma), respectively, for 15 min at 50 °C and pH 4.0 (50 mM Na acetate buffer). The reaction was stopped by the addition of 1 M Na2C03, and the absorbance was read at 410 nm from a 4-nilrophenol standard curve. One unit of activity was defined as the amount of enzyme that released 1 pmol of 4-nitrophenol per min. 

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