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Various C-glucopyranosyl-1,2,4-triazolones were designed as potential inhibitors of glycogen phosphorylase. Syntheses of these compounds were performed with O-perbenzoylated glucose derivatives as precursors. High temperature ring closure of N(1)-carbamoyl-C-β-D-glucopyranosyl formamidrazone gave 3-β-D-glucopyranosyl-1,2,4-triazol-5-one. Reaction of N(1)-tosyl-C-β-D-glucopyranosyl formamidrazone with ClCOOEt furnished 3-β-D-glucopyranosyl-1-tosyl-1,2,4-triazol-5-one. In situ prepared β-D-glucopyranosylcarbonyl isocyanate was transformed by PhNHNHBoc into 3-β-D-glucopyranosyl-1-phenyl-1,2,4-triazol-5-one, while the analogous 1-(2-naphthyl) derivative was obtained from the unsubstituted triazolone by naphthalene-2-boronic acid in a Cu(II) catalyzed N-arylation. Test compounds were prepared by Zemplén deacylation. The new glucose derivatives had weak or no inhibition of rabbit muscle glycogen phosphorylase b: the best inhibitor was 3-β-D-glucopyranosyl-1-(2-naphthyl)-1,2,4-triazol-5-one (Ki = 80 µM)., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Synthetic methods were elaborated for d-glucals attached to oxadiazoles by a C-C bond. Introduction of the double bond was effected by either DBU induced elimination of PhCOOH from the O-perbenzoylated glucopyranosyl precursors or Zn/N-methylimidazole mediated reductive elimination from the 1-bromoglucopyranosyl starting compounds. Alternatively, heterocyclizations of 2-deoxy-d-arabino-hex-1-enopyranosyl cyanide were also carried out. Test compounds were obtained by Zemplén debenzoylation, however, none of them showed significant inhibition of rabbit muscle glycogen phosphorylase b., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Glycogen phosphorylase (GP) appears as a key enzyme for the control of hyperglycemia in the context of type 2 diabetes. In order to gain additional data for structure-activity studies of the inhibition of this enzyme, a series of eight GP inhibitor candidates were prepared from peracetylglucopyranosyl azide 1 by click-chemistry. The need for a N-Boc-protected propargylamine was identified in the CuAAC with azide 1 under Meldal's conditions, while Sharpless' conditions were better adapted to the CuAAC of azide 1 with propargyl bromide. Cycloaddition of Boc-propargylamine with azide 1 afforded the N-Boc precursor of a 4-aminomethyl-1-glucosyl-1,2,3-triazole which gave access to a series of eight amide and sulfonamide derivatives. After deacetylation, enzymatic studies revealed poor to moderate inhibitions toward this enzyme. The N-Boc-protected amine was the best inhibitor (IC50=620 μM) unexpectedly slightly better than the 2-naphthylamido substituted analogue (IC50=650 μM)., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Various acetylenic derivatives and acetylated β-D-xylopyranosyl azide or the 5-thio-β-d-xylopyranosyl analogue were coupled by Cu(I)-catalyzed azide alkyne 1,3-dipolar cycloaddition (CuAAC) to afford a series of 1-xylosyl-4-substituted 1,2,3-triazoles. Controlled oxidation of the endocyclic sulfur atom of the 5-thioxylose moiety led to the corresponding sulfoxides and sulfones. Deacetylation afforded 19 hydroxylated xylose and 5-thioxylose derivatives, found to be only sparingly water-soluble. Compared to glucose-based analogues, they appeared to be much weaker inhibitors of glycogen phosphorylase, as the absence of a hydroxymethyl group weakens their binding at the enzyme active site. However, such new xylose derivatives might be useful glycomimetics., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Glucosylated heterocycles have been identified as potent inhibitors of glycogen phosphorylase (GP), a biomolecular target for the treatment of hyperglycemia and therefore type 2 diabetes. Several glucosylated triazoles have been evaluated as GP inhibitors and additional structures are being considered in the present study with the introduction of a substituent at the 5-position of the triazole ring. The 1,3-dipolar cycloaddition of azide and alkyne using stoichiometric amounts of Cu(I) halides favored the formation of the 5-halogenated 1,2,3-triazoles. The influence of the copper halide introduced (CuI, CuBr, or CuCl) provided different results and more specifically for the CuCl system which afforded a dimeric 5,5'-bistriazole in good yield (56%) as evidenced by crystallographic data., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In a DCC-mediated coupling 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylamine and propiolic acid gave N-propynoyl-2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylamine which was transformed by 1,3-dipolar cycloadditions with aromatic azides and nitrile-oxides to the corresponding O-peracetylated N-(β-D-glucopyranosyl)-1-substituted-1,2,3-triazole-4-carboxamides and N-(β-D-glucopyranosyl)-3-substituted-isoxazole-5-carboxamides, respectively. These compounds were O-deacetylated by Zemplén's protocol to be tested as inhibitors of rabbit muscle glycogen phosphorylase b. The best inhibitors of the two series were N-(β-D-glucopyranosyl)-1-(3,5-dimethyl-phenyl)-1,2,3-triazole-4-carboxamide (K(i)=34 μM) and N-(β-D-glucopyranosyl)-3-(indol-2-yl)-isoxazole-5-carboxamide (K(i)=164 μM)., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A series of pyranosyl homo-C-nucleosides have been synthesized by reaction of butenonyl C-glycosides (5a-5j, and 8) and cyanoacetamide in presence of t-BuOK followed by further modifications. The reaction proceeds by Michael addition of cyanoacetamide to the butenonyl C-glycosides and subsequent dehydrative cyclization and oxidative aromatization to give glycosylmethyl pyridones (6a-6j, 7a-7j, 9, and 10). The glycosylmethyl pyridones (6a-6e) on reaction with POCl(3) under reflux gave respective glycosylmethyl pyridines (11a-11e and 12a-12e) in good yields. The synthesized compounds were screened for their in vitro α-glucosidase, glucose-6-phosphatase and glycogen phosphorylase inhibitory activities. One of the pyridylmethyl homo-C-nucleoside, compound 11d, displayed 52% inhibition of glucose-6-phosphatase as compared to the standard drug sodium orthovanadate while compound 12a showed a significant antihyperglycemic effect of 17.1% in the diabetic rats as compared to the standard drug metformin., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

An efficient synthesis of novel 1,2,3-1H-triazolyl glycohybrids with two or more than two sugar units or a chromenone moiety via copper-catalysed azide-alkyne cycloaddition (CuAAC), a 1,3-dipolar cycloaddition of glycosyl azides to 2,3-unsaturated alkynyl glycosides or propargyloxy coumarins is described. The synthesised glycohybrids were screened for their α-glucosidase, glycogen phosphorylase and glucose-6-phosphatase inhibitory activities. A few of the glycohybrids showed promising inhibitory activities against these enzymes., (2010 Elsevier Ltd. All rights reserved.)

O-peracetylated 1-(beta-D-glucopyranosyl)-5-phenylbiuret was prepared in the reaction of O-peracetylated beta-D-glucopyranosylisocyanate and phenylurea. The reaction of O-peracetylated N-beta-D-glucopyranosylurea with phenylisocyanate furnished the corresponding 1-(beta-D-glucopyranosyl)-3,5-diphenyl- as well as 3-(beta-D-glucopyranosyl)-1,5-diphenyl biurets besides 1-(beta-D-glucopyranosyl)-3-phenylurea. O-Peracetylated 1-(beta-D-glucopyranosyl)-5-(beta-D-glycopyranosyl)biurets were obtained in one-pot reactions of O-peracetylated beta-D-glucopyranosylamine with OCNCOCl followed by a second glycopyranosylamine of beta-D-gluco, beta-D-galacto and beta-D-xylo configurations. O-Acyl protected 1-(beta-D-glucopyranosyl)-3-(beta-D-glycopyranosylcarbonyl)ureas were obtained from the reaction of beta-D-glucopyranosylisocyanate with C-(glycopyranosyl)formamides of beta-D-gluco and beta-D-galacto configurations. The O-acyl protecting groups were removed under acid- or base-catalyzed transesterification conditions, except for the N-acylurea derivatives where the cleavage of the N-acyl groups was faster than deprotection. Some of the new compounds exhibited moderate inhibition against rabbit muscle glycogen phosphorylase b and human salivary alpha-amylase., (2009 Elsevier Ltd. All rights reserved.)

Synthesis and biological evaluation of glucoconjugates of oleanolic acid, linked by either a triazole moiety or an ester function, as novel inhibitors of glycogen phosphorylase have been described. Several triterpene-glycoside conjugates exhibited moderate-to-good inhibitory activity against rabbit muscle GPa. Compound 12 showed the best inhibition with an IC(50) value of 1.14 microM. Structure-activity relationship (SAR) analysis of these inhibitors is also discussed. Possible binding modes of compound 12 were explored by molecular docking simulations.

Per-O-benzoylated derivatives (amide, methyl ester and glycinamide) of C-(1-azido-1-deoxy-alpha-D-glucopyranosyl)formic acid obtained by azide substitution in the corresponding C-(1-bromo-1-deoxy-beta-D-glucopyranosyl)formic acid derivatives were debenzoylated by the Zemplén-protocol. Per-O-benzoylated C-(1-azido-1-deoxy-alpha-D-glucopyranosyl)formamide was dehydrated by oxalyl chloride-DMF to give the corresponding nitrile, while from its reduction mixture obtained by Raney-nickel or sodium hydrogentelluride C-(1-amino-1-deoxy-beta-D-glucopyranosyl)formamide could be isolated. Acetylation of this amino-amide by Ac2O/Py and subsequent debenzoylation gave C-(1-acetamido-1-deoxy-beta-D-glucopyranosyl)formamide. Applying the same conditions to the crude reduction mixture allowed the alpha-anomer to be isolated as a minor component. An alternative pathway to produce the above beta-anomer appeared in the reaction of C-(1-bromo-1-deoxy-beta-D-glucopyranosyl)formamide with CH3CN in the presence of Ag2CO3 to yield 1-acetamido-2,3,4,6,-tetra-O-benzoyl-1-deoxy-beta-D-glucopyranosyl cyanide, which was hydrated, in the presence of TiCl4, to the formamide. Some of the new compounds were shown to be weak inhibitors of muscle glycogen phosphorylase b.