1-4-dideoxy-1-4-imino-d-arabinitol and Gaucher-Disease

Enantiomeric series of C-4 hydroxymethyl depleted DAB and LAB derivatives (trans, trans-2-C-aryl-3,4-dihydroxypyrrolidines), designed as β-glucosidase inhibitors by molecular docking calculations, have been synthesized in 2 steps from l- and d-tartaric acid derived enantiomeric cyclic nitrones 29L and 29D, respectively. Both series of C-4 hydroxymethyl depleted DAB and LAB derivatives 28Da-e and 28La-e, which are structurally trans, trans-2-C-aryl-3,4-dihydroxypyrrolidines, were potent and selective human lysosome acid β-glucosidase (GCase) inhibitors, of which 28Dd and 28Ld with C-4 biphenyls showed the highest potency relative to other compounds of the same series. The work provided a series of pyrrolidine-type potent and selective GCase inhibitors with minimal hydroxyl substitutions and synthetic procedures. Structure-activity relationship study revealed not only the rationality of hydrophobic and aromatic properties of the binding sites in GCase, but also the great potential of pyrrolidine family in development of new GCase inhibitors with minimized undesirable side effects. The results indicate a strategy for the development of drugs for the treatment of related diseases targeting acid β-glucosidase, such as Gaucher disease and Parkinson's disease.

Topics: beta-Glucosidase; Enzyme Inhibitors; Gaucher Disease; Glucosylceramidase; Humans; Molecular Docking Simulation; Pyrrolidines

A library of sp(2)-iminosugar conjugates derived from the piperidine iminosugar d-fagomine and the enantiomeric pyrrolidine iminosugars DAB and LAB has been generated in only two steps involving direct coupling of the fully unprotected polyhydroxylated heterocycles with isothiocyanates, to give monocyclic thiourea adducts, and further intramolecular nucleophilic displacement of the δ-located primary hydroxyl group by the thiocarbonyl sulphur atom, affording bicyclic isothioureas. These transformations led to a dramatic shift in the inhibitory selectivity from α- to β-glucosidases, with inhibition potencies that depended strongly on the nature of the aglycone-type moiety in the conjugates. Some of the new derivatives behaved as potent inhibitors of human β-glucocerebrosidase (GCase), the lysosomal enzyme whose dysfunction is responsible for Gaucher disease. Moreover, GCase inhibition was 10-fold weaker at pH 5 as compared to pH 7, which is generally considered as a good property for pharmacological chaperones. Surprisingly, most of the compounds strongly inhibited GCase in wild type fibroblasts at rather low concentrations, showing an unfavourable chaperone/inhibitor balance on disease-associated GCase mutants in cellulo. A structure-activity relationship analysis points to the need for keeping a contiguous triol system in the glycone moiety of the conjugates to elicit a chaperone effect. In any case, the results reported here represent a proof of concept of the utmost importance of implementing diversity-oriented strategies for the identification and optimization of potent and specific glycosidase inhibitors and chaperones.

Topics: Enzyme Inhibitors; Fibroblasts; Gaucher Disease; Glycoside Hydrolases; Humans; Imino Pyranoses; Imino Sugars; Structure-Activity Relationship

We investigated in vitro inhibition of mammalian carbohydrate-degrading enzymes by six-membered sugar mimics and their evaluation in cell cultures. 1-Deoxynojirimycin (DNJ) showed no significant inhibition toward glycogen phosphorylase (GP) but was a potent inhibitor of another glycogen-degrading enzyme, amylo-1,6-glucosidase (1,6-GL), with an IC(50) value of 0.16 microM. In primary rat hepatocytes, the inhibition of glycogen breakdown by DNJ reached plateau at 100 microM with 25% inhibition and then remained unchanged. The potent GP inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1) inhibited hepatic glucose production with an IC(50) value of about 9 microM and the inhibition by D-AB1 was further enhanced in the presence of DNJ. DNJ and alpha-homonojirimycin (HNJ) are very potent inhibitors of rat intestinal maltase, with IC(50) values of 0.13 and 0.08 microM, respectively, and also showed a similar strong inhibition toward maltase in Caco-2 cell model system, with IC(50) value of 0.05 and 0.10 microM, respectively. D-Isofagomine (D-IFG) and L-IFG are competitive and noncompetitive inhibitors of human lysosomal beta-glucosidase (beta-GL), respectively, with K(i) values of 8.4 nM and 6.9 microM. D-IFG increased intracellular beta-GL activity by twofold at 10 microM in Gaucher N370S cell line as an 'active-site-specific' chaperone, and surprisingly a noncompetitive inhibitor L-IFG also increased intracellular beta-GL activity by 1.6-fold at 500 microM.

Topics: Animals; Caco-2 Cells; Carbohydrate Conformation; Cells, Cultured; Dose-Response Relationship, Drug; Fibroblasts; Gaucher Disease; Glycogen; Glycoside Hydrolases; Hepatocytes; Humans; Imino Sugars; Lysosomes; Rats; Structure-Activity Relationship