Convenient synthesis and evaluation of enzyme inhibitory activity of several N-Alkyl-, N-Phenylalkyl, and cyclic isourea derivatives of 5a-Carba-α-dl-fucopyranosylamine

Remodeling of N-Heterocyclic Iminato Ligand Frameworks for the Facile Synthesis of Isoureas from Alcohols and Carbodiimides Promoted by Organoactinide (Th, U) Complexes

A new class of actinide complexes [(L)An(N{SiMe₃}₂)₃] (An = Th or U) (Th1-Th3 and U1-U3) supported by highly nucleophilic seven-membered N-heterocyclic iminato ligands were synthesized and fully characterized by single-crystal X-ray diffraction. These complexes were successfully exploited as powerful catalysts for the addition of alcohols to carbodiimides to yield the corresponding desirable isourea products at room temperature with short reaction times and excellent yields. Thorough stoichiometric, thermodynamic, and kinetic studies were carried out, allowing us to propose a plausible mechanism for the catalytic reaction.

Synthesis of 5a,5a'-dicarba-d-glucobioses from conformationally restricted carbaglucosyl triflates using SN2-type inversion with carbaglucosyl nucleophiles

Novel carbohydrate mimics were designed which contain two 5a-carba-d-glucose residues, one each at reducing and nonreducing end, and thus these mimics are 5a,5a'-dicarba-d-glucobioses. Dicarbadisaccharides have attractive features such as stability against endogenous degradative enzymes and being resistant to glycation reactions such as the Maillard reaction. For the synthesis of dicarba-β-d-isomaltose derivatives, the carbaglucosyl triflate locked in ⁴C₁ conformation was synthesized by protecting with butane-2,3-diacetal group or benzylidene group. Then, 5a,5a'-dicarba-β-d-maltose and 5a,5a'-dicarba-α,β-d-trehalose were synthesized by the S_N2-type inversion reaction using 4,6-O-benzylidene carbaglucosyl triflate with 4-OH and 1-OH carba-β-d-glucose derivatives, respectively, and similarly 5a,5a'-dicarba-α-d-isomaltose with 6-OH carba-α-d-glucose derivative.

Synthetic and Crystallographic Insight into Exploiting sp2 Hybridization in the Development of α-l-Fucosidase Inhibitors

The sugar fucose plays a myriad of roles in biological recognition. Enzymes hydrolyzing fucose from glycoconjugates, α-l-fucosidases, are important targets for inhibitor and probe development. Here we describe the synthesis and evaluation of novel α-l-fucosidase inhibitors, with X-ray crystallographic analysis using an α-l-fucosidase from Bacteroides thetaiotamicron helping to lay a foundation for future development of inhibitors for this important enzyme class.

Rhodium-Catalyzed Tandem Reaction of Isocyanides with Azides and Oxygen Nucleophiles: Synthesis of Isoureas

A novel rhodium-catalyzed tandem reaction of isocyanides with azides and various oxygen nucleophiles has been developed. The reaction provides a simple and highly efficient one-pot synthesis of various N-sulfonyl/acylisoureas with broad substrate scope in an atom-economical manner from readily available starting materials in a highly stereoselective manner.

N-Alkyl-1,5-dideoxy-1,5-imino-l-fucitols as fucosidase inhibitors: Synthesis, molecular modelling and activity against cancer cell lines

1,5-Dideoxy-1,5-imino-l-fucitol (1-deoxyfuconojirimycin, DFJ) is an iminosugar that inhibits fucosidases. Herein, N-alkyl DFJs have been synthesised and tested against the α-fucosidases of T. maritima (bacterial origin) and B. taurus (bovine origin). The N-alkyl derivatives were inactive against the bacterial fucosidase, while inhibiting the bovine enzyme. Docking of inhibitors to homology models, generated for the bovine and human fucosidases, was carried out. N-Decyl-DFJ was toxic to cancer cell lines and was more potent than the other N-alkyl DFJs studied.

Biosynthesis and Biological Activity of Carbasugars

The first synthesis of carbasugars, compounds in which the ring oxygen of a monosaccharide had been replaced by a methylene moiety, was described in 1966 by Professor G. E. McCasland’s group. Seven years later, the first true natural carbasugar (5a-carba-R-D-galactopyranose) was isolated from a fermentation broth of Streptomyces sp. MA-4145. In the following decades, the chemistry and biology of carbasugars have been extensively studied. Most of these compounds show interesting biological properties, especially enzymatic inhibitory activities, and, in consequence, an important number of analogues have also been prepared in the search for improved biological activities. The aim of this review is to give coverage on the progress made in two important aspects of these compounds: the elucidation of their biosynthesis and the consideration of their biological properties, including the extensively studied carbapyranoses as well as the much less studied carbafuranoses.

Spirocyclopropyl pyrrolidines as a new series of α-l-fucosidase inhibitors

Polyhydroxy 4-azaspiro[2.4]heptane derivatives (spirocyclopropyl iminosugars) were prepared in four to six steps from readily available protected aldoses. The key step of the reaction sequence involves a titanium-mediated aminocyclopropanation of glycononitriles with subsequent cyclization. Five new polyhydroxypyrrolidines so-obtained have been evaluated for their ability to inhibit 16 glycosidases. One of them exhibits selective inhibition of alpha-L-fucosidase from bovine kidney (Ki=1.6 microM, competitive).

Synthesis of 5a-carba-hexopyranoses and hexopyranosylamines, as well as 5a,5a′-dicarbadisaccharides, from 3,8-dioxatricyclo[4.2.1.02,4]nonan-9-ol: glycosidase inhibitory activity of N-substituted 5a-carba-β-gluco- and β-galactopyranosylamines, and derivatives thereof

Since glycosidase and glycosyltransferase inhibitors, composed of carba-sugars, have recently attracted much attention, it is desirable to develop effective preparative routes for provision of new carba-sugar derivatives of potential biological interest. 1,2:3,6-Dianhydro-5a-carba-alpha-glucopyranose was here chosen for study of synthetic utility, and demonstrated to be a promising intermediate for supplying several carba-beta-glycosylamines and N-linked dicarba-oligosaccharides. An N-linked 5a,5a'-dicarbalactose derivative obtained here was found to be a strong alpha-galactosidase inhibitor (IC50 1.2 microM, green coffee beans).

Synthesis and glycosidase inhibitory activity of some N -Substituted 6-Deoxy-5a-carba-β- dl - and l -galactopyranosylamines

Chemical modification of 5a-carba-beta-DL-fucopyranosylamine (3) generated six N-substituted derivatives 9a-f, among which N-octyl 9b, decyl 9c, and phenylbutyl ones 9f were found to be very strong beta-galactosidase as well as beta-glucosidase inhibitors. The inhibitory activity appeared attributable to D-enantiomers from biological assays of prepared L-enantiomers. Therefore, 6-deoxy-5a-carba-beta-D-galactopyranosylamine (D-3) might be a promising lead compound for further design of new carba sugar-type beta-galactosidase inhibitors.