Synthesis and evaluation of glycosidase inhibitory activity of N-butyl 1-deoxy-D-gluco-homonojirimycin and N-butyl 1-deoxy-L-ido-homonojirimycin

Conjugate addition of n-butyl amine to d-glucose derived alpha,beta-unsaturated ester 4 afforded beta-amino esters 5a,b that on reduction of ester group, 1,2-acetonide deprotection, and reductive amination led to the formation of corresponding N-butyl 1-deoxy-D-gluco-homonojirimycin 2c and N-butyl 1-deoxy-L-ido-homonojirimycin 2d which were found to be selective beta-glucosidase inhibitors with an IC(50) value in millimolar range.     

Convenient synthesis and evaluation of glycosidase inhibitory activity of alpha- and beta-galactose-type valienamines, and some N-alkyl derivatives

Valienamine analogues having alpha- and beta-galactose-type structures were synthesized by racemic modification from (1SR,2RS,3SR)-6-methylenecyclohex-4-ene-1,2,3-triol. Four N-alkyl derivatives of the beta-anomer were readily prepared selectively by treatment of key intermediate 2,6-di-O-acetyl-3,4-O-isopropylidene-5a-carba-alpha- and beta-l-arabino-hex-5(5a)-enopyranosyl bromides with alkyl amines. All compounds were assayed for inhibitory activity against six glycosidases, and the N-dodecyl derivative was shown to be a very strong inhibitor of beta-galactosidase (IC(50) 0.01 microM, bovine liver).     

Polyhydroxylated azetidine iminosugars: Synthesis,glycosidase inhibitory activity and molecular docking studies

An efficient and practical strategy for the synthesis of unknown azetidine iminosugars (2S,3R,4S)-2-((R)-1,2-dihydroxyethyl)-3-hydroxy-4-(hydroxymethyl)azetidine 2, (2S,3r,4R)-3-hydroxy-2,4-bis(hydroxymethyl)azetidine 3 and (2S,3R,4S)-3-hydroxy-4-(hydroxymethyl)-N-methylazetidine-2-carboxylic acid 4, starting from the d-glucose has been reported. The methodology involves preparation of the 3-amino-N-benzyloxycarbonyl-3-deoxy-6-O-tert-butyldimethylsillyl-1,2-O-isopropylidene-α-d-glucofuranose 9, which was converted to the C-5-OMs derivative 11. Intramolecular nucleophilic displacement of the C-5-OMs group with in situ generated 3-amino functionality provided the required key azetidine ring skeletons 10 with additional hydroxymethyl group. Removal of 1,2-acetonide protection, followed by reduction and hydrogenolysis afforded azetidine iminosugar 2. Alternatively, removal of 1,2-acetonide group and chopping of C1-anomeric carbon gave C2-aldehyde that on reduction or oxidation followed by hydrogenolysis gave 2,4-bis(hydroxymethyl) azetidine iminosugars 3 and N-methylazetidine-2-carboxylic acid 4 respectively. The glycosidase inhibitory activity of 2–4 iminosugars was screened against various glycosidase enzymes and compared with a standard miglitol. Amongst synthesized targets, the compound 2 was found to be more potent amyloglucosidase inhibitor than miglitol. These results were supported by molecular docking studies.     

1-Aza-sugars from D-glucose. Preparation of 1-deoxy-5-dehydroxymethyl-nojirimycin, its analogues and evaluation of glycosidase inhibitory activity

D-glucose derived pentodialdoses 11a-c on reduction followed by tosylation, azide displacement, hydrogenation and protection with -Cbz group gave N-Cbz protected compounds 14a-c, respectively, which on removal of 1,2-acetonide functionality and hydrogenation afforded corresponding 1-aza-sugars 3, 9 and 10 in good overall yields. The glycosidase inhibition activity of these 1-aza-sugars was tested with sweet almond as a rich source of different glycosidases.     

Synthesis and glycosidase inhibitory activity of some N-substituted 6-deoxy-5a-carba-beta-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.     

Synthesis and glycosidase inhibitory activities of chain-modified analogues of the glycosidase inhibitors salacinol and blintol

The synthesis of chain-modified analogues of the naturally-occurring glycosidase inhibitor, salacinol, and its selenium analogue, blintol is described. The modification consists of a frame shift of the sulfate moiety by one carbon atom in the zwitterionic structures as well as an extension of the acyclic chain to five carbons. The target molecules were synthesized by alkylation of 1,4-anhydro-2,3,5-tri-O-p-methoxybenzyl-4-thio (or seleno)-D-arabinitol at the ring heteroatom by 2,3,5-tri-O-p-methoxybenzyl D- or L-xylitol-1,4-cyclic sulfate, followed by deprotection with trifluoroacetic acid. Two of the four compounds inhibit recombinant human maltase glucoamylase, one of the key intestinal enzymes involved in the breakdown of glucose oligosaccharides in the small intestine, with Ki values of 20+/-4 and 53+/-5 microM.     

Antimicrobial activity of glycosidase inhibitory protein isolated from Cyphomandra betacea Sendt. fruit

Broad-spectrum antimicrobial activity of an invertase inhibitory protein (IIP) isolated from Cyphomandra betacea ripe fruits is documented. Minimal inhibitory concentration (MIC) values were determined by agar macrodilution and broth microdilution assays. This IIP inhibited the growth of xylophagous and phytopatogenic fungi (Ganoderma applanatum, Schizophyllum commune, Lenzites elegans, Pycnoporus sanguineous, Penicillium notatum, Aspergillus niger, Phomopsis sojae and Fusarium mango) and phytopathogenic bacteria (Xanthomonas campestris pvar vesicatoria CECT 792, Pseudomonas solanacearum CECT 125, Pseudomonas corrugata CECT 124, Pseudomonas syringae pv. syringae and Erwinia carotovora var carotovora). The IIP concentration required to completely inhibit the growth of all studied fungi ranged from 7.8 to 62.5 microg/ml. Phytopatogenic bacteria were the most sensitive, with MIC values between 7.8 and 31.25 microg/ml. Antifungal and antibacterial activities can be associated with their ability to inhibit hydrolytic enzymes. Our results indicate the possible participation of IIP in the plant defense mechanism and its potential application as a biocontrol agent against phytopathogenic fungi and bacteria.     

Synthesis and glycosidase inhibitory activity of 5-thioglucopyranosylamines. Molecular modeling of complexes with glucoamylase

The synthesis of a series of 5-thio-D-glucopyranosylarylamines by reaction of 5-thio-D-glucopyranose pentaacetate with the corresponding arylamine and mercuric chloride catalyst is reported. The products were obtained as anomeric mixtures of the tetraacetates which can be separated and crystallized. The tetraacetates were deprotected to give alpha/beta mixtures of the parent compounds which were evaluated as inhibitors of the hydrolysis of maltose by glucoamylase G2 (GA). A transferred NOE NMR experiment with an alpha/beta mixture of 7 in the presence of GA showed that only the alpha isomer is bound by the enzyme. The Ki values, calculated on the basis of specific binding of the alpha isomers, are 0.47 mM for p-methoxy-N-phenyl-5-thio-D-glucopyranosylamine (7), 0.78 mM for N-phenyl-5-thio-D-glucopyranosylamine (8), 0.27 mM for p-nitro-N-phenyl-5-thio-D-glucopyranosylamine (9) and 0.87 mM for p-trifluoromethyl-N-phenyl-5-thio-D-glucopyranosylamine (10), and the K(m) values for the substrates maltose and p-nitrophenyl alpha-D-glucopyranoside are 1.2 and 3.7 mM, respectively. Methyl 4-amino-4-deoxy-4-N-(5'-thio-alpha-D-glucopyranosyl)-alpha-D-glucopyrano side (11) is a competitive inhibitor of GA wild-type (Ki 4 microM) and the active site mutant Trp120-->Phe GA (Ki 0.12 mM). Compounds 7, 8, and 11 are also competitive inhibitors of alpha-glucosidase from brewer's yeast, with Ki values of 1.05 mM, > 10 mM, and 0.5 mM, respectively. Molecular modeling of the inhibitors in the catalytic site of GA was used to probe the ligand-enzyme complementary interactions and to offer insight into the differences in inhibitory potencies of the ligands.     

Synthesis and glycosidase inhibitory activity of some N-substituted 5a-carba-beta-fuco- and beta-galactopyranosylamines, and selected derivatives

In the course of chemical modification of alpha-fucosidase inhibitors of 5a-carba-fucopyranosylamine type, an N-dodecyl derivative of the enantiomer 6-deoxy-5a-carba-beta-D-galactopyranosylamine demonstrated very strong inhibition of beta-galactosidase and beta-glucosidase. This finding led us to synthesize corresponding 6-hydroxy compounds, in order to elucidate structure-activity relationships for inhibitors of this type. Among four N-alkyl-5a-carba-beta-D-galactopyranosylamines prepared, the N-octyl derivative could be demonstrated to possess moderate activity toward alpha- and beta-galactosidases, and beta-glucosidase.     

Synthesis and glycosidase inhibitory profiles of functionalised morpholines and oxazepanes

In this work libraries of morpholines and oxazepanes have been prepared via the reductive amination reaction between dialdehydes, derived from carbohydrates, and a range of amines. In this way, functionalised morpholines and oxazepanes have been prepared that include N-alkylated derivatives, disaccharide analogues, and ester containing derivatives. The abilities of these functionalised morpholines and oxazepanes to inhibit a broad panel of glycosidase enzymes, that are associated with a range of diseases, have been probed and in this way new inhibitors of a range of glycosidases, but particularly β-d-galactosidase derived from Bovine kidney, have been discovered. N-Alkyl morpholines demonstrated the best inhibition profiles for this enzyme and derivatives (15a)-(15d) acted as non-competitive inhibitors with IC(50) values of 55.1-88.6 μM. Within this study, some preliminary structure-activity relationships are proposed, and it is demonstrated that N-substituted morpholines display better inhibitory profiles for the enzymes analysed than any of the N-substituted oxazepanes.     

Synthesis and evaluation of glycosidase inhibitory activity of octahydro-2H-pyrido[1,2-a]pyrimidine and octahydro-imidazo[1,2-a]pyridine bicyclic diazasugars

An efficient chiron approach for the synthesis of bicyclic diazasugars 4a and 4b having both -CH(2)OH and -OH functionality at the same carbon atom (C-6) is reported. Thus, easily available alpha-D-xylo-pentodialdo-1,4-furanose 5, obtained from D-glucose, on aldol-crossed Cannizzaro reaction followed by hydrogenolysis afforded 7. The regio-selective beta- and alpha-sulfonylation of hydroxymethyl groups in 7 afforded 8a (beta-sulfonylation) and 11 (alpha-sulfonylation) in good yields. The cleavage of the 1,2-acetonide functionality, individually in 8a and 11, followed by reaction with ethylenediamine gave in situ formation of sugar aminals that undergo concomitant nucleophilic displacement of the sulfonyloxy group, by amino functionality, to give hitherto unknown bicyclic diazasugars 4a and 4b, respectively. The inhibitory potency of the earlier reported bicyclic diazasugars 3a,b and 4a,b was evaluated against alpha- and beta-glycosidases and they were found to be potent and specific against the beta-glycosidases with IC(50) and K(1) values in the micro molar range.     

Iminoalditol-amino acid hybrids: synthesis and evaluation as glycosidase inhibitors

Cyclization by double reductive amination of D-xylo-hexos-5-ulose with the terminal amino group of alpha-N-Boc-lysine methyl ester gave a 4:1-mixture of (1'R)-N-methoxycarbonyl-(1-N-Boc-amino)pentyl-1-deoxynojirimycin and the corresponding L-ido epimer whereas D-lyxo-hexos-5-ulose furnished the desired N-alkylated 1-deoxymannojirimycin derivative without any observable epimer formation at C-5. By subsequent modification of the lysine moiety, additional chain-extended derivatives as well as fluorescent compounds were obtained. All fluorescent iminoalditol-amino acid hybrids prepared in this study exhibited glycosidase inhibitory activities better than or comparable to the parent compounds'.     

Synthesis and RT inhibitory activity evaluation of new pyrimidine-based seco-nucleosides

Eleven new 3',4'-seco acyclic nucleosides (4-14) were prepared by nucleophilic substitution of protected pyrimidine bases on ethyl 3,3-diethoxypropanoate (3). Structures were characterized spectroscopically and a brief analysis of their conformation in solution was performed by the vicinal coupling constants (3)JH2'aH3' and (3)JH2'bH3'. In solid state, compound 6 forms a homodimer linked by hydrogen bonding. In preliminary tests all compounds show low toxicity and gentle activity against HIV-1 RT in vitro.     

Synthesis of polyhydroxylated piperidines and evaluation as glycosidase inhibitors

A series of 16 new chiral nonracemic polyhydroxylated piperidines was synthesized utilizing several chiral beta-amino-alcohols. They act as a nitrogen source, chirality inducer and iminium stabilizer, in the desymmetrization of meso-trihydroxylated glutaraldehyde. The biological activity of these compounds towards several glycosidases (alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-fucosidase) has been evaluated.     

Synthesis and evaluation of sulfamide-type indolizidines as glycosidase inhibitors

A practical synthesis of reducing sulfamide-derived iminosugar glycomimetics related to the indolizidine glycosidase inhibitor family is reported. The polyhydroxylated bicyclic system was built from readily accessible hexofuranose derivatives through a synthetic scheme that involves 5,6-cyclic sulfamides. Further intramolecular nucleophilic addition of the sulfamide nitrogen atom to the masked aldehyde group of the monosaccharide in the open chain form afforded the target sugar mimics. By starting from d-glucose and d-mannose precursors, 2-aza-3,3-dioxo-3-thiaindolizidine derivatives with hydroxylation profiles that matched those of (+)-castanospermine and 6-epi-(+)-castanospermine were obtained. In vitro screening against a panel of glycosidases evidenced a high selectivity towards -mannosidase.     

Synthesis and glycosidase inhibitory activity of 1-amino-3,6-anhydro-1-deoxy-d-sorbitol derivatives

3,6-Anhydro-1-(aryl or alkylamino)-1-deoxy-d-sorbitol derivatives have been prepared in four steps from isosorbide, a by-product from the starch industry. The inhibitory activities of these new compounds have been evaluated towards 13 glycosidases. A first lead-compound was identified, which inhibited β-N-acetylglucosaminidase from bovine kidney (82% inhibition at 1 mM).     

Stereoselective synthesis and glycosidase inhibitory activity of 3,4-dihydroxy-pyrrolidin-2-one, 3,4-dihydroxy-piperidin-2-one and 1,2-dihydroxy-pyrrolizidin-3-one

3,4-Dihydroxy-pyrrolidin-2-one, 3,4-dihydroxy-piperidin-2-one and 1,2-dihydroxy-pyrrolizidin-3-one have been synthesized, using a simple strategy based on the asymmetric dihydroxylation of vinylogous aminoesters and subsequent mild intramolecular cyclization. All these compounds show a partial inhibition of alpha-glucosidase, but were inactive towards other glycosidases.     

The preparation and microbiological evaluation of the inhibitory effects of some acrylic acid derivatives

The following acrylic acid derivatives have been prepared and microbiologically evaluated as possible inhibitors of the growth of lactobacilli; indoleacrylic acid, β-(2-quinolyl)-, β-(3-quinolyl)-, β-(4-quinolyl) acrylic acids, cinnamic acid, p-hydroxycinnamic acid, p-dimethylaminocinnamic acid, p-diethylaminocinnamic acid, thienylacrylic acid, furylacrylic acid, and α-ethylacrylic acid.The utilization of tryptophan by Leuconostoc mesenteroides P-60 and Lactobacillus arabinosus was inhibited by the isomeric quinolylacrylic acid derivatives as well as by indoleacrylic acid. With this latter compound and the β-(3-quinolyl)acrylic acid, competitive inhibition was shown.p-Hydroxycinnamic acid inhibited the utilization of phenylalanine and tyrosine by all the organisms tested. At similar concentrations neither cinnamic acid nor phenol exerted any inhibitory effect.The effects of all inhibitors could be at least partially reversed by the addition of larger quantities of the corresponding amino acids.     

Lysosomal glycosidase activity in cultured human fibroblasts

A study was made of the activity of 3 lysosomal glycosidases -beta-D-galactosidase (K. P. 3.2.1.23), alpha-L-fucosidase (K. P. 3.2.1.51), N-acetyl-beta-D-hexosoaminidase (K. P. 3.2.1.52) depending on the time after subcultivation and duration of the passage of human skin embryonal and postembryonal fibroblasts. It was established that changes in the specific activity of the enzymes should be calculated with reference to the cell rather than to protein whose amount might vary considerably. It was also found that for measuring the specific activity of enzymes, of great importance are the procedures of cell removal from the base layer (by mechanical scraping off or by trypsin solution) and the regimen of the homogenization of cell preparations.     

Alkyl and alkoxycarbonyl derivatives of ginkgolide B: synthesis and biological evaluation of PAF inhibitory activity

Alkyl and alkoxycarbonyl derivatives 6-24 of ginkgolide B, prepared in one step from ginkgolide B through alkylation and acylation and evaluated for their in vitro ability to inhibit the PAF-induced aggregation of rabbit platelets, show equivalent or superior activities to ginkgolide B.