Kenichi Hamayasu

6-O-α-(4-O-α-D-glucuronyl)-D-glucosyl-β-cyclodextrin: Solubilizing ability and some cellular effects

Some physicochemical and biopharmaceutical properties of a new branched cyclodextrin, 6-O-α-(4-O-α-d-glucuronyl)-d-glucosyl-β-cyclodextrin (GUG-β-CyD), were investigated. The interaction of GUG-β-CyD with drugs was studied by spectroscopic and solubility methods, and compared with those of parent β-CyD and 6-O-α-maltosyl-β-CyD (G2-β-CyD). The hemolytic activity of GUG-β-CyD on rabbit erythrocytes was lower than those of β-CyD and G2-β-CyD. GUG-β-CyD and G2-β-CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG-β-CyD to neutral and acidic drugs was comparable to or slightly smaller than those of β-CyD and G2-β-CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG-β-CyD showed greater affinity for the basic drugs, compared with β-CyD and G2-β-CyD, owing to an electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus, GUG-β-CyD may be useful as a safe solubilizing agent particularly for basic drugs.

Enzymatic Synthesis of Mannosyl-cyclodextrin by α-Mannosidase from Jack Bean

Mannosylated derivatives of cyclodextrins (CDs), mannosyl-α, β, and γCD were synthesized from a mixture of mannose and α, β, and γCD by the reverse action of α-mannosidase from jack bean, respectively. Their structures were analyzed by FAB-MS and 13C-NMR spectroscopies, and they were identified as 6-O-α-d-mannosyl-α, β, and γCD. The optimum conditions for the production of 6-O-α-d-mannosyl-αCD by α-mannosidase were examined. Optimum pH and temperature were pH 4.5 and 60°C, respectively. Yield of mannosyl-αCD increased with increasing mannose concentration and reached more than 35% (mol/mol) at the concentration of 2 m mannose and 0.4 m αCD.

Complex of branched cyclodextrin and lidocaine prolonged the duration of peripheral nerve block

Although laboratories have tried to synthesize new local anesthetics, currently available local anesthetics rarely provide prolonged regional blockade. New models of sustained-release preparations of local anesthetics with liposomes and microspheres have been studied to prolong the duration of the effects of the local anesthetics. In the present study, we examined whether a complex of a branched cyclodextrin (CD), 6-O-α-D-maltosyl-β-cyclodextrin (G2-β-CD) and lidocaine could prolong local nerve block when compared with plain lidocaine. The sciatic nerve in male Sprague-Dawley rats was blocked with plain lidocaine (n = 10), the complex of G2-β-CD + lidocaine (n = 10), or plain G2-β-CD (n = 4). Sensory block was assessed with a hotplate set at 56°C. The median duration of the block was longer in the complex group than in the plain lidocaine group (110 min; range, 70–150 min vs 55 min; range, 40–80 min; P < 0.05), thus demonstrating that the complex with CyD significantly prolonged the nerve block effect of lidocaine. In conclusion, the present study showed that this encapsulating technique with CyD is useful to expand local anesthetic effect in peripheral nerve blockade.

Some Pharmaceutical Properties of a New Branched Cyclodextrin, 6-O-α-(4-O- α-D-Glucuronyl)-D-glucosylβ-cyclodextrin

Some physicochemical and biological properties of a new branched cyclodextrin, 6-O-α-(4-O-α-d-glucuronyl)-d-glucosyl-β-cyclodextrin GUG-β-CyD) were investigated. Further, theinteraction of GUG-β-CyD with several drugs was studied by the solubility and spectroscopic methods, and compared with those of parent β-CyD and 6-O-α-maltosyl-β-CyD(2-β-CyD).The hemolytic activity of GUG-β-CyD on rabbit erythrocytes was lower than those of β-CyD and 2-β-CyD. GUG-β-CyD and 2-β-CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG-β-CyD to neutral and acidic drugs was comparable to or slightly smaller than those of β-CyD and 2-β-CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG-β-CyD showed greater affinity for the basic drugs, compared with β-CyD and 2-β-CyD, owing to the electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus GUG-β-CyD may be useful as a safe solubilizing agent particularly for basic drugs.

Isolation and characterization of di- and tri-mannosyl-cyclomaltoheptaoses (β-cyclodextrins) produced by reverse action of α-mannosidase from jack bean

Abstract Di- and tri-mannosyl-cyclomaltoheptaoses (β-cyclodextrins, βCDs), which were synthesized together with mono-mannosyl-βCD in a large-scale production by reverse action of α-mannosidase from jack bean, were isolated and purified by HPLC. The structures of seven isomers of di-mannosyl-βCD and six isomers of tri-mannosyl-βCD were elucidated by FABMS and NMR spectroscopy, and by enzymatic methods.

Inhibition of β-fructofuranosidases and α-glucosidases by synthetic thio-fructofuranoside

A synthetic β-thio-fructofuranoside of mercaptoethanol inhibited not only β-fructofuranosidases but also α-glucosidases. The compound was hardly hydrolyzed by the glycosidases. The thio-fructoside competitively inhibited β-fructofuranosidases from Aspergillus niger, Candida sp., and Saccharomyces cerevisiae, but not Arthrobacter β-fructofuranosidase at all. Sucrase activity of rat intestinal sucrase/isomaltase complex was also suppressed in the presence of the thio-fructoside. The thio-fructoside showed noncompetitive inhibition toward maltase activity of the rat intestinal enzyme complex and Saccharomyces sp. α-glucosidase. Inhibition against the Bacillus stearothermophilus α-glucosidase, Rhizopus glucoamylase, and porcine kidney trehalase were more slight than that against these two α-glucosidases.

Isolation and structural analyses of positional isomers of 61,6m-di-O-α-d-mannopyranosyl-cyclomaltooctaose (m=2–5) and 6-O-α-(n-O-α-d-mannopyranosyl)-α-d-mannopyranosyl-cyclomaltooctaose (n=2, 3, 4, and 6)

Eight positional isomers of 6(1),6m-di-O-alpha-D-mannopyranosyl-cyclomaltooctaose (gamma CD) (m = 2-5) and 6-O-alpha-(n-O-alpha-D-mannopyranosyl)-D-mannopyranosyl-gamma CD (n = 2, 3, 4, and 6) in a mixture of products from gamma CD and D-mannose by condensation reaction of alpha-mannosidase from jack bean were isolated by HPLC. The structures of four isomers of 6-O-alpha-(n-O-alpha-D-mannopyranosyl)-D-mannopyranosyl-gamma CD were elucidated by NMR spectroscopy. On the other hand, four positional isomers of 6(1),6m-di-O-alpha-D-mannopyranosyl-gamma CD were determined by LC-MS analysis of degree of polymerization of the branched oligosaccharides produced by enzymatic degradation with bacterial saccharifying alpha-amylase (BSA), and combination of BSA and glucoamylase. Similarly cyclomaltodextrin glucanotransferase also digested these isomers.

Isolation and structural analyses of positional isomers of 61,6n-di-O-(N-acetyl-β-d-glucosaminyl)cyclomaltoheptaose (n=2, 3, and 4) and 6-O-[6-O-(N-acetyl-β-d-glucosaminyl)-N-acetyl-β-d-glucosaminyl]cyclomaltoheptaose

Abstract 6- O -[6- O -( N -acetyl-β- d -glucosaminyl)- N -acetyl-β- d- glucosaminyl]cyclomaltoheptaose (βCD) and three positional isomers of 6 1 ,6 n -di- O -( N -acetyl-β- d -glucosaminyl)cyclomaltoheptaose ( n =2, 3, and 4) in a mixture of products from βCD and N -acetylglucosamine by the reversed reaction of β- N -acetylhexosaminidase from jack bean were isolated and purified by HPLC. The structures of four isomers of di- N -acetylglucosaminyl-βCDs were determined by FABMS and NMR spectroscopy. The degree of polymerization of the branched oligosaccharides produced by enzymatic degradation with bacterial saccharifying α-amylase (BSA) was established by LC–MS methods.