Kaname Katsuraya

Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy

The constitution of konjac glucomannan was determined by methylation analysis and 13C NMR spectroscopy. The results of methylation analysis showed that the branching point is C-6 carbon of glucosyl units. 13C NMR spectroscopy (1D and DEPT) of konjac glucomannan supported the presence of β-C-1-linked C-6 carbon of glucosyl units as the branching units. This result differs from previous investigations. The 13C NMR spectra indicated that the ratio of terminal glucosyl units to terminal mannosyl units is ca. 2 and branching frequency is ca. 8%, supporting the results by Smith et al. From the splitting of main chain signals the sequences of glucosyl and mannosyl units in konjac glucomannan are estimated and a model structure for the glucomannan is proposed.

Sulfated alkyl oligosaccharides with potent inhibitory effects on human immunodeficiency virus infection

Compounds with medium relative molecular masses active against human immunodeficiency virus (HIV) were synthesized. Sulfated alkyl oligosaccharides such as sulfated octadecyl maltohexaoside, sulfated dodecyl laminaripentaoside and sulfated dodecyl laminari-oligomer caused 50% inhibition of virus infection in the EC50 range of 0.4-0.7 microgram/mL in vitro using the MT-4 cell line and HIV-1HTLV-IIIB virus isolate, though sulfated oligosaccharides without alkyl groups showed low anti-HIV activities. This anti-HIV activity was close to the EC50 of 0.43 microgram/mL for a highly active sulfated polysaccharide curdlan sulfate which was reported to inhibit completely the HIV infection at a concentration as low as 3.3 micrograms/mL. These compounds were also active against HIV-2 and a clinically isolated HIV-1 with reduced AZT sensitivity. For such sulfated alkyl oligosaccharides, the mechanism of inhibition of HIV infection was assumed to be the inhibition of HIV binding to the cell and to some extent the interaction of the alkyl portion with the lipid bilayer of the virus.

Synthesis of sulfated oligosaccharide glycosides having high anti-HIV activity and the relationship between activity and chemical structure.

Sulfated laminara-oligosaccharide glycosides having high anti-human immunodeficiency virus (HIV) activities were synthesized from laminara-tetraose, -pentaose and -hexaose. The oligosaccharide glycosides were synthesized by treating peracetylated beta-oligosaccharides with various alcohols and Lewis acid catalysts. The effects of the number of glucose residues and the alkyl chain-length on anti-HIV activity were examined. The anti-HIV activity of sulfated dodecyl laminara-pentaosides and -hexaosides increased with increasing degree of sulfation (DS) and the pentaoside having an almost fully-sulfated saccharide portion had the highest activity, whereas for the hexaoside a somewhat lower DS manifested the highest activity. Sulfated laminara-oligosaccharide glycosides having fluoroalkyl-containing aglycons of high hydrophobicity showed potent inhibitory effects against HIV infection. In contrast, hydrophilic substituents containing oligo(ethyleneoxy) groups as aglycons in the sulfated oligosaccharides did not show high anti-HIV activity.

Synthesis of sulfated alkyl malto- and laminara-oligosaccharides with potent inhibitory effects on AIDS virus infection

A series of sulfated alkyl oligosaccharides, including a sulfate dodecyl laminarapentaoside and a sulfated octadecyl maltohexaoside with potent anti-human immunodeficiency virus (HIV) activity, has been synthesized. An alkyl oligosaccharide in which a long alkyl group is bonded to the reducing end of the oligosaccharide was first synthesized in high yield. Peracetylated oligosaccharides reacted with such aliphatic alcohols as 1-decyl and 1-dodecyl alcohols with Lewis acids as catalysts. As in the glycosylation of the alpha and beta peracetylated glycosides, the beta anomer reacted exclusively, the acetylation was carried out with a sodium acetate-acetic anhydride at high temperatures to maximize the proportion of the beta anomer.

β-Cyclodextrin Conjugates with Glucose Moieties Designed as Drug Carriers: Their Syntheses, Evaluations Using Concanavalin A and Doxorubicin, and Structural Analyses by NMR Spectroscopy

Three kinds of beta-cyclodextrin derivatives conjugated with glucose moieties, which were expected as models for a drug carrier targeting the drug delivery systems, were designed and synthesized from beta-cyclodextrin and the natural product, 4-hydroxyphenyl-beta-D-glucopyranoside called arbutin. Arbutin was used because it had a phenyl group with a hydroxyl function which could be used to link the glucose moiety to beta-cyclodextrin. The evaluations of these conjugates as the drug-carrying molecules were done by investigating the molecular interactions with the carbohydrate-binding Concanavalin A (Con A) lectin and the anticancer agent, doxorubicin (DXR), using an SPR optical biosensor. The association constants of the conjugates with immobilized Con A were 2.0 x 10(3) approximately 8.8 x 10(3) M(-1). The result showed that the Con A bound to the glucose moieties from arbutin in the conjugates with prospective association constants. The inclusion associations of the conjugates with immobilized DXR reached 2.2 x 10(5) approximately 1.4 x 10(8) M(-1). The extremely high inclusion associations for DXR suggested their potential abilities as drug-carrying molecules for carrying DXR. The NMR analyses indicated that the phenyl group of the conjugates greatly served to increase the inclusion associations for DXR. In their DXR inclusion complexes, the formation of the stacking complexes by the pi;-pi interactions between the phenyl groups and the included DXR also enhanced their inclusion abilities for DXR.

Assignment of finely resolved 13C NMR spectra of polyacrylonitrile

Abstract Finely resolved 13C NMR spectra of atactic and isotactic-rich polyacrylonitriles were determined. Assignments of nitrile carbon spectra with pentads were quantitatively confirmed. Methylene carbon spectra were assigned with hexads. Radically obtained polymer obeyed Bernoullian statistics. The polymerization mechanism of isotactic-rich polymer obtained from urea–canal complex is complicated and both the first and the second-order Markov statistics do not hold. The chemical shifts of nitrile carbon signals moved considerably toward up-field as the temperature is raised, due to change of solvation.

Sulfated Alkyl Oligosaccharides Inhibit Human Immunodeficiency virus in vitro and Provide Sustained Drug Levels in Mammals

This study provides an estimate of the relative anti-human immunodeficiency virus (HIV) activities of synthetic sulfated alkyl oligosaccharides in vitro and of their mechanism of action, and an assessment of the levels of alkyl oligosaccharides in small mammals. The antiviral activities of the compounds against several human immunodeficiency virus type-1 and type-2 strains were determined in human CD4+ cells, including primary lymphocytes and macrophages. Laser flow cytometry and a cell-based syncytium assay were used to elucidate the anti-binding/fusion properties of the oligosaccharides. The sulfated alkyl laminarioligosaccharide DL-110 was shown to be the most potent and selective anti-HIV agent in culture with a median inhibitory concentration of 0.2 μM in primary human lymphocytes. This compound did not markedly interact with the CD4+ receptor on lymphocytes at 50 μM, but demonstrated potent anti-syncytium properties in vitro at submicromolar concentrations. DL-110 had no anti-coagulation activity at 38 μM. Mice, rabbits and beagle dogs were given an intravenous injection of test compounds and the drug levels in serum were quantified. When 32 mg kg−1 of DL-110 was administered to mice, significant antiviral concentrations in serum were achieved even 12 h after treatment. Similarly, prolonged antiviral effects were noted in rabbits and dogs 24 h after injection of DL-110. The half-life of DL-110 in mice, rabbits and dogs was estimated to be 5 h. DL-110 and some of its derivatives are promising candidates for further evaluation of the prophylaxis and therapy of HIV infections.

Assignment of finely resolved 13C NMR spectra of poly(vinyl acetate)

13 C NMR spectra of two poly(vinyl acetate)s (PVAC) with different tacticities (r-diad, 0.54 and 0.57) were measured, and their peak intensities were compared with the calculated ones. The methine carbon signals were assigned with pentads in the order on mmmm, mmmr + rmmr, rmrr + mmrr, rrrr, mmrm, rmrm, mrrr, mrrm from low field. The methylene carbon signals were assigned with tetrads (partly with hexads) as rmr, rrr(mrrrm, mrrrr, rrrrr), mmr + mrr, mrm and mmm from low field. Some assignments are different from those previously reported. The methyl carbon signals showed splittings which were partly assigned. ―

Assignment of finely resolved 13C NMR spectra of poly(vinyl alcohol)

Abstract 13C NMR spectra of three poly(vinyl alcohol)s differing in the stereoregularity (atactic, syndiotactic-rich and isotactic-rich) were determined in DMSO-d6 and D2O. The methylene and methine carbon absorptions including so far unassigned ones (mmmr heptad signals in mm-centered region and all heptad signals in mr-centered region) were completely assigned with hexads and heptads, respectively, and the assignments were quantitatively confirmed for atactic and syndiotactic-rich poly(vinyl alcohol)s. The isotactic-rich polymer showed a discrepancy between the observed and the calculated intensities, assuming the first-order Markov statistics, due to difficulty in determining its polymerization mechanism.

Chemo-enzymatic production of fuel ethanol from cellulosic materials utilizing yeast expressing β-glucosidases

Ethanol was produced in a considerably high yield by fermenting hydrolyzates from cellulosic materials by means of a recombinant laboratory yeast expressing β-glucosidases. Tissue paper, cotton, and sawdust were hydrolyzed by two-step sulfuric acid hydrolysis to give mixtures containing glucose, cellobiose, and higher cello-oligosacc arides. After the cellulosic material was partially hydrolyzed with 80% sulfuric acid, the hydrolysis was continued with 5% sulfuric acid. Except for non-carbohydrate components, all constitutents in the hydrolyzates were fermented by the yeast that was preincubated in the medium that the plasmid encoded by the β-glucosidases gene was kept in the muliplicated yeast. A solution containing 4% hydrolyzates from paper was fermented to give as high as 1.9% maximum ethanol concentration and 70% ethanol conversion. Cotton also gave a similar result. Sawdust was converted into ethanol in approx 22% conversion. Accordingly, it was revealed that the β-glucosidases-expressing yeast can ferment the cello-oligosaccharides obtained by hydrolysis of cellulosic materials into ethanol. In addition, a hydrolyzate containing a high glucose proportion gave a high ethanol concentration in a short time.