Ryuichi Oshima

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.

Resolution of the enantiomers of aldoses by liquid chromatography of diastereoisomeric 1-(N-acetyl-α-methylbenzylamino)-1-deoxyalditol acetates

Abstract Acyclic diastereoisomers, namely, 1-( N -acetyl-α-methylbenzylamino)-1-deoxyalditol acetates are readily obtained by reductive amination of aldoses with chiral α-methylbenzylamine (MBA) in the presence of sodium cyanoborohydride, and may be separated by reversed-phase 1.c. and, more effectively, by adsorption 1.c. According to this procedure, enantiomers of the common, neutral aldoses are resolved. In adsorption 1.c., l-l * [defined as an adduct of an l -aldose and l -(-)-MBA] is eluted before d-l * for erythrose, xylose, ribose, glucose, 4- O -methylglucose, galactose, and fucose, and the elution order is the reverse for arabinose, lyxose, mannose, rhamnose, and glyceraldehyde. This behavior is probably related to the configuration of C-2 of the aldoses.

Reversed-phase liquid chromatographic separation and identification of constituents of uroshiol in the sap of the lac tree, Rhus vernicifera

Abstract Uroshiol in the sap of lac tree, Rhus vernicifera , is directyly into more than ten components by reversed-phase liquid chromatography using acetonitrile—water—acetic acid (80:20:2 of 90:10:2) as the eluent. The 1 H NMR parameters, especially those for the triolefinic components, are presented. New substances, 3-(10′ Z , 13′ E , 15′ Z -heptadecatrienyl)catechol and 4-(8′ Z , 11′ E , 13′ z -pentadecatrienyl)catechol, were found, although they were contaminated with 3-(10′ Z , 13′ Z , 16′-heptadecatrienyl)catechol and 4-(8′ Z , 11′ Z 14′-pentadecatrienyl)catechol, respectively. The quantitation by this separation system with refractive index dection nearly coincides with the weight content of each component. Samples from two different sources, Hupei and Kiangsi in China, were analysed by this method.

Configuration of the olefinic bonds in the heteroolefinic side-chains of japanese lacquer urushiol: separation and identification of components of dimethylurushiol by means of reductive ozonolysis and high- performance liquid chromatography

Abstract The configuration of the olefinic bonds in the heteroolefinic side-chains of japanese lacquer urushiol components has been determined. Dimethylurushiol is resolved into ten components by combined high-performance liquid chromatography (HPLC) with Unisil QC18 and Hitachi 3043Ag gel columns due to the difference in the degree of unsaturation and the cis and trans configuration. Each resolved di- or triolefinic dimethylurushiol component was partially rreduced with hydrazine, and the monoelfinci side-chain dimethylurushiol formed was separated by HPLC on a Unisil QC18 gel column and submitted to reductive ozozolysis, followed by derivatization of the resulting aldeydes into the 2,4-dinitrophenylhydrazones. The hydrazones were identified by HPLC using a Hewlett-Packard 1084B chromatograph with a Deveosil ODS-3 gel column.

Structural studies of plant gum from sap of the lac tree, Rhus vernicifera

Abstract The plant gum isolated from sap of the lac tree, Rhus vernicifera (China), was separated into two fractions having mol. wt. 84,000 and 27,700 by aqueous-phase gel-permeation chromatography. The fractions contain d -galactose (65 mol%), 4- O -methyl- d -glucuronic acid (24 mol%), d -glucuronic acid (3 mol%), l -arabinose (4 mol%), and l -rhamnose (3 mol%). Smith degradation of the carboxyl-reduced polysaccharides gives products of halved molecular weight, and these consist of a β-(1→3)-linked galactopyranan main chain and side chains made up of galactopyranose residues. Peripheral groups, such as α- d -Gal p -, α- d -Gal p -(1→6)-β- d -Gal p -, 4- O -methyl-β- d -Glc p A-, and 4- O -methyl-β- d -Glc p A-(1→6)-β- d -Gal p -, are attached to this interior core through β-(1→3)- or β-(1→6)-linkages.

High-resolution gas—liquid chromatographic analysis of urushiol of the lac tree, rhus vernicifera, without derivatization

Abstract Fused-silica capillary gas—liquid chromatography has been successfully applied to the determination of urushiol congeners in the sap of the lac tree, Rhus vernicifera . A mixture of the urushiol congeners is satisfactorily separated into ten components on a 25 m x 0.2mm I.D. WCOT column coated with methylsilicone (thickness of stationary phase film, 0.33 μm) without any derivatization within 13 min with temperature-programmed operation from 230 to 290°C at 5dgC/min. The relatives standard deviation of quantification was less than 4% for abundant components, and that of retention time was as low as 0.4%. A number of saps of different origins were analysed by this method. The performance of saps is discussed in terms of the content of the triolefinic component, which has been accurately determined here.

Synthesis of water-soluble, branched polysaccharides having d-mannopyranose, d-arabinofuranose, or oligo-d-arabinofuranose side-chains and their antitumor activity☆

Branched polysaccharides having D-mannopyranose, D-arabinofuranose, or oligo-D-arabinofuranose side-chains were synthesized by the reaction of 3,4,6-tri-O-acetyl-(1,2-O-ethylorthoacetyl)-beta-D-mannopyranose, 3,5-di-O-benzoyl-(1,2-O-ethylorthobenzoyl)-beta-D-arabinofuranose, or 3-O-benzoyl-(1,2,5-O-orthobenzoyl)-beta-D-arabinofuranose with cellulose acetate or curdlan acetate, followed by desterification. The structure and antitumor activity of the water-soluble portion of the polysaccharides thus obtained were investigated. Polysaccharides synthesized from (1----3)-beta-D-glucan as the main chain with oligo-D-arabinofuranose side-chains exhibited high antitumor activity.

Separation of Japanese lac urushiol diacetate on silver nitrate-coated silica gel columns by high-performance liquid chromatography

Abstract Urushiol diacetate, derived from urushiol, a major component of the sap of Japanese lac trees (Rhus vernicifera), was separated into 14–16 peaks by high-performance liquid chromatography on 10% silver nitrate-coated LiChrosorb Si-60 and LiChroprep Si-60 columns (15 cm × 4 mm I.D. and 60 cm × 2.2 cm I.D., respectively) using benzene-chloroform (4:1) as eluent. Peaks were identified from UV and mass spectroscopic data, indicating that the separation of urushiol diacetate was due to the difference in the degree of unsaturation of the side-chain. Hexanol-1 was used for slurry packing the column.

Long chain phenols from the Burmese lac tree, Melanorrhoea usitate

Abstract Twenty eight constituents of the sap of the Burmese lac tree, Melanorrhoea usitate have been identified. The sap consists of homologues of thitsiol ( ca 20 %), laccol ( ca 10 %), urushiol (4 %), 3-substituted catechols with 12-phenyldodecyl ( ca 30 %), or 10-phenyldecyl groups ( ca 8 %), 4-substituted catechols ( ca 3 %), and 5-substituted resorcinols ( ca 1 %), with the same substituents. 3-Substituted phenols with characteristic side chain groups are also contained in smaller amount. The biosynthetic route of these secondary plant metabolites, especially of novel phenolic lipids with (ω-phenylalkyl side chains, is discussed.

3-(ω-Phenylalkyl)catechols: novel phenolic lipids found in sap of the Burmese lac tree, Melanorrhoea usitate

Novel phenolic lipids, 3-(12-phenyldodecyl)catechol (1) and 3-(10-phenyldecyl)catechol (2) have been isolated from sap of the Burmese lac tree, Melanorrhoea usitate.