Gwendolyn M. Bebault

Synthesis of 4-O-β-D-mannopyranosyl-L-rhamnopyranose

Abstract The title disaccharide ( 16 ) has been synthesized in 50% overall yield by way of condensation of 4,6-di- O -acetyl-2,3- O -carbonyl-α- D -mannopyranosyl bromide 5 with methyl 2,3- O -isopropylidene-α- L -rhamnopyranoside ( 1 ) in chloroform solution, in the presence of silver oxide. The disaccharide was characterized as the crystalline isopropyl alcoholate of methyl 4- O -β- D -mannopyranosyl-α- L -rhamnopyranoside ( 11 ) and as 1,2,3-tri- O acetyl-4- O - (2,3,4,6-tetra- O -acetyl-β- D -mannopyranosyl)-α- L -rhamnopyranose ( 15 ). Methyl β- D -mannopyranoside isopropyl alcoholate 7 was readily obtained in 85% yield via the reaction of bromide 5 with methanol. Reduction of 2,3-di- O -methyl- L -rhamnose with sodium borohydride, followed by acetylation, may result in the formation of an appreciable proportion of a boric ester, namely 1,5-di- O -acetyl-4-deoxy-2,3-di- O -methyl- L -rhamnitol-4-yl dimethyl borate, depending on the procedure used.

Synthesis of 4-O-α-D-Mannopyranosyl-L-rhamnopyranose

4-O-α-D-Mannopyranosyl- L-rhamnopyranose has been synthesized in 55% yield by condensation of 2,3,4,6-tetra-O-benzoyl- α-D-mannopyranosyl bromide with methyl 2,3-O-isopropylidene-α-L-rhamno-pyranos...

Assay of keratan sulfate as anion-Exchanger bound hexose

An assay for keratan sulfate in papain digests of human intervertebral disc and other tissues has been developed. The digest is applied to the acetate form of a tertiary amine acrylic anion-exchange resin, the oligosaccharide hexose is removed by washing the resin with 0.2 M sodium acetate buffer pH 5.0, then the keratan sulfate is eluted quantitatively with 1.0 M pyridinium sulfate pH 2.5 and assayed for hexose by the anthrone reaction. The keratan sulfate content of human intervertebral disc tissues ranged from 7 to 78 mumole galactose equivalents/g fresh weight; the root mean square error was 2 mumole/g; 10-25 mg of tissue were required. The separation of oligosaccharides from keratan sulfate was confirmed by gel permeation chromatography, sugar composition, ester sulfate analysis, and nuclear magnetic resonance.