Fucose 2-0-methyl

The synthesis of 2-methyl-D-fucose was carried out first directly from D-fucose. Methylation of methyl 3,4-isopropylidene-D-fucopyranoside (XI) and hydrolysis of the glycosidic methyl group in the product (XII) led directly to the desired sugar (XIII). 

The carbohydrate has sites for ionic interaction (clusters of sialic acid or sulphate residues) and also hydrophobic interaction (clusters of hydrophobic methyl groups offered by fucose residues). Sedimentation velocity has been a valuable tool in the selection of appropriate mucoadhesives and in the characterisation of the complexes [ 138-143]. 

The glycosyl-residue compositions of the three purified fractions (Table 1) were very similar with a predominance of galacturonic acid, rhamnose and arabinose. The presence in the three purified fractions of the rare monosaccharides characteristic of RG-II (e.g. 2-( -methyl-L-fucose, 2-O-methyl-D-xylose, apiose, Kdo, Dha and aceric acid) was confirmed by GC-CIMS analysis. The molar ratios corresponded approximately to the known structure of the RG-II molecule (Figure 1) and to previously published data for RG-II from sycamore [26], rice [4], arabidospis leaves [8] and Pectinol [12]. 

The glycosyl-linkage compositions of our three RG-II preparations were similar (Table 2) and corresponded to the relative sugar molar ratios obtained from compositional (TMS derivatives) analyses indicating that methylation was complete. Almost all the methyl ethers obtained could be attributed to known residues of the RG-II molecule (Figure 1) and our data were in accordance to that previously reported for RG-II from different plant origins [3,8,12,20,26]. The relative molar ratios of these "characteristic" methyl ethers (calculated on the basis of 1 residue of 3,4-linked fucose) were almost all in stoichiometric amounts (Table 3), confirming thus that our three preparations corresponded to the accepted model for RG-II. 

Relative molar ratios (calculated on the basis of 1 residue of 3,4-linked fucose) of methyl ethers characteristic for RG-II in the preparations isolated from fruit-derived products... 

The latter was isolated in the form of fully methylated methyl fuco-side, i. e., methyl 2,3,4-trimethyl-a-L-fucoside (XLVII), a compound previously obtained from methylated gum tragacanth.128 The recognition of this particular derivative indicates that the n-fucose residues in part at least must constitute end groups linked glycosidically to the rest of the molecule. The same compound128 was isolated by methylation and... 

Maher, George G., The Methyl Ethers of the Aldopentoses and of Rhamnose and Fucose, X, 257-272 Maher, George G., The Methyl Ethers of D-Galactose, X, 273-282 McColloch, R. J. See Kertesz, Z. I. McDonald, Emma J., The Polyfructo-sans and Difructose Anhydrides, II, 253-277... 

From his time at the Squibb research laboratories, he was interested in the chemistry of antibiotics, and in this area, he elucidated the partial structure of curamycin, an antibiotic produced by Streptomyces curacoi. From curamycin, he isolated and characterized the new natural sugar derivatives D-curacose (4-O-methyl-D-fucose), curacin [4-0-(dichlo-roisoeveminyl)-2,6-dideoxy-D-araW/io-hexose], and curamycose (2,6-di-O-methyl-D-mannose). 

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