Apiose methylation

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]. 

A free disaccharide containing apiose has been extracted from an Australian shrub, the native hop bush, Daviesia latifolia.40 The disaccharide was isolated as a dibenzoate. Methylation followed by de-benzoylation, as well as comparison with the disaccharide of D-apiose from apiin, suggested that they are similar in every aspect measured. Thus, the structure of the disaccharide without its two benzoyl groups is, tentatively, 2-O-D-apiofuranosyl-D-gIucose.40 The... 

The value of some nucleosides for use as flavor enhancers,1348 and the possible antiviral or antitumor activity of certain nucleosides,135 have led to the synthesis of purine nucleosides containing analogs of D-apiose in which the ring-oxygen atom of the furanose forms has been replaced.136 Monomolar p-toluenesulfonylation of 3-C-(hydroxy-methyl)-l,2-0-isopropylidene-/3-L-threofuranose (50) yielded 3-C-(hydroxymethyl)-l,2-0-isopropylidene-31-0-p-tolylsulfonyl-/3-L-thre-ofuranose (51) which, through a series of steps, was converted into either methyl 2,3-O-isopropylidene- [3-C-(hydroxymethyl)-4-thio-/3-D-... 

Add (pick) saccharide residues from the list of aldoses (hexoses in al-dopyranose form, pentoses in aldofuranose form, and tetraoses in open-chain form), ketoses (hexoses in ketofuranose form, pentoses and tetraose in open-chain form), derivatives (glucosamine, galactosamine, N-acetylnuraminic acid, N-acetyl muramic acid, inositol, 2-deoxyribose, rhamnose, fucose, and apiose), and blocking groups (H, NH2, =0, COO—, methyl, lactyl, O-methyl, iV-methyl, O-acetyl, iV-acetyl, phosphoric acid, sulfate, iV-sulfonic acid) to build polysaccharides. 

The reader is invited to construct the models, formulas and names for two Y-laotones of apionic acid and for the four methyl apiohexofuranosides and eight methyl apiohexopyranosides that are indicated by theory as derivable from the hexoses that should result frona the application of the cyanohydrin synthesis to apiose. 

Overend, W G, White, A C, Williams, N R, Branched-chain sugar Part XII. Branched-chain sugars derived from methyl 2,3-0-isopropylidene-p-L-ery/hro-pentopyranosid-4-ulose, and a synthesis of L-apiose, Carbohydr. Res., 15, 185-195, 1970. 

The unusual sugars such as apiose, aceric acid, or KDO require special techniques for their detection and characterization. However, 0-methylated sugars can be characterized by GLC-MS of their alditol acetates (Darvill et al., 1978). Mono-O-methylated derivatives elute faster than their completely acetylated homologues. This can be illustrated by comparison of the retention times (on a SP-1000 glass capillary column) of the acetylated derivatives of xylitol (R-0.71) and 4-0-methylxylitol (R-... 

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