Rhamnose apiose

Fig. 18.—Sequence of Heptasaccharide Isolated from RG-II. [Fragment-ions of the deuteropermethylated derivative are shown. Cleavages are all of the A, Type. (Rha = rhamnose, Ara = arabinose, AceA = aceric acid, MeFuc = 2-0-methylfucose, and Api = apiose).]...

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]. 

According to Bell and associates,10 apiose, chromatographically examined, may be mistaken for rhamnose. This, and the fact that the sugar is now known to be present in two totally unrelated plants, suggests that it may be much more abundant in Nature than has been so far noted. 

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. 

In comparison with mammals, plants contain considerably more GTs because, in addition to the reactions carried out by mammalian GTs, they are required to convert the products of photosynthesis into diverse cell carbohydrates. For example, these GTs synthesize cell wall polysaccharides as well as secondary metabolites and xenobiotics. Plant GTs differ from mammalian GTs even more by their diversity of nucleotide donors. They use not only eight of the nine mammalian nucleotide donors, but numerous others such as UDP-L-rhamnose, GDP-L-glucose, GDP-L-galactose, UDP-L-arabinose, UDP-D-galacturonic acid, UDP-D-apiose, and so on. (29). 

About 130 saponins have been described in Astragalus spp. untill now. Table (2). D-xylose (xyl), D-glucose (g c), L-rhamnose (rha), L-arabinose (ara) represent the carbohydrate components of these glycosides pentoses are more frequent then hexoses. Apiose (apio), in the furanosic form, occurs only in cycloaraloside C, named also astrailienin A [140,61]. Glucuronic acid has been found only in pentacyclic triterpene saponins (as in soyasaponins). Astragalus saponins of cycloartane series... 

Pathways in the formation of NDP-sugars. A seiection of monosaccharide conversions occurring at the phosphate ester and nucieotide-monosaccharide ievei in animais, piants and bacteria are shown all pathways radiate from fructose-6-phosphate, indicating the central role of this metabolite. The dTDP, GDP and UDP-yV-acetylmu-ramic pathways are peculiar to bacteria, whereas ADP-o-glucose, UDP-o-apiose and UDP-L-arabinose are found in plants. For reasons of simplicity, other pathways, e. g., to UDP-L-rhamnose in plants, GDP-o-rhamnose in Pseudomonas aeroginosa and GDP-o-arabinose in trypanosomatids are not included. The figure is reproduced from Chap. 6.4 of the first edition of this book... 

Mol., Molecular WP, white powder AP, amorphous powder WAS, white amorphous solid WAP, white amorphous powder AS, amorphous solid Pyr, pyridine Glu, glucose Gal, galactose Gul, gulose Rha, rhamnose Fuc, fucose Apio, apiose Xyl, xylose Ara, arabinose Qui, quinovose p, pyranosyl f, furanosyl. 

Also it might compare the activity of forsythoside with poliumoside and angoroside A, all of them with three sugars moieties, but, differing on the last one, apiose, rhamnose and arabinose, respectively, joined at the same position of the second sugar moiety, rhamnose. 

Fig. 3.21. Structure of rhamnogalacturonan II (RG-II) (Doco and Brillouet, 1993). a-o-GalAp galacturonic acid a-D-Galp galactopyranoside /3-L-Rhap /3-L-rhamnopyranose (rhamnose) a-L-Ara/ a-L-arabinofuranose (arabinose) a-L-Fucp = a-L-fucopyranose (fucose) 2-0-Me-a-D-xylose 2-0-methyl-a-D-xylose /3-D-GlcAp /3-D-glucuropyranosic acid (glucuronic acid) /3-D-Api/ /3-D-apiofuranose (apiose) KDOp 3-dioxy-D-manno-2-octululopyranosic acid /3-D-DHA/ /3-deoxy-D-lyxo-2-heptulafuronosic acid /3-L-AceA/ /3-3-C-carboxy-5-deoxy-L-xylofuranose (aceric acid) Me methyl...

The existence of a non-volatile, odorless fraction of the terpene aroma in Muscat grapes which could be revealed by chemical or enzymic means was demonstrated for the first time by Cordonnier and Bayonove (1974). Several teams (Williams et al, 1982 Giinata, 1984 Voirin et al, 1990) later established that the main monoterpenols and terpene polyols were present in grapes in glycoside form, including the basic oses glucose, arabinose, rhamnose and apiose. 

Acid hydrolysis of compound 2 afforded echinocystic acid la, as well as glucuronic acid, arabinose, xylose, rhamnose and apiose. While on alkaline hydrolysis of 2, the prosapogenin lb was obtained. They were identified by direct comparison (PC and HRTLC) with authentic samples. 

The monosaccharides in the glycosides include o-xylose, o-glucose, o-galactose, D-aUose, D-apiose, D-fucose, o-quinovose, o-glucuronic acid, L-arabinose, and L-rhamnose. 

A series of polysaccharides have been isolated from the sea grass, Phyllos-padix torreyi, which are unusual in containing residues of o-apiose (2—28 One of these polysaccharides had the composition, L-rhamnose, L-arabinose, D-xylose, D-apiose, D-galactose, and D-mannuronic acid in the molar ratio 4 1 5 2 4 9. Of the D-apiose residues 80 % were oxidized by periodate and the major neutral sugar residues found in the hydrolysate of the methylated polysaccharide were 2,3,5-tri-O-methyl-L-arabinose, 2,5-di-O-methyl-L-arabinose, 3,4-di-O-methyl-L-rhamnose, 2,3-di-O-methyl-D-xylose, 2,3,6-tri-0-methyl-D-galactose, and 2,4-di-O-methyl-D-galactose in the ratio 1 1 6 6 3 3. 

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