Methylation-GC-MS analysis of arabinofuranose- and galactofuranose-containing structures: rapid synthesis of partially O-methylated alditol acetate standards
Abstract:Arabinose and galactose were treated with MeOH containing traces of H 2 SO 4 or HCl at 25 • C to give mixtures of their methyl alpha-and beta-furanosides, as shown by 1D and 2D nuclear magnetic resonance (NMR). Oxidation of the Me alpha,beta-Araf mixture with NaIO 4 preferentially oxidised the beta-isomer, to give pure Me alpha-Araf . Each product was progressively O-methylated using the Purdie reagent (MeI/Ag 2 O) at 25 • C and resulting mixtures of partially methylated glycosides (PMGs) were rapidly assayed … Show more
“…1B). The mass spectrum of the former peak was different from that of the latter peak, but rather the same spectrum as terminal Galf electron impact ionization spectrum (Sassaki, Iacomini, & Gorin, 2005). Thus, these results confirmed that the terminal furanose residue was a Galf.…”
“…1B). The mass spectrum of the former peak was different from that of the latter peak, but rather the same spectrum as terminal Galf electron impact ionization spectrum (Sassaki, Iacomini, & Gorin, 2005). Thus, these results confirmed that the terminal furanose residue was a Galf.…”
“…49. Briefly, 30 mg of galactose were stirred in 2 ml of 0.5% (w/w) methanolic hydrogen chloride (MeOH-HCl) at 25°C until complete dissolution (16 h).…”
Section: Synthesis Of the Methyl Galactofuranoside Standard-mentioning
Background: Galactofuranose, the five-membered ring form of galactose, occurs in the encapsulated pathogenic fungus Cryptococcus neoformans but not in humans. Results: We established the position of galactofuranose within a capsule polysaccharide and characterized cryptococci lacking this modification. Conclusion: Galactofuranose occurs in an unusual linkage but is not required for growth or virulence. Significance: This work fills a gap in knowledge about a pathogen-specific modification.
“…The results showed that it was not prone to the oxidative deficiencies of the original and that, given its reduced tendency towards polysaccharide undermethylation. The preparation of permethylated carbohydrates for GC and LC analysis has been the subject of several reviews (91)(92)(93).…”
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