Synthesis of octyl O- and S-glycosides related to the GPI anchor of Trypanosoma brucei and their in vitro galactosylation by trypanosomal α-galactosyltransferases
摘要:
Octyl O- and S-glycosides of mono- to tri-saccharides related to the core structure alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->6)-alpha-D-Manp of the GPI anchor of Trypanosoma brucei have been prepared via regioselective protodesilylation and glycodesilylation of octyl O- and S-glycosides of 2-O-benzoyl-4,6-O-(1,1,3,3-tetraisopropyl-1,3-disiloxane-1,3-diyl)-alpha-D-mannopyranoside. The synthetic saccharides have been used as substrates for enzymatic alpha-galactosylation with membrane fractions of bloodstream forms of T. brucei strain 427 variants MIT at 1.4, MIT at 1.2, and MIT at 1.5, respectively. (C) 1996 Elsevier Science Ltd.
The synthesis of a series of alkyl (having from C6 to C20 aglycones), cyclohexyl, and cyclohexylalkyl alpha-d-mannopyranosides, 6-deoxygenated analogs, thioglycosides, and sulfones derived thereof, is reported. Here, under the in vitro assay conditions used, none of the 15 tested compounds acted as an inhibitor of the mannose transfer catalyzed by the enzymes present in mycobacterial membrane and cell
Synthesis, purification and liquid-crystalline behaviour of several alkyl 1-thio-d-glycopyranosides
作者:Saskia A. Galema、Jan B.F.N. Engberts、Henk A. van Doren
DOI:10.1016/s0008-6215(97)00185-7
日期:1997.10
This paper describes the synthesis, purification, and liquid-crystalline behaviour of a series of alkyl 1-thioglycopyranosides. The synthesis of these derivatives was carried out via a Lewis acid mediated coupling of the fully acetylated monosaccharide with an alkanethiol. The choice of the Lewis acid depends on the configuration of AcO-2, The carbohydrate-derived surfactants exhibit thermotropic liquid-crystalline behaviour. The alkyl 1-thioglycopyranosides form the expected smectic A phases upon heating. The clearing temperatures vary with alkyl chain length which is in accordance with the accepted model for the S-A phase of amphiphilic carbohydrate mesogens. For the alkyl 1-thiotalopyranosides, the clearing points are much lower than expected, presumably due to the formation of an intramolecular hydrogen bond in the talose moiety. (C) 1997 Elsevier Science Ltd.