1350309-52-2Relevant academic research and scientific papers
Synthetic study and structural analysis of the antifreeze agent xylomannan from Upis ceramboides
Ishiwata, Akihiro,Sakurai, Ayaka,Nishimiya, Yoshiyuki,Tsuda, Sakae,Ito, Yukishige
experimental part, p. 19524 - 19535 (2012/02/01)
The novel antifreeze factor, xylomannan, first isolated from the freeze-tolerant Alaskan beetle Upis ceramboides, demonstrates a high degree of thermal hysteresis, comparable to that of the most active insect antifreeze proteins. Although the presence of a lipid component in this factor has not yet been verified, it has been proposed that the glycan backbone consists of a β-d-mannopyranosyl-(1→4)-β-d-xylopyranose-disaccharide-repeating structure according to MS and NMR analyses. In this contribution, we report the stereoselective synthesis of the tetrasaccharide β-d-mannopyranosyl- (1→4)-β-d-xylopyranosyl-(1→4)-β-d-mannopyranosyl-(1→4) -d-xylopyranoside, a structural component of xylomannan. Our synthesis features the use of 2-naphthylmethyl (NAP)-ether-mediated intramolecular aglycon delivery (IAD) as the key reaction in obtaining β-mannopyranoside stereoselectively. Various donors for NAP-IAD were tested to determine the most suitable for the purposes of this synthesis. Fragment coupling between a disaccharyl fluoride and a disaccharide acceptor obtained from a common β-d-mannopyranosyl-(1→4)-β-d-xylopyranoside derivative was successfully carried out to afford the desired tetrasaccharide in the presence of Cp2HfCl2-AgClO4. Structural analysis of the resulting synthetic tetrasaccharide using NMR techniques and molecular modeling was performed in order to demonstrate the presence of the proposed xylomannan linkages in this molecule.
