A Chemoenzymatic Total Synthesis of the Neurogenic Starfish Ganglioside LLG‐3 Using an Engineered and Evolved Synthase
作者:Jamie R. Rich、Stephen G. Withers
DOI:10.1002/anie.201204578
日期:2012.8.20
An LLG‐3 oligosaccharide–fluoride (see scheme) can be assembled chemoenzymatically and readily coupled with various sphingosines by an engineered endoglycoceramidase glycosynthase. The lyso ganglioside products are acylated to generate the individual isomers identified in the heterogeneous natural isolates, as well as modified glycosphingolipids.
New glycosphingolipids, named agelasphins (1-8), have been isolated by antitumor and immunostimulatory bioassay-guided purification from an extract of a marine sponge, Agelas mauritianus. Strongly active agents in agelasphins had characteristic ol-galactosylceramide structures, the isolation of which from natural products has not previously been reported. The absolute configurations of agelasphins were elucidated by the total synthesis.