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The total synthesis of ganglioside PNG-2A from the starfish Protoreaster nodosus and its neuritogenic activity toward neuron-like cells is described. The unique galactose-enriched glycan moiety, in which an 8- O-methyl sialic acid residue is sandwiched between galactose residues, was constructed through an efficient 8- O-methylation and subsequent di- tert-butylsilylene-assisted α-glycosylation at the 4-OH of the sialic acid residue with a Gal fβ(1,3)Gal donor. In vitro biological evaluation in a rat adrenal pheochromocytoma (PC12) cell line revealed that the synthesized PNG-2A potentiated the neurite outgrowth of PC12 cells in the presence of nerve growth factor (NGF). [ABSTRACT FROM AUTHOR]

The first total synthesis of neuritogenic ganglioside GAA-7 was achieved using the glucosyl ceramide (Glc-Cer) cassette approach. The stereocenter triad within the ceramide moiety of the target molecule was efficiently established from D-lyxose. The assembly of the ceramide moiety was followed by glycosylation with glucosyl donors to give Glc-Cer cassettes, which underwent conjugation with the oligosaccharide moiety, followed by global deprotection. By using the most suitable Glc-Cer cassette, the target molecule was successfully synthesized. In vitro evaluation indicated that the synthesized GAA-7 and its glycan moiety both showed strong neuritogenic activity towards neuron-like rat adrenal pheochromocytoma (PC12) cells in the presence of neurite growth factor. [ABSTRACT FROM AUTHOR]