N-methyl-O-benzylhydroxylamine derivatives of sialylated oligosaccharides, their synthesis and separation with reversed-phase HPLC

The human milk trisaccharide 3'- sialyllactose was reacted with an excess of N-methyl-O-benzylhydroxylamine (MBHA) and the product 3'- sialyllactose-MBHA was isolated in high (91%) yield by solid-phase extraction. The isomeric trisaccharide 6'-sialyllactose-MBHA was also prepared, in this case by enzymatic sialylation of lactose-MBHA. A 50/50 mixture of the two sialyllactose-MBHA derivatives was easily separated by reversed-phase HPLC. The free oligosaccharides were recovered from their respective MBHA derivatives by acid hydrolysis.