3β-Hydroxysialic Acid Glycosides. I. Calcium-Binding Ability and Chemical and Enzymatic Stabilities

Methyl α- and β-glycosides of N-acetylneuraminic acid (Neu5Ac) and N-acetyl-3β-hydroxyneuraminic acid (Neu5Acβ3OH) (1-4) were prepared to evaluate their calcium-binding ability. (Methyl α-glucopyranosidonyl) α- and β-, and 4-methylumbelliferyl α-glycosides of Neu5Ac and Neu5Acβ3OH (5-10) were also synthesized for the comparison of chemical and enzymatic stabilities, respectively. Methyl β-glycosides of Neu5Ac and Neu5Acβ3OH, 3 and 4, respectively, showed intense calcium-binding abilities, while no such ability was observed in the corresponding α-glycosides, 1 and 2. The Neu5Aβ3OH glycosides, 6, 8, and 10, showed much stronger resistance to acidic hydrolysis and sialidase digestion than the corresponding Neu5Ac glycosides, 5, 7, and 9.