Synthesis of monomethyl derivatives of p-nitrophenyl α-D-gluco, galacto, and mannopyranosides and their hydrolytic properties against α-glycosidases

All possible monomethyl derivatives of p-nitrophenyl alpha-D-gluco, galacto, and mannopyranosides were synthesized. Hydrolytic activities of alpha-glucosidase (rice), alpha-galactosidases (green coffee bean, Mortierella vinacea, and Aspergillus niger), and alpha-mannosidases (almond and jack bean) against them were elucidated. The 6-O-methyl galactopyranoside and mannopyranoside were hydrolyzed by the M. vinacea alpha-galactosidase and the almond and jack bean alpha-mannosidases, respectively, while these enzymes did not act on the 2-, 3-, and 4-O-methyl derivatives. On the other hand, lice alpha-glucosidase and green coffee bean and A. niger alpha-galactosidases had no hydrolyzing activities at all against the respective four monomethylated substrates.