New enzymatic synthesis of 63-modified maltooligosaccharides and their inhibitory activities for human α-amylases

Ten new 63-modified maltopentaoses and tetraoses were synthesized by enzymatic reactions utilizing cyclodextrin glycosyltransferase (EC 2.4.1.19) and subsequent human salivary α-amylase (HSA) (EC 3.2.1.1). Among these compounds, α-d-glucopyranosyl-(1→4)-α-d-glucopyranosyl-(1→4)-(6-deoxy-α-d-glucopyranosyl)-(1→4)-α-d-glucopyranosyl-(1→4)-d-glucopyranose (11) and α-d-glucopyranosyl-(1→4)-(6-deoxy-α-d-glucopyranosyl)-(1→4)-α-d-glucopyranosyl-(1→4)-d-glucopyranose (12) showed strong inhibitory activities for human pancreatic α-amylase (HPA) and HSA. The IC50 of 63-deoxymaltopentaose 11 (8.0×10−5 M for HPA, 1.0×10−4 M for HSA) and 63-deoxymaltotetraose 12 (2.0×10−3 M for HPA, 2.0×10−3 M for HSA) were lower than that of 63-deoxymaltotriose [(6-deoxy-α-d-glucopyranosyl)-(1→4)-α-d-glucopyranosyl-(1→4)-d-glucopyranose 13; 2.0×10−3 M for HPA, 4.2×10−2 M for HSA].