α‑1‑<i>C</i>‑Butyl-1,4-dideoxy-1,4-imino‑l‑arabinitol as a Second-Generation Iminosugar-Based Oral α‑Glucosidase Inhibitor for Improving Postprandial Hyperglycemia

We report on the synthesis and the biological evaluation of a series of α-1-<i>C</i>-alkylated 1,4-dideoxy-1,4-imino-l-arabinitol (LAB) derivatives. The asymmetric synthesis of the derivatives was achieved by asymmetric allylic alkylation, ring-closing metathesis, and Negishi cross-coupling as key reactions. α-1-<i>C</i>-Butyl-LAB is a potent inhibitor of intestinal maltase, isomaltase, and sucrase, with IC₅₀ values of 0.13, 4.7, and 0.032 μM, respectively. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis revealed that this compound differs from miglitol in that it does not influence oligosaccharide processing and the maturation of glycoproteins. A molecular docking study of maltase-glucoamylase suggested that the interaction modes and the orientations of α-1-<i>C</i>-butyl-LAB and miglitol are clearly different. Furthermore, α-1-<i>C</i>-butyl-LAB strongly suppressed postprandial hyperglycemia at an early phase, similar to miglitol in vivo. It is noteworthy that the effective dose was about 10-fold lower than that for miglitol. α-1-<i>C</i>-Butyl-LAB therefore represents a new class of promising compounds that can improve postprandial hyperglycemia