Aspulvinones Suppress Postprandial Hyperglycemia As Potent Alpha-Glucosidase Inhibitors From Aspergillus Terreus Asm-1

Chemical investigation of Aspergillus terreus ASM-1 fermentation resulted in the isolation of three new prenylated aspulvinones V-X (1-3), together with the previously reported analogs, aspulvinone H (4), J-CR (5), and R (6). Their structures were elucidated by various spectroscopic methods including HRESIMS and NMR, and the absolute configurations of 2 and 3 were determined by ECD comparison. Compounds 1-6 were evaluated for alpha-glucosidase inhibitory effects with acarbose as positive control. As a result, compounds 1 and 4 exhibited potent alpha-glucosidase inhibitory activities with IC50 values of 2.2 and 4.6 mu M in mixed-type manners. The thermodynamic constants recognized the interaction between inhibitors and alpha-glucosidase was hydrophobic force-driven spontaneous exothermic reaction. The CD spectra also indicate that the compounds 1 and 4 changed the enzyme conformation. Furthermore, compound 4 significantly suppressed the increases in postprandial blood glucose levels in the C57BL/6J mice.