Investigation on the anti-α-glucosidase mechanism of aspergillus triazolate A from Oxalis corniculate L.

Diabetes mellitus characterized by abnormal glucose concentration is a metabolic disease. α-Glu inhibitors from natural sources are a good choice for searching for high-efficiency and low-toxicity hypoglycemic drugs. In this study, a naturally effective α-Glu inhibitor aspergillus triazolate A (ATA) with a peculiar structure was first found in Oxalis corniculate L., then its activity and mechanism were first elucidated through various methods. These mechanisms included enzyme kinetics, circular dichroism spectra, fluorescence spectra, synchronous fluorescence spectrum, 3D fluorescence spectrum, and molecular docking. Meanwhile, the ability to reduce postprandial blood glucose was further investigated in vivo. Research results revealed that ATA was a mixed type α-Glu inhibitor with an IC50 value of 66.87 ± 1.50 μM, which bound to the enzyme from a single site through hydrogen bonding and hydrophobic forces causing the looser secondary structure of α-Glu. It was also found that the binding site of α-Glu was closer to the Trp residue, and the endogenous fluorescence of α-Glu was quenched in a static quenching form. Moreover, the sucrose loading test in vivo revealed that the ATA of 20 mg/kg could effectively reduce the postprandial blood glucose level. Hence, ATA could be used as lead compound to develop novel α-Glu inhibitors.