An on-line detection system for screening small molecule inhibitors of α-Amylase and α-Glucosidase in Prunus mume

High-throughput screening of inhibitors from natural products is an efficient approach to target key enzymes in diabetes progression. In this study, an on-line detection system was established for the first time to rapidly screen inhibitors of α-amylase and α-glucosidase from Prunus mume. Among 28 identified compounds, 26 and 21 compounds showed strong inhibitory effect against α-amylase and α-glucosidase, respectively. Their inhibitory effects were validated by in vitro enzyme assay and fluorescence quenching which demonstrated that these inhibitors effectively interfered enzyme active sites. The inhibition kinetics suggested that chemical structures are of great importance for interfering the enzyme structures and their microenvironment polarity. Among evaluated compounds, isorhamnetin-3-O-glucoside (19) showed the strongest binding activities to α-amylase and α-glucosidase (6.34×10⁶·nmol⁻¹ and 6.28×10⁶·nmol⁻¹, respectively) by the on-line detection system. Its IC₅₀ values were 0.16 ± 0.06 and 0.09 ± 0.01 µM against α-amylase and α-glucosidase, respectively. 19 gave a much higher K_i for α-amylase (0.1307 mM) than α-glucosidase (0.0063 mM), indicating its selectivity towards α-glucosidase. This reported method was rapid and reliable to identify prototype inhibitors against key enzymes in diabetes, and thus might serve as a general platform to screen enzyme inhibitors from natural products.