Identification of Polyphenolic Components in Gastrodia elata and Their Inhibitory Effects on α-Amylase and α-Glucosidase

To investigate the composition and hypoglycemic activity of polyphenols in Gastrodia elata, this study utilized ultra-high performance liquid chromatography coupled with quadrupole and electrostatic field Orbitrap high-resolution mass spectrometry (UPLC-Q-Exactive Orbitrap-MS) to identify the components of the purified polyphenols. In vitro experiments were conducted to evaluate the inhibitory effects of G. elata polyphenols on α-amylase and α-glucosidase activities and to explore the mechanism underlying their hypoglycemic effects. The results indicated that G. elata polyphenols contained 30 compounds, including 23 flavonoids, 2 phenolic acids, and 5 phenolic compounds. In vitro hypoglycemic experiments showed that G. elata polyphenols exhibited significantly inhibitory effects on both α-amylase and α-glucosidase, which were positively correlated with polyphenol concentration. At a concentration of 0.5 mg/mL, the inhibitory rates of G. elata polyphenols on α-amylase and α-glucosidase were (79.71 ± 2.51) % and (77.33 ± 2.31) %, respectively. The half-maximal inhibitory concentrations (IC₅₀) were (0.057 ± 0.011) and (0.189 ± 0.017) mg/mL, respectively. The types of inhibition were determined to be mixed uncompetitive-noncompetitive inhibition for α-amylase and mixed competitive-noncompetitive inhibition for α-glucosidase. These findings could provide a theoretical foundation for further research into the hypoglycemic mechanisms of G. elata polyphenols and for their development and utilization.