Novel Biphenyls From Garcinia multiflora: Isolation and α-Amylase Inhibitory Properties

Garcinia multiflora Champ. ex Benth. is a microphanerophyte species belonging to the genus Garcinia in the family Clusiaceae. This study focused on the biphenyl compounds in the stems and leaves of G. multiflora Champ. ex Benth., analyzing their binding to α-amylase and verifying this interaction through enzyme activity inhibition experiments. The results showed that seven biphenyl compounds, including four new ones, were isolated from the stems and leaves of G. multiflora and structurally identified using 1D/2D nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The interactions between the seven compounds and α-amylase were calculated using AutoDock Vina and visualized via PyMOL, respectively. The results showed that all seven compounds exhibited strong binding to α-amylase. Additionally, further enzyme inhibition assays using a multifunctional microplate reader revealed that, compared with the positive control acarbose (half-maximal inhibitory concentration [IC₅₀] = 17.23 ± 2.43 µM), only compounds 5 (IC₅₀ = 2190 ± 180 µM) and 6 (IC₅₀ = 4420 ± 1480 µM) exhibited relatively weak α-amylase inhibitory activity.