Purification, Identification and Pancreatic Lipase Inhibitory Effect of Naringin from the Peel of Guanxi Honey Pomelo (Citrus grandis (L.) Osbeck)

In order to explore the potential of flavonoids from Guanxi honey pomelo as a pancreatic lipase inhibitor, flavonoids from the fruit’s peel were purified by Sephadex LH-20 column chromatography and identified by high performance liquid chromatography-mass spectrometry (HPLC-MS) and Fourier transform infrared (FTIR) spectroscopy. Moreover, the type of inhibition and the molecular interaction between the flavonoids and pancreatic lipase were studied by enzymatic reaction kinetics and molecular docking. The results of purification and identification showed the major flavonoid compound in Guanxi honey pomelo was naringin. The half-maximal inhibitory concentration (IC₅₀) of naringin on pancreatic lipase was 0.99 μg/mL. The inhibition was reversible non-competitive. The inhibition constant K_i was 0.58 μg/mL. Molecular docking showed that the binding free energy between the flavonoid compound and the enzyme was −30.14 kJ/mol. They interacted with each other at a position outside the catalytic core via van der Waals force, hydrophobic interaction, hydrogen bond and π bond. This study revealed that naringin as one of the main flavonoids in Guanxi honey pomelo could strongly inhibit pancreatic lipase, which will provide a theoretical basis for the development of flavonoids from Guanxi honey pomelo as new and safe pancreatic lipase inhibitors.