Ultrafiltration coupled with high-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry for screening lipase binders from different extracts of Dendrobium officinale.

Pancreatic lipase plays essential roles in the digestion, transport, and processing of dietary lipids in humans. Inhibition of pancreatic lipase leading to the decrease of lipid absorption may be used for treating obesity. In the present study, a new approach of ultrafiltration coupled with high-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry was established for rapidly detecting lipase binders from different extracts of medicinal plants. Rutin, a model inhibitor of lipase, was selected to optimize the screening conditions, including ion strength, temperature, pH, and incubation time. Meanwhile, the specificity of the approach was investigated by using denatured lipase and inactive compound emodin. The optimal screening conditions were as follows: ion strength 75 mM, temperature 37 °C, pH 7.4, and incubation time 10 min. Furthermore, linearity, accuracy, precision, and matrix effect of the approach were well validated. Finally, lipase binders were screened from different extracts of Dendrobium officinale by applying the established approach and were subsequently subjected to traditional lipase inhibitory assay. Eleven lipase inhibitors were identified, eight of which, namely naringenine, vicenin II, schaftoside, isoschaftoside, isoquercetrin, kaempferol 3-O-β-D-glucopyranoside, vitexin 2″-O-glucoside, and vitexin 2″-O-rhamnoside, were reported for the first time. In addition, docking experiments were performed to determine the preferred binding sites of these new lipase inhibitors.