Phillyrin: an adipose triglyceride lipase inhibitor supported by molecular docking, dynamics simulation, and pharmacological validation

CONTEXT: Adipose triglyceride lipase (ATGL), a key enzyme responsible for lipolysis, catalyzes the first step of lipolysis and converts triglycerides to diacylglycerols and free fatty acids (FFA). Our previous work suggested that phillyrin treatment improves insulin resistance in HFD-fed mice, which was associated with ATGL inhibition. In this study, using docking simulation, we explored the binding pose of phillyrin and atglistatin (a mouse ATGL inhibitor) to ATGL in mouse. From the docking results, the interactions with Ser47 and Asp166 were speculated to have caused phillyrin to inhibit ATGL in mice. Further, molecular dynamics simulation of 100 ns and MM-GBSA were conducted for the protein-ligand complex, which indicated that the system was stable and that phillyrin displayed a better affinity to ATGL than did atglistatin throughout the simulation period. Moreover, the results of pharmacological validation were consistent with those of the in silico simulations. In summary, our study illustrates the potential of molecular docking to accurately predict the binding protein produced by AlphaFold and suggests that phillyrin is a potential small molecule that targets and inhibits ATGL enzymatic activity.

METHODS: The ATGL-predicted protein structure, verified by PROCHECK, was determined using AlphaFold. Molecular docking, molecular dynamics simulation, and prime molecular mechanic-generalized born surface area were performed using LigPrep, Desmond, and prime MM-GBSA modules of Schrödinger software release 2021-2, respectively. For pharmacological validation, immunoblotting was performed to assess ATGL protein expression. The fluorescence intensity and glycerol concentration were quantified to evaluate the efficiency of phillyrin in inhibiting ATGL.