Design, synthesis, and biological evaluation of novel sesquiterpene lactone derivatives as PKM2 activators with potent anti-ulcerative colitis activities.

Pyruvate kinase isoform 2 (PKM2) is closely related to the regulation of Th17/Treg balance, which is considered to be an effective strategy for UC therapy. Parthenolide (PTL), a natural product, only possesses moderate PKM2-activating activity. Thus, five series of PTL derivatives are designed and synthesized to improve PKM2-activated activities and anti-UC abilities. Through detailed structure optimization, B4 demonstrates potent T-cell anti-proliferation activity (IC50 = 0.43 µM) and excellent PKM2-activated ability (AC50 = 0.144 µM). Subsequently, through mass spectrometry analysis, B4 is identified to interact with Cys423 of PKM2 via covalent-bond. Molecular docking and molecular dynamic simulation results reveal that the trifluoromethoxy of B4 forms a stronger hydrophobic interaction with Ala401, Pro402, and Ile403. In addition, B4 has a significant effect only on Th17 cell differentiation, thereby regulating the Th17/Treg balance. The effect of B4 on Th17/Treg imbalance can be attributed to inhibition of PKM2 dimer translocation and suppression of glucose metabolism. Finally, B4 can notably ameliorate the symptoms of dextran sulfate sodium (DSS)-induced colitis in mouse model in vivo. Thus, B4 is confirmed as a potent PKM2 activator, and has the potential to develop as a novel anti-UC agent.