β-glucuronidase inhibitors(National Sun Yat-Sen University)

Unraveling the intricacies of β-glucuronidase inhibition is pivotal for developing effective strategies in applications specific to gastrointestinal health and drug metabolism. Our study investigated the efficacy of some Hibiscus trionum phytochemicals as β-glucuronidase inhibitors. The results showed that cleomiscosin A and mansonone H emerged as the most potent inhibitors, with IC₅₀ values of 3.97 ± 0.35 μM and 10.32 ± 1.85 μM, respectively. Mechanistic analysis of β-glucuronidase inhibition indicated that cleomiscosin A and the reference drug EGCG displayed a mixed inhibition mode against β-glucuronidase, while mansonone H exhibited noncompetitive inhibition against β-glucuronidase. Docking studies revealed that cleomiscosin A and mansonone H exhibited the lowest binding affinities, occupying the same site as EGCG, and engaged significant key residues in their binding mechanisms. Using a 30 ns molecular dynamics (MD) simulation, we explored the interaction dynamics of isolated compounds with β-glucuronidase. Analysis of various MD parameters showed that cleomiscosin A and mansonone H exhibited consistent trajectories and significant energy stabilization with β-glucuronidase. These computational insights complemented experimental findings, underscoring the potential of cleomiscosin A and mansonone H as β-glucuronidase inhibitors.

β-Glucuronidase, a crucial enzyme in drug metabolism and detoxification, represents a promising target for therapeutic intervention due to its potential to modulate drug pharmacokinetics and enhance therapeutic efficacy. Herein, we assessed the inhibitory potential of phytochemicals from Hibiscus trionum against β-glucuronidase. Grossamide and grossamide K emerged as the most potent β-glucuronidase inhibitors with IC₅₀ values of 0.73 ± 0.03 and 1.24 ± 0.03 μM, respectively. The investigated alkaloids effectively inhibited β-glucuronidase-catalyzed PNPG hydrolysis through a noncompetitive inhibition mode, whereas steppogenin displayed a mixed inhibition mechanism. Molecular docking analyses highlighted grossamide and grossamide K as inhibitors with the lowest binding free energy, all compounds successfully docked into the same main binding site occupied by the reference drug Epigallocatechin gallate (EGCG). We explored the interaction dynamics of isolated compounds with β-glucuronidase through a 200 ns molecular dynamics (MD) simulation. Analysis of various MD parameters revealed that grossamide and grossamide K maintained stable trajectories and demonstrated significant energy stabilization upon binding to β-glucuronidase. Additionally, these compounds exhibited the lowest average interaction energies with the target enzyme. The MM/PBSA calculations further supported these findings, showing the lowest binding free energies for grossamide and grossamide K. These computational results are consistent with experimental data, suggesting that grossamide and grossamide K could be potent inhibitors of β-glucuronidase.