Amentoflavone from Selaginella tamariscina as a potent inhibitor of gut bacterial β-glucuronidase: Inhibition kinetics and molecular dynamics stimulation | JoVE Visualize

Amentoflavone from Selaginella tamariscina as a potent inhibitor of gut bacterial β-glucuronidase: Inhibition kinetics and molecular dynamics stimulation

Xiang-Ge Tian¹, Jian-Kun Yan², Cheng-Peng Sun¹

¹Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China.

Chemico-Biological Interactions|March 31, 2021

View abstract on PubMed

Summary

Selaginella tamariscina and its compound amentoflavone inhibit gut bacterial β-glucuronidase (GUS), offering potential to reduce drug-induced gastrointestinal toxicity. These findings support the use of S. tamariscina for treating enteropathy.

Area of Science:

Pharmacology
Microbiology
Natural Products Chemistry

Background:

Gut bacterial β-glucuronidase (GUS) is crucial for metabolizing glucuronide conjugates in the GI tract.
GUS activity is implicated in drug-induced gastrointestinal toxicity.
Inhibiting gut microbial GUS presents a therapeutic strategy for mitigating GI toxicity.

Purpose of the Study:

To evaluate the inhibitory potential of Selaginella tamariscina and its major biflavonoid, amentoflavone (AMF), against Escherichia coli GUS.
To characterize the inhibition kinetics and molecular interactions of AMF with GUS.

Main Methods:

Enzyme inhibition assays using selective probe substrates (DDAOG and SN38G) for GUS.
Determination of IC50 and Ki values for AMF inhibition.
Molecular docking and molecular dynamics simulations to elucidate binding interactions.

Main Results:

Both S. tamariscina extract and AMF demonstrated significant inhibitory effects on GUS activity.
AMF exhibited potent inhibition with IC50 values of 0.62 μM (DDAOG) and 0.49 μM (SN38G).
AMF displayed mixed-type inhibition for DDAOG hydrolysis and competitive inhibition for SN38G hydrolysis, with Ki values of 0.24 μM and 1.25 μM, respectively.

Conclusions:

Selaginella tamariscina and its major biflavonoid, amentoflavone, are effective inhibitors of bacterial GUS.
AMF's inhibition mechanisms involve specific interactions with key amino acid residues (Leu361, Ile363, Glu413) in GUS.
These findings support the potential clinical application of S. tamariscina and AMF in managing drug-induced enteropathy.