Kinetics and Mechanism Study of Competitive Inhibition of Jack‐Bean Urease by Baicalin

Abstract

Baicalin (BA) is the principal component of Radix Scutellariae responsible for its pharmacological activity. In this study, kinetics and mechanism of inhibition by BA against jack-bean urease were investigated for its therapeutic potential. It was revealed that the IC50 of BA against jack-bean urease was 2.74 ± 0.51 mM, which was proved to be a competitive and concentration-dependent inhibition with slow-binding progress curves. The rapid formation of initial BA-urease complex with an inhibition constant of K i = 3.89 × 10−3 mM was followed by a slow isomerization into the final complex with an overall inhibition constant of K i* = 1.47 × 10−4 mM. High effectiveness of thiol protectors against BA inhibition indicated that the strategic role of the active-site sulfhydryl group of the urease was involved in the blocking process. Moreover, the inhibition of BA was proved to be reversible due to the fact that urease could be reactivated by dithiothreitol but not reactant dilution. Molecular docking assay suggested that BA made contacts with the important activating sulfhydryl group Cys-592 residues and restricted the mobility of the active-site flap. Taken together, it could be deduced that BA was a competitive inhibitor targeting thiol groups of urease in a slow-binding manner both reversibly and concentration-dependently, serving as a promising urease inhibitor for treatments on urease-related diseases.

Selective Antibacterial Activity of Patchouli Alcohol Against Helicobacter pylori Based on Inhibition of Urease

“…Therefore, SH‐blocking reagent was employed to examine its effects on the inhibitory activity of PA against ureases. When DTT was added to the pre‐incubation medium, instead restoring the inhibition of urease activity by some reported compounds like allicin, quinine, and flavonoid (Juszkiewicz et al ., ; Kot, ; Tan et al ., ), the inhibitory activity of PA was strengthened by DTT. Chemical studies have shown that various sesquiterpenes react with thiols (Kupchan et al ., ; Kupchan et al ., ).…”

Urease Inhibitors of Agricultural Interest Inspired by Structures of Plant Phenolic Aldehydes

“…Besides methyl gallate and related derivatives, 37 other plant phenolic compounds, such as (iso) quercitrin, avicularin, guaijaverin, flavonoid glucosides and shoreaphenol, were also reported to inhibit jack bean urease. 29,30,38,39 Interestingly, structural modifications on PA, VN and SA dramatically improved their ability to inhibit the ureolytic activity of jack bean urease (Figure 2). Indeed, the conversion of phenolic aldehydes to derivatives bearing urea or thiourea core (Figure 1) yielded the VN derivative The compounds 2A7 and 2B10 (PA derivatives), 2A9 (SA derivative) and 2D2 (VN derivative) were employed at different concentrations (0.3 to 1.6 mM) in reactions containing urea ranging from 1 to 32 mmol L -1 and 12.5 mU urease.…”

Molecular Role of EGFR-MAPK Pathway in Patchouli Alcohol-Induced Apoptosis and Cell Cycle Arrest on A549 CellsIn VitroandIn Vivo

“…PA is used for the quality control objective of patchouli oil in pharmaceutical industry (The Pharmacopoeia Commission of PRC 2010). Accumulating reports have demonstrated that PA had multiple effects such as anti-inflammatory [7, 8], antivirus [9–12], antimicrobial [13–17], and insecticidal [18, 19], protective effect on fluidity of intestinal epithelial cells [20], protective effect on acute lung injury [21], radical-scavenging activity [22], inhibitory activity on platelet-activating factor (PAF) activation [23], and antiemetic activity [24]. …”