2-(Pyridin-4yl)benzothiazole and Its Benzimidazole-Analogue: Biophysical and in silico Studies on Their Interaction with Urease and in vitro Anti-Helicobacter pylori Activities

Luzia Modolo,Josué Santos,Thiago De Aquino,Felipe Martins,Edeildo Da Silva-Júnior,Camila Pereira,Breno Oliveira,Francesca Sisto,Igor Nascimento,Isis Figueiredo,Ana De Lyra,Ângelo De Fátima

doi:10.21577/0103-5053.20220020

Abstract

In this study, the interaction between benzothiazole (BTA, concentration of a drug required for 50% inhibition in vitro (IC50) = 0.77 mM) and benzimidazole (BIA, IC50 = 2.14 mM) with urease was quantitatively assessed, using UV-Vis, molecular fluorescence, and circular dichroism. The results showed that both compounds interact with urease by a static fluorescence quenching mechanism with a non-fluorescent complex formation. The main forces responsible for stabilizing the supramolecular complex between BTA and urease were hydrophobic while, for BIA, van der Waals interactions and hydrogen bonds were the main ones. Urease conformation changes due to the interaction process were analyzed by circular dichroism and synchronous fluorescence. Besides, a competitive assay with substrate and inhibitors was used to evaluate the preferential urease site of interaction with BTA and BIA. Our experimental and theoretical studies supported that both, BTA and BIA, are mixed-inhibitors of ureases with a slight preference to the active site of such enzymes. Finally, both BTA and BIA showed to possess anti-H. pylori (one reference strain and six clinical isolates) activity, presenting minimal inhibitory concentration (MIC) values ranging from 38-150 and 20-164 μM, respectively. The urease inhibitors omeprazole and hydroxyurea showed MIC values in the range of 46-185 μM and 1683-> 3366 μM, respectively.

Highlights

For the respective preparation of benzothiazole BTA and benzimidazole BIA, we carried out reactions
According to Ross and Subramanian[75] and Santana et al.,[76] hydrophobic interactions are fundamental in complex stability between compound BTA and urease, since DH > 0 and DS > 0, while van der Waals forces and hydrogen bonds are crucial to the binding of BIA to the enzyme, since DH < 0 and DS < 0
Based on circular dichroism (CD) results, it is possible to justify the differentiation in the urease secondary structure variations, probably due to the forces of each ligand involved in the interaction process since both (BTA and BIA) are mixed inhibitors

Summary

Introduction

Urease is a Ni-dependent enzyme widely synthesized by plants, fungi, bacteria, and some invertebrates.[1,2,3,4] In the presence of ureases, the conversion of urea to ammonia (NH3) and carbon dioxide (CO2) is enhanced by one‐hundred-trillion-fold.[1,2,5,6] Urease is a pathogenic factor for the bacteria Helicobacter pylori, Proteus mirabilis, Staphylococcus saprophyticus, and some plasmidcontaining Escherichia coli strains known to trigger urinary tract infection, kidney stone formation, pyelonephritis, hepatic encephalopathy, and hepatic coma.[1,6,7,8,9,10] H. pylori can grow in the stomach (pH lower than 2.0) due to the ability to excrete ureases.[3,11] The increment of pH in the stomach due to NH3 accumulation contributes to gastric inflammation and the formation of duodenal and gastric ulcers and gastric adenocarcinoma and lymphoma.[1,2,3] For these reasons, the development of urease inhibitors is an important tool for medical applications.[12,13,14]. KSV values presented a tendency of decreasing with the increase in temperature for both evaluated compounds (Table 3); the interaction process among BTA and BIA with urease can occur possibly through the static quenching mechanism.

Results

Conclusion