Synthesis of Chalcones, Screening In silico and In vitro and Evaluation of Helicobacter pylori Adhesion by Molecular Docking
Authors: de Almeida Romagna Rodrigo , dos Santos Reginaldo Bezerra , de Cassia Ribeiro Gonçalves Rita , Kitagawa Rodrigo Rezende 
Published: September 2024

Aims:

We synthetized 10 hydroxylated and methoxylated chalcones and evaluated them targeting
MMP-9 inhibition, looking for the rate of adhesion of H. pylori in gastric cells, and then, reduction of the inflammatory
response as alternative therapeutic agents for controlling the infection.

Background:

Helicobacter pylori is a Gram-negative bacterium that chronically infects the human stomach, a
risk factor for the development of inflammatory gastrointestinal diseases, including cancer, and is classified as
a group I carcinogen. It is estimated that it infects around 45% of the global population and that the persistence
of the infection is related to the adhesion of the bacteria in the gastric epithelium. The progression of
gastric lesions to cancer is connected to the activation of the NF-κB and MAPK pathways, especially in
cagA+ strains, which are related to increased expression of MMP-9. The activation of these metalloproteinases
(MMPs) contributes to the adhesion of the bacterium in gastric cells and the evolving stages of cancer, such
as enabling metastasis. Due to the increasing resistance to the current therapy protocols, the search for alternative
targets and candidate molecules is necessary. In this way, controlling adhesion seems to be a suitable option
since it is a crucial step in the installation of the bacterium in the gastric environment.

Objective:

Synthetize ten hydroxylated and methoxylated chalcones. Assess their anti-H. pylori potential,
minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Evaluate their cytotoxicity
in AGS cells and selectivity with L-929 cells. Analyze the results and correlate them with in silico
predictions to evaluate potential anti-adhesive properties for the chalcones against H. pylori.

Methods:

The chalcones were synthetized by Claisen-Schmidt condensation using Ba(OH)2 or LiOH as catalysts.
Predictive in silico assays in PASS Online, tanimoto similarity, ADME properties and molecular docking
in MMP-9 (PDB code: 6ESM) were performed. The in vitro assays carried out were the cell viability in
gastric adenocarcinoma cells (AGS) and fibroblasts (L-929) by the MMT method and anti-H. pylori, by the
broth microdilution method, through the minimum inhibitory concentration (MIC) and minimum bactericidal
concentration (MBC).

Results:

Ten chalcones were synthesized through Claisen-Schimdt condensation with yields of 10 to 52% and
characterized by 1H and 13C nuclear magnetic resonance (NMR) and mass spectrometry (MS). In silico data
revealed the possibility of anti-H. pylori, anti-inflammatory, and MMP-9 inhibition for the chalcones. Chalcone
9 showed the best growth inhibition values for MIC and MBC, at 1 μg/mL and 2 μg/mL, respectively.
Chalcones 14 and 15 likewise demonstrated excellent inhibitory results, being 2 μg/mL for both MIC and
MBC. Additionally, 15 had the best MMP-9 inhibition score. Despite not corroborating the in silico findings,
chalcones 10, 13, and 18 showed good cytotoxicity and the best selectivity indices.

Conclusion:

All compounds exhibited strong activity against H. pylori, specially 15. The predicted MMP-9
inhibition by molecular docking added to the reasonable SI and CI50 values for 15 and the satisfactory reduction
in the rate of survival of the bacteria, reveals that it may be acting synergically to reduce the inflammatory
response and the possibilities for developing a tumor by inhibiting both bacteria and malignant cells.