Antimicrobial evaluation of the Cynara cardunculus extract in Helicobacter pylori cells using mid-infrared spectroscopy and chemometric methods

J Appl Microbiol. 2022 Jun 21. doi: 10.1111/jam.15679. Online ahead of print.

Abstract

The treatment effectiveness of gastric diseases caused by the bacteria Helicobacter pylori is failing due to high resistance to some antibiotics. Consequently, it is urgent to develop an accurate methodology to screen new antimicrobial agents.

Methods and results: A preliminary assay, using both therapeutic-based antibiotics (clarithromycin and metronidazole), was conducted to optimize experimental conditions in terms of the sensibility of the Fourier-transform mid-infrared (MIR-FTIR) spectroscopy associated with chemometric methods. Principal component analysis was applied to understand how the Cynara extract concentration acts differentially against H. pylori bacteria. The partial least squares model, characterized by R2 = 0.98, and root mean square error cross-validation, 0.011, was developed for the spectral regions (3600-2500 cm-1 and 2000-698 cm-1 ).

Conclusions: MIR-FTIR spectroscopy associated with chemometric methods can be considered a suitable approach to discover and analyse the promissory antimicrobial agents based on the biomolecular changes observed according to the Cynara extract.

Significance and impact of the study: MIR-FTIR spectroscopy and chemometric methods allowed to register the biomolecular changes due to the potential antimicrobial drugs at reduced concentrations comparatively to the conventional assay based on an agar-dilution method, being considered a useful approach to develop a platform to discover new bioactive molecules, allowing to reduce time and costs related to the exploratory step.

Keywords: Helicobacter pylori; Cynara extract; MIR-FTIR spectroscopy; chemometrics; drug screening; high-throughput analysis.