BIOPHYSICAL TOOLS TO EXPLORE THE ANTI-VIRULENCE MODE OF ACTION OF PHYTOCHEMICALS AGAINST PATHOGENIC BACTERIA

Antibiotic resistance is one of the major threats to global health; therefore, the challenge is developing strategies to attack this problem. Anti-virulence therapy is an alternative that has gained attention in the last years, and it is aimed to attenuate the bacterial strategies to infect and cause disease, and sometimes it does not aim to affect the pathogen viability. Phytochemicals have been demonstrated anti-virulence properties against a wide range of pathogenic bacteria. Studies on this topic are commonly focused on the characterization of physiological changes of treated bacteria such as bacterial membrane damage, biofilm inhibition or changes in expression of virulence-related genes. However, few studies delve into the molecular targets of these compounds and their molecular interactions. In this sense, biophysical techniques that include spectroscopy methods (X-ray crystallography, UV-Vis, IR, fluorescence, and others), surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and nuclear magnetic resonance (NMR) can help to validate the action sites of molecular targets of natural compounds. These tools have been used for decades in drug design in the pharmaceutical industry since they allow a detailed mechanistic characterization of compound binding. This information is quite useful when studying the mechanisms of action of natural plant compounds. Therefore, this chapter provides an overview of biophysical techniques that can validate targets of phytochemicals with anti-virulence properties that can help elucidate their mode of action.