Adjuvant Effect of Crateva tapia L. (Capparaceae) Extract in Enhancing Antibiotics Against Multidrug-Resistant Bacteria

Bacterial resistance has become a growing global challenge, highlighting the importance of therapeutic alternatives, such as the use of medicinal plant extracts in inhibiting resistant bacteria. Brazil is one of the most biodiverse countries in the world, including medicinal plants with pharmacological potential and promising biological activities against pathogenic microorganisms. The species Crateva tapia L. exhibits significant therapeutic potential in traditional medicine due to its antioxidant and antimicrobial properties. In this context, this study evaluated the antibacterial activity and synergistic potential of the ethanolic extract from C. tapia leaves in combination with antibiotics. For this purpose, C. tapia leaves were collected, dried, ground, and subjected to ethanol extraction to obtain the ethanolic extract (EECT). Antimicrobial assays were conducted using conventional bacterial strains (ATCC) and multidrug-resistant (MDR) strains. The inhibitory activity was assessed through the Minimum Inhibitory Concentration (MIC). The potentiating capacity of EECT was analyzed at sub-inhibitory concentrations (MIC/8) in combination with the antibiotics gentamicin, ampicillin, and norfloxacin, with results analyzed statistically. The results demonstrated that EECT did not exhibit isolated antibacterial activity (MIC > 512 μg/mL) against ATCC and MDR bacteria. However, it proved to be effective as an antibiotic potentiator, significantly reducing the MIC of gentamicin and norfloxacin against MDR strains of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. These findings indicate that the ethanolic extract of C. tapia has potential for use in combined therapies, representing a promising alternative in addressing bacterial resistance.