Antibacterial and Antibiotic‐Enhancing Activity of 3‐Hydroxy‐4‐methoxycinnamic Acid: Experimental Data and In Silico Predictions

ABSTRACT The growing bacterial resistance, driven by the inappropriate use of antibiotics, poses a global health threat and demands new therapeutic strategies. Natural phenolic compounds, such as 3‐hydroxy‐4‐methoxycinnamic acid (3H4MCA), stand out due to their antimicrobial and antioxidant properties, showing potential in combating resistant pathogens. This study aims to evaluate the antibacterial activity and in silico characteristics of 3H4MCA, including ADMET parameters and molecular interactions with protein targets. 3H4MCA, obtained from Sigma‐Aldrich, was assessed for its antibacterial activity by determining the minimum inhibitory concentration (MIC) against Gram‐negative and Gram‐positive bacteria, as well as through synergy analysis with gentamicin, ampicillin, and norfloxacin. ADMET and physicochemical properties were predicted using the ADMETlab 2.0 platform. For molecular docking studies, the proteins 5KDR, 6GJ1, and 4WEL were used with predefined grids. Data were statistically analyzed. Although our results indicate that 3H4MCA did not show direct antibacterial activity against the tested strains (MIC > 512 µg/mL), with the same MIC value observed for all Gram‐negative and Gram‐positive bacteria, it significantly modulated the action of antibiotics, demonstrating previously unreported synergistic effects with gentamicin against Escherichia coli 06 MDR and with ampicillin against Staphylococcus aureus 10 MDR, it is possible to point out as a potential compost for combination therapy. In silico analyses indicate that 3H4MCA exhibits physicochemical features compatible with bioactive compounds, but its predicted toxicity profile suggests the need for further safety assessment. The docking results showed stable binding (4WEL, 5KDR, and 6GJ1 proteins, with binding energies of −5.067, −5.629, and −5.857 kcal/mol) to all evaluated protein targets, mediated by hydrogen bonding, hydrophobic, and electrostatic interactions. Collectively, the findings reveal the novel synergistic potential of 3H4MCA as an antibiotic adjuvant, supporting its relevance as a promising bioactive ligand with therapeutic applications.