Antibacterial and antibiotic modulating activity of the aqueous extract of the fruits of Luffa operculata Cogn.

The excessive use of antibiotics has driven the development of bacterial resistance, highlighting the importance of new therapeutic alternatives such as plant oils and extracts. This study aimed to evaluate the antibacterial activity of the aqueous extract from the fruit of Luffa operculata against Staphylococcus aureus and Pseudomonas aeruginosa , both alone and in combination with antibiotics. The antibacterial effect of the aqueous fruit extract of L. operculata and its ability to modify antibiotic activity were assessed using the broth microdilution method, and the Minimum Inhibitory Concentration (MIC) was determined. The isolated extract did not show relevant antibacterial activity; however, significant effects were observed when it was combined with antibiotics. For S. aureus , the combination with gentamicin reduced the MIC from 16.0 µg/mL to 5.0 µg/mL, indicating synergism. In P. aeruginosa , the combination with norfloxacin reduced the MIC from 128.0 µg/mL to 50.8 µg/mL, whereas the combination with gentamicin was not significant. In conclusion, although the isolated extract of L. operculata did not demonstrate direct efficacy, its interaction with antibiotics, particularly aminoglycosides (gentamicin) and fluoroquinolones (norfloxacin), showed synergistic potential, highlighting its possible role as an adjuvant in combating multidrug-resistant strains. • Luffa operculata extract did not show direct antibacterial action against the tested strains. • With gentamicin, the extract potentiated the effect against Staphylococcus aureus . • Luffa operculata extract increased the action of erythromycin and norfloxacin against Pseudomonas aeruginosa .