Evaluation of antibacterial and enhancement of antibiotic action by the flavonoid kaempferol 7-O-β-D-(6″-O-cumaroyl)-glucopyranoside isolated from Croton piauhiensis müll

There has been a rapid increase in the incidence and prevalence of opportunistic bacterial infections. Inappropriate use of current antibiotics has continuously contributed to the emergence of resistance to conventional antibiotic therapy. Therefore, the search for natural molecules that are able to combat infections is of great public interest, and many of these compounds with antimicrobial properties can be obtained from phytochemical studies of medicinal plants. In this context, this study reports the isolation and characterization of the flavonoid, kaempferol 7-O-β-D-(6″-O-cumaroyl)-glucopyranoside, from Croton piauhiensis leaves. Additionally, the intrinsic antimicrobial action of the compound and its enhancement against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus strains were assessed. The minimum inhibitory concentration (MIC) of the compound was determined using broth microdilution assays. To evaluate the modulatory effect of the flavonoid, the MIC of antibiotics amikacin and gentamicin, belonging to the class aminoglycosides was assessed, with and without the compound in sterile microplates. The results of intrinsic antibacterial activity tests revealed that the compound had no antibacterial activity against strains tested at concentrations