Zusammenfassung
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-beta-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 < 1024
mu g/mL. The combination of the flavonoid at a concentration of 128 mu
g/mL with gentamicin presented synergistic effects against S. aureus 10
and E. coli 06, and also reduced the MIC from 16 mu g/mL to 4 mu g/mL
and 8 mu g/mL, respectively. Amikacin also showed synergistic effects
against S. aureus 10 and E. coli 06. We also observed reduced MIC for
both, from 128 mu g/mL to 32 mu g/mL; however, antagonism for P.
aeruginosa increased the MIC from 16 mu g/mL to 64 mu g/mL. The
combination of the flavonoid with the aminoglycosides may be an
alternative to potentiate the expected results in treatment against S.
aureus and E. coli, since their association leads to a synergistic
effect, reducing the MIC of these drugs and decreasing the dose
necessary for therapeutic success.
Nutzer