Banca de DEFESA: CAMILA APARECIDA PEREIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CAMILA APARECIDA PEREIRA DA SILVA
DATE: 10/07/2025
TIME: 09:30
LOCAL: Sala de Videoconferência da Faculdade de Medicina - UFCA (campus Barbalha)
TITLE:

POTENTIAL OF BETULINIC ACID TO REVERSE BACTERIAL
RESISTANCE ASSOCIATED WITH EFFLUX PUMPS AND BIOFILMS

KEY WORDS:

Bioactivity, Eradication, Inhibition, Infections, pharmacokinetics.

PAGES: 123
BIG AREA: Ciências da Saúde
AREA: Medicina
SUMMARY:

Treatment for various bacterial infectious diseases is seriously threatened by
the rapid development of resistance mechanisms. The adaptation and evolution of microorganisms
occurs much faster than the development of new antibiotic substances, which makes the treatment
of infectious diseases increasingly ineffective and costly for the public health system. In order to
alleviate this problem, new strategies are urgently needed, including the discovery of substances
that subsidize the production of new drugs and/or the search for adjuvant compounds to
conventional therapy. Betulinic acid is a pentacyclic triterpene of the lupane type, which has a range
of biological activities such as antitumor, anti-inflammatory, antiviral, antimalarial, antifungal and
antibacterial action. In this context, this study aims to evaluate the potential of betulinic acid in
reversing bacterial resistance associated with efflux pumps and bacterial biofilms. the minimum
inhibitory concentrations (MIC) were determined using the broth microdilution method.
Subsequently, their effects on antibiotic resistance mediated by efflux pumps were evaluated by
reducing the MIC of the antibiotics norfloxacin, ciprofloxacin and ethidium bromide (EtBr), while
fluorimetry and permeability potential tests were carried out using the fluorescence method.
Molecular docking experiments were carried out to evaluate the interaction with efflux proteins,
using AutoDock Vina 1.2.5. Biofilm formation, inhibition and treatment tests were carried out using
the crystal violet method. Pharmacokinetic and toxicological predictions were made using the
ADMETlab software. AB did not show significant intrinsic antibacterial activity against any of the
strains analyzed, with a MIC ≥ 1024 μg/mL. However, against MepA the compound was able to
reduce the MIC of ciprofloxacin and BrEt by 4 times. In the NorA assays, AB reduced the 

norfloxacin MIC sixteenfold and the BrEt MIC fourfold, indicating possible inhibitory effects for
Nora and MepA. AB induced a significant increase in the fluorescence emission of the two pumps,
with increases of 71% and 88%, respectively. The permeability test showed that AB increased the
fluorescence of sytox green, inducing an increase of 61% for MepA and 66% for NorA,

demonstrating the ability to permeabilize the bacterial membrane of Staphylococus aureus SA-
1199B and SA- K2068. In silico modeling showed that AB has a high affinity for the NorA binding

site, suggesting that efflux pump inhibition may result from competition for the binding site. The
in silico modeling of MepA indicates that the binding of BA to the transporter occurs with high
thickness, preventing the binding and translocation of substrates, which keeps these substances
inside the cell. AB showed variable capacity to inhibit and eradicate biofilms, especially in
preventing initial formation. In-silico ADMET analyses indicate that betulinic acid has favorable
physicochemical and pharmacokinetic properties, with emphasis on its intestinal absorption, oral
bioavailability and systemic distribution. Although toxicity predictions indicate a potential risk of
some adverse effects. In conclusion, these findings indicate that AB can act as a possible therapeutic
adjuvant in the fight against bacterial resistance, this being the first study to show its inhibitory
action on the NorA and MepA pumps.

COMMITTEE MEMBERS:
Presidente - JACQUELINE COSMO ANDRADE PINHEIRO
Interna - MARIA DO SOCORRO VIEIRA DOS SANTOS
Externa à Instituição - MARIA FLAVIANA BEZERRA MORAIS BRAGA