Publicações

@article{nokey,

title = {Antibacterial Activity of Isobavachalcone (IBC) Is Associated with Membrane Disruption},

author = {Leticia Ribeiro Assis and Reinaldo Dos Santos Theodoro and Maria Beatriz Silva Costa and Julyanna Andrade Silva Nascentes and Miguel Divino Rocha and Meliza Arantes Souza Bessa and Ralciane Paula Menezes and Guilherme Dilarri and Giovane Böerner Hypolito and Vanessa Rodrigues Dos Santos and Cristiane Duque and Henrique Ferreira and Carlos Henrique Gomes Martins and Luis Octavio Regasini},

url = {https://www.mdpi.com/2077-0375/12/3/269/htm https://www.mdpi.com/2077-0375/12/3/269},

doi = {10.3390/MEMBRANES12030269/S1},

issn = {20770375},

year  = {2022},

date = {2022-01-01},

journal = {Membranes},

volume = {12},

issue = {3},

pages = {269},

publisher = {MDPI},

abstract = {Isobavachalcone (IBC) is a natural prenylated chalcone with a broad spectrum of pharmacological properties. In this work, we newly synthesized and investigated the antibacterial activity of IBC against Gram-positive, Gram-negative and mycobacterial species. IBC was active against Grampositive bacteria, mainly against Methicillin-Susceptible Staphylococcus aureus (MSSA) and MethicillinResistant Staphylococcus aureus (MRSA), with minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL, respectively. On the other hand, IBC was not able to act against Gram-negative species (MIC > 400 µg/mL). IBC displayed activity against mycobacterial species (MIC = 64 µg/mL), including Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium kansasii. IBC was able to inhibit more than 50% of MSSA and MRSA biofilm formation at 0.78 µg/mL. Its antibiofilm activity was similar to vancomycin, which was active at 0.74 µg/mL. In order to study the mechanism of the action by fluorescence microscopy, the propidium iodide (PI) and SYTO9 fluorophores indicated that IBC disrupted the membrane of Bacillus subtilis. Toxicity assays using human keratinocytes (HaCaT cell line) showed that IBC did not have the capacity to reduce the cell viability. These results suggested that IBC is a promising antibacterial agent with an elucidated mode of action and potential applications as an antibacterial drug and a medical device coating.},

keywords = {Antibacterial, Biofilm, Chalcone, Membrane, Natural product},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Antibacterial Activity of Isobavachalcone (IBC) Is Associated with Membrane Disruption},

author = {Leticia Ribeiro Assis and Reinaldo Dos Santos Theodoro and Maria Beatriz Silva Costa and Julyanna Andrade Silva Nascentes and Miguel Divino Rocha and Meliza Arantes Souza Bessa and Ralciane Paula Menezes and Guilherme Dilarri and Giovane Böerner Hypolito and Vanessa Rodrigues Dos Santos and Cristiane Duque and Henrique Ferreira and Carlos Henrique Gomes Martins and Luis Octavio Regasini},

url = {https://www.mdpi.com/2077-0375/12/3/269/htm https://www.mdpi.com/2077-0375/12/3/269},

doi = {10.3390/MEMBRANES12030269/S1},

issn = {20770375},

year  = {2022},

date = {2022-01-01},

journal = {Membranes},

volume = {12},

issue = {3},

pages = {269},

publisher = {MDPI},

abstract = {Isobavachalcone (IBC) is a natural prenylated chalcone with a broad spectrum of pharmacological properties. In this work, we newly synthesized and investigated the antibacterial activity of IBC against Gram-positive, Gram-negative and mycobacterial species. IBC was active against Grampositive bacteria, mainly against Methicillin-Susceptible Staphylococcus aureus (MSSA) and MethicillinResistant Staphylococcus aureus (MRSA), with minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL, respectively. On the other hand, IBC was not able to act against Gram-negative species (MIC > 400 µg/mL). IBC displayed activity against mycobacterial species (MIC = 64 µg/mL), including Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium kansasii. IBC was able to inhibit more than 50% of MSSA and MRSA biofilm formation at 0.78 µg/mL. Its antibiofilm activity was similar to vancomycin, which was active at 0.74 µg/mL. In order to study the mechanism of the action by fluorescence microscopy, the propidium iodide (PI) and SYTO9 fluorophores indicated that IBC disrupted the membrane of Bacillus subtilis. Toxicity assays using human keratinocytes (HaCaT cell line) showed that IBC did not have the capacity to reduce the cell viability. These results suggested that IBC is a promising antibacterial agent with an elucidated mode of action and potential applications as an antibacterial drug and a medical device coating.},

keywords = {Antibacterial, Biofilm, Chalcone, Membrane, Natural product},

pubstate = {published},

tppubtype = {article}

}

@article{Granato2019,

title = {The ECNA antitoxin is important not only for human pathogens: Evidence of Its Role in the Plant Pathogen Xanthomonas citri subsp. Citri},

author = {Laís Moreira Granato and Simone Cristina Picchi and Maxuel De Oliveira Andrade and Paula Maria Moreira Martins and Marco Aurélio Takita and Marcos Antonio Machado and Alessandra Alves De Souza},

url = {https://journals.asm.org/doi/10.1128/JB.00796-18},

doi = {10.1128/JB.00796-18/SUPPL_FILE/JB.00796-18-S0001.PDF},

issn = {10985530},

year  = {2019},

date = {2019-01-01},

journal = {Journal of Bacteriology},

volume = {201},

issue = {20},

pages = {25-38},

publisher = {American Society for Microbiology},

abstract = {Xanthomonas citri subsp. citri causes citrus canker disease worldwide in most commercial varieties of citrus. Its transmission occurs mainly by wind-driven rain. Once X. citri reaches a leaf, it can epiphytically survive by forming a biofilm, which enhances the persistence of the bacteria under different environmental stresses and plays an important role in the early stages of host infection. Therefore, the study of genes involved in biofilm formation has been an important step toward understanding the bacterial strategy for survival in and infection of host plants. In this work, we show that the ecnAB toxin-antitoxin (TA) system, which was previously identified only in human bacterial pathogens, is conserved in many Xanthomonas spp. We further show that in X. citri, ecnA is involved in important processes, such as biofilm formation, exopolysaccharide (EPS) production, and motility. In addition, we show that ecnA plays a role in X. citri survival and virulence in host plants. Thus, this mechanism represents an important bacterial strategy for survival under stress conditions. IMPORTANCE Very little is known about TA systems in phytopathogenic bacteria. ecnAB, in particular, has only been studied in bacterial human pathogens. Here, we showed that it is present in a wide range of Xanthomonas sp. phytopathogens; moreover, this is the first work to investigate the functional role of this TA system in Xanthomonas citri biology, suggesting an important new role in adaptation and survival with implications for bacterial pathogenicity.},

keywords = {Biofilm, Quorum sensing, Stress tolerance, TA system},

pubstate = {published},

tppubtype = {article}

}

@article{Monteiro2017,

title = {Stiffness signatures along early stages of Xylella fastidiosa biofilm formation},

author = {Moniellen P. Monteiro and João H. Clerici and Prasana K. Sahoo and Carlos L. Cesar and Alessandra A. Souza and Mônica A. Cotta},

doi = {10.1016/J.COLSURFB.2017.07.075},

issn = {0927-7765},

year  = {2017},

date = {2017-01-01},

journal = {Colloids and Surfaces B: Biointerfaces},

volume = {159},

pages = {174-182},

publisher = {Elsevier},

abstract = {The pathogenicity of Xylella fastidiosa is associated with its systematic colonization of the plant xylem, forming bacterial biofilms. Mechanisms of bacterial transport among different xylem vessels, however, are not completely understood yet, but are strongly influenced by the presence of extracellular polymeric substances (EPS), which surrounds the assembly of cells forming the biofilm. In this work, we show quantitative measurements on the elastic properties of the system composed by EPS and bacterial cell. In order to investigate the mechanical properties of this system, force spectroscopy and confocal Raman measurements were carried out during Xylella fastidiosa subsp. pauca initial stages of adhesion and cluster formation. We show that stiffness progressively decreases with increasing culture growth time, from two to five days. For early adhesion samples, stiffness values are quite different at the bacterial polar and body regions. Lower stiffness values at the cell pole suggest a flexible mechanical response at this region, associated with first cell adhesion to a surface. These results correlate very well with our observations of cell motion within microchannels, under conditions simulating xylem flow. Both the oscillatory movement of vertically attached single cells, as well as the transport of cell clusters within the biofilm matrix can be explained by the presence of softer materials at the cell pole and EPS matrix. Our results may thus add to a more detailed understanding of mechanisms used by cells to migrate among vessels in plant xylem.},

keywords = {Biofilm, Extracellular polymeric substances, Stiffness, Xylella fastidiosa},

pubstate = {published},

tppubtype = {article}

}