Navegando por Autor "Moraes, Thaís de Fátima Silva"

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Evaluation of the activity of Tontelea micrantha extracts against Bacteria, Candida and Mayaro virus.
(2018) Nizer, Waleska Stephanie da Cruz; Ferraz, Ariane Coelho; Lima, William Gustavo de; Moraes, Thaís de Fátima Silva; Ferreira, Fernanda Lopes; Ferreira, Jaqueline Maria Siqueira; Magalhães, Cíntia Lopes de Brito; Duarte, Lucienir Pains; Vieira Filho, Sidney Augusto; Magalhães, José Carlos de
Objectives: This work aimed to evaluate the antibacterial, antifungal, and anti-Mayaro virus(MAYV) activity of leaf and branch extracts from Tontelea micrantha. Materials and Methods: T. micrantha extracts were prepared through the partition of the leaf and branch samples in different solvents. Then, the antibacterial and antifungal activity was assessed against bacterial pathogens and Candida sp. by the determination of the minimum inhibitory concentration (MIC) by the broth microdilution method. The activity against anti-MAYV was evaluated through the quantification of the extract concentration that promoted the protection of 50% of the cells after the viral infection. Results: The extracts of T. micrantha were inactive (MIC >500 µg/mL) against Gram-positive, Gram-negative and Candida species at the highest concentration tested (500 µg/mL). Anti-MAYV activity was also not detected, with SI <10, ranging from 1.2 to 3.6. Conclusion: Although it is used in traditional medicine, Leaf and branch extracts from T. micrantha did not present antimicrobial activity, which could be caused by the antagonistic effect of the compounds present in the extract.
High prevalence of dengue antibodies and the arginine variant of the FcγRIIa polymorphism in asymptomatic individuals in a population of Minas Gerais State, Southeast Brazil.
(2017) Pereira, Anna Carolina Toledo da Cunha; Siqueira, Tatiane Ribeiro de; Prado, Andressa Anunciação de Oliveira; Silva, Camila Almeida Veiga da; Moraes, Thaís de Fátima Silva; Aleixo, Alan Alex; Magalhães, José Carlos de; Souza, Gabriel Augusto Pires de; Drumond, Betânia Paiva; Ferreira, Gustavo Portela; Silva, Breno de Mello; Magalhães, Cíntia Lopes de Brito; Santos, Luciana Lara; Ferreira, Jaqueline Maria Siqueira; Malaquias, Luiz Cosme Cotta; Coelho, Luiz Felipe Leomil
Dengue is the most prevalent arthropod-borne viral illness in humans worldwide. Single-nucleotide polymorphisms (SNPs) in genes involved in the immune response, such as dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), IgG Fc receptor II-A (FcγRIIa), vitamin D receptor (VDR), and tumor necrosis factor alpha (TNF-α), were previously reported to be associated with susceptibility to dengue disease in different human populations. Therefore, due to the relevant association of host immune and genetic status with disease susceptibility/severity of dengue, this work aims to verify the frequency of anti-dengue virus antibodies and some dengue-associated risk SNPs in a population in Minas Gerais State, Southeast Brazil. A total of 1560 individuals were genotyped for polymorphisms in DC-SIGN (rs4804803), FcγRIIa (rs1801274), VDR (rs7975232), and TNF-α (rs1800629). The presence of anti-dengue antibodies (IgM and/or IgG) in these samples was also assayed. Anti-dengue antibodies were detected at an overall frequency of 16.86%, indicating a virus infection in asymptomatic individuals. The genotypic frequencies of all SNPs studied did not differ between the asymptomatic and control groups. Regarding the allelic frequencies of the four SNPs analyzed, a higher frequency was detected of the G allele of FcγRIIa/rs1801274 in the asymptomatic individuals when compared to that in the control group (p =0.03). Therefore, the results showed a high prevalence of asymptomatic individuals in Minas Gerais State, with a potential association between the presence of the G allele of FcγRIIa/rs1801274 and protection against symptomatic disease.
Lack of activity of rutin isolated from Tontelea Micrantha leaves against Vero and BHK, Fungi, Bacteria and Mayaro virus and its in silico activity.
(2020) Nizer, Waleska Stephanie da Cruz; Ferraz, Ariane Coelho; Moraes, Thaís de Fátima Silva; Ferreira, Fernanda Lopes; Magalhães, Cíntia Lopes de Brito; Vieira Filho, Sidney Augusto; Duarte, Lucienir Pains; Magalhães, José Carlos de
This work aimed to evaluate the antibacterial, antifungal, and anti-Mayaro virus (MAYV) activity of rutin, a flavonoid isolated from the leaves of Tontelea micrantha (Celastraceae). Materials and Methods: The antibacterial and antifungal activities were evaluated by the broth microdilution method through the determination of the minimum inhibitory concentration. The anti-MAYV activity was determined by the rutin concentration required to protect 50% of the cells after viral infection. The indirect 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay was used to determine the cytotoxic concentration of rutin to 50% of Vero and BHK cells. The antimicrobial activity spectrum of rutin was predicted using the online software prediction of activity spectra for substances (PASS). Results: Although the PASS prediction had shown that a higher probability of rutin acts as an antifungal agent, the in vitro assays showed no antimicrobial activity. Regarding the cytotoxicity assay, rutin was not toxic to Vero and BHK cells. Conclusions: Many biological activities have been described for flavonoids, but the flavone rutin did not show antimicrobial activity in vitro. The results obtained in this work suggest that rutin is not a promising antimicrobial agent.
Methanol extract and N,N-dimethyltryptamine from psychotria viridis ruiz & pav. inhibit in vitro the Zika virus infection.
(2021) Moraes, Thaís de Fátima Silva; Ferraz, Ariane Coelho; Nizer, Waleska Stephanie da Cruz; Tótola, Antônio Helvécio; Soares, Débora Barbosa da Silva; Duarte, Lucienir Pains; Vieira Filho, Sidney Augusto; Magalhães, Cíntia Lopes de Brito; Magalhães, José Carlos de
Zika virus (ZIKV) is a public health problem due to its association with serious fetal and neurological complications and the lack of antiviral agents and licensed vaccines against this virus. Surveillance studies have alerted about the potential occurrence of a new South American epidemic episode due to the recent circulation of an African ZIKV strain detected in Brazil. Therefore, it is essential to discover antiviral agents, including natural substances, that are capable of neutralizing the action of ZIKV. Several Psychotria species have antimicrobial and anti-infammatory properties. Thus, a methanol extract and dimethyltryptamine from Psychotria viridis were evaluated for their ability to inhibit ZIKV infection in vitro by measur- ing the efective concentration that protects 50% of cells and investigating their possible mechanisms of action. The tested samples showed antiviral activity against ZIKV. The extract showed virucidal activity, afecting viral and non-cellular ele- ments, inactivating the virus before infection or when it becomes extracellular after the second cycle of infection. It was also observed that both extract and dimethyltryptamine could inhibit the virus at intracellular stages of the viral cycle. In addition to dimethyltryptamine, it is believed that other compounds also contribute to the promising virucidal efect observed for the methanol extract. To our knowledge, this is the frst report of the activity of a methanolic extract and dimethyltryptamine from Psychotria viridis against cellular ZIKV infection. These two samples, extracted from natural sources, are potential candidates for use as antiviral drugs to inhibit ZIKV infections.
Netzahualcoyonol from Salacia multiflora (Lam.) DC. (Celastraceae) roots as a bioactive compound against gram-positive pathogens.
(2022) Nizer, Waleska Stephanie da Cruz; Ferraz, Ariane Coelho; Moraes, Thaís de Fátima Silva; Lima, William Gustavo de; Santos, Josana Pereira dos; Duarte, Lucienir Pains; Magalhães, Cíntia Lopes de Brito; Vieira Filho, Sidney Augusto; Magalhães, José Carlos de
The expression of virulence factors, such as biofilm formation, in association with the acquisition of resistance to multiple drugs, has evidenced the need for new and effective antimicrobial agents against Staphylococcus aureus. The evaluation of the pharmacological properties of plant-derived compounds is a promising alternative to the development of new antimicrobials. In this study, we aimed to evaluate the antibacterial, antibiofilm, and the synergistic and cytotoxic effects of netzahualcoyonol isolated from Salacia multiflora (Lam.) DC. roots. Netzahualcoyonol presented bacteriostatic (1.56–25.0 mg/mL) and bactericidal (25.0–400.0 mg/mL) effects against Gram-positive bacteria, disrupted the biofilm of S. aureus, and presented a synergistic effect after its combination with b-lactams and aminoglycosides. The low cytotoxicity of netzahualcoyonol (Selectivity Index (SI) for S. aureus (2.56), S. saprophyticus (20.56), and Bacillus subtilis (1.28)) suggests a good security profile. Taken together, these results show that netzahualcoyonol is promising for the development of a new effective antibacterial agent.
Pristimerin isolated from Salacia crassifolia (Mart. Ex. Schult.) G. Don. (Celastraceae) roots as a potential antibacterial agent against Staphylococcus aureus.
(2021) Nizer, Waleska Stephanie da Cruz; Ferraz, Ariane Coelho; Moraes, Thaís de Fátima Silva; Lima, William Gustavo de; Santos, Josana Pereira dos; Duarte, Lucienir Pains; Ferreira, Jaqueline Maria Siqueira; Magalhães, Cíntia Lopes de Brito; Vieira Filho, Sidney Augusto; Andrade, Ana Cláudia dos Santos Pereira; Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Magalhães, José Carlos de
Ethnopharmacological relevance: Pristimerin is a triterpenoid considered the main component of Salacia crassifolia extracts. This terpene has shown promising antitumor, anti-inflammatory, and antimicrobial effects. Likewise, S. crassifolia has been used in traditional medicine to treat cancer and as an antimicrobial and anti-inflammatory agent. Aim of the study: This study aimed to evaluate the antibacterial activity of the hexane extract of Salacia crassifolia roots (HER) and its isolate, pristimerin, against pathogenic bacteria. Materials and methods: First, we evaluated the spectrum of action of HER and pristimerin by the determination of the minimum inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC). Subsequently, we analyzed the time-kill curve of these plant-derived compounds against Staphylococcus aureus. Then, we examined their mode of action by three different assays: the crystal violet methodology, the release of intracellular material, and transmission electron microscopy methods (TEM). Finally, we evaluated the effect of HER and pristimerin on the pre-formed biofilm of S. aureus by the crystal violet assay, the synergistic effect by the checkerboard method, the cytotoxicity against Vero cells, and the in silico activity using the online software PASS. Results: HER and pristimerin presented a narrow spectrum of action against Gram-positive bacteria (MIC 0.195–25 μg/mL), and their primary mode of action is the alteration of membrane permeability of S. aureus. Our results show that the compounds disrupted the pre-formed biofilm of S. aureus in a dose-dependent manner. Furthermore, HER and pristimerin presented a significant synergic effect after the combination with well-known antibiotics, which was associated with the ability of these phytomedicines to change membrane permeability. Regarding the cytotoxic effect, the selective index (SI) of HER ranged from 0.37 to 11.86, and the SI of pristimerin varied from 0.24 to 30.87, according to the bacteria tested. Conclusions: Overall, HER and pristimerin showed a promising antibacterial effect in vitro through the alteration of membrane permeability of S. aureus.
Virucidal activity of proanthocyanidin against Mayaro virus.
(2019) Ferraz, Ariane Coelho; Moraes, Thaís de Fátima Silva; Nizer, Waleska Stephanie da Cruz; Santos, Michelli dos; Tótola, Antônio Helvécio; Ferreira, Jaqueline Maria Siqueira; Vieira Filho, Sidney Augusto; Rodrigues, Vanessa Gonçalves; Duarte, Lucienir Pains; Magalhães, Cíntia Lopes de Brito; Magalhães, José Carlos de
Mayaro virus (MAYV) is a sublethal arbovirus transmitted by mosquitoes with possible installation of an urban cycle in the Americas. Its infection causes disabling arthralgia, and still, there is no vaccine or treatment to it. We recently investigated nearly 600 compounds by molecular docking and identified epicatechin as a potent antiviral against MAYV. The root extract of Maytenus imbricata showed anti-MAYV activity and two isolated compounds from this plant were also evaluated in vitro. Proanthocyanidin (PAC), a dimer containing epicatechin, showed an effective concentration for 50% of the cells infected by MAYV (EC50) of 37.9 ± 2.4 μM and a selectivity index (SI) above 40. PAC showed significant virucidal activity, inhibiting 100% of the virus proliferation (7 log units), and caused moderate effect during adsorption and virus internalization stage. However, PAC was unable to block the infection when only the cells were pretreated. It was observed a reduction in virus yields when adding PAC at different moments after infection. The set of results indicates that PAC binds to viral and non-cellular elements and may inactivate the MAYV. The inactivation occurs before infection or when the virus reaches the extracellular environment from the 2nd cycle of infection that could block its progression cellto-cell or to tissues not yet infected.