Browsing by Author "Fonseca, Thaisa Helena Silva"

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    Biological screening of extracts of Brazilian Asteraceae plants.
    (2013) Carvalho, Cintia Cristina de; Machado, Kamilla Nunes; Ferreira, Paulo Michel Pinheiro; Pessoa, Cláudia; Fonseca, Thaisa Helena Silva; Gomes, Maria Aparecida; Nascimento, Andréa Mendes do
    Natural products are a very productive source of leads for the development of medicines. Seven Brazilian Asteraceae adult plants were randomly chosen. The current study was designed to evaluate the antiprotozoal and cytotoxic activities in vitro of 21 extracts obtained. Phytochemical properties of the most active extracts also were checked. Cytotoxic activity was evaluated by 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) method against human tumor cell lines (HCT-116, OVCAR 8 and SF-295). The antiprotozoal activity was evaluated against Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia. None of the extracts showed antiprotozoal activity. However, 76% of the extracts displayed moderate to high in vitro cytotoxic activities against human cancer cell which suggests that they are a promising source of anticancer compound, since none of the extracts showed hemolytic activity. Terpenoids, flavonoids, saponins, tannins, besides other compound classes, were identified and may be responsible for their antitumor activity. Cytotoxic assays indicate the anticancer potential of Asteraceae species from Brazil.
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    Chemiluminescent ELISA with multi-epitope proteins to improve the diagnosis of canine visceral leishmaniasis.
    (2019) Fonseca, Thaisa Helena Silva; Faria, Angélica Rosa; Leite, Heloine Martins; Silveira, Júlia Angélica Gonçalves da; Carneiro, Cláudia Martins; Andrade, Hélida Monteiro de
    Diagnosing canine visceral leishmaniasis (CVL) is difficult because clinical signs of the disease are non-specific and a many infected animals in endemic areas, as in Brazil, are asymptomatic. Serological tests are the most common diagnostic methods employed, but most have limitations. For this reason, the implementation of a rapid, sensitive, and specific diagnostic test for CVL has become increasingly important. In this study, we adapted a chemiluminescent enzyme-linked immunosorbent assay (CL ELISA), using two multi-epitope recombinant proteins (PQ10 and PQ20) and a crude Leishmania antigen produced using promastigotes of L. infantum, as antigens to detect CVL infection in animals from Belo Horizonte. To investigate cross-reactions, samples from dogs with other infections (babesiosis, ehrlichiosis and Trypanosoma cruzi) were tested. Assay performance validations were conducted to analyse parameters such as variability, reproducibility, and stability. CL ELISA sensitivity/specificity with PQ10 antigen was 93.1%/80.0%; with the PQ20 protein 93.1%/96.6%; and with the crude antigen 75%/73.3%. Inter-assay variability and inter-operator coefficient of variation were <7% and <15%, with PQ10 and PQ20, respectively. The accuracy of the CL ELISA was classified as excellent for PQ10 (AUC = 0.95) and PQ20 (AUC = 0.98) and moderate for the crude antigen (AUC = 0.77). The kappa score for qualitative agreement between two plate lots was excellent for PQ10 (0.89) and good for PQ20 (0.65). PQ20 remained more stable than PQ10. The CL ELISA with recombinant proteins is a promising tool to diagnose CVL.
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    Insignificant level of in vitro cytotoxicity, anti‑rotavirus, antibacterial, and antifungal activities of N‑alkylmaleamic acids.
    (2013) Belinelo, Valdenir José; Campos, Michele Soares Tacchi; Antunes, R. M.; Assenço, Regina Aparecida Gomes; Vieira Filho, Sidney Augusto; Lanna, Maria Célia da Silva; Marçal, E. C.; Fonseca, Thaisa Helena Silva; Gomes, Maria Aparecida; Magalhães, José Carlos de
    By reacting maleic anhydride with amines, we synthesized the derivatives N‑ethyl, N‑(2‑ethylamine), N‑piperidinyl, N‑phenyl, and N‑phenylhydrazinyl maleamic acids. The purity of these products was initially verified by melting range and the presence of only one spot observed by thin layer chromatography. The chemical structures of the obtained N‑alkyl maleamic acids were confirmed through infrared (IR) and hydrogen and carbon nuclear magnetic resonance (1 H and 13C NMR) spectrometry. Due to the already proven pharmacological activity of maleimides, maleic anhydride and its N‑alkyl maleamic acids were subjected to in vitro assays to observe antiviral (SA‑11 rotavirus), antibacterial (Escherichia coli, Staphylococcus aureus, and Bacillus cereus), antifungal (Colletotrichum musae, Fusarium solani f. sp. phaseoli, Fusarium solani f. sp. piperis Alb., and Penicillium sp.), and antiprotozoal (Trichomonas vaginalis, Giardia lamblia, and Entamoeba histolytica) effects. To study the anti‑rotavirus properties, firstly the 3‑(4,5‑dimethylthiazol‑2‑yl)‑2‑5‑diphenyltetrazolium bromide (MTT) method was used to establish the median cytotoxicity concentration (CC50) of the compounds, using MA‑104 cell line. Under the experimental conditions used, cytotoxic, anti‑rotavirus, antibacterial, and antifungal properties were not observed for these compounds.
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    Salacia crassifolia (Celastraceae) : chemical constituents and antimicrobial activity.
    (2015) Rodrigues, Vanessa Gregório; Duarte, Lucienir Pains; Silva, Roqueline Rodrigues; Silva, Grácia Divina de Fátima; Simões, Maria O. Mercadante; Takahashi, Jacqueline Aparecida; Matildes, Bibiane Lindsay Guimarães; Fonseca, Thaisa Helena Silva; Gomes, Maria Aparecida; Vieira Filho, Sidney Augusto
    The phytochemical study of hexane extract from leaves of Salacia crassifolia resulted in the isolation of 3β-palmitoxy-urs-12-ene, 3-oxofriedelane, 3β-hydroxyfriedelane, 3-oxo-28-hydroxyfriedelane, 3-oxo-29-hydroxyfriedelane, 28,29-dihydroxyfriedelan-3-one, 3,4-seco-friedelan-3-oic acid, 3β-hydroxy-olean-9(11):12-diene and the mixture of α-amirin and β-amirin. β-sitosterol, the polymer gutta-percha, squalene and eicosanoic acid were also isolated. The chemical structures of these constituents were established by IR, 1H and 13C NMR spectral data. Crude extracts and the triterpenes were tested against Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis and no activity was observed under the in vitro assay conditions. The hexane, chloroform, ethyl acetate and ethanol crude extracts, and the constituent 3,4-seco-friedelan-3-oic acid and 28,29-dihydroxyfriedelan-3-one showed in vitro antimicrobial activity against Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Streptococcus sanguinis and Candida albicans.
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    Trichomonicidal activity of Maytenus imbricata (Celastraceae).
    (2014) Batista, Carla Ribeiro Álvares; Fonseca, Thaisa Helena Silva; Rodrigues, Vanessa Gregório; Sousa, Grasiely Faria de; Chacon, Michelle Oliveira; Vieira Filho, Sidney Augusto; Duarte, Lucienir Pains; Gomes, Maria Aparecida
    Trichomoniasis, most common non-viral sexually transmitted infection worldwide, is produced by protozoan Trichomonas vaginalis. The therapy of choice is metronidazole (MTZ). The drug has undesirable side effects, which may result in treatment discontinuation, leading to further spread of infection and emergence of resistant strains. This feature highlights the importance of studying new trichomonicidal substances. In this context, the importance of plants in relation to the research of new drugs is undeniable. The genus Maytenus, distributed throughout Brazil, is the largest of family Celastraceae, including about 80 recognized species with different biological activities. Therefore, the trichomonicidal activity of MTZ and extracts obtained from Maytenus robusta leaves and Maytenus imbricata roots on the JT strain of T. vaginalis, sensitive (JT) and resistant (JTR) to MTZ was investigated. Sample of T. vaginalis trophozoites were associated with extracts in 6 increasing concentrations ranging from 0.43 to 13.76 μg/ml. The solid that precipitated from the hexane/ethyl ether - 1:1 extract (SEH), obtained from M. imbricata roots proved to be active. This extract also impacted the viability of trophozoites of both strains, with IC50 value surprisingly low (1.09 μg/ml for JT and 1.57 μg/ml for JTR) signaling towards a promising candidate for phytotherapy or for isolation of substance with trichomonicidal activity.