Banca de QUALIFICAÇÃO: FLÁVIA EDUARDA VIDAL BARBOSA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : FLÁVIA EDUARDA VIDAL BARBOSA
DATA : 28/01/2022
HORA: 14:00
LOCAL: Remoto
TÍTULO:

EVALUATION OF LEISHMANICIDAL ACTIVITY IN VITRO OF LECTIN from Dioclea Violacea Mart. ex Benth

PALAVRAS-CHAVES:

Keywords: Leishmania infantum. Visceral leishmaniasis. Dioclea violacea. Lectin. DVL

PÁGINAS: 65
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

The leishmaniases are characterized as a set of diseases of clinical and epidemiological interest that have worldwide distribution. The treatment for this disease is based on the use of pentavalent antimonials, primarily, and in some cases the application of secondary drugs. These drugs, despite being efficient, present several problems in their use and important side effects, which encourages the search for new drugs that present low toxicity and few adverse effects. Within this scenario, lectins stand out as proteins that have several functions in the organisms where they are found. In researches developed with the lectin from the seeds of Dioclea violacea (DVL) it was possible to observe that it has specificity of recognition and binding to mannose/glucose and presents itself as a biological tool with promising applications. The present study aimed to evaluate the in vitro leishmanicidal effect of lectin from D. violacea seeds (DVL) in Leishmania infantum strain culture. Promastigote forms were incubated with different concentrations of DVL (324 - 5.06 μg/mL), from the determination of the CI50 the participation of the carbohydrate recognition domain (CRD) in the lectin activity was evaluated. Cell viability was assessed by counting in a Neubauer chamber. Fluorescence assays with 2',7'- dichlorodihydrofluorescein diacetate (DCFH2-DA) and propidium iodide (PI) were performed in order to verify the production of reactive oxygen species (ROS) and damage to parasite cell membrane integrity, respectively. In addition, the morphological changes induced by the DVL in promastigotes were evaluated by scanning electron microscopy. The effect of the association between the DVL and amphotericin B and glucantime on promastigotes was also tested. By means of the 3-(4,5-Dimethylthiazol-2-yl) -2,5- diphenyltetrazolium bromide (MTT) test it was possible to determine the cytotoxicity of the DVL on Raw 264.7 macrophages, as well as the effect of its association with amphotericin B on these same cells. Furthermore, the effect of DVL on amastigotes of the L. infantum strain was also verified. DVL was able to inhibit the growth of promastigotes in a concentration and time dependent manner, with CI50/24h = 49.37 μg/mL; CI50/48h = 37.47 μg/mL; CI50/72h = 34 μg/mL. The data obtained showed that the lectin activity is related to its ability to recognize and bind to glycans present in L. infantum and treatment with it is able to induce the production of ROS, damage to cell membrane integrity and morphological changes in the parasites. Furthermore, the lectin was able to modulate the action of amphotericin B and glucantime, improving their effect on promastigotes. DVL did not show cytotoxicity in Raw 264.7 cells, demonstrating an increase in the viability of these cells, an effect also observed in the evaluation of the association between DVL and amphotericin B on the cells. Furthermore, with the use of CI50 (50 μg/mL) it was possible to observe a reduction in the survival rate of macrophages infected with amastigotes, as well as a reduction in the percentage of infection. The results suggest that DVL is a promising alternative for the treatment of leishmaniasis, however, further studies are needed to elucidate the probable mechanisms of action.

MEMBROS DA BANCA:
Interno - 1185176 - FRANCISCO NASCIMENTO PEREIRA JUNIOR
Presidente - 1528282 - MARCOS ANTONIO PEREIRA DE LIMA
Externo à Instituição - RACQUEL OLIVEIRA DA SILVA SOUZA - FJN