Estudo fitoquimico, avaliação da atividade larvicida e antioxidante de Chresta pacourinoides

• Ano de defesa: 2018
• Autor(a) principal: Silva, Evandro Ferreira da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Farmacologia; Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos; UFPB
• Palavras-chave em Português: Chresta pacourinoides; Cromatografia; Flavonoides; Chromatography; Flavonoids; CNPQ::CIENCIAS BIOLOGICAS::FARMACOLOGIA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/12319

The genus Chresta belongs to the Asteraceae family, but it has been little studied in the literature and it is relatively small, being composed of 15 species and 14 of them are endemic to Brazil. The species Chresta pacourinoides, which can be found in Paraíba, presents only a previous study found in the literature, requiring a broader study, that uses spectroscopic techniques to disseminate more information on the chemical constituents present in the species and evaluating its antioxidant activity. Thus, aerial parts of Chresta Pacourinoides (3 kg) were collected in the Fagundes-PB city. An aliquot (30g) of the crude ethanolic extract (CEE) was subjected to a partition, which generated the hexane and methanolic extracts (ME). Through techniques such as Medium Pressure Liquid Chromatography and Gas Chromatography coupled to Mass Spectrometry (MS), the hexane extract was worked up. The methanolic extract was subjected to analytical and preparative High Performance Liquid Chromatography (HPLC), for analysis and isolation of the constituents present. The isolated compounds were identified by ¹H and ³³C NMR, as well as by two-dimensional techniques and mass spectrometry (MS) by direct injection. Also, the total phenolic content of CEE and the methanolic extract was determined following the Folin-Ciocalteu method. For the determination of the antioxidant activity of the same samples as well as fraction 14-17 (isolated from ME), DPPH radical sequestration method was used. In addition, the larvicidal activity against Aedes aegypti larvae was tested for the extract sample, methanolic phase and one of the isolated fractions. As a result, 14 substances were identified and from the fraction 14-17, 9 substances were isolated, of which eight flavonoids: kaempferol; isoquercetrin; chrysoeryol; apigenin; 3-o-methylquercetin; luteolin; eriodictiol; stricnoblodone, and a phenolic acid (protocatecuic acid). In addition, it was possible to identify 6 compounds by MS: cafeic acid O-hexose; cafeoilquinic Acid; 3,4-dideofeoilquinic acid; luteolin-O-hexose; apigenin; quercetin-OHexose. As results for the total phenolic content, it was possible to observe that the CEE presented 128 ± 3.29 EAG / g of sample and the methanolic extract 98.5 ± 5.4 EAG / g of sample. In the antioxidant activity assay, the CEE presented EC 50 288.83 ± 9.47 μg / mL, the methanolic extract 355.71 ± 9.87 μg / mL and the fraction 14-17 of 35,657 ± 0,6893 μg / mL, showing that the fraction had better activity. In the assay for larvicidal activity the samples tested did not cause significant mortality. Thereby, with the obtained results, it is possible to conclude that the phytochemical study of Chresta pacourinoides resulted in the isolation and identification of 9 compounds from fraction 14-17 isolated from methanolic extract, where 7 were isolated for the first time in the genus, as well as the identification of 7 other substances by MS. In the Hexanic extract, some fractions were analyzed by CG/MS. Regarding the biological activities, the larvicidal activity of the samples tested were not significant, in addition, although the extract and the methanolic extracts presented good concentrations of phenolic compounds, their antioxidant activities were not satisfactory by the DPPH method, however the fraction 14-17 presented antioxidant activity, requiring further studies to confirm it.