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Universidade Estadual de Feira de Santana (UEFS) 2020

Estudo farmacognóstico e atividades biológicas de Polygala boliviensis A.W. Benn

Silva, Danielle Figuerêdo da

Titre : Estudo farmacognóstico e atividades biológicas de Polygala boliviensis A.W. Benn

Auteur : Silva, Danielle Figuerêdo da

Université de soutenance : Universidade Estadual de Feira de Santana (UEFS)

Grade : Doutorado Acadêmico em Recursos Genéticos Vegetais 2020

Résumé
Studies corroborate the popular use of species of the genus Polygala, however Polygala boliviensis A.W. Benn (Polygalaceae), found in the semi-arid region of Bahia, has few chemical and pharmacological studies. Thus, this work aimed to conduct a pharmacognostic study and the biological activities of P. boliviensis. The collection of the aerial parts and roots of the species, for the different stages, was performed at the UEFS campus, in Feira de Santana, Bahia. For the isolation of secondary metabolites, methanolic extract was prepared by maceration, followed by partition with hexane, chloroform and ethyl acetate, and successive procedures by column chromatography. The identification of the isolated metabolites was performed by one- and two-dimensional NMR, resulting in the chemical structures of 1,3,5-trihydroxy-2-methoxyxanthone, α-spinasterol, as well as a coumarin and fatty acid mixture that are in confirmation phase. In the evaluation of biological activity, the coumarins auraptene and polygalen, previously isolated from P. boliviensis, were evaluated by MTT test and in vitro antiplasmodial activity against chloroquine-resistant strain of Plasmodium falciparum (W2), and showed IC50 = 13.46 ± 0.03 μM and EC50 = 0.171 ± 0.016 for auraptene ; and above 100 μM and 0.164 ± 0.012 for poligalen, resulting in the selectivity index of 78.71 and 609.76, respectively. These coumarins were also subjected to docking-based inverse virtual screening using P. falciparum targets from BraMMT, demonstrating better affinity to purine nulceoside phosphorylase and dihydroorotate dehydrogenase enzymes. We also evaluated the seasonal variation of the chemical composition through the identification and quantification of secondary metabolites by HPLC-DAD ; the antioxidant activity, through the DPPH-free radical scavenging test and inhibition of β-carotene auto-oxidation ; and the lethality against Artemia salina. By this method, gallic acid, rutin, poligalen, auraptene, and 7 unknown major peaks were identified, which through UV spectra, are believed to be phenolic acids, flavonoids, xanthones, coumarins, and styrylpyrones. Although there was no seasonal variation in the yield of extracts and chemical profile, there was quantitative variation of metabolites, antioxidant activity and lethality against A. salina

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Page publiée le 9 janvier 2023