Potencial alelopático e identificação de compostos de Cryptostegia madagascariensis Bojer ex Decne

• Autor(a) principal: Araújo, Hellen Thayse Nascimento
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/26675
• topic: Atividade alelopática; Germinação; Crescimento inicial

Abstract: Invasive species are one of the major environmental problems today and one of the negative effects is the release of chemical compounds with allelopathic activity, the allelochemicals. Cryptostegia madagascariensis, is one of these species, causing, in the Northeast of Brazil, environmental and economic damages. The objective of this work is to investigate whether C. madagascariensis has an allelopathic effect, through the bioindicator species Lactuca sativa L, besides identifying the classes of the secondary metabolites present in the extracts of different parts of the plant of this species. The work was divided into two experiments. In the experiment I, in the Seed Analysis Laboratory of the Federal University of Ceará, germination and initial growth of lettuce seedlings (test species) were evaluated. The allelopathic activity was verified by means of aqueous extracts obtained from fresh leaves, roots, fruits, leaves and flowers of the litter, with concentrations of 0, 25, 50, 75 and 100%. The design was completely randomized, in a factorial scheme 5x5, referring to five parts of the plant and five concentrations. For the tests, four replicates of 25 seeds were sown in Petri dishes, evaluating the percentage, speed index and mean germination time, in addition to initial seedling growth (mean shoot and radicular length). The extracts were evaluated for pH, electrical conductivity and osmotic potential. In the experiment II, performed in the Multi-user Laboratory of Chemistry of Natural Products of Embrapa Agroindústria Tropical-Fortaleza, the phytochemical analysis of the extracts was obtained using an UPLC-QToF-MSE system in all the extracts, and later the extract of the fresh leaves was selected for the liquid-liquid partition using ethyl acetate as the solvent. The germination test and chromatographic analysis with the partitions were also carried out. The physicochemical characterization of the samples showed that there was no influence on the germination of the test species. Only the root extract did not show significant results in relation to the evaluated variables, the others presented allelopathic effect, becoming more evident in the concentration of 100%. The variables most sensitive to the allelopathic effect were the speed of germination and the growth of the radicle. After partitioning the aqueous fraction showed similar effects to the crude extract, indicating that the substances present in this fraction may be responsible for the negative allelopathic activity. From the preliminary phytochemical study of C. madagascariensis leaf extracts, it was possible to detect the presence of citric acid, caffeic acid hexose and quercetin-3-O-gal-1,6-rhm, and studies with the isolated fractions of these substances are necessary to prove the allelopathic effect linked to them or to other substances present in the extract that have not been identified. The aqueous extracts from the aerial parts of C. madagascariensis caused a reduction in seed germination and initial growth of L. sativa seedlings, indicating their allelopathic effect.