Extrato padronizado de Ruta graveolens L.: avaliação de seu potencial no controle da brusone em arroz

• Autor(a) principal: Reis, Karinna Bannach
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/3066
• topic: Padronização; Furanocumarina; Psoraleno; Bergapteno; Óleo essencial; Fitopatógeno; Magnaporthe oryzae; Standardization; Furanocoumarin; Psoralen; Bergapten; Essential oil; Plant pathogen; FARMACIA::ANALISE E CONTROLE E MEDICAMENTOS

Ruta graveolens has been successfully applied for many human diseases treatment and promises a well succeed alternative for plant diseases control because it has also phytoalexins in its composition. The aim of this study was to standardise the R. graveolens liquid extract and evaluate its potential for controlling rice (Oryza sativa) leaf blast (Magnaporthe oryzae). The drug has been characterized, the liquid extract obtained and the methodology for quantifying the standards components, furanocoumarins psoralen and bergapten, validated by high performance liquide chromatography. The components of essential oil obtained from standardized liquid extract were characterized by gas chromatography-mass spectrometry. In a completely randomized design, conducted in artificial hydrophobic surface with three replications and eleven treatments composed of M. oryzae conidial suspension (105 con.ml-1) mixed with R. graveolens standardized extract (0.01 to 0.10 g.mL-1), or furocoumarins psoralen (0.18 to 1.82 μg. mL-1), or bergapten (0.29 to 2.91 μg. mL-1), or water (control). It was evaluated the inhibition of conidial germination and appressorium formation and the median lethal dose (LD50). A second assay, in a completely randomized design in three replications was conducted in greenhouse conditions. It was composed of 21 days old rice plants, which were sprayed with a mixture containing M. oryzae conidial suspension (3x105 con.ml-1) and R. graveolens extract, without dilution, or furocoumarins psoralen (18.26 μg. mL-1), or bergapten (29.14 μg. mL-1), or water (control). Nine days after inoculation, leaf blast severity was scored with a diagrammatic scale, the data were statistically analyzed and means compared. The standardized plant extract inhibited M. oryzae conidial germination (LD50=0.237mg) and appressorium formation (LD50=0.121 mg) up to 100% and reduced 80.84% of leaf blast. By fluorescence microscopy it was possible to observe that standardized plant extract did not damage M. oryzae cell wall and plasma membrane, indicating another type of interaction to inhibit conidia development. Isolated standards furanocoumarins psoralen and bergapten did not inhibit conidial germination and appressorium formation and reduce leaf blast severity proportionally, suggesting that synergistic interactions between extract and essential oil components were responsible for the success of R. graveolens in suppressing rice disease, making it an alternative to compose rice blast management.