Navegando por Autor "Meza, Silvia Leticia Rivero"

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Activity of rice bran proteic extracts against Fusarium graminearum
(2013) Pagnussatt, Fernanda Arnhold; Bretanha, Cristiana Costa; Meza, Silvia Leticia Rivero; Buffon, Jaqueline Garda; Furlong, Eliana Badiale
The application of natural antifungal substances is motivated by the need for alternatives to existing methods that are not always applicable, efficient, or that do not pose risk to consumers or the environment. Furthermore, studies on the behaviour of toxigenic species in the presence of natural fungicides have enabled their safe application in the food chain. This study aimed to identify the fraction of the rice grain with greater inhibitory activity of amylase and related to its antifungal and antimycotoxigenic potential against Fusarium graminearum CQ 244 biomass. The greatest inhibitory effect was observed in extracts of bran, which inhibited by 90% the fungal amylase activity. The primary fractionation of the rice bran extract was more efficient when ethanolic extracts was precipitated by acetone, resulting in a specific inhibition estimated at 20 μg min-1mg protein1, PF 45 and recovery 61%. The rice bran protein extracts showed fungistatic activity against F. graminearum, with MIC50 of 419 μg ml-1 and 168 mg ml-1 estimated from glucosamine and amylase inhibition, respectively, which cause 63% biomass inhibition and 40% of the nivalenol (NIV) production.
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Procedure to determine enzyme inhibitors activity in cereal seeds
(2012) Pagnussatt, Fernanda Arnhold; Meza, Silvia Leticia Rivero; Buffon, Jaqueline Garda; Furlong, Eliana Badiale
This work established a procedure for commercial fungal amylase usage as indicator of enzyme inhibitors presence in cereals, intending to screening antifungal resistance properties in cereals. Firstly, the inhibitive effects of oat, wheat and rice protein extracts were assessed against different amylase sources. It was found that the fungal amylase (Fungamyl®) was the most affected by the inhibition property of the extracts. The best conditions for inhibitor-extract-enzyme interaction were established (pH, temperature, starch concentration). Inhibition kinetic allowed their classification as mixed inhibitors. A high quocient (1.7) was observed between enzyme inhibition and Fusarium graminearum multiplication reduction. Fungamyl® amylase demonstrated its potential to detect the protein inhibitor presence in different cereals and might be employed in screening natural resistance to fungal contamination.