Facultad de Ciencias Químicas-Tesis Maestrías

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Browsing Facultad de Ciencias Químicas-Tesis Maestrías by Subject "Actividad Antibacteriana"

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    Desarrollo de un modelo predictivo mediante fingerprint cromatográfico para evaluar el potencial antibacteriano para el género Hypericum
    (2017-09-01) Fajardo Carmona, Sandra Isabel; León Tamariz, Fabián
    The genus Hypericum includes 469 species, which possess diverse bioactivities, including antibacterial activity. The present study intend to establish a predictive model of antibacterial activity for species of the genus Hypericum from the chromatographic fingerprint of H. laricifolium and H. quitense and use data of IC50 against MRSA strains, using multivariate analysis tools. The tests were carried out on 29 extracts of H. laricifolium and 20 extracts of H. quitense. The predictive model was tested on 10 extracts of H. decandrum. Genetic identification of H. quitense and H. decandrum was performed using the genetic barcode technique. The loci rbcL and ITS1 were sequenced. Extracts of the aerial parts of the species under study were obtained by means of supercritical fluids using as CO2 solvent with 10% of ethanol. The evaluation of antibacterial activity was carried out using the microdilution technique in broth against MRSA (strain ATCC BAA 44). The HPLC-DAD method was developed to separate the components present in the species under study and to obtain their chromatographic fingerprint using optimized chromatographic conditions. Samples were analyzed at four wavelengths, resulting at 254 nm the best for analysis. To create the multivariate regression model we used Partial least squares. Using the regression coefficients of the model, the predictor of antibacterial activity was established. The model developed did not have good predictive properties, which can be attributed to the different chemical composition among the species under study.
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    Evaluación del estado de desarrollo de hypericum laricifolium sobre metabolitos responsables de actividad antibacteriana utilizando fingerprint cromatográfico
    (2017-12-20) Tenesaca Sigua, Rodrigo José; León Tamariz, Fabián
    The main objective of this study was to investigate the influence of the development phases of Hypericum laricifolium on metabolites responsible for the antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) using Chromatographic Fingerprint as methodology for modeling. An HPLC-DAD method was developed to separate the components present in H. laricifolium extracts by optimizing the chromatographic conditions, using a factorial design 23. The partial least squares (PLS) method was used to establish a correlation between the antibacterial activity and the chromatographic profiles of H. laricifolium extracts at 254, 280 and 360 nm. A model was constructed using 30 samples with 7501 X variables corresponding to the responses obtained in the UV spectrum at different times; the Y variables consisted of experimental values of inhibitory concentration 50% (IC50) of each extract. Prior to the PLS analysis, the chromatograms were subjected to a pre-treatment of column centering. The PLS model was validated by cross validation; their capacity was evaluated using the correlation parameters (R2) and the root mean square error prediction (RMSEP). The best results were achieved with the 254 nm chromatogram (R2 = 0.90, RMSEP = 2.25). Under these conditions, the optimal number of components was eight. Finally, the Student's T test did not show a significant difference between the antibacterial activities of the young and adult stages of H. laricifolium.