Percorrer por autor "Vicente, Sandra"
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- DNA agarose gel electrophoresis for antioxidant analysis: Development of a quantitative approach for phenolic extractsPublication . Silva, Sara; Costa, Eduardo M.; Vicente, Sandra; Veiga, Mariana; Calhau, Conceição; Morais, Rui M.; Pintado, Manuela E.Most of the fast in vitro assays proposed to determine the antioxidant capacity of a compound/extract lack either biological context or employ complex protocols. Therefore, the present work proposes the improvement of an agarose gel DNA electrophoresis in order to allow for a quantitative estimation of the antioxidant capacity of pure phenolic compounds as well as of a phenolic rich extract, while also considering their possible pro-oxidant effects. The result obtained demonstrated that the proposed method allowed for the evaluation of the protection of DNA oxidation [in the presence of hydrogen peroxide (H2O2) and an H2O2/iron (III) chloride (FeCl3) systems] as well as for the observation of pro-oxidant activities, with the measurements registering interclass correlation coefficients above 0.9. Moreover, this method allowed for the characterization of the antioxidant capacity of a blueberry extract while demonstrating that it had no perceived pro-oxidant effect.
- Investigation of chitosan’s antibacterial activity against vancomycin resistant microorganisms and their biofilmsPublication . Costa, Eduardo M.; Silva, Sara; Veiga, Mariana; Vicente, Sandra; Tavaria, Freni K.; Pintado, Manuela E.Vancomycin-resistant microorganisms are a hurdle that traditional antibiotics struggle to overcome. These difficulties have led to search for new solutions based on natural products. Chitosan has been recognized as an effective antibacterial agent against a vast array of microorganisms including antibiotic resistant ones. As such, this work aimed to evaluate chitosan as an alternative to traditional antibiotics in the management/control of two vancomycin-resistant microorganisms, VRSA and VREF, in planktonic and sessile settings. The results obtained showed that chitosan was highly effective in inhibiting VRSA and VREF planktonic growth and reduced VREF viable counts by 6 log CFU in 30min. Additionally, chitosan was active upon several phases of VRSA and VREF sessile growth inhibiting adhesion, biofilm formation and dual-species biofilms at concentrations as low as 0.0125mg/mL. In lieu of these results chitosan shows great potential as a possible alternative for the control of vancomycin-resistant microorganisms in recalcitrant wound infections.