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Rio de Janeiro, Brazil

Lavaggi M.L.,Institute Quimica Biologica | Cabrera M.,Institute Quimica Biologica | Celano L.,Laboratorio Of Enzimologia | Thomson L.,Laboratorio Of Enzimologia | And 2 more authors.
Journal of Chemical Education

The goal of this work was to include an interdisciplinary research-oriented laboratory experiment taken from medicinal chemistry into the undergraduate biochemistry or organic studies. Phenazine 5,10-dioxides with selective cytotoxicity under hypoxia and with relevance in solid tumor treatment were selected to simulate different metabolism states. In this laboratory experiment, metabolism of 7-bromo-2-hydroxyphenazine-5,10-dioxide under simulated hypoxia and normoxia was studied using rat liver cytosol. Differential hypoxic and normoxic metabolism were monitored by thin-layer chromatography. Specific enzyme inhibitors, dicoumarol, ketoconazole, and menadione, were employed to identify the enzymatic system involved. This experiment introduced students to the concept of drug metabolism, activation, and mechanism of action. Furthermore, basic biochemical techniques of enzyme isolation and study were also discussed. © 2013 The American Chemical Society and Division of Chemical Education, Inc. Source

Cabrera M.,Laboratorio Of Quimica Organica | Lavaggi M.L.,Laboratorio Of Quimica Organica | Croce F.,Laboratorio Of Quimica Organica | Celano L.,Laboratorio Of Enzimologia | And 9 more authors.
Bioorganic and Medicinal Chemistry

Cancer preventive agents (CPA) are drugs able to suppress the carcinogen metabolic activation or block the formation of ultimate carcinogens. CPA could act through various molecular mechanisms, for example by interfering with the action of procarcinogen. This could be attained by increasing the phase II enzymes levels of quinone reductase (QR) and glutathione S-transferase (GST). New flavonoids, especially chalcones, have been identified as in vivo monofunctional phase II enzymes inducers. Oral administration of chalcone, 4, and both p-methoxy-substituted chalcones, 6 and 14, increased hepatic QR activity with concomitant decrease in CYP1A1 activity, a member of the most important group of phase I enzymes cytochrome P450. Among them, 4 also increased GST activity. While p-bromo-substituted chalcone 8 was the best inducer of QR it decreased hepatic GST expression and cytochrome P450, being the most effective decreasing cytochrome P450-expression. Thienyl-chalcone 20 being the bioisostere of chalcone 4 did not display the same in vivo profile in the phase I level modification. As chalcone 4 its bioisostere, chalcone 20, displayed low DNA strand breakage and absence of mutagenicity. Also, in our preliminary in vivo tumourigenesis/chemopreventive and acute-toxicity studies, chalcones 4, 6 and 8 showed the best behaviours as CPA justifying additional studies that are ongoing. © 2010 Elsevier Ltd. All rights reserved. Source

Franca R.C.P.,University of Pernambuco | Amaral I.P.G.,Laboratorio Of Enzimologia | Santana W.M.,Laboratorio Of Enzimologia | Souza-Santos L.P.,Federal University of Pernambuco | And 2 more authors.
Journal of Crustacean Biology

The harpacticoid copepod Tisbe biminiensis has been tested as live prey in marine crustacean and fish larviculture. The aim of the present study was to characterize the proteinases in the crude extract of T. biminiensis. Trypsin activity was assayed in the crude extract prepared by the homogenization of specimens reared under controlled laboratory conditions and fed on diatoms and commercial fish food. The physical-chemical and kinectics parameters were determined using BApNA as substrate. Optimal pH and temperature were 9.0 and 55°C, respectively. This enzyme was thermostable until 50°C. Using BApNA as substrate, the Km was 0.59 mM and the proteolytic activity was strongly inhibited by specific trypsin inhibitors. However, the presence of other proteases was observed using substrate-SDS-PAGE. Eight caseinolytic bands were observed in the zymogram, four of them were not inhibited by classical mammalian trypsin inhibitors. Trypsin from T. biminiensis showed similar properties to those described for species used in commercial aquaculture. These results demonstrate that T. biminiensis may be a source of proteases, including trypsin-like enzymes. © 2010 The Crustacean Society. Source

Vera M.S.,Laboratorio Of Limnologia | Di Fiori E.,Laboratorio Of Limnologia | Lagomarsino L.,Buenos Aires Institute of Technology | Sinistro R.,Laboratorio Of Limnologia | And 7 more authors.

Glyphosate-based formulations are among the most widely used herbicides in the world. The effect of the formulation Glifosato Atanor on freshwater microbial communities (phytoplankton, bacterioplankton, periphyton and zooplankton) was assessed through a manipulative experiment using six small outdoor microcosms of small volume. Three of the microcosms were added with 3.5 mg l-1 of glyphosate whereas the other three were left as controls without the herbicide. The treated microcosms showed a significant increase in total phosphorus, not fully explained by the glyphosate present in the Glifosato Atanor ®. Therefore, part of the phosphorus should have come from the surfactants of the formulation. The results showed significant direct and indirect effects of Glifosato Atanor on the microbial communities. A single application of the herbicide caused a fast increase both in the abundance of bacterioplankton and planktonic picocyanobacteria and in chlorophyll a concentration in the water column. Although metabolic alterations related to oxidative stress were induced in the periphyton community, the herbicide favored its development, with a large contribution of filamentous algae typical of nutrient-rich systems, with shallow and calm waters. An indirect effect of the herbicide on the zooplankton was observed due to the increase in the abundance of the rotifer Lecane spp. as a consequence of the improved food availability given by picocyanobacteria and bacteria. The formulation affected directly a fraction of copepods as a target. It was concluded that the Glifosato Atanor® accelerates the deterioration of the water quality, especially when considering small-volume water systems. © Springer Science+Business Media, LLC 2012. Source

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