Breno Pannia Esposito

Publications (25) View all

• Article: Mechanisms of manganese-induced neurotoxicity in primary neuronal cultures: the role of manganese speciation and cell type.

  R B Hernández, M Farina, B P Espósito, N C Souza-Pinto, F Barbosa, C Suñol
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  ABSTRACT: Manganese (Mn) is an essential trace element required for the proper functioning of a variety of physiological processes. However, chronic exposures to Mn can cause neurotoxicity in humans, especially when it occurs during critical stages of the central nervous system development. The mechanisms mediating this phenomenon as well as the contribution of Mn speciation and the sensitivity of different types of neuronal cells in such toxicity are poorly understood. This study was aimed to investigate the mechanisms mediating the toxic effects of MnCl(2), Mn(II) citrate, Mn(III) citrate, and Mn(III) pyrophosphate in primary cultures of neocortical (CTX) and cerebellar granular (CGC) neurons. Cell viability, mitochondrial function, and glutathione levels were evaluated after Mn exposure. CGC were significantly more susceptible to Mn-induced toxicity when compared with CTX. Moreover, undifferentiated CGC were more vulnerable to Mn toxicity than mature neurons. Mitochondrial dysfunction was observed after the exposure to all the tested Mn species. Ascorbate protected CGC against Mn-induced neurotoxicity, and this event seemed to be related to the dual role of ascorbate in neurons, acting as antioxidant and metabolic energetic supplier. CTX were protected from Mn-induced toxicity by ascorbate only when coincubated with lactate. These findings reinforce and extend the notion of the hazardous effects of Mn toward neuronal cells. In addition, the present results indicate that Mn-induced neurotoxicity is influenced by brain cell types, their origins, and developmental stages as well as by the chemical speciation of Mn, thus providing important information about Mn-induced developmental neurotoxicity and its risk assessment.
  Toxicological Sciences 09/2011; 124(2):414-23. · 4.65 Impact Factor
• Article: Enhancement of hematoporphyrin IX potential for photodynamic therapy by entrapment in silica nanospheres.

  Paulo R Silva, Lucas L R Vono, Breno P Espósito, Maurício S Baptista, Liane M Rossi
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  ABSTRACT: The entrapment of hematoporphyrin IX (Hp IX) in silica by means of a microemulsion resulted in silica spheres of 33 ± 6 nm. The small size, narrow size distribution and lack of aggregation maintain Hp IX silica nanospheres stable in aqueous solutions for long periods and permit a detailed study of the entrapped drug by different techniques. Hp IX entrapped in the silica matrix is accessed by oxygen and upon irradiation generates singlet oxygen which diffuses very efficiently to the outside solution. The Hp IX entrapped in the silica matrix is also reached by iron(II) ions, which causes quenching of the porphyrin fluorescence emission. The silica matrix also provides extra protection to the photosensitizer against interaction with BSA and ascorbic acid, which are known to cause suppression of singlet oxygen generation by the Hp IX free in solution. Therefore, the incorporation of Hp IX molecules into silica nanospheres increased the potential of the photosensitizer to perform photodynamic therapy.
  Physical Chemistry Chemical Physics 09/2011; 13(33):14946-52. · 3.57 Impact Factor
• Article: Labile plasma iron generation after intravenous iron is time-dependent and transitory in patients undergoing chronic hemodialysis.

  Erika B Rangel, Breno P Espósito, Fabiana D Carneiro, Ana Cláudia Mallet, Ana Cristina C Matos, Maria Cláudia C Andreoli, Nádia K Guimarães-Souza, Bento Fc Santos
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  ABSTRACT: Iron supplementation in hemodialysis patients is fundamental to erythropoiesis, but may cause harmful effects. We measured oxidative stress using labile plasma iron (LPI) after parenteral iron replacement in chronic hemodialysis patients. Intravenous iron saccharate (100 mg) was administered in patients undergoing chronic hemodialysis (N = 20). LPI was measured by an oxidant-sensitive fluorescent probe at the beginning of dialysis session (T0), at 10 min (T1), 20 min (T2), and 30 min (T3) after the infusion of iron and at the subsequent session; P < 0.05 was significant. The LPI values were significantly raised according to the time of administration and were transitory: -0.02 +/- 0.20 micromol/L at the beginning of the first session, 0.01 +/- 0.26 micromol/L at T0, 0.03 +/- 0.23 micromol/L at T1, 0.09 +/- 0.28 micromol/L at T2, 0.18 +/- 0.52 micromol/L at T3, and -0.02 +/- 0.16 micromol/L (P = 0.001 to 0.041) at the beginning of the second session. The LPI level in patients without iron supplementation was -0.06 +/- 0.16 micromol/L. Correlations of LPI according to time were T1, T2, and T3 vs. serum iron (P = 0.01, P = 0.007, and P = 0.0025, respectively), and T2 and T3 vs. transferrin saturation (P = 0.001 and P = 0.0003, respectively). LPI generation after intravenous saccharate administration is time-dependent and transitorily detected during hemodialysis. The LPI increment had a positive correlation to iron and transferrin saturation.
  Therapeutic apheresis and dialysis: official peer-reviewed journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy 04/2010; 14(2):186-92. · 1.39 Impact Factor
• Article: Quercetin as a shuttle for labile iron.

  Mayara Marinovic Baccan, Orlando Chiarelli-Neto, Regina Mara Silva Pereira, Breno Pannia Espósito
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  ABSTRACT: The antioxidant activity of flavonoids may involve their ability to complex body iron in non-redox-active forms. In this study, it was found that the catechol flavonoids rutin and quercetin are able to suppress redox-active labile plasma iron (LPI) in both buffered solution and in iron-overloaded sera. Both flavonoids are effective in loading the metal into the iron-transport protein transferrin. Iron derivatives of quercetin and rutin are able to permeate cell membranes, however, only free quercetin is able to gain access to the cytosol and decrease intracellular labile iron pools. These results suggest that the antioxidant activity of quercetin may be dependent on its ability to shuttle labile iron from cell compartments followed by its transfer to transferrin.
  Journal of inorganic biochemistry 12/2011; 107(1):34-9. · 3.25 Impact Factor
• Article: Increasing the activity of copper(II) complexes against Leishmania through lipophilicity and pro-oxidant ability.

  Andressa dos Santos Portas, Danilo Ciccone Miguel, Jenicer K U Yokoyama-Yasunaka, Silvia Reni Bortolin Uliana, Breno Pannia Espósito
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  ABSTRACT: Copper complexes with fluorinated β-diketones were synthesized and characterized in terms of lipophilicity and peroxide-assisted oxidation of dihydrorhodamine as an indicator of redox activity. The biological activity of the complexes was tested against promastigotes of Leishmania amazonensis. Inhibition of trypanosomatid-specific trypanothione reductase was also tested. It was found that the highly lipophilic and redox-active bis(trifluoroacetylacetonate) derivative had increased toxicity towards promastigotes. These results indicate that it is possible to modulate the activity of metallodrugs based on redox-active metals through the appropriate choice of lipophilic chelators in order to design new antileishmanials. Further work will be necessary to improve selectivity of these compounds against the parasite.
  European Journal of Biochemistry 08/2011; 17(1):107-12. · 3.42 Impact Factor