Papers em destaque

Novamente, artigos de pesquisadores do INCT de Processos Redox em Biomedicina receberam destaque nas revistas em que foram publicados.

O periódico Dalton Transactions considerou como “Hot Article” o artigo Direct evidence of singlet molecular oxygen generation from peroxynitrate, a decomposition product of peroxynitrite, do Professor Paolo Di Mascio e colaboradores (Sayuri Miyamoto, Graziella E. Ronsein, Thaís C. Corrêa, Glaucia R. Martinez, Marisa H. G. Medeiros). (Dalton Trans., 2009, 5720 - 5729, DOI: 10.1039/b905560f).

Direct evidence of singlet molecular oxygen generation from peroxynitrate, a decomposition product of peroxynitrite

Sayuri Miyamoto, Graziella E. Ronsein, Thaís C. Corrêa, Glaucia R. Martinez, Marisa H. G. Medeiros and Paolo Di Mascio

The decomposition of peroxynitrite to nitrite and dioxygen at neutral pH follows complex kinetics, compared to its isomerization to nitrate at low pH. Decomposition may involve radicals or proceed by way of the classical peracid decomposition mechanism. Peroxynitrite (ONOOH/ONOO^-) decomposition has been proposed to involve formation of peroxynitrate (O₂NOOH/O₂NOO^-) at neutral pH (D. Gupta, B. Harish, R. Kissner and W. H. Koppenol, Dalton Trans., 2009, DOI: 10.1039/b905535e, see accompanying paper in this issue). Peroxynitrate is unstable and decomposes to nitrite and dioxygen. This study aimed to investigate whether O₂NOO^- formed upon ONOOH/ONOO^- decomposition generates singlet molecular oxygen [O₂ (¹ _g)]. As unequivocally revealed by the measurement of monomol light emission in the near infrared region at 1270 nm and by chemical trapping experiments, the decomposition of ONOO^- or O₂NOOH at neutral to alkaline pH generates O₂ (¹ _g) at a yield of ca. 1% and 2–10%, respectively. Characteristic light emission, corresponding to O₂ (¹ _g) monomolecular decay was observed for ONOO^- and for O₂NOOH prepared by reaction of H₂O₂ with NO₂BF₄ and of H₂O₂ with NO₂^- in HClO₄. The generation of O₂ (¹ _g) from ONOO^- increased in a concentration-dependent manner in the range of 0.1–2.5 mM and was dependent on pH, giving a sigmoid profile with an apparent pK_a around pD 8.1 (pH 7.7). Taken together, our results clearly identify the generation of O₂ (¹ _g) from peroxynitrate [O₂NOO^- NO₂^- + O₂ (¹ _g)] generated from peroxynitrite and also from the reactions of H₂O₂ with either NO₂BF₄ or NO₂^- in acidic media.

    A revisão Exocyclic DNA adducts: Challenges in developing methods for clinical studies, da Professora Marisa Medeiros, não apenas foi capa da Chemical Research in Toxicology (CRT), revista da American Chemical Society, como também foi destacada e recomendada pelo editor da revista.  (Chem. Res. Toxicol., 2009, 22 (3), pp 419–425 DOI: 10.1021/tx800367d).

O comentário a respeito da revisão foi o seguinte:

Special Features

A quick look at this month's In This Issue reveals a prevalence of articles on DNA damage and DNA damaging agents. This was a purely chance occurrence, resulting from the recommendations of reviewers and editors, but it illustrates the relevance that the topic of DNA damage continues to have for mechanistic toxicology. Thus, the review by Marisa Medeiros (p 419) on exocyclic DNA adducts as biomarkers of lipid oxidation is particularly timely. Be sure to take advantage of this opportunity to learn more about this important topic.