• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Doctoral Thesis
DOI
10.11606/T.75.2009.tde-13012010-145505
Document
Author
Full name
José Clayston Melo Pereira
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2009
Supervisor
Committee
Franco, Douglas Wagner (President)
Beraldo, Heloisa de Oliveira
Cotrim, Paulo Cesar
Gushikem, Yoshitaka
Rodrigues, Elaine Guadelupe
Title in Portuguese
Liberação de HNO e NO por nitrosilos de rutênio e sua atividade antileishmania
Keywords in Portuguese
Leishmania
Nitrosilos de rutênio
Nitroxil
Óxido Nítrico
Abstract in Portuguese
Foram testados complexos de rutênio trans-[RuNO(NH3)4L](X)3 (X = BF4- ou PF6- e L = imN, 4-pic, isn, py, pz, L - hist, nic, imC, P(OEt)3, SO3-2) e [Ru(NO)Hedta)] como agentes antiproliferativos contra o parasito Leishamania major. Os complexos onde L = imN, pz, 4-pic, py, isn, e P(OEt)3 exibem IC50pro na faixa de 36 (L = imN) a 280μM (L= isn). A curva de crescimento das formas promastigotas, incubadas com os compostos mais promissores, trans-[RuNO(NH3)4L](BF4)3 (L= imN, pz, py, 4-pic), foi avaliada por meio de contagem de células viáveis e por ensaio colorimétrico (MTT). Uma relação entre os valores de k-NO e efeito antipromastigota segue a seguinte ordem: imN>4-pic>pz>py. Foi observado um aumento na inibição do crescimento das formas promastigotas incubadas com o complexo trans-[RuNO(NH3)4P(OEt)3](PF6)3 na presença de ácido ascórbico, confirmando o mecanismo de nitrosilação dos complexos utilizados. O complexo trans-[RuNO(NH3)4imN](BF4)3 e o sal de Angeli (Na2N2O3) exibiram efeitos similares frente as formas amastigotas intracelulares. O composto trans-[RuNO(NH3)4imN](BF4)3 apresentou efeito antileishmania em experimentos in vivo. A reação entre trans-[RuNO(NH3)4L](X)3 (X = BF4- or PF6- and L = imN, 4-pic, py, isn, P(OEt3)) e excesso de L-cisteína foi investigada e os seus produtos analisados. HNO e NO0 foram encontrados como produtos da redução do ligante nitrosônio. Esta reação ocorre em varias etapas com a formação dos complexos trans-[Ru(NH3)4LN(O)SR]n-1 e trans-[Ru(NH3)4LN(O)(SR)2]n-2 cujo as constantes de formação k1 (1,7×107 - 2,2×104 mol-1Ls-1) e k2 (3,3×104 - 4,9×101mol-1Ls-1) foram calculados para L = P(OEt)3, 4-pic, py e isn). Estas espécies podem sofrer reações subseqüentes com dissociação de HNO e NO. Exceto para L = P(OEt3), a reação não ocorre quando CH+>= 1×10-6 mol L-1. Em solução onde CH+ = 4×108 mol L-1, a reação ocorre principalmente segundo:

trans-[RuNO(NH3)4L]+3 + 2RS- + H2O → trans-[Ru(NH3)4L(H2O)]2+ + RSSR + NO-

Para L = P(OEt3), e em meio ácido, NO0 é preferencialmente o produto da redução do ligante NO+:

trans-[RuNO(NH3)4P(OEt)3]+3 + RSH + H2O → trans-[Ru(NH3)4P(OEt)3(H2O)]2+ + ½ RSSR + NO0 + H+

Os resultados experimentais em solução sugerem que ambas as espécies NO e HNO podem ser responsáveis pelo efeito antiparasitário dos nitrosilos de rutênio aqui estudados. A relação entre a concentração das espécies NO/HNO será determinada pelas condições de pH do meio e concentração do redutor.
Title in English
Dissociation of HNO and NO: leishmanicidal activity of nitrosil of ruthenium
Keywords in English
Leishmania
Nitric oxide
Nitrosil of ruthenium
Nitroxyl
Abstract in English
Ruthenium complexes type trans-[RuNO(NH3)4L](X)3 (X = BF4- or PF6- and L = imN, 4-pic, isn, py, pz, L- hist, nic, imC, P(OEt)3, SO32-), and [RuNO(Hedta)] were tested as antiproliferative agents against the Leishmania major parasite. The complexes where L = imN, pz, 4-pic, py, isn, and P(OEt)3 exhibited IC50pro ranging from 36 for trans-[RuNO(NH3)4imN](BF4)3 to 280 μM for trans-[RuNO(NH3)4isn](BF4)3. The growth rate of the promastigote forms incubated with the most promising compounds, trans-[RuNO(NH3)4L](BF4)3 (L= imN, pz, py, 4-pic) had been evaluated trough motile cell counting and colorimetric assay (MTT). The trend between k-NO values and the antipromastigote effect follows the order: imN>4-pic>pz>py. An increase on the inhibition of the promastigote forms growth by the trans-[RuNO(NH3)4P(OEt)3](PF6)3 and trans-[RuNO(NH3)4imN](BF4)3 species was observed when the ruthenium complexes and ascorbic acid were simultaneously incubated, confirming the nitrosylation behavior of these complexes. Inhibitory effects of the trans-[RuNO(NH3)4imN](BF4)3 and of the Angeli's salt (Na2N2O3) were similar on the intramacrophage amastigote form grown. Encouraged by the antileishmanial effect of the complex trans-[RuNO(NH3)4imN](BF4)3 observed in vitro, in vivo experiments were carried out in infected BALB/c mice. The reaction between trans-[RuNO(NH3)4L](X)3 (X = BF4- or PF6- and L = imN, 4-pic, isn, P(OEt)3) and excess of L-cysteine was investigated and the products analysed. HNO and NO are the products of nitrosonium ligand reduction. This reaction yields the complexes trans-[Ru(NH3)4LN(O)SR]n-1 and trans-[Ru(NH3)4LN(O)(SR)2]n-2 which present k1 (1,7×107 - 2,2×104 mol-1Ls-1) and k2 (3,3×104 - 4,9×101mol-1Ls-1) for L = P(OEt)3, 4-pic, py e isn). This species react with RS- producing HNO and/or NO. Exception for L = P(OEt)3, this reaction does not occurs when CH+>= 1×10-6 mol L-1. For solution in which CH+ = 4×10-8 mol L-1, the reaction occur mainly trough:

trans-[RuNO(NH3)4L]+3 + 2RS- + H2O → trans-[Ru(NH3)4L(H2O)]2+ + RSSR + NO-

For L = P(OEt)3, and in acid media, NO0 is preferentially the reduction product of NO+ ligand.

trans-[RuNO(NH3)4P(OEt)3]+3 + RSH + H2O → trans-[Ru(NH3)4P(OEt)3(H2O)]2+ + ½RSSR + NO0 + H+

The experimental results from solution studies suggest that both NO and HNO could be responsible for the antiparasitaric effect of these ruthenium nitrosyl. The concentration ratio of NO/HNO could be dictated by the local conditions of pH.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2010-08-17
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.