Molecules 2012, 17(11), 12622-12635; doi:10.3390/molecules171112622
Article

Improved Antileishmanial Activity of Dppz through Complexation with Antimony(III) and Bismuth(III): Investigation of the Role of the Metal

1 Department of Chemistry, Institute of Exact Sciences, Federal University of Minas Gerais (UFMG), Av. Antônio Carlos 6627, 31270-901, Belo Horizonte, MG, Brazil 2 Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Antônio Carlos 6627, 31270-901, Belo Horizonte, MG, Brazil 3 Department of Physics, Institute of Exact Sciences, Federal University of Minas Gerais (UFMG), Av. Antônio Carlos 6627, 31270-901, Belo Horizonte, MG, Brazil 4 Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Antônio Carlos 6627, 31270-901, Belo Horizonte, MG, Brazil
* Author to whom correspondence should be addressed.
Received: 24 August 2012; in revised form: 21 October 2012 / Accepted: 22 October 2012 / Published: 25 October 2012
(This article belongs to the Section Medicinal Chemistry)
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Abstract: Two novel trivalent antimony(III) and bismuth(III) complexes with the nitrogen-donor heterocyclic ligand dipyrido[3,2-a:2',3'-c]phenazine (dppz) were synthesized and characterized as [Sb(dppz)Cl3]∙H2O∙CH3OH and [Bi(dppz)Cl3]. The crystal structure of Sb(III) complex was determined by X-ray crystallography. These complexes were evaluated for their activity against the promastigote form of Sb(III)-sensitive and –resistant Leishmania infantum chagasi and Leishmania amazonensis strains. Both complexes were more effective than dppz alone in inhibiting the growth of Leishmania promastigotes and were at least 77 and 2,400 times more active than potassium antimonyl tartrate in Sb(III)-sensitive and -resistant Leishmania, respectively. The cytotoxicity of dppz and its complexes against mouse peritoneal macrophages occurred at dppz concentrations at least 6-fold greater than those found to be active against Leishmania promastigotes.To investigate the role of the metal in the improved antileishmanial activity of dppz, the activity of the Sb(III) complex was compared between the Sb-resistant mutants and their respective parental sensitive strains. The lack of cross-resistance to the Sb(III)-dppz complex together with the much lower activity of antimonyl tartrate, SbCl3 and BiCl3 strongly support the model that the metal is not active by itself but improves the activity of dppz through complexation.
Keywords: crystal structure; dipyrido [3,2-a:2',3'-c] phenazine; antimony; bismuth; Leishmania; drug resistance

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MDPI and ACS Style

Lizarazo-Jaimes, E.H.; Monte-Neto, R.L.; Reis, P.G.; Fernandes, N.G.; Speziali, N.L.; Melo, M.N.; Frézard, F.; Demicheli, C. Improved Antileishmanial Activity of Dppz through Complexation with Antimony(III) and Bismuth(III): Investigation of the Role of the Metal. Molecules 2012, 17, 12622-12635.

AMA Style

Lizarazo-Jaimes EH, Monte-Neto RL, Reis PG, Fernandes NG, Speziali NL, Melo MN, Frézard F, Demicheli C. Improved Antileishmanial Activity of Dppz through Complexation with Antimony(III) and Bismuth(III): Investigation of the Role of the Metal. Molecules. 2012; 17(11):12622-12635.

Chicago/Turabian Style

Lizarazo-Jaimes, Edgar H.; Monte-Neto, Rubens L.; Reis, Priscila G.; Fernandes, Nelson G.; Speziali, Nivaldo L.; Melo, Maria N.; Frézard, Frédéric; Demicheli, Cynthia. 2012. "Improved Antileishmanial Activity of Dppz through Complexation with Antimony(III) and Bismuth(III): Investigation of the Role of the Metal." Molecules 17, no. 11: 12622-12635.

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