Inhibition of Leishmania infantum Trypanothione Reductase by Azole-Based Compounds: a Comparative Analysis with Its Physiological Substrate by X-ray Crystallography

Authors

  • Dr. Paola Baiocco,

    1. Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Giovanna Poce,

    1. Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Salvatore Alfonso,

    1. Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Martina Cocozza,

    1. Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Giulio Cesare Porretta,

    1. Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Gianni Colotti,

    Corresponding author
    1. Istituto Pasteur Fondazione Cenci-Bolognetti and Istituto di Biologia e Patologia Molecolari–CNR c/o Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
    • Istituto Pasteur Fondazione Cenci-Bolognetti and Istituto di Biologia e Patologia Molecolari–CNR c/o Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Mariangela Biava,

    Corresponding author
    1. Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
    • Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Francesca Moraca,

    1. Dipartimento di Biochimica, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena (Italy)
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  • Dr. Maurizio Botta,

    1. Dipartimento di Biochimica, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena (Italy)
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  • Dr. Vanessa Yardley,

    1. Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT (UK)
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  • Dr. Annarita Fiorillo,

    1. Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Antonella Lantella,

    1. Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Francesco Malatesta,

    1. Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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  • Dr. Andrea Ilari

    1. Istituto Pasteur Fondazione Cenci-Bolognetti and Istituto di Biologia e Patologia Molecolari–CNR c/o Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma (Italy)
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Abstract

Herein we report a study aimed at discovering a new class of compounds that are able to inhibit Leishmania donovani cell growth. Evaluation of an in-house library of compounds in a whole-cell screening assay highlighted 4-((1-(4-ethylphenyl)-2-methyl-5-(4-(methylthio)phenyl)-1H-pyrrol-3-yl)methyl)thiomorpholine (compound 1) as the most active. Enzymatic assays on Leishmania infantum trypanothione reductase (LiTR, belonging to the Leishmania donovani complex) shed light on both the interaction with, and the nature of inhibition by, compound 1. A molecular modeling approach based on docking studies and on the estimation of the binding free energy aided our rationalization of the biological data. Moreover, X-ray crystal structure determination of LiTR in complex with compound 1 confirmed all our results: compound 1 binds to the T(SH)2 binding site, lined by hydrophobic residues such as Trp21 and Met113, as well as residues Glu18 and Tyr110. Analysis of the structure of LiTR in complex with trypanothione shows that Glu18 and Tyr110 are also involved in substrate binding, according to a competitive inhibition mechanism.

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