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Dana D, Pathak SK. A Review of Small Molecule Inhibitors and Functional Probes of Human Cathepsin L. Molecules 2020; 25:E698. [PMID: 32041276 PMCID: PMC7038230 DOI: 10.3390/molecules25030698] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 01/06/2023] Open
Abstract
Human cathepsin L belongs to the cathepsin family of proteolytic enzymes with primarily an endopeptidase activity. Although its primary functions were originally thought to be only of a housekeeping enzyme that degraded intracellular and endocytosed proteins in lysosome, numerous recent studies suggest that it plays many critical and specific roles in diverse cellular settings. Not surprisingly, the dysregulated function of cathepsin L has manifested itself in several human diseases, making it an attractive target for drug development. Unfortunately, several redundant and isoform-specific functions have recently emerged, adding complexities to the drug discovery process. To address this, a series of chemical biology tools have been developed that helped define cathepsin L biology with exquisite precision in specific cellular contexts. This review elaborates on the recently developed small molecule inhibitors and probes of human cathepsin L, outlining their mechanisms of action, and describing their potential utilities in dissecting unknown function.
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Affiliation(s)
- Dibyendu Dana
- Chemistry and Biochemistry Department, Queens College of The City University of New York, 65-30 Kissena Blvd, Flushing, NY 11367, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York (CUNY), 365 5th Ave, New York, NY 10016, USA
| | - Sanjai K. Pathak
- Chemistry and Biochemistry Department, Queens College of The City University of New York, 65-30 Kissena Blvd, Flushing, NY 11367, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York (CUNY), 365 5th Ave, New York, NY 10016, USA
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2
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Yus M, Foubelo F, Maciá E. Indium Mediated Allylation of N-tert-Butanesulfinyl Imines with 1,3-Dibromopropene: Stereoselective Synthesis of Aziridines. HETEROCYCLES 2019. [DOI: 10.3987/com-18-s(f)18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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3
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Ettari R, Pinto A, Tamborini L, Angelo IC, Grasso S, Zappalà M, Capodicasa N, Yzeiraj L, Gruber E, Aminake MN, Pradel G, Schirmeister T, De Micheli C, Conti P. Synthesis and biological evaluation of papain-family cathepsin L-like cysteine protease inhibitors containing a 1,4-benzodiazepine scaffold as antiprotozoal agents. ChemMedChem 2014; 9:1817-25. [PMID: 24919925 DOI: 10.1002/cmdc.201402079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Indexed: 11/10/2022]
Abstract
Novel papain-family cathepsin L-like cysteine protease inhibitors endowed with antitrypanosomal and antimalarial activity were developed, through an optimization study of previously developed inhibitors. In the present work, we studied the structure-activity relationships of these derivatives, with the aim to develop new analogues with a simplified and more synthetically accessible structure and with improved antiparasitic activity. The structure of the model compounds was significantly simplified by modifying or even eliminating the side chain appended at the C3 atom of the benzodiazepine scaffold. In addition, a simple methylene spacer of appropriate length was inserted between the benzodiazepine ring and the 3-bromoisoxazoline moiety. Several rhodesain and falcipain-2 inhibitors displaying single-digit micromolar or sub-micromolar antiparasitic activity against one or both parasites were identified, with activities that were one order of magnitude more potent than the model compounds.
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Affiliation(s)
- Roberta Ettari
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, 20133 Milano (Italy).
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4
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Ettari R, Tamborini L, Angelo IC, Grasso S, Schirmeister T, Lo Presti L, De Micheli C, Pinto A, Conti P. Development of Rhodesain Inhibitors with a 3-Bromoisoxazoline Warhead. ChemMedChem 2013; 8:2070-6. [DOI: 10.1002/cmdc.201300390] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 11/11/2022]
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5
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Ettari R, Micale N, Grazioso G, Bova F, Schirmeister T, Grasso S, Zappalà M. Synthesis and Molecular Modeling Studies of Derivatives of a Highly Potent Peptidomimetic Vinyl Ester as Falcipain-2 Inhibitors. ChemMedChem 2012; 7:1594-600. [DOI: 10.1002/cmdc.201200274] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Indexed: 11/10/2022]
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6
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Selected gold compounds cause pronounced inhibition of Falcipain 2 and effectively block P. falciparum growth in vitro. J Inorg Biochem 2011; 105:1576-9. [DOI: 10.1016/j.jinorgbio.2011.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/18/2022]
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7
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Peptidomimetics containing a vinyl ketone warhead as falcipain-2 inhibitors. Eur J Med Chem 2011; 46:2058-65. [DOI: 10.1016/j.ejmech.2011.02.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 02/21/2011] [Accepted: 02/23/2011] [Indexed: 11/23/2022]
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8
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Aziridine-2,3-dicarboxylate-based cysteine cathepsin inhibitors induce cell death in Leishmania major associated with accumulation of debris in autophagy-related lysosome-like vacuoles. Antimicrob Agents Chemother 2010; 54:5028-41. [PMID: 20855728 DOI: 10.1128/aac.00327-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The papain-like cysteine cathepsins expressed by Leishmania play a key role in the life cycle of these parasites, turning them into attractive targets for the development of new drugs. We previously demonstrated that two compounds of a series of peptidomimetic aziridine-2,3-dicarboxylate [Azi(OBn)(2)]-based inhibitors, Boc-(S)-Leu-(R)-Pro-(S,S)-Azi(OBn)(2) (compound 13b) and Boc-(R)-Leu-(S)-Pro-(S,S)-Azi(OBn)(2) (compound 13e), reduced the growth and viability of Leishmania major and the infection rate of macrophages while not showing cytotoxicity against host cells. In the present study, we characterized the mode of action of inhibitors 13b and 13e in L. major. Both compounds targeted leishmanial cathepsin B-like cysteine cathepsin cysteine proteinase C, as shown by fluorescence proteinase activity assays and active-site labeling with biotin-tagged inhibitors. Furthermore, compounds 13b and 13e were potent inducers of cell death in promastigotes, characterized by cell shrinkage, reduction of mitochondrial transmembrane potential, and increased DNA fragmentation. Transmission electron microscopic studies revealed the enrichment of undigested debris in lysosome-like organelles participating in micro- and macroautophagy-like processes. The release of digestive enzymes into the cytoplasm after rupture of membranes of lysosome-like vacuoles resulted in the significant digestion of intracellular compartments. However, the plasma membrane integrity of compound-treated promastigotes was maintained for several hours. Taken together, our results suggest that the induction of cell death in Leishmania by cysteine cathepsin inhibitors 13b and 13e is different from mammalian apoptosis and is caused by incomplete digestion in autophagy-related lysosome-like vacuoles.
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Ettari R, Zappalà M, Micale N, Schirmeister T, Gelhaus C, Leippe M, Evers A, Grasso S. Synthesis of novel peptidomimetics as inhibitors of protozoan cysteine proteases falcipain-2 and rhodesain. Eur J Med Chem 2010; 45:3228-33. [DOI: 10.1016/j.ejmech.2010.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/16/2010] [Accepted: 04/07/2010] [Indexed: 11/16/2022]
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10
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Constrained peptidomimetics as antiplasmodial falcipain-2 inhibitors. Bioorg Med Chem 2010; 18:4928-38. [DOI: 10.1016/j.bmc.2010.06.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 05/28/2010] [Accepted: 06/04/2010] [Indexed: 11/23/2022]
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11
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Novel 2H-isoquinolin-3-ones as antiplasmodial falcipain-2 inhibitors. Bioorg Med Chem 2009; 17:6505-11. [PMID: 19709887 DOI: 10.1016/j.bmc.2009.08.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/29/2009] [Accepted: 08/06/2009] [Indexed: 11/20/2022]
Abstract
A series of 1-aryl-6,7-disubstituted-2H-isoquinolin-3-ones (2-10) was synthesized and evaluated for their inhibition against Plasmodium falciparum cysteine protease falcipain-2, as well as against cultured P. falciparum strain FCBR parasites. All compounds displayed inhibitory activity against recombinant falcipain-2 and against in vitro cultured intraerythrocytic P. falciparum, with the exception of 9. The new compounds exhibited no selectivity against human cysteine proteases such as cathepsins B and L. The inhibitory activity of the synthesized compounds was also evaluated against another protozoal cysteine protease, namely rhodesain of Trypanosoma brucei rhodesiense.
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Buback V, Mladenovic M, Engels B, Schirmeister T. Rational Design of Improved Aziridine-Based Inhibitors of Cysteine Proteases. J Phys Chem B 2009; 113:5282-9. [DOI: 10.1021/jp810549n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Verena Buback
- Institut für Pharmazie and Lebensmittelchemie, Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Milena Mladenovic
- Institut für Pharmazie and Lebensmittelchemie, Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Bernd Engels
- Institut für Pharmazie and Lebensmittelchemie, Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Tanja Schirmeister
- Institut für Pharmazie and Lebensmittelchemie, Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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13
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Dude MA, Kaeppler U, Herb M, Schiller M, Schulz F, Vedder B, Heppner S, Pradel G, Gut J, Rosenthal PJ, Schirmeister T, Leippe M, Gelhaus C. Synthesis and evaluation of non-peptidic cysteine protease inhibitors of P. falciparum derived from etacrynic acid. Molecules 2008; 14:19-35. [PMID: 19104483 PMCID: PMC6253875 DOI: 10.3390/molecules14010019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 12/12/2008] [Accepted: 12/19/2008] [Indexed: 11/28/2022] Open
Abstract
A series of etacrynic acid derivatives was synthesized and screened for their in vitro activity against Plasmodium falciparum, as well as their activity against recombinantly expressed falcipain-2 and -3. The two most active compounds of the series displayed IC50 values of 9.0 and 18.8 μM against Plasmodia.
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Affiliation(s)
- Marie-Adrienne Dude
- Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany; E-mail: (M-A. D.), (G. P.)
| | - Ulrich Kaeppler
- Institute of Pharmacy and Food Chemistry, Am Hubland, D-97074 Würzburg, Germany E-mail: (T. S.)
| | - Monika Herb
- Institute of Pharmacy and Food Chemistry, Am Hubland, D-97074 Würzburg, Germany E-mail: (T. S.)
| | - Markus Schiller
- Institute of Pharmacy and Food Chemistry, Am Hubland, D-97074 Würzburg, Germany E-mail: (T. S.)
| | - Franziska Schulz
- Zoological Institute, University of Kiel, Olshausenstr. 40, D-24098 Kiel, GermanyE-mail: (M. L.)
| | - Birgit Vedder
- Institute of Pharmacy and Food Chemistry, Am Hubland, D-97074 Würzburg, Germany E-mail: (T. S.)
| | - Saskia Heppner
- Zoological Institute, University of Kiel, Olshausenstr. 40, D-24098 Kiel, GermanyE-mail: (M. L.)
| | - Gabriele Pradel
- Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany; E-mail: (M-A. D.), (G. P.)
| | - Jiri Gut
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143-0811, USA; E-mail: (P-J. R.)
| | - Philip J. Rosenthal
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143-0811, USA; E-mail: (P-J. R.)
| | - Tanja Schirmeister
- Institute of Pharmacy and Food Chemistry, Am Hubland, D-97074 Würzburg, Germany E-mail: (T. S.)
| | - Matthias Leippe
- Zoological Institute, University of Kiel, Olshausenstr. 40, D-24098 Kiel, GermanyE-mail: (M. L.)
| | - Christoph Gelhaus
- Zoological Institute, University of Kiel, Olshausenstr. 40, D-24098 Kiel, GermanyE-mail: (M. L.)
- Author to whom correspondence should be addressed; E-mail:
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14
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Ettari R, Nizi E, Di Francesco M, Micale N, Grasso S, Zappalà M, Vičík R, Schirmeister T. Nonpeptidic Vinyl and Allyl Phosphonates as Falcipain‐2 Inhibitors. ChemMedChem 2008; 3:1030-3. [DOI: 10.1002/cmdc.200800050] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Mladenovic M, Junold K, Fink RF, Thiel W, Schirmeister T, Engels B. Atomistic insights into the inhibition of cysteine proteases: first QM/MM calculations clarifying the regiospecificity and the inhibition potency of epoxide- and aziridine-based inhibitors. J Phys Chem B 2008; 112:5458-69. [PMID: 18393547 DOI: 10.1021/jp711287c] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Epoxides and aziridines are important building blocks for inhibitors of cysteine proteases which are promising drug targets for many diseases. In spite of the large amount of experimental data concerning inhibition potency, structure-activity relationships, and structural arrangements of enzyme-inhibitor complexes, little is known about the basic principles which connect the substitution pattern with the resulting activities. To shed some light on this issue which is essential for the rational design of improved compounds, we have studied the inhibition processes theoretically for various inhibitors using quantum mechanical/molecular mechanical hybrid approaches and classical molecular dynamics simulations. The careful analysis of the computational results allows insight into the interactions which govern the regio- and stereospecificity of the interactions. Known structure-activity relationships are rationalized in terms of the same interactions that determine the measured pH dependencies. Inconsistencies in existing X-ray structures are resolved through comparison with the computed structures, which leads to a reassessment of the factors that control the inhibition potency. Similarities and differences in the mode of action of epoxide- and aziridine-based inhibitors are elucidated. Finally the small reaction barriers computed for the irreversible step in E64 analogues call into question the commonly accepted two-step model of inhibition since the second, irreversible step is predicted to be so fast that suitably oriented enzyme-inhibitor complexes will react rather than dissociate and equilibrate.
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Affiliation(s)
- Milena Mladenovic
- Institut für Organische Chemie, and Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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16
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Ettari R, Nizi E, Di Francesco ME, Dude MA, Pradel G, Vičík R, Schirmeister T, Micale N, Grasso S, Zappalà M. Development of Peptidomimetics with a Vinyl Sulfone Warhead as Irreversible Falcipain-2 Inhibitors. J Med Chem 2008; 51:988-96. [DOI: 10.1021/jm701141u] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Rupp I, Bosse R, Schirmeister T, Pradel G. Effect of protease inhibitors on exflagellation in Plasmodium falciparum. Mol Biochem Parasitol 2008; 158:208-12. [PMID: 18243365 DOI: 10.1016/j.molbiopara.2007.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/13/2007] [Accepted: 12/14/2007] [Indexed: 11/19/2022]
Abstract
Enzymes involved in sexual differentiation and fertilization of the human malaria parasite Plasmodium falciparum represent potential targets for transmission blocking strategies. Parasite proteases are putatively involved in several steps during fertilization, but the types of proteases, their targets and modes of action remain hitherto unknown. We investigated the involvement of proteases in gametogenesis via exflagellation and immunofluorescence assays, using a variety of commercially available as well as newly designed protease inhibitors. The assays revealed a blockade of microgamete formation by the cysteine/serine protease inhibitors TLCK and TPCK. The serine protease inhibitor PMSF, the falcipain-targeting inhibitor RV112D, and the aspartic protease inhibitor EPNP also significantly decreased formation of microgametes. The metalloprotease inhibitor 1,10-phenanthroline, on the other hand, inhibited exflagellation by interfering with microgamete motility. Furthermore, EPNP reduced the activation of male and female gametocytes. Our data point to a major involvement of serine proteases and a non-thermolysin-like zinc metalloprotease in microgametocyte exflagellation.
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Affiliation(s)
- Ingrid Rupp
- Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany
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18
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Vicik R, Busemann M, Gelhaus C, Stiefl N, Scheiber J, Schmitz W, Schulz F, Mladenovic M, Engels B, Leippe M, Baumann K, Schirmeister T. Aziridide-Based Inhibitors of Cathepsin L: Synthesis, Inhibition Activity, and Docking Studies. ChemMedChem 2006; 1:1126-41. [PMID: 16933358 DOI: 10.1002/cmdc.200600106] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A comprehensive screening of N-acylated aziridine (aziridide) based cysteine protease inhibitors containing either Boc-Leu-Caa (Caa=cyclic amino acid), Boc-Gly-Caa, or Boc-Phe-Ala attached to the aziridine nitrogen atom revealed Boc-(S)-Leu-(S)-Azy-(S,S)-Azi(OBn)(2) (18 a) as a highly potent cathepsin L (CL) inhibitor (K(i)=13 nM) (Azy=aziridine-2-carboxylate, Azi=aziridine-2,3-dicarboxylate). Docking studies, which also accounted for the unusual bonding situations (the flexibility and hybridization of the aziridides) predict that the inhibitor adopts a Y shape and spans across the entire active site cleft, binding into both the nonprimed and primed sites of CL.
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Affiliation(s)
- Radim Vicik
- Institute of Pharmacy and Food Chemistry, Department of Pharmaceutical/Medicinal Chemistry, University of Würzburg, Am Hubland, Würzburg, Germany
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19
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Ponte-Sucre A, Vicik R, Schultheis M, Schirmeister T, Moll H. Aziridine-2,3-dicarboxylates, peptidomimetic cysteine protease inhibitors with antileishmanial activity. Antimicrob Agents Chemother 2006; 50:2439-47. [PMID: 16801424 PMCID: PMC1489792 DOI: 10.1128/aac.01430-05] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemotherapy of leishmaniasis is mainly based on antimonials. However, they are extremely toxic and cause serious side effects, and there is a worldwide increasing frequency of chemoresistance to antimonials. These issues emphasize the urgent need for affordable alternative drugs against leishmaniasis. Leishmania cysteine proteases are essential for parasite growth, differentiation, pathogenicity, and virulence and are thus attractive targets for combating leishmaniasis. Herein we demonstrate that the cysteine protease inhibitors aziridine-2,3-dicarboxylates 13b and 13e impaired promastigote growth at mid-micromolar concentrations and decreased the infection rate of peritoneal macrophages at concentrations 8- to 13-fold lower than those needed to inhibit parasite replication. Simultaneous treatment of infected cells with compound 13b and gamma interferon resulted in an even further reduction of the concentration needed for a significant decrease in macrophage infection rate. Notably, treatment with the compounds alone modulated the cytokine secretion of infected macrophages, with increased levels of interleukin-12 and tumor necrosis factor alpha. Furthermore, the decreased infection rate in the presence of compound 13b correlated with increased nitric oxide production by macrophages. Importantly, at the concentrations used herein, compounds 13b and 13e were not toxic against fibroblasts, macrophages, or dendritic cells. Together, these results suggest that the aziridine-2,3-dicarboxylates 13b and 13e are potential antileishmanial lead compounds with low toxicity against host cells and selective antiparasitic effects.
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Affiliation(s)
- Alicia Ponte-Sucre
- Institute for Molecular Infection Biology, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany
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20
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Hogg T, Nagarajan K, Herzberg S, Chen L, Shen X, Jiang H, Wecke M, Blohmke C, Hilgenfeld R, Schmidt CL. Structural and functional characterization of Falcipain-2, a hemoglobinase from the malarial parasite Plasmodium falciparum. J Biol Chem 2006; 281:25425-37. [PMID: 16777845 DOI: 10.1074/jbc.m603776200] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Malaria is caused by protozoan erythrocytic parasites of the Plasmodium genus, with Plasmodium falciparum being the most dangerous and widespread disease-causing species. Falcipain-2 (FP-2) of P. falciparum is a papain-family (C1A) cysteine protease that plays an important role in the parasite life cycle by degrading erythrocyte proteins, most notably hemoglobin. Inhibition of FP-2 and its paralogues prevents parasite maturation, suggesting these proteins may be valuable targets for the design of novel antimalarial drugs, but lack of structural knowledge has impeded progress toward the rational discovery of potent, selective, and efficacious inhibitors. As a first step toward this goal, we present here the crystal structure of mature FP-2 at 3.1 A resolution, revealing novel structural features of the FP-2 subfamily proteases including a dynamic beta-hairpin hemoglobin binding motif, a flexible N-terminal alpha-helical extension, and a unique active-site cleft. We also demonstrate by biochemical methods that mature FP-2 can proteolytically process its own precursor in trans at neutral to weakly alkaline pH, that the binding of hemoglobin to FP-2 is strictly pH-dependent, and that FP-2 preferentially binds methemoglobin over hemoglobin. Because the specificity and proteolytic activity of FP-2 toward its multiple targets appears to be pH-dependent, we suggest that environmental pH may play an important role in orchestrating FP-2 function over the different life stages of the parasite. Moreover, it appears that selectivity of FP-2 for methemoglobin may represent an evolutionary adaptation to oxidative stress conditions within the host cell.
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Affiliation(s)
- Tanis Hogg
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
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Vicik R, Hoerr V, Glaser M, Schultheis M, Hansell E, McKerrow JH, Holzgrabe U, Caffrey CR, Ponte-Sucre A, Moll H, Stich A, Schirmeister T. Aziridine-2,3-dicarboxylate inhibitors targeting the major cysteine protease of Trypanosoma brucei as lead trypanocidal agents. Bioorg Med Chem Lett 2006; 16:2753-7. [PMID: 16516467 DOI: 10.1016/j.bmcl.2006.02.026] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 02/02/2006] [Accepted: 02/03/2006] [Indexed: 11/18/2022]
Abstract
The protozoan parasite Trypanosoma brucei causes Human African trypanosomiasis, which is fatal if left untreated. Due to the toxicity of currently used drugs and emerging drug resistance, there is an urgent need for novel therapies. The major trypanosome papain-like cysteine protease expressed by the parasite (e.g., rhodesain in T. b. rhodesiense) is considered an important target for the development of new trypanocidal drugs. Series of aziridine-2,3-dicarboxylate-based cysteine protease inhibitors have been tested, most of them inhibiting rhodesain in the low micromolar range. Among these, only dibenzyl aziridine-2,3-dicarboxylates display trypanocidal activity being equipotent to the drug eflornithine. The Leu-Pro-containing aziridinyl tripeptides 13a-f are the most promising as they are not cytotoxic to macrophages up to concentrations of 125microM.
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Affiliation(s)
- Radim Vicik
- Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany
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22
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Gelhaus C, Vicik R, Schirmeister T, Leippe M. Blocking effect of a biotinylated protease inhibitor on the egress of Plasmodium falciparum merozoites from infected red blood cells. Biol Chem 2005; 386:499-502. [PMID: 15927894 DOI: 10.1515/bc.2005.059] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The malaria parasite Plasmodium falciparum invades human red blood cells. Before infecting new erythrocytes, the merozoites have to exit their host cell to get into the blood plasma. Knowledge about the mechanism of egress is scarce, but it is thought that proteases are basically involved in this step. We have introduced a biotinylated dibenzyl aziridine-2,3-dicarboxylate (bADA) as an irreversible cysteine protease inhibitor to study the mechanism of merozoite release and to identify the proteases involved. The compound acts on parasite proteins in the digestive vacuole and in the host cell cytosol, as judged by fluorescence microscopy. The inhibitor blocks rupture of the host cell membrane, leading to clustered merozoite structures, as evidenced by immunoelectron microscopy. Interestingly, bADA did not prevent rupture of the parasitophorous vacuole membrane (PVM) that surrounds the parasite during the period of intraerythrocytic maturation. The compound appears to be a valuable template for the development of inhibitors specific for individual plasmodial proteases, which would be useful tools to dissect the molecular mechanisms underlying the process of merozoite release and consequently to develop potent antimalarial drugs.
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Affiliation(s)
- Christoph Gelhaus
- Zoologisches Institut der Universität Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
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Chan C, Goh LL, Sim TS. Differences in biochemical properties of the Plasmodial falcipain-2 and berghepain-2 orthologues: implications for in vivo screens of inhibitors. FEMS Microbiol Lett 2005; 249:315-21. [PMID: 16019160 DOI: 10.1016/j.femsle.2005.06.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 06/13/2005] [Accepted: 06/13/2005] [Indexed: 11/17/2022] Open
Abstract
Falcipain-2A, the cysteine protease of Plasmodium falciparum has been proposed as a good drug target. This study evaluated the suitability of Plasmodium berghei as the animal model and reports the first functional expression and characterization of the falcipain-2A orthologue, berghepain-2. Comparative studies revealed that the orthologues exhibited different biochemical properties. Berghepain-2 demonstrated optimal activity at a narrower pH optima of 5.5-6 and a lack of preference for substrates with leucine at position 2. Mutagenesis studies revealed roles for residues Val63 and Arg230 of berghepain-2 in contributing to its distinctive biochemical properties. This warrants re-evaluation of employing P. berghei as the murine model for the in vivo screening of falcipain-2A inhibitors. More importantly, these findings stress the underlying importance of establishing the functionality of relevant genes of P. falciparum with concomitant relevance to its murine counterpart prior to its use as the animal model for the screening of potential antimalarials.
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Affiliation(s)
- Cheryl Chan
- Department of Microbiology, National University of Singapore, 5 Science Drive 2, MD4A, Singapore 117597, Singapore
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Bitar Y, Degel B, Schirmeister T, Holzgrabe U. Comparison of the separation of aziridine isomers applyingheptakis(2,3-di-O-methyl-6-sulfato)β-CD andheptakis(2,3-di-O-acetyl-6-sulfato)β-CD in aqueous and nonaqueous systems. Electrophoresis 2005; 26:3897-903. [PMID: 16167307 DOI: 10.1002/elps.200500176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Aziridines are attracting interest as protease inhibitors, which might be used, e.g., for treatment of parasitic diseases. Within the framework of greater projects dealing with the search of new selective protease inhibitors, a huge number of aziridines with two stereogenic centers will be synthesized. Thus, a fast and reliable screening method for the evaluation of the isomeric composition is needed. Robust baseline separations were obtained using heptakis(2,3-di-O-acetyl-6-sulfato)beta-CD (HDAS) in acidic methanol and sulfated beta-CD in acidic phosphate buffer. With HDAS the resolutions were higher and migration times shorter. Thus, the method will be used as a screening method for further isomeric mixtures of aziridines.
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Affiliation(s)
- Yaser Bitar
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Würzburg, Germany
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