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Di Chio C, Starvaggi J, Totaro N, Previti S, Natale B, Cosconati S, Bogacz M, Schirmeister T, Legac J, Rosenthal PJ, Zappalà M, Ettari R. Development of Novel Peptidyl Nitriles Targeting Rhodesain and Falcipain-2 for the Treatment of Sleeping Sickness and Malaria. Int J Mol Sci 2024; 25:4410. [PMID: 38673995 PMCID: PMC11050014 DOI: 10.3390/ijms25084410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/10/2024] [Accepted: 04/14/2024] [Indexed: 04/28/2024] Open
Abstract
In recent decades, neglected tropical diseases and poverty-related diseases have become a serious health problem worldwide. Among these pathologies, human African trypanosomiasis, and malaria present therapeutic problems due to the onset of resistance, toxicity problems and the limited spectrum of action. In this drug discovery process, rhodesain and falcipain-2, of Trypanosoma brucei rhodesiense and Plasmodium falciparum, are currently considered the most promising targets for the development of novel antitrypanosomal and antiplasmodial agents, respectively. Therefore, in our study we identified a novel lead-like compound, i.e., inhibitor 2b, which we proved to be active against both targets, with a Ki = 5.06 µM towards rhodesain and an IC50 = 40.43 µM against falcipain-2.
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Affiliation(s)
- Carla Di Chio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
| | - Josè Starvaggi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
| | - Noemi Totaro
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
| | - Santo Previti
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
| | - Benito Natale
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania Luigi Vanvitelli, Via Vivaldi 43, 81100 Caserta, Italy; (B.N.); (S.C.)
| | - Sandro Cosconati
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania Luigi Vanvitelli, Via Vivaldi 43, 81100 Caserta, Italy; (B.N.); (S.C.)
| | - Marta Bogacz
- Institute of Organic Chemistry & Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstraße, 10, DE 07743 Jena, Germany;
| | - Tanja Schirmeister
- Institute of Pharmacy and Biochemistry, University of Mainz, Staudingerweg 5, DE 55128 Mainz, Germany;
| | - Jenny Legac
- Department of Medicine, San Francisco General Hospital, University of California, 1001 Potrero Avenue, San Francisco, CA 94110, USA; (J.L.); (P.J.R.)
| | - Philip J. Rosenthal
- Department of Medicine, San Francisco General Hospital, University of California, 1001 Potrero Avenue, San Francisco, CA 94110, USA; (J.L.); (P.J.R.)
| | - Maria Zappalà
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
| | - Roberta Ettari
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d’Alcontres, 98166 Messina, Italy; (C.D.C.); (J.S.); (N.T.); (S.P.); (M.Z.)
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Maus H, Müller P, Meta M, Hoba SN, Hammerschmidt SJ, Zimmermann RA, Zimmer C, Fuchs N, Schirmeister T, Barthels F. Next Generation of Fluorometric Protease Assays: 7-Nitrobenz-2-oxa-1,3-diazol-4-yl-amides (NBD-Amides) as Class-Spanning Protease Substrates. Chemistry 2023; 29:e202301855. [PMID: 37313627 DOI: 10.1002/chem.202301855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/15/2023]
Abstract
Fluorometric assays are one of the most frequently used methods in medicinal chemistry. Over the last 50 years, the reporter molecules for the detection of protease activity have evolved from first-generation colorimetric p-nitroanilides, through FRET substrates, and 7-amino-4-methyl coumarin (AMC)-based substrates. The aim of further substrate development is to increase sensitivity and reduce vulnerability to assay interferences. Herein, we describe a new generation of substrates for protease assays based on 7-nitrobenz-2-oxa-1,3-diazol-4-yl-amides (NBD-amides). In this study, we synthesized and tested substrates for 10 different proteases from the serine-, cysteine-, and metalloprotease classes. Enzyme- and substrate-specific parameters as well as the inhibitory activity of literature-known inhibitors confirmed their suitability for application in fluorometric assays. Hence, we were able to present NBD-based alternatives for common protease substrates. In conclusion, these NBD substrates are not only less susceptible to common assay interference, but they are also able to replace FRET-based substrates with the requirement of a prime site amino acid residue.
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Affiliation(s)
- Hannah Maus
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Patrick Müller
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Mergim Meta
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Sabrina N Hoba
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Stefan J Hammerschmidt
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Robert A Zimmermann
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Collin Zimmer
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Natalie Fuchs
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Tanja Schirmeister
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
| | - Fabian Barthels
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, Staudingerweg 5, 55128, Mainz, Germany
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Alves ETM, Pernichelle FG, Nascimento LA, Ferreira GM, Ferreira EI. Covalent Inhibitors for Neglected Diseases: An Exploration of Novel Therapeutic Options. Pharmaceuticals (Basel) 2023; 16:1028. [PMID: 37513939 PMCID: PMC10385647 DOI: 10.3390/ph16071028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Neglected diseases, primarily found in tropical regions of the world, present a significant challenge for impoverished populations. Currently, there are 20 diseases considered neglected, which greatly impact the health of affected populations and result in difficult-to-control social and economic consequences. Unfortunately, for the majority of these diseases, there are few or no drugs available for patient treatment, and the few drugs that do exist often lack adequate safety and efficacy. As a result, there is a pressing need to discover and design new drugs to address these neglected diseases. This requires the identification of different targets and interactions to be studied. In recent years, there has been a growing focus on studying enzyme covalent inhibitors as a potential treatment for neglected diseases. In this review, we will explore examples of how these inhibitors have been used to target Human African Trypanosomiasis, Chagas disease, and Malaria, highlighting some of the most promising results so far. Ultimately, this review aims to inspire medicinal chemists to pursue the development of new drug candidates for these neglected diseases, and to encourage greater investment in research in this area.
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Affiliation(s)
- Erick Tavares Marcelino Alves
- Department of Pharmacy, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Butantã, São Paulo 05508-000, Brazil
| | - Filipe Gomes Pernichelle
- Department of Pharmacy, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Butantã, São Paulo 05508-000, Brazil
| | - Lucas Adriano Nascimento
- Department of Pharmacy, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Butantã, São Paulo 05508-000, Brazil
| | - Glaucio Monteiro Ferreira
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Butantã, São Paulo 05508-000, Brazil
| | - Elizabeth Igne Ferreira
- Department of Pharmacy, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Butantã, São Paulo 05508-000, Brazil
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Di Chio C, Previti S, Totaro N, De Luca F, Allegra A, Schirmeister T, Zappalà M, Ettari R. Dipeptide Nitrile CD34 with Curcumin: A New Improved Combination Strategy to Synergistically Inhibit Rhodesain of Trypanosoma brucei rhodesiense. Int J Mol Sci 2023; 24:ijms24108477. [PMID: 37239824 DOI: 10.3390/ijms24108477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/28/2023] [Accepted: 05/07/2023] [Indexed: 05/28/2023] Open
Abstract
Rhodesain is the main cysteine protease of Trypanosoma brucei rhodesiense, the parasite causing the acute lethal form of Human African Trypanosomiasis. Starting from the dipeptide nitrile CD24, the further introduction of a fluorine atom in the meta position of the phenyl ring spanning in the P3 site and the switch of the P2 leucine with a phenylalanine led to CD34, a synthetic inhibitor that shows a nanomolar binding affinity towards rhodesain (Ki = 27 nM) and an improved target selectivity with respect to the parent dipeptide nitrile CD24. In the present work, following the Chou and Talalay method, we carried out a combination study of CD34 with curcumin, a nutraceutical obtained from Curcuma longa L. Starting from an affected fraction (fa) of rhodesain inhibition of 0.5 (i.e., the IC50), we observed an initial moderate synergistic action, which became a synergism for fa values ranging from 0.6 to 0.7 (i.e., 60-70% inhibition of the trypanosomal protease). Interestingly, at 80-90% inhibition of rhodesain proteolytic activity, we observed a strong synergism, resulting in 100% enzyme inhibition. Overall, in addition to the improved target selectivity of CD34 with respect to CD24, the combination of CD34 + curcumin resulted in an increased synergistic action with respect to CD24 + curcumin, thus suggesting that it is desirable to use CD34 and curcumin in combination.
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Affiliation(s)
- Carla Di Chio
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
- Department of Clinical and Experimental Medicine, University of Messina, Via C. Valeria, 98125 Messina, Italy
| | - Santo Previti
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Noemi Totaro
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Fabiola De Luca
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Alessandro Allegra
- Department of Human Pathology in Adulthood and Childhood "Gaetano Barresi", University of Messina, Via Consolare Valeria 1, 98125 Messina, Italy
| | - Tanja Schirmeister
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, Staudingerweg 5, 55128 Mainz, Germany
| | - Maria Zappalà
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Roberta Ettari
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy
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Previti S, Ettari R, Di Chio C, Legac J, Bogacz M, Zimmer C, Schirmeister T, Rosenthal PJ, Zappalà M. Influence of amino acid size at the P3 position of N-Cbz-tripeptide Michael acceptors targeting falcipain-2 and rhodesain for the treatment of malaria and human african trypanosomiasis. Bioorg Chem 2023; 137:106587. [PMID: 37163812 DOI: 10.1016/j.bioorg.2023.106587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/18/2023] [Accepted: 05/01/2023] [Indexed: 05/12/2023]
Abstract
In recent decades, several structure-activity relationship (SAR) studies provided potent inhibitors of the cysteine proteases falcipain-2 (FP-2) and rhodesain (RD) from Plasmodium falciparum and Trypanosoma brucei rhodesiense, respectively. Whilst the roles of the warhead and residues targeting the P1 and P2 pockets of the proteases were extensively investigated, the roles of the amino acids occupying the S3 pocket were not widely assessed. Herein we report the synthesis and biological evaluation of a set of novel Michael acceptors bearing amino acids of increasing size at the P3 site (1a-g/2a-g, SPR20-SPR33) against FP-2, RD, P. falciparum, and T. brucei. Overall, the Michael acceptors bearing small amino acids at the P3 site exhibited the most potent inhibitory properties towards FP-2. In contrast, analogues with bulky residues at the P3 position were very potent rhodesain inhibitors. In cell based assays, single-digit micromolar EC50 values against the two protozoa were observed. These findings can be a starting point for the development of peptide-based FP-2 and RD inhibitors.
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Affiliation(s)
- Santo Previti
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Stagno d'Alcontres 31, 98166 Messina, Italy.
| | - Roberta Ettari
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Carla Di Chio
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Jenny Legac
- Department of Medicine, University of California, San Francisco, CA 94143, United States
| | - Marta Bogacz
- Institute of Organic Chemistry & Macromolecular Chemistry, Friedrich-Schiller-University of Jena, 07743 Jena, Germany
| | - Collin Zimmer
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, 55128 Mainz, Germany
| | - Tanja Schirmeister
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, 55128 Mainz, Germany
| | - Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, CA 94143, United States
| | - Maria Zappalà
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Viale Stagno d'Alcontres 31, 98166 Messina, Italy
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Müller P, Meta M, Meidner JL, Schwickert M, Meyr J, Schwickert K, Kersten C, Zimmer C, Hammerschmidt SJ, Frey A, Lahu A, de la Hoz-Rodríguez S, Agost-Beltrán L, Rodríguez S, Diemer K, Neumann W, Gonzàlez FV, Engels B, Schirmeister T. Investigation of the Compatibility between Warheads and Peptidomimetic Sequences of Protease Inhibitors-A Comprehensive Reactivity and Selectivity Study. Int J Mol Sci 2023; 24:ijms24087226. [PMID: 37108388 PMCID: PMC10138721 DOI: 10.3390/ijms24087226] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 04/29/2023] Open
Abstract
Covalent peptidomimetic protease inhibitors have gained a lot of attention in drug development in recent years. They are designed to covalently bind the catalytically active amino acids through electrophilic groups called warheads. Covalent inhibition has an advantage in terms of pharmacodynamic properties but can also bear toxicity risks due to non-selective off-target protein binding. Therefore, the right combination of a reactive warhead with a well-suited peptidomimetic sequence is of great importance. Herein, the selectivities of well-known warheads combined with peptidomimetic sequences suited for five different proteases were investigated, highlighting the impact of both structure parts (warhead and peptidomimetic sequence) for affinity and selectivity. Molecular docking gave insights into the predicted binding modes of the inhibitors inside the binding pockets of the different enzymes. Moreover, the warheads were investigated by NMR and LC-MS reactivity assays against serine/threonine and cysteine nucleophile models, as well as by quantum mechanics simulations.
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Affiliation(s)
- Patrick Müller
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Mergim Meta
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Jan Laurenz Meidner
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Marvin Schwickert
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Jessica Meyr
- Institute of Physical and Theoretical Chemistry, Julius-Maximilians-University of Wuerzburg, Emil-Fischer-Straße 42 Süd, D-97074 Wuerzburg, Germany
| | - Kevin Schwickert
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Christian Kersten
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Collin Zimmer
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Stefan Josef Hammerschmidt
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Ariane Frey
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | - Albin Lahu
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
| | | | - Laura Agost-Beltrán
- Departament de Química Inorgànica i Orgànica, Universitat Jaume I, 12080 Castelló de la Pana, Spain
| | - Santiago Rodríguez
- Departament de Química Inorgànica i Orgànica, Universitat Jaume I, 12080 Castelló de la Pana, Spain
| | - Kira Diemer
- Institute of Physical and Theoretical Chemistry, Julius-Maximilians-University of Wuerzburg, Emil-Fischer-Straße 42 Süd, D-97074 Wuerzburg, Germany
| | - Wilhelm Neumann
- Institute of Physical and Theoretical Chemistry, Julius-Maximilians-University of Wuerzburg, Emil-Fischer-Straße 42 Süd, D-97074 Wuerzburg, Germany
| | - Florenci V Gonzàlez
- Departament de Química Inorgànica i Orgànica, Universitat Jaume I, 12080 Castelló de la Pana, Spain
| | - Bernd Engels
- Institute of Physical and Theoretical Chemistry, Julius-Maximilians-University of Wuerzburg, Emil-Fischer-Straße 42 Süd, D-97074 Wuerzburg, Germany
| | - Tanja Schirmeister
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 5, D-55128 Mainz, Germany
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Structure-based lead optimization of peptide-based vinyl methyl ketones as SARS-CoV-2 main protease inhibitors. Eur J Med Chem 2023; 247:115021. [PMID: 36549112 PMCID: PMC9751013 DOI: 10.1016/j.ejmech.2022.115021] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/30/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022]
Abstract
Despite several major achievements in the development of vaccines and antivirals, the fight against SARS-CoV-2 and the health problems accompanying COVID-19 are still ongoing. SARS-CoV-2 main protease (Mpro), an essential viral cysteine protease, is a crucial target for the development of antiviral agents. A virtual screening analysis of in-house cysteine protease inhibitors against SARS-CoV-2 Mpro allowed us to identify two hits (i.e., 1 and 2) bearing a methyl vinyl ketone warhead. Starting from these compounds, we herein report the development of Michael acceptors targeting SARS-CoV-2 Mpro, which differ from each other for the warhead and for the amino acids at the P2 site. The most promising vinyl methyl ketone-containing analogs showed sub-micromolar activity against the viral protease. SPR38, SPR39, and SPR41 were fully characterized, and additional inhibitory properties towards hCatL, which plays a key role in the virus entry into host cells, were observed. SPR39 and SPR41 exhibited single-digit micromolar EC50 values in a SARS-CoV-2 infection model in cell culture.
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Drug Combination Studies of the Dipeptide Nitrile CD24 with Curcumin: A New Strategy to Synergistically Inhibit Rhodesain of Trypanosoma brucei rhodesiense. Int J Mol Sci 2022; 23:ijms232214470. [PMID: 36430948 PMCID: PMC9698140 DOI: 10.3390/ijms232214470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/31/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Rhodesain is a cysteine protease that is crucial for the life cycle of Trypanosoma brucei rhodesiense, a parasite causing the lethal form of Human African Trypanosomiasis. CD24 is a recently developed synthetic inhibitor of rhodesain, characterized by a nanomolar affinity towards the trypanosomal protease (Ki = 16 nM), and acting as a competitive inhibitor. In the present work, we carried out a combination study of CD24 with curcumin, the multitarget nutraceutical obtained from Curcuma longa L., which we demonstrated to inhibit rhodesain in a non-competitive manner. By applying the Chou and Talalay method, we obtained an initial additive effect at IC50 (fa = 0.5, Combination Index = 1), while for the most relevant fa values, ranging from 0.6 to 1, i.e., from 60% to 100% of rhodesain inhibition, we obtained a combination index < 1, thus suggesting that an increasingly synergistic action occurred for the combination of the synthetic inhibitor CD24 and curcumin. Furthermore, the combination of the two inhibitors showed an antitrypanosomal activity better than that of CD24 alone (EC50 = 4.85 µM and 10.1 µM for the combination and CD24, respectively), thus suggesting the use of the two inhibitors in combination is desirable.
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