alisporivir and (melle-4)cyclosporin

The mitochondrial permeability transition pore (PTP) is now recognized as playing a key role in a wide variety of human diseases whose common pathology may be based in mitochondrial dysfunction. Recently, PTP assays have been adapted to high-throughput screening approaches to identify small molecules specifically inhibiting the PTP. Following extensive secondary chemistry, the most potent inhibitors of the PTP described to date have been developed. This review will provide an overview of each of these screening efforts, use of resulting compounds in animal models of PTP-based diseases, and problems that will require further study. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

Topics: Anilides; Benzamidines; Cyclosporine; Drug Design; High-Throughput Screening Assays; Isoxazoles; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Permeability Transition Pore; Oximes; Peptides, Cyclic; Quinolinium Compounds; Secosteroids; Structure-Activity Relationship

Mitochondria are critical for sustaining life, not only as the essential powerhouses of cells but as critical mediators of cell survival and death. Mitochondrial dysfunction has been identified as a key perturbation underlying numerous pathologies including myocardial ischemia-reperfusion injury and the subsequent development of impaired left ventricular systolic function and compensatory cardiac hypertrophy. This article outlines the role of mitochondrial dysfunction in these important cardiac pathologies and highlights current cardioprotective strategies and their clinical efficacy in acute myocardial infarction and heart failure patients. Finally, we explore novel mitochondrial targets and evaluate their potential future translation for clinical cardioprotection.

Topics: Cardiopulmonary Bypass; Cardiotonic Agents; Cardiovascular Diseases; Cell Death; Cyclosporine; Free Radical Scavengers; Humans; Immunosuppressive Agents; Ischemic Postconditioning; Ischemic Preconditioning; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitophagy; Myocytes, Cardiac; Organophosphorus Compounds; Oximes; Percutaneous Coronary Intervention; Reactive Oxygen Species; Secosteroids; Ubiquinone

This article highlights a unique time in the history of hepatitis C therapy. In the last few years new families of direct-acting antivirals have emerged, that block different viral proteins to interrupt viral replication, such as protease, NS5A inhibitors, and NS5B inhibitors. There are few host-targeted agents in development; currently cyclophilin inhibitors are the only host-targeted agents in advanced development. One of these new agents has now progressed to phase 3 clinical trials; in this review article their potential role as a future therapy to cure hepatitis C is discussed.

Topics: Antiviral Agents; Cyclophilins; Cyclosporine; Cyclosporins; Drug Therapy, Combination; Enzyme Inhibitors; Hepacivirus; Hepatitis C; Humans; Interferon-alpha; Polyethylene Glycols; Recombinant Proteins; Ribavirin; Viral Nonstructural Proteins

The percentage of patients chronically infected with hepatitis C virus (HCV) who have reached sustained antiviral response has increased since the introduction of the pegylated interferon-alpha (pIFNa) and ribavirin (RBV) treatment. However, the current standard pIFNa/RBV therapy not only has a low success rate (about 50%) but is often associated with serious side effects. Thus, there is an urgent need for the development of new anti-HCV agents. Cyclophilin (Cyp) inhibitors are among the most promising of the new anti-HCV agents under development. Recent clinical studies demonstrate that Cyp inhibitors are potent anti-HCV drugs, with a novel mechanism of action and efficacy profiles that make them attractive candidates for combination with current and future HCV treatments.

Topics: Antiviral Agents; Cyclophilins; Cyclosporine; Cyclosporins; Drug Discovery; Hepacivirus; Hepatitis C; Humans; Virus Replication

The cyclophilins are widely expressed enzymes that catalyze the interconversion of the cis and trans peptide bonds of prolines. The immunosuppressive natural products cyclosporine A and sanglifehrin A inhibit the enzymatic activity of the cyclophilins. Chemical modification of both the cyclosporine and sanglifehrin scaffolds has produced many analogues that inhibit cyclophilins in vitro but have reduced immunosuppressive properties. Three nonimmunosuppressive cyclophilin inhibitors (alisporivir, SCY-635, and NIM811) have demonstrated clinical efficacy for the treatment of hepatitis C infection. Additional candidates are in various stages of preclinical development for the treatment of hepatitis C or myocardial reperfusion injury. Recent publications suggest that cyclophilin inhibitors may have utility for the treatment of diverse viral infections, inflammatory indications, and cancer. In this review, we document the structure-activity relationships of the nonimmunosuppressive cyclosporins and sanglifehrins in clinical and preclinical development. Aspects of the pharmacokinetic behavior and chemical biology of these drug candidates are also described.

Topics: Antiviral Agents; Chemistry, Pharmaceutical; Cyclophilins; Cyclosporine; Cyclosporins; Enzyme Inhibitors; Hepacivirus; Hepatitis C; Host-Pathogen Interactions; Humans; Lactones; Models, Molecular; Molecular Structure; Protein Binding; Protein Structure, Tertiary; Spiro Compounds; Structure-Activity Relationship

Until recently, there were no effective drugs available blocking coronavirus (CoV) infection in humans and animals. We have shown before that CsA and FK506 inhibit coronavirus replication (Carbajo-Lozoya, J., Müller, M.A., Kallies, S., Thiel, V., Drosten, C., von Brunn, A. Replication of human coronaviruses SARS-CoV, HCoV-NL63 and HCoV-229E is inhibited by the drug FK506. Virus Res. 2012; Pfefferle, S., Schöpf, J., Kögl, M., Friedel, C., Müller, M.A., Stellberger, T., von Dall'Armi, E., Herzog, P., Kallies, S., Niemeyer, D., Ditt, V., Kuri, T., Züst, R., Schwarz, F., Zimmer, R., Steffen, I., Weber, F., Thiel, V., Herrler, G., Thiel, H.-J., Schwegmann-Weßels, C., Pöhlmann, S., Haas, J., Drosten, C. and von Brunn, A. The SARS-Coronavirus-host interactome: identification of cyclophilins as target for pan-Coronavirus inhibitors. PLoS Pathog., 2011). Here we demonstrate that CsD Alisporivir, NIM811 as well as novel non-immunosuppressive derivatives of CsA and FK506 strongly inhibit the growth of human coronavirus HCoV-NL63 at low micromolar, non-cytotoxic concentrations in cell culture. We show by qPCR analysis that virus replication is diminished up to four orders of magnitude to background levels. Knockdown of the cellular Cyclophilin A (CypA/PPIA) gene in Caco-2 cells prevents replication of HCoV-NL63, suggesting that CypA is required for virus replication. Collectively, our results uncover Cyclophilin A as a host target for CoV infection and provide new strategies for urgently needed therapeutic approaches.

Topics: Antiviral Agents; Caco-2 Cells; Coronavirus NL63, Human; Cyclophilin A; Cyclosporine; Humans; Real-Time Polymerase Chain Reaction; Tacrolimus; Virus Replication

Cyclosporine A (CsA) is an immunosuppressive drug that targets cyclophilins, cellular cofactors that regulate the immune system. Replication of hepatitis C virus (HCV) is suppressed by CsA, but the molecular basis of this suppression is still not fully understood. To investigate this suppression, we cultured HCV replicon cells (Con1, HCV genotype 1b, FLR-N cell) in the presence of CsA and obtained nine CsA-resistant FLR-N cell lines. We determined full-length HCV sequences for all nine clones, and chose two (clones #6 and #7) of the nine clones that have high replication activity in the presence of CsA for further analysis. Both clones showed two consensus mutations, one in NS3 (T1280V) and the other in NS5A (D2292E). Characterization of various mutants indicated that the D2292E mutation conferred resistance to high concentrations of CsA (up to 2 μM). In addition, the missense mutation T1280V contributed to the recovery of colony formation activity. The effects of these mutations are also evident in two established HCV replicon cell lines-HCV-RMT ([1], genotype 1a) and JFH1 (genotype 2a). Moreover, three other missense mutations in NS5A-D2303H, S2362G, and E2414K-enhanced the resistance to CsA conferred by D2292E; these double or all quadruple mutants could resist approximately 8- to 25-fold higher concentrations of CsA than could wild-type Con1. These four mutations, either as single or combinations, also made Con1 strain resistant to two other cyclophilin inhibitors, N-methyl-4-isoleucine-cyclosporin (NIM811) or Debio-025. Interestingly, the changes in IC50 values that resulted from each of these mutations were the lowest in the Debio-025-treated cells, indicating its highest resistant activity against the adaptive mutation.

Topics: Amino Acid Sequence; Antiviral Agents; Cell Line, Tumor; Cyclophilins; Cyclosporine; Drug Resistance, Viral; Hepacivirus; Humans; Mutation; Viral Nonstructural Proteins; Virus Replication

The current standard of care for hepatitis C virus (HCV) infection, pegylated alpha interferon in combination with ribavirin, has a limited response rate and adverse side effects. Drugs targeting viral proteins are in clinical development, but they suffer from the development of high viral resistance. The inhibition of cellular proteins that are essential for viral amplification is thought to have a higher barrier to the emergence of resistance. Three cyclophilin inhibitors, the cyclosporine analogs DEBIO-025, SCY635, and NIM811, have shown promising results for the treatment of HCV infection in early clinical trials. In this study, we investigated the frequency and mechanism of resistance to cyclosporine (CsA), NIM811, and a structurally unrelated cyclophilin inhibitor, SFA-1, in replicon-containing Huh7 cells. Cross-resistance between all clones was observed. NIM811-resistant clones were selected only after obtaining initial resistance to either CsA or SFA-1. The time required to select resistance against cyclophilin inhibitors was significantly longer than that required for resistance selection against viral protein inhibitors, and the achievable resistance level was substantially lower. Resistance to cyclophilin inhibitors was mediated by amino acid substitutions in NS3, NS5A, and NS5B, with NS5A mutations conferring the majority of resistance. Mutation D320E in NS5A mediated most of the resistance conferred by NS5A. Taken together, the results indicate that there is a very low frequency and level of resistance to cyclophilin-binding drugs mediated by amino acid substitutions in three viral proteins. The interaction of cyclophilin with NS5A seems to be the most critical, since the NS5A mutations have the largest impact on resistance.

Topics: Antiviral Agents; Cell Line; Cyclophilins; Cyclosporine; Cyclosporins; Drug Resistance, Viral; Enzyme Inhibitors; Hepacivirus; Humans; Lactones; Mutagenesis, Site-Directed; Replicon; RNA, Viral; Spiro Compounds; Transfection; Viral Nonstructural Proteins

Cyclosporin A (CsA) is highly neuroprotective in several animal models of acute neurological damage and neurodegenerative disease with inhibition of the mitochondrial permeability transition (mPT) having emerged as a possible mechanism for the observed neuroprotection. In the present study, we have evaluated two new nonimmunosuppressive cyclosporin analogs NIM811 (Novartis) and UNIL025 (Debiopharm) for their ability to inhibit mPT in rat brain-derived mitochondria. Both NIM811 and UNIL025 were found to be powerful inhibitors of calcium-induced mitochondrial swelling under energized and deenergized conditions, and the maximal effects were identical to those of native CsA. The potencies of mPT inhibition by NIM811 and UNIL025 were stronger, with almost one order of magnitude higher potency for UNIL025 compared to CsA, correlating to their respective inhibitory action of cyclophilin activity. These compounds will be instrumental in the evaluation of mPT as a central target for neuroprotection in vivo.

Topics: Animals; Calcium; Cell Membrane Permeability; Cells, Cultured; Cerebral Cortex; Cyclosporine; Dose-Response Relationship, Drug; Immunosuppressive Agents; Microchemistry; Mitochondria; Rats