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Freidel MR, Vakhariya PA, Sardarni SK, Armen RS. The Dual-Targeted Fusion Inhibitor Clofazimine Binds to the S2 Segment of the SARS-CoV-2 Spike Protein. Viruses 2024; 16:640. [PMID: 38675980 PMCID: PMC11054727 DOI: 10.3390/v16040640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/29/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
Clofazimine and Arbidol have both been reported to be effective in vitro SARS-CoV-2 fusion inhibitors. Both are promising drugs that have been repurposed for the treatment of COVID-19 and have been used in several previous and ongoing clinical trials. Small-molecule bindings to expressed constructs of the trimeric S2 segment of Spike and the full-length SARS-CoV-2 Spike protein were measured using a Surface Plasmon Resonance (SPR) binding assay. We demonstrate that Clofazimine, Toremifene, Arbidol and its derivatives bind to the S2 segment of the Spike protein. Clofazimine provided the most reliable and highest-quality SPR data for binding with S2 over the conditions explored. A molecular docking approach was used to identify the most favorable binding sites on the S2 segment in the prefusion conformation, highlighting two possible small-molecule binding sites for fusion inhibitors. Results related to molecular docking and modeling of the structure-activity relationship (SAR) of a newly reported series of Clofazimine derivatives support the proposed Clofazimine binding site on the S2 segment. When the proposed Clofazimine binding site is superimposed with other experimentally determined coronavirus structures in structure-sequence alignments, the changes in sequence and structure may rationalize the broad-spectrum antiviral activity of Clofazimine in closely related coronaviruses such as SARS-CoV, MERS, hCoV-229E, and hCoV-OC43.
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Affiliation(s)
| | | | | | - Roger S. Armen
- Department of Pharmaceutical Sciences, College of Pharmacy, Thomas Jefferson University, 901 Walnut St. Suite 918, Philadelphia, PA 19170, USA (P.A.V.); (S.K.S.)
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2
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Naranjo MF, Kumar A, Ratrey P, Hudson SP. Pre-formulation of an additive combination of two antimicrobial agents, clofazimine and nisin A, to boost antimicrobial activity. J Mater Chem B 2024; 12:1558-1568. [PMID: 38252026 DOI: 10.1039/d3tb01800h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
According to the World Health Organization, antimicrobial resistance is one of the top ten issues that pose a major threat to humanity. The lack of investment by the pharmaceutical industry has meant fewer novel antimicrobial agents are in development, exacerbating the problem. Emerging drug design strategies are exploring the repurposing of existing drugs and the utilization of novel drug candidates, like antimicrobial peptides, to combat drug resistance. This proactive approach is crucial in fighting global health threats. In this study, an additive combination of a repurposed anti-leprosy drug, clofazimine, and an antimicrobial peptide, nisin A, are preformulated using liquid antisolvent precipitation to generate a stable amorphous, ionized nanoparticle system to boost antimicrobial activity. The nanotechnology aims to improve the physicochemical properties of the inherently poorly water-soluble clofazimine molecules while also harnessing the previously unreported additive effect of clofazimine and nisin A. The approach transformed clofazimine into a more water-soluble salt, yielding amorphous nanoparticles stabilized by the antimicrobial peptide; and combined the two drugs into a more soluble and more active formulation. Blending pre-formulation strategies like amorphization, salt formation, and nanosizing to improve the inherent low aqueous solubility of drugs can open many new possibilities for the design of new antimicrobial agents. This fusion of pre-formulation technologies in combination with the multi-hurdle approach of selecting drugs with different effects on microbes could be key in the design platform of new antibiotics in the fight against antimicrobial resistance.
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Affiliation(s)
- Mateo Flores Naranjo
- Department of Chemical Sciences, SSPC, Science Foundation Ireland Research Centre for Pharmaceuticals, Bernal Institute, University of Limerick, Castletroy, Limerick, V94 T9PX, Ireland.
| | - Ajay Kumar
- Department of Chemical Sciences, SSPC, Science Foundation Ireland Research Centre for Pharmaceuticals, Bernal Institute, University of Limerick, Castletroy, Limerick, V94 T9PX, Ireland.
| | - Poonam Ratrey
- Department of Chemical Sciences, SSPC, Science Foundation Ireland Research Centre for Pharmaceuticals, Bernal Institute, University of Limerick, Castletroy, Limerick, V94 T9PX, Ireland.
| | - Sarah P Hudson
- Department of Chemical Sciences, SSPC, Science Foundation Ireland Research Centre for Pharmaceuticals, Bernal Institute, University of Limerick, Castletroy, Limerick, V94 T9PX, Ireland.
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3
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Koval A, Bassanini I, Xu J, Tonelli M, Boido V, Sparatore F, Amant F, Annibali D, Leucci E, Sparatore A, Katanaev VL. Optimization of the clofazimine structure leads to a highly water-soluble C3-aminopyridinyl riminophenazine endowed with improved anti-Wnt and anti-cancer activity in vitro and in vivo. Eur J Med Chem 2021; 222:113562. [PMID: 34116325 DOI: 10.1016/j.ejmech.2021.113562] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/10/2021] [Accepted: 05/17/2021] [Indexed: 12/15/2022]
Abstract
Triple-negative breast cancer (TNBC) is a cancer subtype critically dependent upon excessive activation of Wnt pathway. The anti-mycobacterial drug clofazimine is an efficient inhibitor of canonical Wnt signaling in TNBC, reducing tumor cell proliferation in vitro and in animal models. These properties make clofazimine a candidate to become first targeted therapy against TNBC. In this work, we optimized the clofazimine structure to enhance its water solubility and potency as a Wnt inhibitor. After extensive structure-activity relationships investigations, the riminophenazine 5-(4-(chlorophenyl)-3-((2-(piperazin-1-yl)ethyl)imino)-N-(pyridin-3-yl)-3,5-dihydrophenazin-2-amine (MU17) was identified as the new lead compound for the riminophenazine-based targeted therapy against TNBC and Wnt-dependent cancers. Compared to clofazimine, the water-soluble MU17 displayed a 7-fold improved potency against Wnt signaling in TNBC cells resulting in on-target suppression of tumor growth in a patient-derived mouse model of TNBC. Moreover, allowing the administration of reduced yet effective dosages, MU17 displayed no adverse effects, most notably no clofazimine-related skin coloration.
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Affiliation(s)
- Alexey Koval
- Department of Cell Physiology and Metabolism, Translational Research Centre in Oncohaematology, Faculty of Medicine, University of Geneva, 1206, Geneva, Switzerland
| | - Ivan Bassanini
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, 20133, Milano, Italy; Istituto di Scienze e Tecnologie Chimiche "Giulio Natta", Consiglio Nazonale delle Ricerche, 20131, Milano, Italy
| | - Jiabin Xu
- Department of Cell Physiology and Metabolism, Translational Research Centre in Oncohaematology, Faculty of Medicine, University of Geneva, 1206, Geneva, Switzerland; Department of Biomedical Sciences, Faculty of Biology and Medicine, 1011, University of Lausanne, Lausanne, Switzerland
| | - Michele Tonelli
- Dipartimento di Farmacia, Università di Genova, 16132, Genova, Italy
| | - Vito Boido
- Dipartimento di Farmacia, Università di Genova, 16132, Genova, Italy
| | - Fabio Sparatore
- Dipartimento di Farmacia, Università di Genova, 16132, Genova, Italy
| | - Frederic Amant
- Gynecological Oncology Laboratory, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), 3000, Leuven, Belgium; Department of Obstetrics and Gynecology, University Hospitals Leuven and Department of Oncology, 3000, Leuven, Belgium; Centre for Gynecologic Oncology Amsterdam (CGOA), Antoni Van Leeuwenhoek-Netherlands Cancer Institute (AvL-NKI), University Medical Center (UMC), 1066, Amsterdam, the Netherlands
| | - Daniela Annibali
- Gynecological Oncology Laboratory, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), 3000, Leuven, Belgium
| | - Eleonora Leucci
- Laboratory for RNA Cancer Biology, Department of Oncology, KU Leuven, 3000, Leuven, Belgium; Trace, LKI Leuven Cancer Institute, KU Leuven, 3000, Leuven, Belgium
| | - Anna Sparatore
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, 20133, Milano, Italy.
| | - Vladimir L Katanaev
- Department of Cell Physiology and Metabolism, Translational Research Centre in Oncohaematology, Faculty of Medicine, University of Geneva, 1206, Geneva, Switzerland; School of Biomedicine, Far Eastern Federal University, 690922, Vladivostok, Russia.
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4
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Saravanan P, Dusthackeer VNA, Rajmani RS, Mahizhaveni B, Nirmal CR, Rajadas SE, Bhardwaj N, Ponnuraja C, Bhaskar A, Hemanthkumar AK, Ramachandran G, Tripathy SP. Discovery of a highly potent novel rifampicin analog by preparing a hybrid of the precursors of the antibiotic drugs rifampicin and clofazimine. Sci Rep 2021; 11:1029. [PMID: 33441878 PMCID: PMC7806721 DOI: 10.1038/s41598-020-80439-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 12/10/2020] [Indexed: 12/26/2022] Open
Abstract
Tuberculosis (TB) is an infectious disease caused by the bacillus Mycobacterium tuberculosis (Mtb). The present work reports the design and synthesis of a hybrid of the precursors of rifampicin and clofazimine, which led to the discovery of a novel Rifaphenazine (RPZ) molecule with potent anti-TB activity. In addition, the efficacy of RPZ was evaluated in-vitro using the reference strain Mtb H37Rv. Herein, 2,3 diamino phenazine, a precursor of an anti-TB drug clofazimine, was tethered to the rifampicin core. This 2,3 diamino phenazine did not have an inherent anti-TB activity even at a concentration of up to 2 µg/mL, while rifampicin did not exhibit any activity against Mtb at a concentration of 0.1 µg/mL. However, the synthesized novel Rifaphenzine (RPZ) inhibited 78% of the Mtb colonies at a drug concentration of 0.1 µg/mL, while 93% of the bacterial colonies were killed at 0.5 µg/mL of the drug. Furthermore, the Minimum Inhibitory Concentration (MIC) value for RPZ was 1 µg/mL. Time-kill studies revealed that all bacterial colonies were killed within a period of 24 h. The synthesized novel molecule was characterized using high-resolution mass spectroscopy and NMR spectroscopy. Cytotoxicity studies (IC50) were performed on human monocytic cell line THP-1, and the determined IC50 value was 96 µg/mL, which is non-cytotoxic.
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Affiliation(s)
| | | | - R S Rajmani
- Centre for Infectious Disease and Research, Indian Institute of Science, Bangalore, India
| | - B Mahizhaveni
- ICMR-National Institute for Research in Tuberculosis, Chennai, India
| | - Christy R Nirmal
- ICMR-National Institute for Research in Tuberculosis, Chennai, India
| | | | - Neerupma Bhardwaj
- Centre for Infectious Disease and Research, Indian Institute of Science, Bangalore, India
| | - C Ponnuraja
- ICMR-National Institute for Research in Tuberculosis, Chennai, India
| | - Adhin Bhaskar
- ICMR-National Institute for Research in Tuberculosis, Chennai, India
| | - A K Hemanthkumar
- ICMR-National Institute for Research in Tuberculosis, Chennai, India
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5
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Bvumbi MV. Activity of Riminophenazines against Mycobacterium tuberculosis: A Review of Studies that Might be Contenders for Use as Antituberculosis Agents. ChemMedChem 2020; 15:2207-2219. [PMID: 32844566 PMCID: PMC7756396 DOI: 10.1002/cmdc.202000580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Indexed: 02/01/2023]
Abstract
Tuberculosis is one of the leading cause of death in the world, mainly due to the increasing number of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) strains. Factors such as the HIV pandemic contribute further. Also, the ineffectiveness of the chemotherapy in current use increases the mortality rate. Therefore, new and repurposed antituberculosis drugs are urgently needed for the treatment of MDR-TB, and riminophenazines are among those drugs that are being reinvestigated for their potential in the treatment of TB. This review delivers a brief historical account of riminophenazines, their general synthesis, mechanisms of action, and their physicochemical properties. The discussion is limited to those studies that investigated the activity of these compounds as antituberculosis agents. Given their unique properties, this review will be of great significance in giving direction towards the design and development of new riminophenazine analogues.
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6
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Sbaraglini ML, Bellera CL, Quarroz Braghini J, Areco Y, Miranda C, Carrillo C, Kelly J, Buchholz B, Gelpi RJ, Talevi A, Alba Soto CD. Combined therapy with Benznidazole and repurposed drugs Clofazimine and Benidipine for chronic Chagas disease. Eur J Med Chem 2019; 184:111778. [PMID: 31630056 DOI: 10.1016/j.ejmech.2019.111778] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/09/2019] [Indexed: 11/19/2022]
Affiliation(s)
- María L Sbaraglini
- Laboratorio de Investigación y Desarrollo de Bioactivos (LIDeB), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), 47 y 115 (B1900AJI) La Plata, Buenos Aires, Argentina
| | - Carolina L Bellera
- Laboratorio de Investigación y Desarrollo de Bioactivos (LIDeB), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), 47 y 115 (B1900AJI) La Plata, Buenos Aires, Argentina
| | - Juan Quarroz Braghini
- Instituto de Microbiología y Parasitología Médica (IMPaM, CONICET-UBA), Departamento de Microbiología, Facultad de Medicina, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Yésica Areco
- Instituto de Microbiología y Parasitología Médica (IMPaM, CONICET-UBA), Departamento de Microbiología, Facultad de Medicina, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Cristian Miranda
- Instituto de Microbiología y Parasitología Médica (IMPaM, CONICET-UBA), Departamento de Microbiología, Facultad de Medicina, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Carolina Carrillo
- Instituto de Ciencias y Tecnología Dr. César Milstein (ICT Milstein), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
| | - Jazmín Kelly
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Patología, Instituto de Fisiopatología Cardiovascular (INFICA) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Bioquímica y Medicina Molecular (IBIMOL), Buenos Aires, Argentina
| | - Bruno Buchholz
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Patología, Instituto de Fisiopatología Cardiovascular (INFICA) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Bioquímica y Medicina Molecular (IBIMOL), Buenos Aires, Argentina
| | - Ricardo J Gelpi
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Patología, Instituto de Fisiopatología Cardiovascular (INFICA) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Bioquímica y Medicina Molecular (IBIMOL), Buenos Aires, Argentina
| | - Alan Talevi
- Laboratorio de Investigación y Desarrollo de Bioactivos (LIDeB), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), 47 y 115 (B1900AJI) La Plata, Buenos Aires, Argentina
| | - Catalina D Alba Soto
- Instituto de Microbiología y Parasitología Médica (IMPaM, CONICET-UBA), Departamento de Microbiología, Facultad de Medicina, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina.
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7
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Angiolini L, Cohen B, Douhal A. Single Crystal FLIM Characterization of Clofazimine Loaded in Silica-Based Mesoporous Materials and Zeolites. Int J Mol Sci 2019; 20:E2859. [PMID: 31212750 PMCID: PMC6627708 DOI: 10.3390/ijms20122859] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 06/06/2019] [Accepted: 06/10/2019] [Indexed: 01/19/2023] Open
Abstract
Clofazimine (CLZ) is an effective antibiotic used against a wide spectrum of Gram-positive bacteria and leprosy. One of its main drawbacks is its poor solubility in water. Silica based materials are used as drug delivery carriers that can increase the solubility of different hydrophobic drugs. Here, we studied how the properties of the silica framework of the mesoporous materials SBA-15, MCM-41, Al-MCM-41, and zeolites NaX, NaY, and HY affect the loading, stability, and distribution of encapsulated CLZ. Time-correlated single-photon counting (TCSPC) and fluorescence lifetime imaging microscopy (FLIM) experiments show the presence of neutral and protonated CLZ (1.3-3.8 ns) and weakly interacting aggregates (0.4-0.9 ns), along with H- and J-type aggregates (<0.1 ns). For the mesoporous and HY zeolite composites, the relative contribution to the overall emission spectra from H-type aggregates is low (<10%), while for the J-type aggregates it becomes higher (~30%). For NaX and NaY the former increased whereas the latter decreased. Although the CLZ@mesoporous composites show higher loading compared to the CLZ@zeolites ones, the behavior of CLZ is not uniform and its dynamics are more heterogeneous across different single mesoporous particles. These results may have implication in the design of silica-based drug carriers for better loading and release mechanisms of hydrophobic drugs.
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Affiliation(s)
- Lorenzo Angiolini
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain.
| | - Boiko Cohen
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain.
| | - Abderrazzak Douhal
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain.
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8
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Guo C, Chang T, Sun T, Wu Z, Dai Y, Yao H, Lin D. Anti-leprosy drug Clofazimine binds to human Raf1 kinase inhibitory protein and enhances ERK phosphorylation. Acta Biochim Biophys Sin (Shanghai) 2018; 50:1062-1067. [PMID: 30137201 DOI: 10.1093/abbs/gmy095] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Indexed: 12/26/2022] Open
Abstract
Human Raf1 kinase inhibitory protein (hRKIP) is an important modulator of the Ras/Raf1/MEK/ERK signaling pathway. Here, we demonstrated that anti-leprosy drug Clofazimine can bind to hRKIP with a significantly stronger affinity than the endogenous substrate phosphatidylethanolamine (PE) by using Biolayer interference technology. Moreover, we identified that residues P74, S75, K80, P111, P112, V177, and P178 play crucial roles in the binding of hRKIP to Clofazimine by using a combination of Nuclear Magnetic Resonance spectroscopy and molecular docking approach. These residues are located at the conserved ligand-binding pocket of hRKIP. Furthermore, we found that 3.2 μM Clofazimine could significantly increase the ERK phosphorylation level by about 37%. Our results indicate that Clofazimine can enhance Ras/Raf1/MEK/ERK signaling transduction pathway via binding to hRKIP. This work provides valuable hints for exploiting Clofazimine as a potential lead compound to efficiently treat the diseases related to RKIP or the Ras/Raf/MEK/ERK pathway.
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Affiliation(s)
- Chenyun Guo
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Ting Chang
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Tao Sun
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Zhihua Wu
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Yazhuang Dai
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Hongwei Yao
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Donghai Lin
- Department of Chemical Biology, Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
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9
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Horstman EM, Keswani RK, Frey BA, Rzeczycki PM, LaLone V, Bertke JA, Kenis PJA, Rosania GR. Elasticity in Macrophage-Synthesized Biocrystals. Angew Chem Int Ed Engl 2017; 56:1815-1819. [PMID: 28079296 PMCID: PMC5514847 DOI: 10.1002/anie.201611195] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Indexed: 01/22/2023]
Abstract
Supramolecular crystalline assembly constitutes a rational approach to bioengineer intracellular structures. Here, biocrystals of clofazimine (CFZ) that form in vivo within macrophages were measured to have marked curvature. Isolated crystals, however, showed reduced curvature suggesting that intracellular forces bend these drug crystals. Consistent with the ability of biocrystals to elastically deform, the inherent crystal structure of the principal molecular component of the biocrystals-the hydrochloride salt of CFZ (CFZ-HCl)-has a corrugated packing along the (001) face and weak dispersive bonding in multiple directions. These characteristics were previously found to be linked to the elasticity of other organic crystals. Internal stress in bent CFZ-HCl led to photoelastic effects on the azimuthal orientation of polarized light transmittance. We propose that elastic, intracellular crystals can serve as templates to construct functional microdevices with different applications.
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Affiliation(s)
- Elizabeth M Horstman
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-Champaign, 600 South Mathews Street, Urbana, IL, 61801, USA
| | - Rahul K Keswani
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, 428 Church Street, Ann Arbor, MI, 48109, USA
| | - Benjamin A Frey
- Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD, 21251, USA
| | - Phillip M Rzeczycki
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, 428 Church Street, Ann Arbor, MI, 48109, USA
| | - Vernon LaLone
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, 428 Church Street, Ann Arbor, MI, 48109, USA
| | - Jeffery A Bertke
- School of Chemical Sciences, University of Illinois, Urbana-Champaign, 505 South Mathews Street, Urbana, IL, 61801, USA
| | - Paul J A Kenis
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-Champaign, 600 South Mathews Street, Urbana, IL, 61801, USA
| | - Gus R Rosania
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, 428 Church Street, Ann Arbor, MI, 48109, USA
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10
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Liu B, Liu K, Lu Y, Zhang D, Yang T, Li X, Ma C, Zheng M, Wang B, Zhang G, Wang F, Ma Z, Li C, Huang H, Yin D. Systematic evaluation of structure-activity relationships of the riminophenazine class and discovery of a C2 pyridylamino series for the treatment of multidrug-resistant tuberculosis. Molecules 2012; 17:4545-59. [PMID: 22510605 PMCID: PMC6269036 DOI: 10.3390/molecules17044545] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/09/2012] [Accepted: 04/10/2012] [Indexed: 11/16/2022] Open
Abstract
Clofazimine, a member of the riminophenazine class of drugs, is the cornerstone agent for the treatment of leprosy. This agent is currently being studied in clinical trials for the treatment of multidrug-resistant tuberculosis to address the urgent need for new drugs that can overcome existing and emerging drug resistance. However, the use of clofazimine in tuberculosis treatment is hampered by its high lipophilicity and skin pigmentation side effects. To identify a new generation of riminophenazines that is less lipophilic and skin staining, while maintaining efficacy, we have performed a systematic structure-activity relationship (SAR) investigation by synthesizing a variety of analogs of clofazimine and evaluating their anti-tuberculosis activity. The study reveals that the central tricyclic phenazine system and the pendant aromatic rings are important for anti-tuberculosis activity. However, the phenyl groups attached to the C2 and N5 position of clofazimine can be replaced by a pyridyl group to provide analogs with improved physicochemical properties and pharmacokinetic characteristics. Replacement of the phenyl group attached to the C2 position by a pyridyl group has led to a promising new series of compounds with improved physicochemical properties, improved anti-tuberculosis potency, and reduced pigmentation potential.
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Affiliation(s)
- Binna Liu
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Kai Liu
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Yu Lu
- Beijing Tuberculosis and Thoracic Tumor Research Institute, 97 Ma Chang Street, Beijing 101149, China
| | - Dongfeng Zhang
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Tianming Yang
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Xuan Li
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Chen Ma
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Meiqin Zheng
- Beijing Tuberculosis and Thoracic Tumor Research Institute, 97 Ma Chang Street, Beijing 101149, China
| | - Bin Wang
- Beijing Tuberculosis and Thoracic Tumor Research Institute, 97 Ma Chang Street, Beijing 101149, China
| | - Gang Zhang
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Fei Wang
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Zhenkun Ma
- Global Alliance for TB Drug Development, 40 Wall Street, New York, NY 10005, USA
- Authors to whom correspondence should be addressed; (Z.M.); (D.Y.); Tel.: +1-646-616-8633 (Z.M.); Fax: +1-212-227-7541 (Z.M.); Tel./Fax: +86-10-6303-7952 (D.Y.)
| | - Chun Li
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Haihong Huang
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Dali Yin
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
- Authors to whom correspondence should be addressed; (Z.M.); (D.Y.); Tel.: +1-646-616-8633 (Z.M.); Fax: +1-212-227-7541 (Z.M.); Tel./Fax: +86-10-6303-7952 (D.Y.)
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11
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Abstract
Clofazimine is a poorly-soluble but orally-bioavailable small molecule drug that massively accumulates in macrophages when administered over prolonged periods of time. To determine whether crystal-like drug inclusions (CLDIs) that form in subcellular spaces correspond to pure clofazimine crystals, macrophages of clofazimine-fed mice were elicited with an intraperitoneal thioglycollate injection. Inside these cells, CLDIs appeared uniform in size and shape, but were sensitive to illumination. Once removed from cells, CLDIs were unstable. Unlike pure clofazimine crystals, isolated CLDIs placed in distilled water burst into small birefringent globules, which aggregated into larger clusters. Also unlike pure clofazimine crystals, CLDIs fragmented when heated, and disintegrated in alkaline media. In contrast to all other organelles, CLDIs were relatively resistant to sonication and trypsin digestion, which facilitated their biochemical isolation. The powder x-ray diffraction pattern obtained from isolated CLDIs was consistent with the diffraction pattern of liquid crystals and inconsistent with the expected molecular diffraction pattern of solid, three dimensional crystals. Observed with the transmission electron microscope (TEM), CLDIs were bounded by an atypical double-layered membrane, approximately 20 nanometers thick. CLDIs were polymorphic, but generally exhibited an internal multilayered organization, comprised of stacks of membranes 5 to 15 nanometers thick. Deep-etch, freeze-fracture electron microscopy of unfixed snap-frozen tissue samples confirmed this supramolecular organization. These results suggest that clofazimine accumulates in macrophages by forming a membrane-bound, multilayered, liquid crystal-like, semi-synthetic cytoplasmic structure.
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Affiliation(s)
- Jason Baik
- Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, Ann Arbor, Michigan, United States of America
| | - Gus R. Rosania
- Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, Ann Arbor, Michigan, United States of America
- * E-mail:
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12
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Abstract
Clofazimine, a water insoluble substituted iminophenazine derivative with anti-mycobacterial and anti-inflammatory activity, is recommended by the WHO for the treatment of leprosy. It is also active against disseminated Mycobacterium avium complex (MAC) disease in HIV-infected patients. Recently, we achieved a 4000-fold increase of clofazimine water solubility using a novel modified clofazimine-cyclodextrin complex synthesized and patented by our group [Wasserlösliche, Iminiophenazinderivate enthaltende pharmazeutische Zusammensetzungen, deren Herstellung und Verwendung, German Patent, DE19814814C2]. In this paper we examine the activity of this complex against MAC in human macrophages, and evaluate its cytotoxicity. MAC-infected macrophages were treated for 24h with free or complexed clofazimine. The in vitro minimum inhibitory concentrations of both free and complexed clofazimine were 0.1 microg/ml. Free and complexed clofazimine inhibited the growth of MAC inside macrophages to a similar extent, while modified cyclodextrin alone had no observable effects on MAC or macrophages. Complexed clofazimine was not toxic to cells at concentrations effective against MAC. The TD(50) of the modified cyclodextrin in THP-1 cell line was 297 microg/ml.
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Affiliation(s)
- Isam Ismail Salem
- Department of Microbiology, University of the Pacific, 2155 Webster Street, San Francisco, CA 94115, USA.
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13
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Abstract
Clofazimine (CLF) was formulated with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) as a solid solid dispersion (SSD) to increase the aqueous solubility and dissolution rate of the drug. Different molecular weights of PEG (1500, 4000, 6000, and 9000 Da) and PVP (14,000 and 44,000 Da) were used in different drug:carrier weight ratios (1:1, 1:5, and 1:9) and their effect on the dissolution performance of the drug was evaluated in USP Type 2 apparatus using 0.1 N HCl medium. The dissolution rate was compared with corresponding physical mixtures, a currently marketed soft gelatin capsule product, and free CLF. The effect of different methods of preparation (solvent/melt) on the dissolution rate of CLF was evaluated for PEG solid dispersions. Saturation solubility and phase solubility studies were carried out to indicate drug:carrier interactions in liquid state. Infrared (IR) spectroscopy and X-ray diffraction (XRD) were used to indicate drug:carrier interactions in solid state. Improvement in the drug dissolution rate was observed in solid dispersion formulations as compared to the physical mixtures. The dissolution rate improved with the decreasing weight fraction of the drug in the formulation. Polyvinyl pyrrolidone solid dispersion systems gave a better drug release profile as compared to the corresponding PEG solid dispersions. The effect of molecular weight of the PEG polymers did not follow a definite trend, while PVP 14,000 gave a better dissolution profile as compared to PVP 44,000. Improvement in saturation solubility of the drug in the solid dispersion systems was noted in all cases. Further, IR spectroscopy indicated drug:carrier interactions in solid state in one case and XRD indicated reduction in the crystallinity of CLF in another. It was concluded that solid-dispersion formulations of Clofazimine can be used to design a solid dosage form of the drug, which would have significant advantages over the currently marketed soft gelatin capsule dosage form.
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Affiliation(s)
- Ajit S Narang
- Department of Pharmaceutics, Institute of Technology, Banaras Hindu University, Varanasi 221005, India.
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14
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De Logu A, Onnis V, Saddi B, Congiu C, Schivo ML, Cocco MT. Activity of a new class of isonicotinoylhydrazones used alone and in combination with isoniazid, rifampicin, ethambutol, para-aminosalicylic acid and clofazimine against Mycobacterium tuberculosis. J Antimicrob Chemother 2002; 49:275-82. [PMID: 11815568 DOI: 10.1093/jac/49.2.275] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The activities of six derivatives of a new class of isonicotinoylhydrazones were investigated in vitro against Mycobacterium tuberculosis H37Rv ATCC 27294, isoniazid-resistant M. tuberculosis ATCC 35822, rifampicin-resistant ATCC 35838, pyrazinamide-resistant ATCC 35828, streptomycin-resistant ATCC 35820 and 16 clinical isolates of M. tuberculosis. Several compounds showed interesting antimycobacterial activity against both ATCC strains and clinical isolates, but were less active against isoniazid-resistant M. tuberculosis. Combinations of five isonicotinoylhydrazone derivatives and rifampicin, ethambutol, para-aminosalicylic acid, isoniazid and clofazimine were also investigated against M. tuberculosis H37Rv ATCC 27294 and against ATCC drug-resistant strains. Addition of sub-MICs of some isonicotinoylhydrazone derivatives resulted in a four- to 16-fold reduction in MICs of ethambutol, para-aminosalicylic acid and rifampicin with fractional inhibitory concentrations (FICs) ranging between 0.17 and 0.37, suggesting a synergic interaction against M. tuberculosis H37Rv. Increased activity was also observed with other combinations (FICs 0.53-0.75), including isoniazid, and a synergic interaction between one of the isonicotinoylhydrazone derivatives and isoniazid (FIC 0.26) was shown against isoniazid-resistant M. tuberculosis ATCC 35822, whereas no effects were observed on combining the isonicotinoylhydrazones with clofazimine. The ability of isonicotinoylhydrazones to inhibit specifically the growth of M. tuberculosis, the high selectivity index and their ability to enhance the activity of standard antituberculous drugs in vitro indicate that they may serve as promising lead compounds for future drug development for the treatment of M. tuberculosis infections.
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Affiliation(s)
- Alessandro De Logu
- Sezione di Microbiologia e Virologia, Dipartimento di Scienze Chirurgiche e Trapianti d'Organo, Università di Cagliari, Viale Frà Ignazio 38, 09123 Cagliari, Italy.
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15
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van Rensburg CE, Jooné GK, Sirgel FA, Matlola NM, O'Sullivan JF. In vitro investigation of the antimicrobial activities of novel tetramethylpiperidine-substituted phenazines against Mycobacterium tuberculosis. Chemotherapy 2000; 46:43-8. [PMID: 10601797 DOI: 10.1159/000007255] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The intra- and extracellular activities of 5 novel tetramethylpiperidine (TMP)-substituted phenazines against Mycobacterium tuberculosis H37Rv (ATCC 27294) were determined and compared with those of clofazimine and rifampicin. Two of these agents, together with clofazimine, were also tested for their activities against drug-resistant strains of M. tuberculosis. Three of the TMP-substituted phenazine compounds were significantly more active than clofazimine against M. tuberculosis, including multidrug-resistant clinical strains of this microbial pathogen, demonstrating a lack of cross-resistance between the riminophenazines and standard anti-tuberculous drugs. Using M. tuberculosis-infected monocyte-derived macrophages, all of the TMP-substituted phenazines were found to possess intracellular activity which was superior to that of both clofazimine and rifampicin. In this model of intracellular bioactivity, the experimental compounds inhibited bacterial growth at concentrations which were approximately 10-fold lower than the corresponding minimal inhibitory concentration values obtained using conventional in vitro sensitivity testing procedures. These results demonstrate that the novel TMP phenazines are active against multidrug-resistant M. tuberculosis strains, and particularly effective intracellularly.
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Affiliation(s)
- C E van Rensburg
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, Institute for Pathology, Faculty of Medicine, University of Pretoria, South Africa
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16
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Peters K, Leitzke S, Diederichs JE, Borner K, Hahn H, Müller RH, Ehlers S. Preparation of a clofazimine nanosuspension for intravenous use and evaluation of its therapeutic efficacy in murine Mycobacterium avium infection. J Antimicrob Chemother 2000; 45:77-83. [PMID: 10629016 DOI: 10.1093/jac/45.1.77] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Clofazimine nanosuspensions were produced by high pressure homogenization and the formulation was optimized for lyophilization. Characterization of the product by photon correlation spectroscopy, laser diffraction and Coulter counter analysis showed that the clofazimine nanosuspensions were suitable for iv injection with a particle size permitting passive targeting to the reticuloendothelial system. Following iv administration to mice of either the nanocrystalline or a control liposomal formulation at a dose of 20 mg clofazimine/kg bodyweight, drug concentrations in livers, spleens and lungs reached comparably high concentrations, well in excess of the MIC for most Mycobacterium avium strains. When C57BL/6 mice were experimentally infected with M. avium strain TMC 724, nanocrystalline clofazimine was as effective as liposomal clofazimine in reducing bacterial loads in the liver, spleen and lungs of infected mice. Nanocrystalline suspensions of poorly soluble drugs such as riminophenazines are easy to prepare and to lyophilize for extended storage and represent a promising new drug formulation for intravenous therapy of mycobacterial infections.
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Affiliation(s)
- K Peters
- Department of Pharmaceutics, Biopharmaceutics and Biotechnology, Free University of Berlin, Kelchstrasse 31, D-12169 Berlin, Germany
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17
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Abstract
The entrapment of clofazimine (CLO) in a liposomal delivery system for topical application can protect it from absorption into the blood circulation and increase its residence time within the skin. This may reduce the very long mean period of leprosy treatment, as well as the side effects due to the long term administration of large doses of the drug. This investigation deals with critical parameters controlling the formulation and stabilization of liposomes with encapsulated CLO. The entrapment efficiency of CLO in liposomes was increased by altering the proportion of phosphatidyl choline (PC) and cholesterol (CHOL) in liposomes. The stability of liposomal suspensions and the liposomal gels (HPMC K4M) in terms of retention of CLO was measured at refrigeration temperature (2-8 degrees C), room temperature (25 +/- 2 degrees C) and body temperature (37 degrees C) for a period of 3 months. The results show that entrapment of CLO in liposomes can be increased by increasing the proportion of PC. However, the optimum encapsulation and retention of CLO was achieved only with a specific PC:CHOL molar ratio (5.13:1.00). An almost identical value of the entrapment efficiency was obtained when gel filtration and ultracentrifugation methods were used to separate the CLO-carrying liposomes from free drug. The effect of vortexing and sonication on the entrapment efficiency gave similar results, although the mean particle size was different. CLO liposomal gels were found to be stable at room temperature for up to 3 months.
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Affiliation(s)
- V B Patel
- Pharmacy Department, Faculty of Technology and Engineering, M.S. University of Baroda, Gujarat, India
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18
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Abstract
Clofazimine has been in clinical use for almost 40 years, but little is known of its mechanism of action. The primary indication for clofazimine is multibacillary leprosy, but it is useful in several infectious and noninfectious diseases, such as typical myocobacterial infections, rhinoscleroma, pyoderma gangrenosum, necrobiosis lipoidica, severe acne, pustular psoriasis, and discoid lupus erythematosus. Postulated mechanisms of action include intercalation of clofazimine with bacterial DNA and increasing levels of cellular phospholipase A2. Clinical experience, possible mechanisms of action, and side effects of clofazimine are summarized.
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Affiliation(s)
- J L Arbiser
- Department of Dermatology, Harvard Medical School, Boston, Massachusetts
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19
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Affiliation(s)
- R O'Connor
- School of Biological Sciences, Dublin City University, Ireland
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20
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Silverman JF, Holter JF, Berns LA, Benning TL, Neill JS. Negative images due to clofazimine crystals simulating MAI infection in a bronchoalveolar lavage specimen. Diagn Cytopathol 1993; 9:534-9; discussion 539-40. [PMID: 8287762 DOI: 10.1002/dc.2840090512] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
"Negative images" of bacilli in mycobacterial infections have been recently described in air-dried, Romanovsky-stained cytologic material. We report a case of negative images due to crystalline deposition of clofazimine, a drug used to treat Mycobacterium avium-intracellulare complex infection in AIDS patients. The negative images of clofazimine crystals seen in bronchoalveolar lavage (BAL) macrophages resemble the negative images of mycobacterial infection due to the pseudogaucher appearance of the cells. Crystals are distinguished by their refractile reddish appearance in unfixed, unstained smears, and by their birefringence on polarization. Crystals were found in both Pap-stained and Diff-Quik-stained smears and were negative with Ziehl-Neelsen stains. Clofazimine crystals in BAL specimens must be distinguished from the pseudogaucher type cells of mycobacterial infection in this patient population. We believe that this is the first report of clofazimine crystal deposition diagnosed in a BAL specimen along with electron microscopic examination of the cytologic material.
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Affiliation(s)
- J F Silverman
- Department of Pathology and Laboratory Medicine, East Carolina University School of Medicine, Greenville, NC 27858-4354
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21
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Van Landingham RM, Walker LL, O'Sullivan JF, Shinnick TM. Activity of phenazine analogs against Mycobacterium leprae infections in mice. Int J Lepr Other Mycobact Dis 1993; 61:406-14. [PMID: 8228439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Twenty-five compounds structurally related to clofazimine were tested for their ability to inhibit the growth of Mycobacterium leprae using the kinetic method of drug evaluation in the mouse foot pad model of leprosy. Seven of the phenazine derivatives displayed anti-M. leprae activity comparable to that of clofazimine when administered at a concentration of 0.01% (w/w) in the diet. Three of the compounds, B746, B4087, and B4101, were active when administered at 0.001% in the diet. At a dietary concentration of 0.0001%, B4087 and B4101 were slightly more active than clofazimine, while B746 was less active. In the kinetic method of drug evaluation, greater anti-M. leprae activity of phenazine derivatives was generally associated with greater pigmentation of abdominal fat. Of the compounds which did not cause pigmentation when fed at a concentration of 0.01% in the diet B4090 was the most active. This compound also inhibits the growth of a clofazimine-resistant M. smegmatis strain.
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Affiliation(s)
- R M Van Landingham
- Division of Bacterial and Mycotic Diseases, Centers for Disease Control, Atlanta, Georgia 30333
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22
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Affiliation(s)
- K M Fahelelbom
- Department of Pharmaceutical Chemistry, School of Pharmacy, Trinity College, Dublin, Ireland
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