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Baartzes N, Jordaan A, Warner DF, Combrinck J, Taylor D, Chibale K, Smith GS. Antimicrobial evaluation of neutral and cationic iridium(III) and rhodium(III) aminoquinoline-benzimidazole hybrid complexes. Eur J Med Chem 2020; 206:112694. [PMID: 32861176 DOI: 10.1016/j.ejmech.2020.112694] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 10/23/2022]
Abstract
A series of neutral and cationic Ir(III) and Rh(III) aminoquinoline-benzimidazole hybrid complexes were synthesised and their inhibitory activities evaluated against Plasmodium falciparum and Mycobacterium tuberculosis. In general, the hybrid complexes display good activity against the chloroquine-sensitive NF54 strain of P. falciparum. The neutral Ir(III)- and Rh(III)-Cp∗ complexes were the most active (IC50 = 0.488 μM for IrIII), maintaining activity against the multidrug-resistant K1 strain. Low to no cytotoxicity against the Chinese hamster ovarian cell line was observed for the tested complexes. Selected active hybrid complexes demonstrated significant inhibition of β-haematin formation in a cell-free NP-40 assay, suggesting an effect on the host haemoglobin degradation pathway as a potential contributing mechanism of action. When tested against M. tuberculosis H37Rv, most hybrid complexes displayed moderate to good activity. Again, the neutral complexes outperformed the cationic complexes, with the neutral Ir(III)-Cp∗ complexes proving most active (MIC90 = 0.488-1.490 μM).
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Affiliation(s)
- Nadia Baartzes
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - Audrey Jordaan
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical TB Research, Department of Clinical Laboratory Sciences, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - Digby F Warner
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical TB Research, Department of Clinical Laboratory Sciences, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa; Wellcome Centre for Infectious Diseases Research in Africa, University of Cape Town, Rondebosch, 7701, South Africa
| | - Jill Combrinck
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, 7925, Cape Town, South Africa
| | - Dale Taylor
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, Cape Town, South Africa
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa; South African Medical Research Council, Drug Discovery and Development Research Unit, Department of Chemistry and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Gregory S Smith
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa.
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Baartzes N, Stringer T, Seldon R, Warner DF, Taylor D, Wittlin S, Chibale K, Smith GS. Bioisosteric ferrocenyl aminoquinoline-benzimidazole hybrids: Antimicrobial evaluation and mechanistic insights. Eur J Med Chem 2019; 180:121-133. [PMID: 31301563 DOI: 10.1016/j.ejmech.2019.06.069] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/08/2019] [Accepted: 06/25/2019] [Indexed: 01/29/2023]
Abstract
Phenyl- and bioisosteric ferrocenyl-derived aminoquinoline-benzimidazole hybrid compounds were synthesised and evaluated for their in vitro antiplasmodial activity against the chloroquine-sensitive NF54 and multi-drug resistant K1 strains of the human malaria parasite, Plasmodium falciparum. All compounds were active against the two strains, generally showing enhanced activity in the K1 strain, with resistance indices less than 1. Cytotoxicity studies using Chinese hamster ovarian cells revealed that the hybrids were relatively non-cytotoxic and demonstrated selective killing of the parasite. Based on favourable in vitro antiplasmodial and cytotoxicity data, the most active phenyl (4c) and ferrocenyl (5b) hybrids were tested in vivo against the rodent Plasmodium berghei mouse model. Both compounds caused a reduction in parasitemia relative to the control, with 5c displaying superior activity (92% reduction in parasitemia at 4 × 50 mg/kg oral doses). The most active phenyl and ferrocenyl derivatives showed inhibition of β-haematin formation in a NP-40 detergent-mediated assay, indicating a possible contributing mechanism of antiplasmodial action. The most active ferrocenyl hybrid did not display appreciable reactive oxygen species (ROS) generation in a ROS-induced DNA cleavage gel electrophoresis study. The compounds were also screened for their in vitro activity against Mycobacterium tuberculosis. The hybrids containing a more hydrophobic substituent had enhanced activity (<32.7 μM) compared to those with a less hydrophobic substituent (>62.5 μM).
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Affiliation(s)
- N Baartzes
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - T Stringer
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - R Seldon
- Drug Discovery and Development Centre (H3D), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - D F Warner
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical TB Research, Department of Clinical Laboratory Sciences, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa; Wellcome Centre for Infectious Diseases Research in Africa, University of Cape Town, Rondebosch, 7701, South Africa
| | - D Taylor
- H3D, Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, 7925, Cape Town, South Africa
| | - S Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland; University of Basel, 4003, Basel, Switzerland
| | - K Chibale
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa; South African Medical Research Council, Drug Discovery and Development Research Unit, Department of Chemistry and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch, 7701, South Africa
| | - G S Smith
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa.
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Baartzes N, Stringer T, Okombo J, Seldon R, Warner DF, de Kock C, Smith PJ, Smith GS. Mono- and polynuclear ferrocenylthiosemicarbazones: Synthesis, characterisation and antimicrobial evaluation. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.06.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Baartzes N, Stringer T, Chellan P, Combrinck JM, Smith PJ, Hutton AT, Smith GS. Synthesis, characterization, antiplasmodial evaluation and electrochemical studies of water-soluble heterobimetallic ferrocenyl complexes. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.02.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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