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Wijesinghe TP, Kaya B, Gonzálvez MA, Harmer JR, Gholam Azad M, Bernhardt PV, Dharmasivam M, Richardson DR. Steric Blockade of Oxy-Myoglobin Oxidation by Thiosemicarbazones: Structure-Activity Relationships of the Novel PPP4pT Series. J Med Chem 2023; 66:15453-15476. [PMID: 37922410 DOI: 10.1021/acs.jmedchem.3c01612] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023]
Abstract
The di-2-pyridylketone thiosemicarbazones demonstrated marked anticancer efficacy, prompting progression of DpC to clinical trials. However, DpC induced deleterious oxy-myoglobin oxidation, stifling development. To address this, novel substituted phenyl thiosemicarbazone (PPP4pT) analogues and their Fe(III), Cu(II), and Zn(II) complexes were prepared. The PPP4pT analogues demonstrated potent antiproliferative activity (IC50: 0.009-0.066 μM), with the 1:1 Cu:L complexes showing the greatest efficacy. Substitutions leading to decreased redox potential of the PPP4pT:Cu(II) complexes were associated with higher antiproliferative activity, while increasing potential correlated with increased redox activity. Surprisingly, there was no correlation between redox activity and antiproliferative efficacy. The PPP4pT:Fe(III) complexes attenuated oxy-myoglobin oxidation significantly more than the clinically trialed thiosemicarbazones, Triapine, COTI-2, and DpC, or earlier thiosemicarbazone series. Incorporation of phenyl- and styryl-substituents led to steric blockade, preventing approach of the PPP4pT:Fe(III) complexes to the heme plane and its oxidation. The 1:1 Cu(II):PPP4pT complexes were inert to transmetalation and did not induce oxy-myoglobin oxidation.
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Affiliation(s)
- Tharushi P Wijesinghe
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane 4111, Australia
| | - Busra Kaya
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane 4111, Australia
| | - Miguel A Gonzálvez
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane 4072, Australia
| | - Mahan Gholam Azad
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane 4111, Australia
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia
| | - Mahendiran Dharmasivam
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane 4111, Australia
| | - Des R Richardson
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane 4111, Australia
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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Jansson PJ, Sharpe PC, Bernhardt PV, Richardson DR. Novel thiosemicarbazones of the ApT and DpT series and their copper complexes: identification of pronounced redox activity and characterization of their antitumor activity. J Med Chem 2010; 53:5759-69. [PMID: 20597487 DOI: 10.1021/jm100561b] [Citation(s) in RCA: 187] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The novel chelators 2-acetylpyridine-4,4-dimethyl-3-thiosemicarbazone (HAp44mT) and di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (HDp44mT) have been examined to elucidate the structure-activity relationships necessary to form copper (Cu) complexes with pronounced antitumor activity. Electrochemical studies demonstrated that the Cu complexes of these ligands had lower redox potentials than their iron complexes. Moreover, the Cu complexes where the ligand/metal ratio was 1:1 rather than 2:1 had significantly higher intracellular oxidative properties and antitumor efficacy. Interestingly, the 2:1 complex was shown to dissociate to give significant amounts of the 1:1 complex that could be the major cytotoxic effector. Both types of Cu complex showed significantly more antiproliferative activity than the ligand alone. We also demonstrate the importance of the inductive effects of substituents on the carbonyl group of the parent ketone, which influence the Cu(II/I) redox potentials because of their proximity to the metal center. The structure-activity relationships described are important for the design of potent thiosemicarbazone Cu complexes.
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Affiliation(s)
- Patric J Jansson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia
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