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Yawson GK, Will MF, Huffman SE, Strandquist ET, Bothwell PJ, Oliver EB, Apuzzo CF, Platt DC, Weitzel CS, Jones MA, Ferrence GM, Hamaker CG, Webb MI. A Dual-Pronged Approach: A Ruthenium(III) Complex That Modulates Amyloid-β Aggregation and Disrupts Its Formed Aggregates. Inorg Chem 2022; 61:2733-2744. [PMID: 35102739 DOI: 10.1021/acs.inorgchem.1c01651] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is a devastating neurological disorder for which soluble oligomers of the peptide amyloid-β (Aβ) are now recognized as the neurotoxic species. Metal-based therapeutics are uniquely suited to target Aβ, with ruthenium-based (Ru) complexes emerging as propitious candidates. Recently, azole-based Ru(III) complexes were observed to modulate the aggregation of Aβ in solution, where the inclusion of a primary amine proximal to the ligand coordination site improved the activity of the complexes. To advance these structure-activity relationships, a series of oxazole-based Ru complexes were prepared and evaluated for their ability to modulate Aβ aggregation. From these studies, a lead candidate, Oc, emerged that had superior activity relative to its azole predecessors in modulating the aggregation of soluble Aβ and diminishing its cytotoxicity. Further evaluation of Oc demonstrated its ability to disrupt formed Aβ aggregates, resulting in smaller amorphous species. Because altering both sides of the aggregation equilibrium for Aβ has not been previously suggested for metal-based complexes for AD, this work represents an exciting new avenue for improved therapeutic success.
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Affiliation(s)
- Gideon K Yawson
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Mark F Will
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Samantha E Huffman
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Evan T Strandquist
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Paige J Bothwell
- Core Microscope Facility, Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Ethan B Oliver
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - C Fiore Apuzzo
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - David C Platt
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Christopher S Weitzel
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Marjorie A Jones
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Gregory M Ferrence
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Christopher G Hamaker
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
| | - Michael I Webb
- Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, United States
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Yawson GK, Huffman SE, Fisher SS, Bothwell PJ, Platt DC, Jones MA, Ferrence GM, Hamaker CG, Webb MI. Ruthenium(III) complexes with imidazole ligands that modulate the aggregation of the amyloid-β peptide via hydrophobic interactions. J Inorg Biochem 2020; 214:111303. [PMID: 33166864 DOI: 10.1016/j.jinorgbio.2020.111303] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia, characterized by extracellular protein deposits, comprised primarily of the peptide amyloid-beta (Aβ), are a pathological indicator of the disease. Commonly known as Aβ plaques, these deposits contain a relatively high concentration of metals, making metallotherapeutics uniquely suited to target soluble Aβ, thereby limiting its aggregation and cytotoxicity. Ruthenium-based complexes are promising candidates for advancement, as the complex PMRU20 (2-aminothiazolium [trans-RuCl4(2-aminothiazole)2]) and several thiazole-based derivatives were found to prevent the aggregation of Aβ, with hydrogen-bonding functional groups improving their performance. Further investigation into the impact of the heteroatom in the azole ring on the activity of Ru complexes was achieved through the synthesis and evaluation of a small set of imidazole-based compounds. The ability of the complexes to prevent the aggregation of Aβ was determined where the same sample was subjected to analysis by three complementary methods: ThT fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM). It was found that hydrophobic interactions, along with hydrogen-bonding via the imidazole nitrogen heteroatom, promoted interactions with the Aβ peptide, thereby limiting its aggregation. Furthermore, it was found that having rapid and sequential exchange proved detrimental as it resulted in a decreased association with Aβ. These results highlight important considerations between a balance of intermolecular interactions and ligand exchange kinetics in the design of further therapeutic candidates.
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Affiliation(s)
- Gideon K Yawson
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Samantha E Huffman
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Samuel S Fisher
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Paige J Bothwell
- Core Microscope Facility, Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, United States of America
| | - David C Platt
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Marjorie A Jones
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Gregory M Ferrence
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Christopher G Hamaker
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America
| | - Michael I Webb
- Department of Chemistry, Illinois State University, Normal, IL 61790-4160, United States of America.
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Huffman SE, Yawson GK, Fisher SS, Bothwell PJ, Platt DC, Jones MA, Hamaker CG, Webb MI. Ruthenium(iii) complexes containing thiazole-based ligands that modulate amyloid-β aggregation. Metallomics 2020; 12:491-503. [PMID: 32239079 DOI: 10.1039/d0mt00054j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Alzheimer's Disease (AD) is a devastating neurodegenerative disorder where one of the commonly observed pathological hallmarks is extracellular deposits of the peptide amyloid-β (Aβ). These deposits contain a high concentration of metals and initially presented a promising target for therapy; however it has become increasingly evident that the soluble form of the peptide is neurotoxic, not the amyloidogenic species. Metal-based therapeutics are uniquely suited to target soluble Aβ and have shown considerable promise to prevent the aggregation and induced cytotoxicity of the peptide in vitro. Herein, we have prepared a small series of derivatives of two promising Ru(iii) complexes NAMI-A (imidazolium [trans-RuCl4(1H-imidazole)(dimethyl sulfoxide-S)]) and PMRU20 (2-aminothiazolium [trans-RuCl4(2-aminothiazole)2]), to determine structure-activity relationships (SAR) for Ru(iii) therapeutics for AD. Using the three complementary methods of Thioflavin T fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM), it was determined that the symmetry around the metal center did not significantly impact the activity of the complexes, but rather the attached thiazole ligand(s) mitigated Aβ aggregation. Across both families of Ru(iii) complexes the determined SAR for the functional groups on the thiazole ligands to modulate Aβ aggregation were NH2 > CH3 > H. These results highlight the importance of secondary interactions between the metallotherapeutic and the Aβ peptide where hydrogen-bonding has the greatest impact on modulating Aβ aggregation.
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Affiliation(s)
- Samantha E Huffman
- Department of Chemistry, Illinois State University, Normal, IL, 61790-4160, USA.
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