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Larin ACR, Pfrunder MC, Mullen KM, Wiedbrauk S, Boase NR, Fairfull-Smith KE. Synergistic or antagonistic antioxidant combinations - a case study exploring flavonoid-nitroxide hybrids. Org Biomol Chem 2023; 21:1780-1792. [PMID: 36728689 DOI: 10.1039/d2ob02101c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Neurodegenerative diseases impose a considerable medical and public health burden on populations throughout the world. Oxidative stress, an imbalance in pro-oxidant/antioxidant homeostasis that leads to the generation of reactive oxygen species (ROS), has been implicated in the progression of a number of neurodegenerative diseases. The manipulation of ROS levels may represent a promising treatment option to slow down neurodegeneration, although adequate potency of treatments has not yet been achieved. Using a hybrid pharmacology approach, free radical nitroxide antioxidants were hybridised with a class of natural antioxidants, flavonoids, to form a potential multitargeted antioxidant. Modification of the Baker-Venkataraman reaction achieved the flavonoid-nitroxide hybrids (6-9) in modest yields. Antioxidant evaluation of the hybrids by cyclic voltammetry showed both redox functionalities were still active, with little influence on oxidation potential. Assessment of the peroxyl radical scavenging ability through an ORAC assay showed reduced antioxidant activity of the hybrids compared to their individual components. It was hypothesized that the presence of the phenol in the hybrids creates a more acidic medium which does not favour regeneration of the nitroxide from the corresponding oxammonium cation, disturbing the typical catalytic cycle of peroxyl radical scavenging by nitroxides. This work highlights the potential intricacies involved with drug hybridization as a strategy for new therapeutic development.
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Affiliation(s)
- Astrid C R Larin
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
| | - Michael C Pfrunder
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
| | - Kathleen M Mullen
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
| | - Sandra Wiedbrauk
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
| | - Nathan R Boase
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
| | - Kathryn E Fairfull-Smith
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.,Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.
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Cai M, Huang B, Xie G, Zhan J. Recyclable Palladium-Catalyzed Carbonylative Cyclization of Aryl Iodides and 2-Hydroxyacetophenones towards Flavones. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/s-0042-1753042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractA highly efficient heterogeneous palladium-catalyzed carbonylative cyclization of aryl iodides and 2-hydroxyacetophenones is developed. The reaction proceeds efficiently in DMSO at 120 °C under 3 bar of carbon monoxide by using 2 mol% of an MCM-41-immobilized bidentate phosphine palladium complex [MCM-41-2P-Pd(OAc)2] as the catalyst and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the base, providing a general, efficient and practical approach for the assembly of a wide variety of flavones in mostly good to high yields from readily available starting materials. This supported palladium catalyst can be easily recovered via centrifugation of the reaction mixture and recycled more than nine times without any significant loss of its catalytic efficiency.
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