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Yang X, Lim SHM, Lin J, Wu J, Tang H, Zhao F, Liu F, Sun C, Shi X, Kuang Y, Toy JYH, Du K, Zhang Y, Wang X, Sun M, Song Z, Wang T, Wu J, Houk KN, Huang D. Oxygen mediated oxidative couplings of flavones in alkaline water. Nat Commun 2022; 13:6424. [PMID: 36307433 PMCID: PMC9614196 DOI: 10.1038/s41467-022-34123-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 10/13/2022] [Indexed: 12/25/2022] Open
Abstract
Catalyzed oxidative C-C bond coupling reactions play an important role in the chemical synthesis of complex natural products of medicinal importance. However, the poor functional group tolerance renders them unfit for the synthesis of naturally occurring polyphenolic flavones. We find that molecular oxygen in alkaline water acts as a hydrogen atom acceptor and oxidant in catalyst-free (without added catalyst) oxidative coupling of luteolin and other flavones. By this facile method, we achieve the synthesis of a small collection of flavone dimers and trimers including naturally occurring dicranolomin, philonotisflavone, dehydrohegoflavone, distichumtriluteolin, and cyclodistichumtriluteolin. Mechanistic studies using both experimental and computational chemistry uncover the underlying reasons for optimal pH, oxygen availability, and counter-cations that define the success of the reaction. We expect our reaction opens up a green and sustainable way to synthesize flavonoid dimers and oligomers using the readily available monomeric flavonoids isolated from biomass and exploiting their use for health care products and treatment of diseases.
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Affiliation(s)
- Xin Yang
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Sophie Hui Min Lim
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Jiachen Lin
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Jie Wu
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore ,grid.452673.1National University of Singapore (Suzhou) Research Institute, 377 Linquan Street, 215123 Suzhou, Jiangsu China
| | - Haidi Tang
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore ,grid.452673.1National University of Singapore (Suzhou) Research Institute, 377 Linquan Street, 215123 Suzhou, Jiangsu China
| | - Fengyue Zhao
- grid.27871.3b0000 0000 9750 7019College of Sciences, Nanjing Agricultural University, 210095 Nanjing, China
| | - Fang Liu
- grid.27871.3b0000 0000 9750 7019College of Sciences, Nanjing Agricultural University, 210095 Nanjing, China
| | - Chenghua Sun
- grid.1027.40000 0004 0409 2862Department of Chemistry and Biotechnology, FSET, Swinburne University of Technology, Hawthorn, VIC 3122 Australia
| | - Xiangcheng Shi
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore
| | - Yulong Kuang
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore
| | - Joanne Yi Hui Toy
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Ke Du
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Yuannian Zhang
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Xiang Wang
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Mingtai Sun
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Zhixuan Song
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore
| | - Tian Wang
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore
| | - Ji’en Wu
- grid.4280.e0000 0001 2180 6431Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Republic of Singapore
| | - K. N. Houk
- grid.19006.3e0000 0000 9632 6718Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095 USA
| | - Dejian Huang
- grid.4280.e0000 0001 2180 6431Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542 Republic of Singapore ,grid.452673.1National University of Singapore (Suzhou) Research Institute, 377 Linquan Street, 215123 Suzhou, Jiangsu China
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Desmet S, Morreel K, Dauwe R. Origin and Function of Structural Diversity in the Plant Specialized Metabolome. PLANTS (BASEL, SWITZERLAND) 2021; 10:2393. [PMID: 34834756 PMCID: PMC8621143 DOI: 10.3390/plants10112393] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 05/07/2023]
Abstract
The plant specialized metabolome consists of a multitude of structurally and functionally diverse metabolites, variable from species to species. The specialized metabolites play roles in the response to environmental changes and abiotic or biotic stresses, as well as in plant growth and development. At its basis, the specialized metabolism is built of four major pathways, each starting from a few distinct primary metabolism precursors, and leading to distinct basic carbon skeleton core structures: polyketides and fatty acid derivatives, terpenoids, alkaloids, and phenolics. Structural diversity in specialized metabolism, however, expands exponentially with each subsequent modification. We review here the major sources of structural variety and question if a specific role can be attributed to each distinct structure. We focus on the influences that various core structures and modifications have on flavonoid antioxidant activity and on the diversity generated by oxidative coupling reactions. We suggest that many oxidative coupling products, triggered by initial radical scavenging, may not have a function in se, but could potentially be enzymatically recycled to effective antioxidants. We further discuss the wide structural variety created by multiple decorations (glycosylations, acylations, prenylations), the formation of high-molecular weight conjugates and polyesters, and the plasticity of the specialized metabolism. We draw attention to the need for untargeted methods to identify the complex, multiply decorated and conjugated compounds, in order to study the functioning of the plant specialized metabolome.
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Affiliation(s)
- Sandrien Desmet
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium; (S.D.); (K.M.)
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Kris Morreel
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium; (S.D.); (K.M.)
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Rebecca Dauwe
- Unité de Recherche Biologie des Plantes et Innovation (BIOPI), UMR Transfrontalière BioEcoAgro, Université de Picardie Jules Verne, 80000 Amiens, France
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