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Kim H, Rencoret J, Elder TJ, del Río JC, Ralph J. Biomimetic oxidative copolymerization of hydroxystilbenes and monolignols. SCIENCE ADVANCES 2023; 9:eade5519. [PMID: 36888720 PMCID: PMC9995074 DOI: 10.1126/sciadv.ade5519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Hydroxystilbenes are a class of polyphenolic compounds that behave as lignin monomers participating in radical coupling reactions during the lignification. Here, we report the synthesis and characterization of various artificial copolymers of monolignols and hydroxystilbenes, as well as low-molecular-mass compounds, to obtain the mechanistic insights into their incorporation into the lignin polymer. Integrating the hydroxystilbenes, resveratrol and piceatannol, into monolignol polymerization in vitro, using horseradish peroxidase to generate phenolic radicals, produced synthetic lignins [dehydrogenation polymers (DHPs)]. Copolymerization of hydroxystilbenes with monolignols, especially sinapyl alcohol, by in vitro peroxidases notably improved the reactivity of monolignols and resulted in substantial yields of synthetic lignin polymers. The resulting DHPs were analyzed using two-dimensional NMR and 19 synthesized model compounds to confirm the presence of hydroxystilbene structures in the lignin polymer. The cross-coupled DHPs confirmed both resveratrol and piceatannol as authentic monomers participating in the oxidative radical coupling reactions during polymerization.
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Affiliation(s)
- Hoon Kim
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Jorge Rencoret
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida de la Reina Mercedes, 10, 41012, Seville, Spain
| | - Thomas J. Elder
- USDA-Forest Service, Southern Research Station 521 Devall Dr. Auburn, AL 36849, USA
| | - José C. del Río
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida de la Reina Mercedes, 10, 41012, Seville, Spain
| | - John Ralph
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI 53726, USA
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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Elder T, Del Río JC, Ralph J, Rencoret J, Kim H. Density functional theory study on the coupling and reactions of diferuloylputrescine as a lignin monomer. PHYTOCHEMISTRY 2022; 197:113122. [PMID: 35131641 DOI: 10.1016/j.phytochem.2022.113122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 01/25/2022] [Accepted: 01/29/2022] [Indexed: 06/14/2023]
Abstract
Diferuloylputrescine has been found in a variety of plant species, and recent work has provided evidence of its covalent bonding into lignin. Results from nuclear magnetic resonance spectroscopy revealed the presence of bonding patterns consistent with homo-coupling of diferuloylputrescine and the possibility of cross-coupling with lignin. In the present work, density functional theory calculations have been applied to assess the energetics associated with radical coupling, rearomatization, and dehydrogenation for possible homo-coupled dimers of diferuloylputrescine and cross-coupled dimers of diferuloylputrescine and coniferyl alcohol. The values obtained for these reaction energetics are consistent with those reported for monolignols and other novel lignin monomers. As such, this study shows that there would be no thermodynamic impediment to the incorporation of diferuloylputrescine into the lignin polymer and its addition to the growing list of non-canonical lignin monomers.
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Affiliation(s)
- Thomas Elder
- USDA-Forest Service, Southern Research Station, 521 Devall Drive, Auburn, AL, 36849, USA.
| | - José C Del Río
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Av. Reina Mercedes, 10, 41012, Seville, Spain
| | - John Ralph
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, 1552 University Ave, Madison, WI, 53726, USA; Department of Biochemistry, University of Wisconsin, 433 Babcock Drive, Madison, WI, 53706, USA
| | - Jorge Rencoret
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Av. Reina Mercedes, 10, 41012, Seville, Spain
| | - Hoon Kim
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, 1552 University Ave, Madison, WI, 53726, USA
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Azad T, Torres HF, Auad ML, Elder T, Adamczyk AJ. Isolating key reaction energetics and thermodynamic properties during hardwood model lignin pyrolysis. Phys Chem Chem Phys 2021; 23:20919-20935. [PMID: 34541592 DOI: 10.1039/d1cp02917g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computational studies on the pyrolysis of lignin using electronic structure methods have been largely limited to dimeric or trimeric models. In the current work we have modeled a lignin oligomer consisting of 10 syringyl units linked through 9 β-O-4' bonds. A lignin model of this size is potentially more representative of the polymer in angiosperms; therefore, we used this representative model to examine the behavior of hardwood lignin during the initial steps of pyrolysis. Using this oligomer, the present work aims to determine if and how the reaction enthalpies of bond cleavage vary with positions within the chain. To accomplish this, we utilized a composite method using molecular mechanics based conformational sampling and quantum mechanically based density functional theory (DFT) calculations. Our key results show marked differences in bond dissociation enthalpies (BDE) with the position. In addition, we calculated standard thermodynamic properties, including enthalpy of formation, heat capacity, entropy, and Gibbs free energy for a wide range of temperatures from 25 K to 1000 K. The prediction of these thermodynamic properties and the reaction enthalpies will benefit further computational studies and cross-validation with pyrolysis experiments. Overall, the results demonstrate the utility of a better understanding of lignin pyrolysis for its effective valorization.
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Affiliation(s)
- Tanzina Azad
- Department of Chemical Engineering, Auburn University, Auburn, AL, USA.
| | - Hazl F Torres
- Department of Chemical Engineering, Auburn University, Auburn, AL, USA.
| | - Maria L Auad
- Department of Chemical Engineering, Auburn University, Auburn, AL, USA. .,Center for Polymer and Advanced Composites, Auburn, AL, USA
| | - Thomas Elder
- United States Department of Agriculture (USDA) Forest Service, Southern Research Station, Auburn, AL, USA
| | - Andrew J Adamczyk
- Department of Chemical Engineering, Auburn University, Auburn, AL, USA.
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Zhou S, Jin K, Buehler MJ. Understanding Plant Biomass via Computational Modeling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2003206. [PMID: 32945027 DOI: 10.1002/adma.202003206] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Plant biomass, especially wood, has been used for structural materials since ancient times. It is also showing great potential for new structural materials and it is the major feedstock for the emerging biorefineries for building a sustainable society. The plant cell wall is a hierarchical matrix of mainly cellulose, hemicellulose, and lignin. Herein, the structure, properties, and reactions of cellulose, lignin, and wood cell walls, studied using density functional theory (DFT) and molecular dynamics (MD), which are the widely used computational modeling approaches, are reviewed. Computational modeling, which has played a crucial role in understanding the structure and properties of plant biomass and its nanomaterials, may serve a leading role on developing new hierarchical materials from biomass in the future.
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Affiliation(s)
- Shengfei Zhou
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave 1-290, Cambridge, MA, 02139, USA
| | - Kai Jin
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave 1-290, Cambridge, MA, 02139, USA
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave 1-290, Cambridge, MA, 02139, USA
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Elder T, Rencoret J, del Río JC, Kim H, Ralph J. Radical Coupling Reactions of Hydroxystilbene Glucosides and Coniferyl Alcohol: A Density Functional Theory Study. FRONTIERS IN PLANT SCIENCE 2021; 12:642848. [PMID: 33737945 PMCID: PMC7960926 DOI: 10.3389/fpls.2021.642848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
The monolignols, p-coumaryl, coniferyl, and sinapyl alcohol, arise from the general phenylpropanoid biosynthetic pathway. Increasingly, however, authentic lignin monomers derived from outside this process are being identified and found to be fully incorporated into the lignin polymer. Among them, hydroxystilbene glucosides, which are produced through a hybrid process that combines the phenylpropanoid and acetate/malonate pathways, have been experimentally detected in the bark lignin of Norway spruce (Picea abies). Several interunit linkages have been identified and proposed to occur through homo-coupling of the hydroxystilbene glucosides and their cross-coupling with coniferyl alcohol. In the current work, the thermodynamics of these coupling modes and subsequent rearomatization reactions have been evaluated by the application of density functional theory (DFT) calculations. The objective of this paper is to determine favorable coupling and cross-coupling modes to help explain the experimental observations and attempt to predict other favorable pathways that might be further elucidated via in vitro polymerization aided by synthetic models and detailed structural studies.
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Affiliation(s)
- Thomas Elder
- USDA-Forest Service, Southern Research Station, Auburn, AL, United States
| | - Jorge Rencoret
- Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, Seville, Spain
| | - José C. del Río
- Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, Seville, Spain
| | - Hoon Kim
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, WI, United States
| | - John Ralph
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, WI, United States
- Department of Biochemistry, University of Wisconsin, Madison, WI, United States
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Xue Y, Liu Y, Xie Y, Cong C, Wang G, An L, Teng Y, Chen M, Zhang L. Antioxidant activity and mechanism of dihydrochalcone C-glycosides: Effects of C-glycosylation and hydroxyl groups. PHYTOCHEMISTRY 2020; 179:112393. [PMID: 32836068 DOI: 10.1016/j.phytochem.2020.112393] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/04/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
Dihydrochalcones (DHCs), an important subgroup of flavonoids, have recently received much attention due to their diverse biological activities. In contrast to their O-glycosides, understanding of the antioxidant property and mechanism of DHC C-glycosides remains limited. Herein, the free radical scavenging activity and mechanism of two representative C-glycosyl DHCs, aspalathin (ASP) and nothofagin (NOT) as well as their aglycones, 3-hydroxyphloretin (HPHL) and phloretin (PHL) were evaluated using the density functional theory (DFT) calculations. The results revealed the crucial role of sugar moiety on the conformation and the activity. The o-dihydroxyl in the B-ring and the 2',6'-dihydroxyacetophenone moiety were found significant in determining the activity. Our results showed that hydrogen atom transfer (HAT) is the dominant mechanism for radical-trapping in the gas and benzene phases, while the sequential proton loss electron transfer (SPLET) is more preferable in the polar environments. Also, the results revealed the feasibility of the double HAT and double SPLET as well as the SPLHAT mechanisms, which provide alternative pathways to trap radical for the studied DHCs. These results could deepen the understanding of the antiradical activity and mechanism of DHCs, which will facilitate the design of novel efficient antioxidants.
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Affiliation(s)
- Yunsheng Xue
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China.
| | - Yunping Liu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Yuxin Xie
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Chunxue Cong
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Guirong Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Lin An
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Yangxin Teng
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Mohan Chen
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China
| | - Ling Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, No.209, Tongshan Road, Xuzhou, Jiangsu 221004, China.
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