Sustainable Chemistry and Pharmacy
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2023
·
IF 6
Ying Han,Zihao Ma,Xing Wang,Yuanyuan Sheng,Yu Liu
Natural polyphenol antioxidants have excellent antioxidant activity and degradability which are considered as one of the possible alternatives to chemical synthetic antioxidants. Here, lignin-based polyphenols were prepared from poplar lignin, pine lignin and rice husk lignin by demethylation, and no toxic reagents were used in the preparation process. The phenolic hydroxyl groups of all three lignin were increased and the methoxyl content was significantly reduced after the demethylation without degradation or structural changes in the lignin as shown by GPC and 2D HSQC analyses. Furthermore, the antioxidant activity of the modified lignin was significantly increased. In this paper, a green and efficient strategy was developed to prepare lignin-based polyphenols with high phenolic hydroxyl content, low molecular weight , strong antioxidant activity and low cytotoxicity, which have a promising future in the field of antioxidant applications.
研究领域:
化学工程
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材料科学
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环境科学
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DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2021
·
IF 5.279
Xiaohui Yang,Zheng Li,Long Li,Ning Li,Fei Jing,Lihong Hu,Qianqian Shang,Xiao Zhang,Yonghong Zhou,Xuejun Pan
To improve the reactivity and enrich the functionality of lignin for valorization, kraft lignin was depolymerized and demethylated via cleaving aryl and alkyl ether bonds in acidic lithium bromide trihydrate (∼60% LiBr aqueous solution). It was found that the cleavage of the ether bonds followed the order of β-O-4 ether > aryl alkyl ether in phenylcoumaran > dialkyl ether in resinol > methoxyl (MeO). The depolymerization via β-O-4 cleavage occurred under mild conditions (e.g., <0.5 M HCl at 110 °C), while sufficient demethylation of the lignin needed harsher conditions (>1.5 M HCl). Both depolymerization and demethylation generated new aromatic hydroxyl (ArOH). With 2.4 M HCl, MeO content dropped from 4.85 to 0.95 mmol/g lignin, and ArOH content increased from 2.78 to 5.09 mmol/g lignin. The depolymerized and demethylated kraft lignin showed excellent antioxidant activity and Cr(VI)-scavenging capacity, compared with original kraft lignin and tannins.
研究领域:
化学工程
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环境科学
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2019
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IF 3.131
YinChen Chen,Shiyu Fu,Hui Zhang
Acetic acid lignin (AAL) obtained from Bagasse was used as a partial substitute of polyols for polyurethane (PU) adhesive due to the presence of reactive sites, i.e. aliphatic and aromatic hydroxyl groups, in its structure. To improve its reactivity, lignin is partly demethylated before the copolymerization with polyisocyanate. The demethylation , catalyzed by hydrobromic acid solution under heating conditions, resulted in a decrease of methoxy groups on the phenyl ring and the increase of phenolic hydroxyl groups . It is found that 120 ℃ is the preferred temperature for the demethylation resulted in a 36.5 % increase in hydroxyl content of lignin up to 5.25 mmol/g. Lignin-based polyurethane adhesives were prepared in two steps including preparing a prepolymer based on mixtures of toluene-2,4-diisocyanate (TDI) and unmodified or demethylated lignin, and then the polymerization was completed by adding polyethylene glycol (PEG). The mass ratio (1:1) of TDI: (lignin + PEG) in the compositions was here investigated. The results indicated that the presence of lignin (with and without demethylation) in polyurethane adhesives increased the glass transition temperature , Young’s modulus, and elongation at break. Particularly, the tensile strength was increased by 15–36 MPa with the addition of 10–30 wt% of lignin. Lignin with higher amount of hydroxyl groups prepared by partly demethylation is better integrated into the three-dimensional cross-linking networks of the covalent polymer as a substitute of polyols. Compared to those PU adhesives based on the raw AAL, the adhesives prepared by demethylated lignin have higher tensile strength and thermal stability. It indicates that the demethylation is effective and it is a good strategy to prepare lignin-based PU adhesive with favorable mechanical properties .
研究领域:
材料科学
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化学工程
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DOI
高影响因子
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
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2018
·Vol. 84
·期 13
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IF 3.633
Ya-Hui Shao,Li-Zhong Guo,Yu-Qing Zhang,Hao Yu,Bai-Suo Zhao,Hai-Qiang Pang,Wei-Dong Lu
Although some bacteria, including Chromohalobacter salexigens DSM 3043, can use glycine betaine (GB) as a sole source of carbon and energy, little information is available about the genes and their encoded proteins involved in the initial step of the GB degradation pathway. In the present study, the results of conserved domain analysis, construction of in-frame deletion mutants, and an in vivo functional complementation assay suggested that the open reading frames Csal_1004 and Csal_1005, designated bmoA and bmoB, respectively, may act as the terminal oxygenase and the ferredoxin reductase genes in a novel Rieske-type oxygenase system to convert GB to dimethylglycine in C. salexigens DSM 3043. To further verify their function, BmoA and BmoB were heterologously overexpressed in Escherichia coli, and 13C nuclear magnetic resonance analysis revealed that dimethylglycine was accumulated in E. coli BL21(DE3) expressing BmoAB or BmoA. In addition, His-tagged BmoA and BmoB were individually purified to electrophoretic homogeneity and estimated to be a homotrimer and a monomer, respectively. In vitro biochemical analysis indicated that BmoB is an NADH-dependent flavin reductase with one noncovalently bound flavin adenine dinucleotide (FAD) as its prosthetic group. In the presence of BmoB, NADH, and flavin, BmoA could aerobically degrade GB to dimethylglycine with the concomitant production of formaldehyde. BmoA exhibited strict substrate specificity for GB, and its demethylation activity was stimulated by Fe2+. Phylogenetic analysis showed that BmoA belongs to group V of the Rieske nonheme iron oxygenase (RO) family, and all the members in this group were able to use quaternary ammonium compounds as substrates.IMPORTANCE GB is widely distributed in nature. In addition to being accumulated intracellularly as a compatible solute to deal with osmotic stress, it can be utilized by many bacteria as a source of carbon and energy. However, very limited knowledge is presently available about the molecular and biochemical mechanisms for the initial step of the aerobic GB degradation pathway in bacteria. Here, we report the molecular and biochemical characterization of a novel two-component Rieske-type monooxygenase system, GB monooxygenase (BMO), which is responsible for oxidative demethylation of GB to dimethylglycine in C. salexigens DSM 3043. The results gained in this study extend our knowledge on the catalytic reaction of microbial GB degradation to dimethylglycine.
研究领域:
微生物学
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生物化学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY
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2014
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IF 1.176
Lihong Hu,Hui Pan,Yonghong Zhou,Chung-Yun Hse,Chengguo Liu,Baofang Zhang,Bin Xu
A new approach to increase the reactivity of lignin by thiol-mediated demethylation was investigated in this study. Demethylated lignin was characterized by the changes in its hydroxyl and methoxyl groups, molecular weight, and other properties using titration and spectroscopy methods including FT-IR, 1H NMR, UV, and GPC. The total, phenolic, and aliphatic hydroxyl contents in lignin increased while the methoxyl content decreased after demethylation reaction, which indicated the occurrence of demethylation reaction. The results from FT-IR and UV analysis also indicated that the kraft lignin in this study contains mainly guaiacyl moiety and demethylated lignin has a higher guaiacyl content than original lignin. The average molecular weight of lignin decreased after demethylation reaction due to the cleavage of ether linkages in lignin macromolecules. No severe degradation of lignin was observed during the demethylation reaction.
研究领域:
林产化学
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生物质化学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2024
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IF 7.7
Yumeng Wang,Boyu Du,Qian Zheng,Xiaohong Chen
Poly (vinyl alcohol) (PVA), as an excellent degradable plastic feedstock , is limited by its diminishing stability in wet environment, low strength , thermal instability and nonopaque properties. In response to these concerns, a PVA/demethylated lignin-based supramolecular plastic (DPVA-HA-Fe-5) was designed and produced from PVA, demethylated lignin (DL), humic acid (HA) and Fe 3+ ions via a simple casting method. As compared with pure PVA plastic, the tensile strength of DPVA-HA-Fe-5 were increased by 411 % to 410.61 MPa, and the breaking strain was increased by 149 % to 239.47 %. Notably, the hydrophobicity of DPVA-HA-Fe-5 was also significantly improved. Although in highly humid environment (stored in RH = 100 % for 10 days) or in alkaline organic solvent (stored in pyridine for 3 h), DPVA-HA-Fe-5 also showed excellent mechanical strengths of 302.9 and 222.99 MPa, respectively, which are equivalent or even superior to the most of commercial petroleum-based plastics. Moreover, the prepared plastics showed an outstanding UV resistance and shading performance, and about 98.3 % protection against ultraviolet radiation B rays and 90.7 % protection against visible light were obtained. In short, the introduction of lignin to improve the performance of PVA-based plastic is a feasible method, and it could facilitate the development of high-value utilization of lignin.
研究领域:
材料科学
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环境科学
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产品关联
DOI
PubMed
高影响因子
Reaction Kinetics Mechanisms and Catalysis
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2023
·Vol. 136
·期 3
·1407-1421
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IF 1.8
Zheng Yuxin,Wu Kejing,Zhu Yingming,Liu Yingying,Wang Binshen,Lu Houfang,Liang Bin
In this study, different solid acids were used as catalysts for demethylation of model compound 2-methoxy-4-methylphenol (creosol) to produce 4-methylcatechol (4-MeCat) in halogen-free aqueous system. The results showed that a high 4-MeCat yield of 48.5% was achieved over TiO 2 supported on activated carbon, while the Nb 2 O 5 catalyst with suitable Brønsted/Lewis acid site exhibited the highest average production rate of 0.053 min −1 . The high total acidity improves the 4-MeCat yield and a suitable ratio of Brønsted to Lewis acid sites benefits the catalytic activity over unit acid sites. The stable crystal and acid sites of Nb 2 O 5 catalyst result in high activity stability, while the supported TiO 2 catalyst is deactivated much faster. The loss of acid sites and acid site coverage are the main deactivation reasons for demethylation in aqueous medium.
研究领域:
化学工程
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环境科学
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产品关联
DOI
高影响因子
FEMS MICROBIOLOGY LETTERS
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2018
·Vol. 365
·期 5
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IF 1.735
Ke Xia,Xia Xiao-Yuan,Zheng Ren-Chao,Zheng Yu-Guo
The Erg28p protein is localized to the endoplasmic reticulum, where it acts as a scaffold to tether the C-4 demethylase complex involved in the sterol biosynthesis pathway of Saccharomyces cerevisiae. However, due to the challenges involved in characterizing the interactions of membrane proteins, the precise region of Erg28p that is responsible for the assembly of this enzyme complex remains unknown. To address this question, mutants with serial truncations in the C-terminus of Erg28p were constructed based on a topology prediction of its transmembrane domain. Sterol profiles demonstrated that intermediates involved in the stepwise removal of the two C-4 methyl groups from the tetracyclic sterol ring were accumulated in the ERG28Δ135-447 strain. Homologous alignment of Erg28p further identified a highly conserved 10-amino acid sequence (63LS/QARTFGT/LWT72) within the truncated region of ERG28Δ136-273. Complementation of the BY4741/erg28 strain with the ScERG28Δ175-204 plasmid resulted both in a significant growth inhibition and a reduction of ergosterol biosynthesis compared with the plasmid without the Δ175-204 truncation. Furthermore, homology modeling of the Erg28p mutant indicated that the deletion of residues 63–72 significantly disrupted the 3D structure of the four parallel helices in Erg28p. Taken together, the data indicate that the region spanning amino acids 63–72 constitutes a key consensus motif within Erg28p that is required for sterol C-4 demethylation during ergosterol biosynthesis in S. cerevisiae.
研究领域:
分子生物学
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生物化学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2023
·
IF 8.2
Boyu Du,Wanjing Li,Hongwei Zhu,Jingyu Xu,Qingyu Wang,Xiling Shou,Xing Wang,Jinghui Zhou
Recently, the application of lignin activation by demethylation to improve reactivity and enrich multiple functions has intensively attracted attention. However, it is still challenge up to now due to the low reactivity and complexity of lignin structure. Here, an effective demethylation way was explored by microwave-assisted method for substantially enhancing the hydroxyl (-OH) content and retaining the structure of lignin. Then, the optimum demethylated lignin was used to removal heavy metal ions and promote wound healing, respectively. In detail, for microwave-assisted demethylated poplar lignin (M-DPOL), the contents of phenolic (Ar-OH) and total hydroxyl (Tot-OH) groups reached the maximum for 60 min at 90 °C in DMF with 7.38 and 9.13 mmol/g, respectively. After demethylation, with this M-DPOL as lignin-based adsorbent, the maximum adsorption capacity (Q max ) for Pb 2+ ions reached 104.16 mg/g. Based on the isotherm, kinetic and thermodynamic models analyses, the chemisorption occurred in monolayer on the surface of M-DPOL, and all adsorption processes were endothermic and spontaneous. Meanwhile, M-DPOL as a wound dressing had excellent antioxidant property, outstanding bactericidal activity and remarkable biocompatibility, suggesting that it did not interfere with cell proliferation. Besides, the wounded rats treated with M-DPOL significantly promoted its formation of re-epithelialization and wound healing of full-thickness skin defects. Overall, microwave-assisted method of demethylated lignin can offer great advantages for heavy metal ions removal and wound care dressing, which facilitates high value application of lignin.
研究领域:
材料科学
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环境科学
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生物医学
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产品关联
DOI
PubMed
高影响因子
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2025
·
IF 3.8
Li Yifei,Su Yanfei,Chen Zhengyu,Wu Jianxun,Zhang Weilai,Xu Chunming,Shi Quan,Zhang Linzhou
Comprehensive characterization of petroleum-derived sulfur compounds is crucial for researching and developing desulfurization catalysts, equipment, and processes. However, the complex composition and low concentration of sulfur compounds in oils make it challenging for molecular-level separation and characterization. In this work, sulfur compounds in the straight-run diesel fraction were selectively separated from the oil by the methylation/demethylation method, effectively yielding high-purity thiophenes and sulfides. Molecular-level compositional and structural characterization of sulfur compounds was accomplished through comprehensive two-dimensional gas chromatography (GC × GC) coupled with time-of-flight mass spectrometry. The separation significantly enhances the detection sensitivity for low-content sulfur compounds, thereby enabling a more comprehensive characterization of their molecular compositions and structures. Sulfur compounds with diverse skeletons and carbon numbers were tentatively characterized, including 1~3 cyclic sulfides, thiophenes, benzothiophenes, dihydrobenzothiophenes, dibenzothiophenes, tetrahydrodibenzothiophenes, phenanthrothiophenes, and benzonaphthothiophenes. Additionally, hundreds of individual sulfur compounds were characterized by mass spectrometry. Quantitative analysis for individual compounds and compound types was conducted using a flame ionization detector. Graphical
研究领域:
化学工程
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石油化学
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分析化学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2024
·
IF 7.7
Yi Liu,Shaoyan Wang,Jiarui Liang,Lirong Lu,Yi Xie,Chengrong Qin,Chen Liang,Caoxing Huang,Shuangquan Yao
Demethylation modification of lignin is an effective strategy to overcome the barrier to its high-value conversion. The purpose of this study focuses on the new proton-based ionic liquid (PIL) 1, 2-propanediamine/glycolic acid (PD/GA) as a catalyst and solvent to achieve the targeted oxidation of lignin. The PD/GA solvents have higher selectivity and efficiency. Optimal phenolic hydroxyl (PH)-increment was achieved, demonstrating enhanced demethylating effect on lignin by modulating the acid-base molar ratio, reaction temperature, and reaction time. Compared to ethanolamine/acetic acid (CE/AC) treatment, the PD/GA treatment at molar ratio 1.25, temperature 60 °C, and 3 h increased the PH-content from 37.74 to 59.91 %. Additionally, the lignin treated with PD/GA exhibited excellent recyclability, featuring a larger Brunauer-Emmett-Teller surface area (1.45 m 2 .g −1 ), total pore volume (9.51*10 −3 cm 3 .g −1 ), and mesoporous size (26.15 nm). The treated lignin yielded maximum ultraviolet resistance and antioxidant activity. These results present new avenues for the development of green and efficient lignin demethylation methods.
研究领域:
生物化学
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材料科学
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产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Na Ji,Alazar Alemayehu,Hanyang Li,Poknam Ri,Xinyong Diao
The production of phenol from lignin or its model compounds, instead of cumene oxidation is very interesting from the viewpoint of sustainability and economics. The selective demethylation of anisole was an efficient but challenging route to produce phenol. In this work, we demonstrated the fabrication of nickel sulfide (Ni 9 S 8 +Ni x S 6 ) nanoparticles on Al 2 O 3 matrix by a facile in situ sulfidation of NiAl hydrotalcite and announced that nickel sulfide can serve as efficient active site for the demethylation of anisole for the first time. The as-designed 4Ni1Al-S catalyst exhibited a hierarchical morphology with a high particle density and high dispersion, affording a 95.6% yield of phenol in the demethylation of anisole under relative milder reaction temperature (270 °C) when compared to the reported state-of-the-art results. By comprehensive characterizations and experiments, we inferred that the nickel sulfide exsolved from the LDH structure exhibited stronger metal-support interaction than that obtained from the impregnation method, which not only benefits the uniform dispersion of active nickel sulfide but also results in the electronic transfer from Ni center to Al 2 O 3 support. As a consequence, enhanced demethylation activity was achieved on 4Ni1Al-S in comparison to Ni-S/Al 2 O 3 -IM.
研究领域:
催化
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化学工程
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材料科学
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可持续化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）