Improving the Monophenolic Yield of Lignin Depolymerization in Dualistic Aprotic Solvent System by Organic Solvent Fractionation.

Converting lignin into aromatic chemicals is a promising strategy for the high-value utilization of lignocellulosic feedstock. However, the inherent heterogeneity of lignin poses a significant obstacle to achieving efficient conversion and optimal product yields within bio-refinery systems. Herein, we employed a one-step fractionation method to enhance lignin homogeneity and utilized the THF/DMSO-EtONa (tetrahydrofuran/dimethyl sulfoxide-sodium ethoxide) system to depolymerize the fractionated lignin. Three protic and three aprotic solvents were used for fractionation. The impact of the solvent properties on the structure and the depolymerization efficiency of the fractionated lignin was investigated. Methanol-fractionated lignin generated the benzoic acid compounds with a yield of 30 wt%, 50 % higher than that of the unfractionated lignin. The polarities (δP), hydrogen bonding abilities (δH), and viscosities (η) of selected protic solvents showed strong linear correlation with molecular weight (Mw), polymer dispersity index (PDI), and syringyl/guaiacyl ratio (S/G ratio) of the fractionated lignin, as well as the total yield of benzoic acid compounds derived from the ß-O-4 bond cleavage. This study elucidates the relationship between solvent properties and lignin structure and proposes a promising approach for refining lignin to enhance utilization efficiency, thereby presenting a potential strategy for value-added application of complex lignin polymers.

Cellulose nanocrystal/graphene oxide one-dimensional photonic crystal film with excellent UV-blocking and transparency.

Achieving excellent ultraviolet (UV) blocking properties and maintaining high light transmittance are highly challenging. In this study, a facile and green polymer-assisted vacuum filtration strategy was used to prepare cellulose nanocrystal (CNC) one-dimensional photonic crystal (1DPhC) films with excellent UV-blocking performance and good transparency. The polymer-assisted self-assembly behaviors of CNC and the hydrogen bonding interaction between CNC, polyethylene glycol (PEG), and graphene oxide (GO) drive the homogeneous distribution and parallel alignment of GO. The UV absorption of GO and high reflection of UV resulting from the chiral nematic structure of CNCs result in excellent UV-blocking and high visible light transmission. Besides, the strong hydrogen bonding interaction among CNC, PEG, and GO endows the films with obviously increased mechanical properties. The UV-blocking and the transparency of the CNC composite films could reach 98.3 % and 60.5 %, respectively. Besides, the strain at break of the composite film reached 1.72 ± 0.11 %, which was 535.94 % of neat CNC films. The CNC composite films present great potential in the field of UV-blocking glass, sensors, anti-counterfeiting measures, radiation protection, and so on.

The trait co-variation regulates the response of bryophytes to nitrogen deposition: A meta-analysis.

The nitrogen deposition has the potential to alter the trait composition of plant communities by affecting the fitness and physiological adaptation of species, consequently exerting an influence on ecosystem processes. Despite the importance of bryophytes in nutrient and carbon dynamics across different ecosystems, there is a lack of research examining the relationship between nitrogen deposition and the co-variation of bryophyte traits. To address this gap, a meta-analysis was conducted using data from 27 independent studies to investigate potential associations between trait co-variation of bryophytes and nitrogen deposition. The results revealed that interspecific variability regulates the influence of nitrogen deposition on bryophytes by affecting trait co-variation. Multiple correspondence analysis identified six combinations of closely related traits. For example, species with unbranched main stems frequently exhibit robust leaf midribs, leading to leaf wrinkling and leaf clasping around the stem as a response to water loss. Some weft or mat species tend to obtain resources (nitrogen) through their scale hairs on the main stem. Some species with narrow leaves require leaf teeth to maintain a normal leaf shape. The subgroup analyses indicated that certain traits, including unbranched main stem, changes in leaf morphology, robust leaf midrib, main stem without scale hairs, narrow leaf, leaf margin with teeth, undeveloped apophysis, and erect capsule minimize interaction with pollutants and represent a resource strategy. Conversely, functional traits representing a resource acquisition strategy, such as branched main stem, no changes in leaf morphology, short and weak leaf midrib, main stem with scale hairs, broad leaf, leaf margin without teeth, developed apophysis, and non-erect capsule increase pollutant exposure. Overall, our results suggest that anthropogenic global change may significantly impact bryophytes due to changes in their individual physiology and colony ecological indicators caused by increased nitrogen deposition.

Synergy of Single Atoms and Lewis Acid Sites for Efficient and Selective Lignin Disassembly into Monolignol Derivatives.

Lignin is the most abundant aromatic polymer from the natural and renewable lignocellulosic biomass resource. Developing highly efficient catalysts for lignin depolymerization to produce valuable monophenols with high yield and selectivity remains a desirable but challenging target in this field. Here, we design a synergistic catalyst combining atomically dispersed Mo centers and Al Lewis acid sites on a MgO substrate (Mo1Al/MgO) for the depolymerization of Eucalyptus lignin via the ß-aryl ether bond cleavage. A near-theoretical monophenol yield of 46% with an ultrahigh selectivity of 92% for coniferyl and sinapyl methyl ether, as well as good cycling durability, was achieved simultaneously by Mo1Al/MgO in an inert N2 atmosphere. First-principles calculations and control catalytic experiments confirmed the synergistic catalysis mechanism between Mo1-O5 single-atom centers and the neighboring Al Lewis acid sites with the participation of a methanol solvent. This study validates the feasibility of designing better-performing catalysts with synergistic multiactive sites for the efficient and selective disassembly of complex renewable biopolymers into highly value-added products with lower cost and greater security.

Targeted release of soybean peptide from CMC/PVA hydrogels in simulated intestinal fluid and their pharmacokinetics.

Carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) hydrogels loaded with soybean peptide (SPE) were fabricated via a freeze-thaw method. These hydrogels conquer barriers in simulated gastric fluid (SGF), and then release SPE in simulated intestinal fluid (SIF). The results of in vitro SPE release from these hydrogels showed that in SGF only a little of the SPE released, but in SIF the SPE was completely released. The released SPE had scavenging rates for DPPH and ABTS free radicals of 41.68 and 31.43 %. The pharmacokinetic model of SPE release from the hydrogels in SIF was studied. When the hydrogels are moved from SGF to SIF, the sorption of the shrinkage hydrogel network is entirely controlled by stress-induced relaxations. There are swollen and shrunken regions during SPE release. For SPE release into the SIF, SPE has to be freed from the weak bonds in the swollen regions by changes in the conformation of CMC and PVA. The release rate of SPE was found to be governed by the diffusion and swelling rate of the shrinkage hydrogel network. The Korsmeyer-Peppas equation diffusion exponents (n) for SPE release from the hydrogels are >2.063, indicating a super case II transport. These data demonstrate CMC/PVA hydrogels have potential applications in oral peptide delivery.

Isolation, Characterization, and Depolymerization of l-Cysteine Substituted Eucalyptus Lignin.

Lignin condensation reactions are hard to avoid or control during separation, which is a deterrent to lignin isolation and post-conversation, especially for the full utilization of lignocelluloses. Selective protection of ß-aryl ether linkages in the isolation process is crucial to lignin valorization. Herein, a two-step acid/alkali separation method assisted with l-cysteine for eucalyptus lignin separation is developed, and the isolated l-cysteine lignins (LCLs) are comprehensively characterized by 2D NMR, 31P NMR, thioacidolysis, etc. Compared to the two-step control treatment, a much higher ß-O-4 content is preserved without reducing the separation efficiency assisted by l-cysteine, which is also significantly higher than alkali lignin and kraft lignin. The results of hydrogenolysis show that LCLs generate a much higher monomer yield than that of control sample. Structural analysis of LCLs suggests that lignin condensation reaction, to some extent, is suppressed by adding l-cysteine during the two-step acid/alkali separation. Further, mechanistic studies using dimeric model compound reveals that l-cysteine may be the α-carbon protective agent in the two-step separation. The role of l-cysteine in the two-step lignin isolation method provides novel insights to the selective fractionation of lignin from biomass, especially for the full valorization of lignocellulosic biomass.

Green approach to produce xylo-oligosaccharides and glucose by mechanical-hydrothermal pretreatment.

A pretreatment method combining ball-milling, ultrasound, and hydrothermal treatment was developed to produce xylooligosaccharides (XOS) and glucose with a high yield from corn stover. Under optimal conditions, the yield of XOS reached 80.40%, and the functional XOS (X2-X4) took up to 26.97%. Small amount of inhibitors were formed during the hydrothermal process. Enzymatic hydrolysis of the hydrothermally pretreated residue gave 92.60% yield of glucose, leaving lignin as the final residue which accounted for 66.82% of native lignin. The correlations between the yield of glucose and the physio-chemical properties of corn stover, such as crystalline index, particle size, and the removal of xylan, were established to understand the recalcitrance removal during the pretreatment process. Results demonstrate that this combined pretreatment method is a green and effective process to selectively separate the hemicellulose fractions and improve both production of XOS and glucose yield.

Co-production of functional xylo-oligosaccharides and fermentable sugars from corn stover through fast and facile ball mill-assisted alkaline peroxide pretreatment.

The aim of this work was to develop a feasible ball mill-assisted alkaline peroxide pretreatment followed by stepwise hydrolysis to improve the yield of xylo-oligosaccharides (XOS) and fermentable sugars. The hydrogen peroxide charge, ball-milling time, and solid-to-liquid ratio affected the compositions, particle sizes, morphology, and crystallinity of the corn stover, directly improving the following hydrolytic efficiency. The optimal pretreatment was with 0.45 g/g (H2O2: substrate) and 1:3 solid-to-liquid ratio (w/v) for 1.0 h ball-milling, resulting in 84.29% delignification. Physicochemical properties of the pretreated samples were characterized and their correlations to the enzymatic hydrolysis were revealed. Compared with one-step cellulase hydrolysis, the two-step xylanase-cellulase hydrolysis of the pretreated corn stover showed significant advance in preparing XOS, producing 69.65% (on the base of xylan content in pretreated sample) of XOS, along with 20.55% xylose, 68.94% glucose, and 21.15% gluco-oligosaccharides. The yield of XOS was 2-7 times higher than those in previous studies.

Lung cancer: progression of heat shock protein 70 in association with flap endonuclease 1 protein.

Lung cancer is one of the leading causes of cancer deaths worldwide and existing approaches are not enough to manage, and hence, it is important to concentrate on new drug strategies. This study was aimed to identify the interacting partner of Flap endonuclease 1 (FEN1) and its role in cancer treatment. We identified a new FEN1 interacting partner confirmed it as Heat Shock Protein 70 (HSP 70), and its effect on FEN1 expression, in vitro. Additionally, we found that the 5-Fluorouracil's (5-FU) function was significantly improved when used in combination with HSP 70 inhibitor (KNK 437). The findings are interesting, elucidating the synergistic mechanism between two compounds which helps to develop a novel management strategy for over-expressed FEN1 in the lung. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-020-02598-3.

Preventing Lignin Condensation to Facilitate Aromatic Monomer Production.

Lignin is the most abundant aromatic polymer in nature and as such is an attractive source of aromatic molecules. Efficient lignin utilization will also likely play a key role in the economic success and sustainability of biomass valorization schemes. However, traditional strategies for lignin isolation and depolymerization suffer from repolymerization issues, which result in low yield of low molecular weight fragments. This review summarizes the recent progress in lignin isolation and depolymerization methods that are able to limit lignin condensation and facilitate the high yield production of monomers and oligomers. A general trend in these methods is that condensation and repolymerization is prevented by trapping reactive intermediates during extraction or depolymerization by chemically stabilizing the ß-O-4 structure and/or its derivatives, or physically removing the separated lignin fragments from the reactor. We highlight the challenges and opportunities that these methods will face as they are further developed.

OsCAldOMT1 is a bifunctional O-methyltransferase involved in the biosynthesis of tricin-lignins in rice cell walls.

Lignin is a phenylpropanoid polymer produced in the secondary cell walls of vascular plants. Although most eudicot and gymnosperm species generate lignins solely via polymerization of p-hydroxycinnamyl alcohols (monolignols), grasses additionally use a flavone, tricin, as a natural lignin monomer to generate tricin-incorporated lignin polymers in cell walls. We previously found that disruption of a rice 5-HYDROXYCONIFERALDEHYDE O-METHYLTRANSFERASE (OsCAldOMT1) reduced extractable tricin-type metabolites in rice vegetative tissues. This same enzyme has also been implicated in the biosynthesis of sinapyl alcohol, a monolignol that constitutes syringyl lignin polymer units. Here, we further demonstrate through in-depth cell wall structural analyses that OsCAldOMT1-deficient rice plants produce altered lignins largely depleted in both syringyl and tricin units. We also show that recombinant OsCAldOMT1 displayed comparable substrate specificities towards both 5-hydroxyconiferaldehyde and selgin intermediates in the monolignol and tricin biosynthetic pathways, respectively. These data establish OsCAldOMT1 as a bifunctional O-methyltransferase predominantly involved in the two parallel metabolic pathways both dedicated to the biosynthesis of tricin-lignins in rice cell walls. Given that cell wall digestibility was greatly enhanced in the OsCAldOMT1-deficient rice plants, genetic manipulation of CAldOMTs conserved in grasses may serve as a potent strategy to improve biorefinery applications of grass biomass.

Reduced Expression of CbUFO Is Associated with the Phenotype of a Flower-Defective Cosmos bipinnatus.

LEAFY (LFY) and UNUSUAL FLORAL ORGANS (UFO) homologous genes have been reported to play key roles in promoting the initiation of floral meristems in raceme- and cyme-type plants. Asteraceae, a large family of plants with more than 23,000 species, has a unique head-like inflorescence termed capitulum. Here, we report a floral defective plant of the garden cosmos named green head (gh), which shows homogeneous inflorescence, indistinguishable inflorescence periphery and center, and the replacement of flower meristems by indeterminate inflorescence meristems, coupled with iterative production of bract-like organs and higher order of inflorescences. A comparison of the LFY- and UFO-like genes (CbFLY and CbUFO) isolated from both the wild-type and gh cosmos revealed that CbUFO may play an important role in inflorescence differentiation into different structures and promotion of flower initiation, and the reduced expression of CbUFO in the gh cosmos could be associated with the phenotypes of the flower-defective plants. Further expression analysis indicated that CbUFO may promote the conversion of inflorescence meristem into floral meristem in early ray flower formation, but does not play a role in its later growth period.

Highly Selective Oxidation and Depolymerization of α,γ-Diol-Protected Lignin.

Lignin oxidation offers a potential sustainable pathway to oxygenated aromatic molecules. However, current methods that use real lignin tend to have low selectivity and a yield that is limited by lignin degradation during its extraction. We developed stoichiometric and catalytic oxidation methods using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively deprotect the acetal and oxidize the α-OH into a ketone. The oxidized lignin was then depolymerized using a formic acid/sodium formate system to produce aromatic monomers with a 36 mol % (in the case of stoichiometric oxidation) and 31 mol % (in the case of catalytic oxidation) yield (based on the original Klason lignin). The selectivity to a single product reached 80 % (syringyl propane dione, and 10-13 % to guaiacyl propane dione). These high yields of monomers and unprecedented selectivity are attributed to the preservation of the lignin structure by the acetal.

New Method for Insomnia Mongolian Mind-Body Interactive Psychotherapy in the Assessment of Chronic Insomnia: A Retrospective Study.

INTRODUCTION: Insomnia is a common clinical complaint, and if not addressed it can increase the risk of developing other underlying diseases such as hypertension, depression and anxiety. The use of Mongolian mind-body interactive therapy as a comprehensive psychotherapeutic approach in chronic insomnia has been shown in this retrospective study. METHODS: Subjects who had suffered insomnia for more than 1 month participated in the Mongolian mind-body interactive psychotherapy program between June 2012 and February 2014. They were interviewed by telephone at least 10 months before participating in the program. Their sleep was assessed using the Athens insomnia scale. Descriptive statistics, ANOVA and regression analysis were used for data analysis by SPSS software. RESULTS: Mongolian mind-body interactive psychotherapy significantly improved sleeping conditions. In ANOVA analysis, both short- and long-term outcomes were significantly affected by the treatment period. Patients who previously took medication and pre-treatment sleeping condition (ASI score) had a significant influence on long-term outcomes, as well as treatment time related to the duration of insomnia. CONCLUSION: Mongolian mind-body interactive psychotherapy is a new method for insomnia, and narrative therapy and hypnotic methods together improve the sleeping condition, However, a further controlled randomized clinical study is needed to understand the efficacy.

Elucidating Tricin-Lignin Structures: Assigning Correlations in HSQC Spectra of Monocot Lignins.

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4'⁻Oâ»ß coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H⁻13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4'⁻O⁻ß-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cß/Hß of 4'⁻Oâ»ß unit, producing peaks at around δC/δH 82.5⁻83.5/4.15⁻4.45, that differ from the Cß/Hß correlations from normal 4⁻Oâ»ß units formed solely by monolignols, and that have to date been unassigned.

Protection Group Effects During α,γ-Diol Lignin Stabilization Promote High-Selectivity Monomer Production.

Protection groups were introduced during biomass pretreatment to stabilize lignin's α,γ-diol group during its extraction and prevent its condensation. Acetaldehyde and propionaldehyde stabilized the α,γ-diol without any aromatic ring alkylation, which significantly increased final product selectivity. The subsequent hydrogenolysis catalyzed by Pd/C generated lignin monomers at near-theoretical yields based on Klason lignin (48 % from birch, 20 % from spruce, 70 % from high-syringyl transgenic poplar), and with high selectivity to a single 4-n-propanolsyringol product (80 %) in the case of the poplar. Unlike direct hydrogenation of native wood, hydrogenolysis of protected lignin with Ni/C also led to high selectivity to this single product (78 %), paving the way to high-selectivity lignin upgrading with base metal catalysts. The use of extracted lignin facilitated valorization of polysaccharides, leading to high yields of all three major biomass polymers to a single major product.

In Vitro Enzymatic Depolymerization of Lignin with Release of Syringyl, Guaiacyl, and Tricin Units.

New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the ß-ether linkage. Previous studies have shown that bacterial ß-etherase pathway enzymes catalyze glutathione-dependent cleavage of ß-ether bonds in dimeric ß-ether lignin model compounds. To date, however, it remains unclear whether the known ß-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze ß-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD+ and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin.IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The ß-etherase pathway present in sphingomonad bacteria could cleave the abundant ß-O-4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of ß-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD+) in vitro, and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial ß-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin.

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content.

Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin- and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in ß-ß and ß-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production.

RNAi downregulation of three key lignin genes in sugarcane improves glucose release without reduction in sugar production.

BACKGROUND: Sugarcane is a subtropical crop that produces large amounts of biomass annually. It is a key agricultural crop in many countries for the production of sugar and other products. Residual bagasse following sucrose extraction is currently underutilized and it has potential as a carbohydrate source for the production of biofuels. As with all lignocellulosic crops, lignin acts as a barrier to accessing the polysaccharides, and as such, is the focus of transgenic efforts. In this study, we used RNAi to individually reduce the expression of three key genes in the lignin biosynthetic pathway in sugarcane. These genes, caffeoyl-CoA O-methyltransferase (CCoAOMT), ferulate 5-hydroxylase (F5H) and caffeic acid O-methyltransferase (COMT), impact lignin content and/or composition. RESULTS: For each RNAi construct, we selected three events for further analysis based on qRT-PCR results. For the CCoAOMT lines, there were no lines with a reduction in lignin content and only one line showed improved glucose release. For F5H, no lines had reduced lignin, but one line had a significant increase in glucose release. For COMT, one line had reduced lignin content, and this line and another released higher levels of glucose during enzymatic hydrolysis. Two of the lines with improved glucose release (F5H-2 and COMT-2) also had reduced S:G ratios. CONCLUSIONS: Along with improvements in bagasse quality for the production of lignocellulosic-based fuels, there was only one line with reduction in juice sucrose extraction, and three lines with significantly improved sucrose production, providing evidence that the alteration of sugarcane for improved lignocellulosic ethanol production can be achieved without negatively impacting sugar production and perhaps even enhancing it.