Isolating High Antimicrobial Ability Lignin From Bamboo Kraft Lignin by Organosolv Fractionation

Recent advance in preparation of lignin nanoparticles and their medical applications: A review

BACKGROUND

Lignin has attracted a lot of attention because it is non-toxic, renewable and biodegradable. Lignin nanoparticles (LNPs) have high specific surface area and specific surface charges. It provides LNPs with good antibacterial and antioxidant properties. LNPs preparation has become clear, however, the application remains in the early stages.

PURPOSE

A review centric research has been conducted, reviewing existing literature to accomplish a basic understanding of the medical applications of LNPs.

METHODS

Initially, we extensively counseled the heterogeneity of lignin from various sources. The size and morphology of LNPs from different preparation process were then discussed. Subsequently, we focused on the potential medical applications of LNPs, including drug delivery, wound healing, tissue engineering, and antibacterial agents. Lastly, we explained the significance of LNPs in terms of antibacterial, antioxidant and biocompatibility, especially highlighting the need for an integrated framework to understand a diverse range of medical applications of LNPs.

RESULTS

We outlined the chemical structure of different type of lignin, and highlighted the advanced methods for lignin nanoparticles preparation. Moreover, we provided an in-depth review of the potential applications of lignin nanoparticles in various medical fields, especially in drug carriers, wound dressings, tissue engineering components, and antimicrobial agents.

CONCLUSION

This review provides a detailed overview on the current state and progression of lignin nanoparticles for medical applications.

UV-blocking, antibacterial, corrosion resistance, antioxidant, and fruit packaging ability of lignin-rich alkaline black liquor composite film

The novel multifunctional active packaging composite film with antimicrobial, antioxidant, water-vapor and UV-barrier, and corrosion resistance properties was successfully prepared from waste biomass. In this study, waste poplar sawdust was pretreated using green liquor to extract black liquor (BL). BL was then mixed with polyvinyl alcohol (PVA) solution for synthesizing silver nanoparticles (AgNPs). PVA-BL-AgNPs film was fabricated by solution casting method, and the microstructure characterization and macroscopic performance testing of the composite film were conducted. The results revealed that PVA-BL-AgNPs film exhibited inhibitory effects against Staphylococcus aureus (inhibition zone: 33.6 mm), Pseudomonas aeruginosa (inhibition zone: 31.6 mm), and Escherichia coli (inhibition zone: 32.0 mm). It could eliminate over 99 % of 2,2-diazodi (3-ethyl-benzothiazol-6-sulfonic acid) (ABTS) free radicals and provided 100 % UV-blocking, reducing light-induced food damage. It exhibited the improvement of water-vapor barrier properties and corrosion resistance. In vitro cytotoxicity assays demonstrated that no significant impact occurred on cell proliferation, confirming the safety of the film. Packaging experiments showed that PVA-BL-AgNPs film effectively inhibited milk spoilage and prolonged the shelf-life of bread and bananas. Therefore, PVA-BL-AgNPs film might extend the shelf-life of food and offer significant opportunities in addressing the issues of low safety and environmental pollution associated with traditional packaging films.

Preparation and Characterization of Lignin Nanoparticles from Different Plant Sources

This article presents new research on producing lignin nanoparticles (LNPs) using the antisolvent nanoprecipitation method. Acetone (90%) served as the lignin solvent and water (100%) as the antisolvent, using five types of lignins from various sources. Comprehensive characterization techniques, including NMR, GPC, FTIR, TEM, and DLS, were employed to assess both lignin and LNP properties. The antioxidant activity of the LNPs was evaluated as well. The results demonstrated the successful formation of spherical nanoparticles below 100 nm with initial lignin concentrations of 1 and 2%w/v. The study highlighted the crucial role of lignin purity in LNP formation and colloidal stability, noting that residual carbohydrates adversely affect efficiency. This method offers a straightforward, environmentally friendly approach using cost-effective solvents, applicable to diverse lignin sources. The innovation of this study lies in its demonstration of a cost-effective and eco-friendly method to produce stable, nanometric-sized spherical LNPs. These LNPs have significant potential as reinforcement materials due to their reinforcing capability, hydrophilicity, and UV absorption. This work underscores the importance of starting material purity for optimizing the process and achieving the desired nanometric dimensions, marking a pioneering advancement in lignin-based nanomaterials.

Long-term durability of discarded cork-based composites obtained by geopolymerization

Geopolymers are amorphous aluminosilicate inorganic polymers synthesized by alkaline activation characterized by a lower carbon footprint, greater durability, and excellent mechanical properties compared to traditional concrete, making them promising building materials for sustainable construction. To develop sustainable lightweight geopolymer-based building materials useful as fire resistant thermal insulation materials, we added 5 and 10 wt% of discarded cork dust, a readily available industrial by-product, to metakaolin before and after the alkaline activation with sodium hydroxide 8 M and sodium silicate solutions. We followed the chemical, microstructural, antibacterial, and physical properties of the resulting composites for up to 90 days in order to monitor their long-term durability. The presence of cork does not interfere with the geopolymerization process and in fact reduces the density of the composites to values around 2.5 g/cm3, especially when added after alkaline activation. The composites resulted in chemically stable matrices (less than 10 ppm of cations release) and filler (no hazardous compounds released) with a bacterial viability of around 80%. This study provides valuable insights into the tailoring of discarded cork-based composites obtained by geopolymerization with a porosity between 32 and 48% and a mechanical resistance to compression from 15 to 5 MPa, respectively, suggesting their potential as durable interior panels with low environmental impact and desirable performance.

Treating waste with waste: Lignin acting as both an effective bactericide and passivator to prevent acid mine drainage formation at the source

Acid mine drainage (AMD) induced by pyrite oxidation is a notorious and serious environmental problem, but the management of AMD in an economical and environmentally friendly way remains challenging. Here, lignin, a natural polymer and abundant waste, was employed as both a bactericide and passivator to prevent AMD formation. The addition of lignin to a mimic AMD formation system inoculated with Acidithiobacillus ferrooxidans at a lignin-to-pyrite weight ratio of 2.5: 10 reduced the combined abiotic and biotic oxidation of pyrite by 68.4 % (based on released SO42-). Morphological characterization of Acidithiobacillus ferrooxidans revealed that lignin could act on the cell surface and impair the cell integrity, disrupting its normal growth and preventing biotic oxidation of pyrite accordingly. Moreover, lignin can be used alone as a passivator to form a coating on the pyrite surface, reducing abiotic oxidation by 71.7 % (based on released SO42-). Through multiple technique analysis, it was proposed that the functional groups on lignin may coordinate with iron ions on pyrite, promoting its deposition on the surface. In addition, the inherent antioxidant activity of lignin may also be actively involved in the abatement of pyrite oxidation via the reduction of iron. Overall, this study offered a "treating waste with waste" strategy for preventing AMD formation at the source and opened a new avenue for the management of AMD.

Laccase and dye-decolorizing peroxidase-modified lignin incorporated with keratin-based biodegradable film: An elucidation of structural characterization, antibacterial and antioxidant properties

Lignin valorization to produce functionalized materials is challenging. This study harnessed the versatile properties of lignin through a grafting reaction involving the aryl hydroxyl group of alkali lignin (AL) and enzymatically modified-alkali lignin (EMAL) using Bacillus ligninphilus-derived laccase (Lacc) L1 and C. seriivinvornas-derived dye-decolorizing peroxidase (DyP) with keratin (K) amide group. This reaction was executed utilizing an eco-friendly solvent with the aim of generating thin films. A thorough investigation was conducted, focusing on grafting AL and EMAL onto K. The incorporation of EMAL into the films enhanced tensile strength (TS) (14.8±1.8 MPa) and elongation at break (EAB) (23.7±0.3 %). Additionally, it enhanced thermal stability, suppressed the proliferation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and mitigated oxidative stress. This study introduces a novel approach for lignin valorization, offering the potential to tailor mechanical properties, antibacterial and antioxidant properties of the final material, making it sustainable substitute for petroleum-based products.

Antimicrobial Peptide-Inspired Design of Amino-Modified Lignin with Improved Antimicrobial Activities

A major challenge to make use of lignin as an antimicrobial material is the weak antimicrobial activity of industrial lignin. Inspired by the antimicrobial mechanism of actions of antimicrobial peptides, alkyldiamines were employed as lysine mimics for lignin modifications. Accordingly, aminoalkyl-modified lignins with different degrees of substitution of amino groups and different hydrophobicity were synthesized. The chemical structure, properties, and antimicrobial activities of the as-prepared aminoalkyl lignins were thoroughly characterized with state-of-the-art technologies. The results indicated that aminobutyl lignin showed enhanced antimicrobial activity against S. aureus and E. coli and performed even better than copper ions. The antimicrobial mechanism of action of the as-prepared aminobutyl lignin was similar to that of polylysine, which damaged the cell membrane, leading to the leakage of intracellular molecules and death of the cell. This study provides a feasible approach to afford modified lignin with enhanced antimicrobial performance, which would facilitate the high-value valorization of lignin as biological materials.

Willow Bark-Derived Material with Antibacterial and Antibiofilm Properties for Potential Wound Dressing Applications

Tree stems contain wood in addition to 10-20% bark, which remains one of the largest underutilized biomasses on earth. Unique macromolecules (like lignin, suberin, pectin, and tannin), extractives, and sclerenchyma fibers form the main part of the bark. Here, we perform detailed investigation of antibacterial and antibiofilm properties of bark-derived fiber bundles and discuss their potential application as wound dressing for treatment of infected chronic wounds. We show that the yarns containing at least 50% of willow bark fiber bundles significantly inhibit biofilm formation by wound-isolated Staphylococcus aureus strains. We then correlate antibacterial effects of the material to its chemical composition. Lignin plays the major role in antibacterial activity against planktonic bacteria [i.e., minimum inhibitory concentration (MIC) 1.25 mg/mL]. Acetone extract (unsaturated fatty acid-enriched) and tannin-like (dicarboxylic acid-enriched) substances inhibit both bacterial planktonic growth [MIC 1 and 3 mg/mL, respectively] and biofilm formation. The yarn lost its antibacterial activity once its surface lignin reached 20.1%, based on X-ray photoelectron spectroscopy. The proportion of fiber bundles at the fabricated yarn correlates positively with its surface lignin. Overall, this study paves the way to the use of bark-derived fiber bundles as a natural-based material for active (antibacterial and antibiofilm) wound dressings, upgrading this underappreciated bark residue from an energy source into high-value pharmaceutical use.

Recent advances in lignin antioxidant: Antioxidant mechanism, evaluation methods, influence factors and various applications

Lignin, a by-product of processing lignocellulosic materials, has a polyphenolic structure and can be used as an antioxidant directly or synergistically with synthetic types of antioxidants, leading to different applications. Its antioxidant mechanism is mainly related to the production of ROS, but the details need to be further investigated. The antioxidant property of lignin is mainly related to the content of phenolic hydroxyl group, but methoxy, purity will also have an effect on it. In addition, different methods to detect the antioxidant properties of lignin have different advantages and disadvantages. In this paper, the antioxidant mechanism of lignin, the methods to determine the antioxidant activity and the progress of its application in various fields are reviewed. In addition, the current research on the antioxidant properties of lignin and the hot directions are provided, and an outlook on the research into the antioxidant properties of lignin is provided to broaden its potential application areas.

Bioassay-Guided Assessment of Antioxidative, Anti-Inflammatory and Antimicrobial Activities of Extracts from Medicinal Plants via High-Performance Thin-Layer Chromatography

Natural products and their analogues have contributed significantly to treatment options, especially for anti-inflammatory and infectious diseases. Thus, the primary objective of this work was to compare the bioactivity profiles of selected medicinal plants that are historically used in folk medicine to treat inflammation and infections in the body. Chemical HPTLC fingerprinting was used to assess antioxidant, phenolic and flavonoid content, while bioassay-guided HPTLC was used to detect compounds with the highest antibacterial and anti-inflammatory activities. The results of this study showed that green tea leaf, walnut leaf, St. John's wort herb, wild thyme herb, European goldenrod herb, chamomile flower, and immortelle flower extracts were strong radical scavengers. Green tea and nettle extracts were the most active extracts against E. coli, while calendula flower extract showed significant potency against S. aureus. Furthermore, green tea, greater celandine, and fumitory extracts exhibited pronounced potential in suppressing COX-1 activity. The bioactive compounds from the green tea extract, as the most bioactive, were isolated by preparative thin-layer chromatography and characterized with their FTIR spectra. Although earlier studies have related green tea's anti-inflammatory properties to the presence of catechins, particularly epigallocatechin-3-gallate, the FTIR spectrum of the compound from the most intense bioactive zone showed the strongest anti-inflammatory activity can be attributed to amino acids and heterocyclic compounds. As expected, antibacterial activity in extracts was related to fatty acids and monoglycerides.

Physicochemical Properties, Thermal Stability, and Pyrolysis Behavior of Antioxidative Lignin from Water Chestnut Shell Obtained with Ternary Deep Eutectic Solvents

The molecular weight of lignin extracted from lignocellulosic biomass is an important factor in determining its valorization in industrial processes. Herein, this work aims to explore the extraction of high molecular weight and bioactive lignin from water chestnut shells under mild conditions. Five kinds of deep eutectic solvents were prepared and applied to isolate lignin from water chestnut shells. The extracted lignin was further characterized with element analysis, gel permeation chromatography, and Ultraviolet-visible and Fourier-transform infrared spectroscopy. The distribution of pyrolysis products was identified and quantified with thermogravimetric analysis-Fourier-transform infrared spectroscopy and pyrolysis-gas chromatograph-mass spectrometry. The results showed that choline chloride/ethylene glycol/p-toluenesulfonic acid (1:1.8:0.2 molar ratio) exhibited the highest fractionation efficiency for lignin (84.17% yield) at 100 °C for 2 h. Simultaneously, the lignin showed high purity (90.4%), high relative molecular weight (37,077 g/mol), and excellent uniformity. Furthermore, the aromatic ring structure of lignin remained intact, consisting mainly of p-hydroxyphenyl, syringl, and guaiacyl subunits. The lignin generated a large number of volatile organic compounds during the depolymerization process, mainly composed of ketones, phenols, syringols, guaiacols, esters, and aromatic compounds. Finally, the antioxidant activity of the lignin sample was evaluated with the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay; the lignin from water chestnut shells showed excellent antioxidant activity. These findings confirm that lignin from water chestnut shells has a broad application prospect in valuable chemicals, biofuels and bio-functional materials.

Lignin Nanoparticles for Enhancing Physicochemical and Antimicrobial Properties of Polybutylene Succinate/Thymol Composite Film for Active Packaging

The natural abundance, polymer stability, biodegradability, and natural antimicrobial properties of lignin open a wide range of potential applications aiming for sustainability. In this work, the effects of 1% (w/w) softwood kraft lignin nanoparticles (SLNPs) on the physicochemical properties of polybutylene succinate (PBS) composite films were investigated. Incorporation of SLNPs into neat PBS enhanced T_d from 354.1 °C to 364.7 °C, determined through TGA, whereas T_g increased from -39.1 °C to -35.7 °C while no significant change was observed in T_m and crystallinity, analyzed through DSC. The tensile strength of neat PBS increased, to 35.6 MPa, when SLNPs were added to it. Oxygen and water vapor permeabilities of PBS with SLNPs decreased equating to enhanced barrier properties. The good interactions among SLNPs, thymol, and PBS matrix, and the high homogeneity of the resultant PBS composite films, were determined through FTIR and FE-SEM analyses. This work revealed that, among the PBS composite films tested, PBS + 1% SLNPs + 10% thymol showed the strongest microbial growth inhibition against Colletotrichum gloeosporioides and Lasiodiplodia theobromae, both in vitro, through a diffusion method assay, and in actual testing on active packaging of mango fruit (cultivar "Nam Dok Mai Si Thong"). SLNPs could be an attractive replacement for synthetic substances for enhancing polymer properties without compromising the biodegradability of the resultant material, and for providing antimicrobial functions for active packaging applications.

Ultrasonic-assisted synthesis of lignin-capped Cu2O nanocomposite with antibiofilm properties

Under ultrasonication, cuprous oxide (Cu₂O) microparticles (<5 µm) were fragmented into nanoparticles (NPs, ranging from 10 to 30 nm in diameter), and interacted strongly with alkali lignin (Mw = 10 kDa) to form a nanocomposite. The ultrasonic wave generates strong binding interaction between lignin and Cu₂O. The L-Cu nanocomposite exhibited synergistic effects with enhanced antibiofilm activities against E. coli, multidrug-resistant (MDR) E. coli, S. aureus (SA), methicillin-resistant SA, and P. aeruginosa (PA). The lignin-Cu₂O (L-Cu) nanocomposite also imparted notable eradication of such bacterial biofilms. Experimental evidence unraveled the destruction of bacterial cell walls by L-Cu, which interacted strongly with the bacterial membrane. After exposure to L-Cu, the bacterial cells lost the integrated structural morphology. The estimated MIC for biofilm inhibition for the five tested pathogens was 1 mg/mL L-Cu (92 % lignin and 8 % Cu₂ONPs, w/w %). The MIC for bacterial eradication was noticeably lower; 0.3 mg/mL (87 % lignin + 13 % Cu₂ONPs, w/w %) for PA and SA, whereas this value was appreciably higher for MDR E. coli (0.56 mg/mL, 86 % lignin and 14 % Cu₂O NPs). Such results highlighted the potential of L-Cu as an alternative to neutralize MDR pathogens.

Lignin as a bioactive polymer and heavy metal absorber- an overview

As a pulping and bio-refinery by-product with phenolic chemical structure, lignin indicated high potential as natural antioxidant activity, UV blocker, antibacterial and toxic material absorbent properties. Presence of phenolic hydroxyl groups in lignin structure plays the main role of its antioxidant activity. However, lignin antioxidant power can change depending on its other structural features and functional groups like ortho-methoxy groups, -OCH₃ groups, the α-CH₂ groups, the aliphatic carbonyl groups, and the size of π-conjugated systems. Lignin in mixture with synthetic polymers, improved their thermal stability. Lignin has high UV light absorbing potential in broad-spectrum (UVA, UVB). Adding 1-5% of lignin into hand cream indicated excellent range of sun protection factor (SPF) with more than 95% UV light absorption. Lignin also indicated strong UV light protection when applied in different transparent film and protect paint, oil, and varnish from UV degradation. Lignosulfonate and other modified lignin including chemically modification, nano-particles and lignin hydrogel indicated high potential as heavy metal absorber.

Valorization of Kraft Lignin from Black Liquor in the Production of Composite Materials with Poly(caprolactone) and Natural Stone Groundwood Fibers

The development of new materials is currently focused on replacing fossil-based plastics with sustainable materials. Obtaining new bioplastics that are biodegradable and of the greenest possible origin could be a great alternative for the future. However, there are some limitations-such as price, physical properties, and mechanical properties-of these bioplastics. In this sense, the present work aims to explore the potential of lignin present in black liquor from paper pulp production as the main component of a new plastic matrix. For this purpose, we have studied the simple recovery of this lignin using acid precipitation, its thermoplastification with glycerin as a plasticizing agent, the production of blends with poly(caprolactone) (PCL), and finally the development of biocomposite materials reinforcing the blend of thermoplastic lignin and PCL with stone groundwood fibers (SGW). The results obtained show that thermoplastic lignin alone cannot be used as a bioplastic. However, its combination with PCL provided a tensile strength of, e.g., 5.24 MPa in the case of a 50 wt.% blend. In addition, when studying the properties of the composite materials, it was found that the tensile strength of a blend with 20 wt.% PCL increased from 1.7 to 11.2 MPa with 40 wt.% SGW. Finally, it was proven that through these biocomposites it is possible to obtain a correct fiber-blend interface.

Advancements in antimicrobial nanoscale materials and self-assembling systems

Antimicrobial resistance is directly responsible for more deaths per year than either HIV/AIDS or malaria and is predicted to incur a cumulative societal financial burden of at least $100 trillion between 2014 and 2050. Already heralded as one of the greatest threats to human health, the onset of the coronavirus pandemic has accelerated the prevalence of antimicrobial resistant bacterial infections due to factors including increased global antibiotic/antimicrobial use. Thus an urgent need for novel therapeutics to combat what some have termed the 'silent pandemic' is evident. This review acts as a repository of research and an overview of the novel therapeutic strategies being developed to overcome antimicrobial resistance, with a focus on self-assembling systems and nanoscale materials. The fundamental mechanisms of action, as well as the key advantages and disadvantages of each system are discussed, and attention is drawn to key examples within each field. As a result, this review provides a guide to the further design and development of antimicrobial systems, and outlines the interdisciplinary techniques required to translate this fundamental research towards the clinic.

The Practical Utility of Imidazolium Hydrogen Sulfate Ionic Liquid in Fabrication of Lignin-Based Spheres: Structure Characteristic and Antibacterial Activity

In this study, lignin-based spherical particles (Lig-IL) with the use of 1-(propoxymethyl)-1H-imidazolium hydrogen sulfate were prepared in different biopolymer and ionic liquid (IL) weight ratios. The application of IL during the preparation of spherical particles is an innovative method, which may be beneficial for further applications. The particles were obtained with the use of the soft-templating method and their chemical, structural and morphological characterization was performed. The spherical shape of products and their size (91–615 nm) was confirmed with the use of scanning electron microscopy (SEM) images and the particle size distribution results. The attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra were analyzed to identify functional groups of all precursors and produced material and it was confirmed, that all materials exhibit characteristic hydroxyl and carboxylic groups, but the presence of carbonyl group was detected. Moreover, the zeta potential analysis was performed to evaluate the electrokinetic behavior of obtained materials. It was confirmed, that all materials are colloidally stable in pH above 4. Produced lignin-based spherical particles were used for evaluation of their antibacterial properties. Particles were tested against Staphylococcus aureus (S. aureus), a gram-positive bacterium, and Escherichia coli (E. coli), a gram-negative one. It was observed, that only the material with the highest addition of IL showed the antibacterial properties against both strains. A reduction of 50% in the number of microorganisms was observed for particles with the addition of hydrogen sulfate ionic liquid in a 1:1 ratio after 1 h. However, all prepared materials exhibited the antibacterial activity against a gram-positive bacterium.

Nanostructured Antibiotics and Their Emerging Medicinal Applications: An Overview of Nanoantibiotics

Bacterial strains resistant to antimicrobial treatments, such as antibiotics, have emerged as serious clinical problems, necessitating the development of novel bactericidal materials. Nanostructures with particle sizes ranging from 1 to 100 nanometers have appeared recently as novel antibacterial agents, which are also known as “nanoantibiotics”. Nanomaterials have been shown to exert greater antibacterial effects on Gram-positive and Gram-negative bacteria across several studies. Antibacterial nanofilms for medical implants and restorative matters to prevent bacterial harm and antibacterial vaccinations to control bacterial infections are examples of nanoparticle applications in the biomedical sectors. The development of unique nanostructures, such as nanocrystals and nanostructured materials, is an exciting step in alternative efforts to manage microorganisms because these materials provide disrupted antibacterial effects, including better biocompatibility, as opposed to minor molecular antimicrobial systems, which have short-term functions and are poisonous. Although the mechanism of action of nanoparticles (NPs) is unknown, scientific suggestions include the oxidative-reductive phenomenon, reactive ionic metals, and reactive oxygen species (ROS). Many synchronized gene transformations in the same bacterial cell are essential for antibacterial resistance to emerge; thus, bacterial cells find it difficult to build resistance to nanoparticles. Therefore, nanomaterials are considered as advanced solution tools for the fields of medical science and allied health science. The current review emphasizes the importance of nanoparticles and various nanosized materials as antimicrobial agents based on their size, nature, etc.

Antimicrobial Potential of Conjugated Lignin/Morin/Chitosan Combinations as a Function of System Complexity

As natural biopolymers, chitosan and lignin are characterized by their good biocompatibility, high biodegradability and satisfactory biosafety. The active polymers’ functional groups are responsible for the potential of these biomaterials for use as carrier matrices in the construction of polymer−drug conjugates with prospective applicability in the fields of medicine, food and agriculture—subjects that have attracted attention in recent years. Hence, the aim of this research was to place substantial emphasis on the antimicrobial potential of flavonoid−biopolymer complex systems by assessment of the probable synergetic, additive or antagonistic effects arising as a function of systemic complexity. The joint implementation of morin, chitosan and lignin in conjugated two- and three-component systems provoked species-dependent antimicrobial synergistic and/or potentiation effects against the activity of the tested bacterial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and the clinical isolate Bacillus cereus. The double combinations of morin−chitosan and morin−lignin resulted in a 100% increase in their inhibitory activity against S. aureus as compared to the pure biocompounds. The inhibitory effects of the three-component system, in decreasing order, were: S. aureus (IZ = 15.7 mm) > P. aeruginosa (IZ = 15 mm) > B. cereus and E. coli (IZ = 14 mm). All tested morin-containing two- and three-component systems exhibited clear and significant potentiation effects, especially against S. aureus and B. cereus. The results obtained are a prerequisite for the potential use of the studied conjugated lignin−morin−chitosan combinations in the construction of novel drug-carrier formulations with improved bioactivities.

Effective bioremediation of pulp and paper mill wastewater using Bacillus cereus as a possible kraft lignin-degrading bacterium

The effective degradation of KL from paper mill effluent is an important for environmental safety. This research is primarily concerned with the identification of KL-degrading Bacillus cereus from activated sludge and their possible use for the degradation of Kraft lignin (KL). This strain was involved in the production of lignin peroxidase-LiP (3.20 U/mL), manganese peroxidase-MnP (20.36 U/mL), and laccase (21.35 U/mL) enzymes, which were responsible for high KL degradation (89%) and decolorization (40%) at 1000 mg/L KL in 3 days. The SEM-EDS, UV-Vis, FTIR, and GC-MS analysis were used to analyze the bacterial cell and KL interactions to trace the KL degradation process. The significant reduction of pollutants (KL-72.5%, color-62.0%, COD-45.05%) and reduction in toxicity (80%) of bacterial-treated effluent indicated that B. cereus has the potential to be used in the degradation of pollutants from paper mill effluents.

Chemical Characteristics of Ethanol and Water Extracts of Black Alder (Alnus glutinosa L.) Acorns and Their Antibacterial, Anti-Fungal and Antitumor Properties

The aim of this study was to identify polyphenolic compounds contained in ethanol and water extracts of black alder (Alnus glutinosa L.) acorns and evaluate their anti-cancer and antimicrobial effects. The significant anti-cancer potential on the human skin epidermoid carcinoma cell line A431 and the human epithelial cell line A549 derived from lung carcinoma tissue was observed. Aqueous and ethanolic extracts of alder acorns inhibited the growth of mainly Gram-positive microorganisms (Staphylococcus aureus, Bacillus subtilis, Streptococcus mutans) and yeast-like fungi (Candida albicans, Candida glabrata), as well as Gram-negative (Escherichia coli, Citrobacter freundii, Proteus mirabilis, Pseudomonas aeruginosa) strains. The identification of polyphenols was carried out using an ACQUITY UPLC-PDA-MS system. The extracts were composed of 29 compounds belonging to phenolic acids, flavonols, ellagitannins and ellagic acid derivatives. Ellagitannins were identified as the predominant phenolics in ethanol and aqueous extract (2171.90 and 1593.13 mg/100 g DM, respectively) The results may explain the use of A. glutinosa extracts in folk medicine.

Recent advances in biological activities of lignin and emerging biomedical applications: A short review

As an abundant biopolymer, lignin gains interest owing to its renewable nature and polyphenolic structure. It possesses many biological activities such as antioxidant activity, antimicrobial activity, and biocompatibility. Studies are being carried out to relate the biological activities to the polyphenolic structures. These traits present lignin as a natural compound being used in biomedical field. Lignin nanoparticles (LNPs) are being investigated for safe use in drug and gene delivery, and lignin-based hydrogels are being explored as wound dressing materials, in tissue engineering and 3D printing. In addition, lignin and its derivatives have shown the potential to treat diabetic disease. This review summarizes latest research results on the biological activities of lignin and highlights potential applications exampled by selective studies. It helps to transform lignin from a waste material into valuable materials and products.

Utilization of lignin upon successive fractionation and esterification in polylactic acid (PLA)/lignin biocomposite

The study presents the preparation of novel biocomposites based on different lignin fractions and polylactic acid (PLA). The lignin was extracted from pine residue using deep eutectic solvent (DES) and was subjected to fractionation with ethanol and acetone as well as esterification modification with succinic anhydride (SAn). Different lignin fractions were characterized and analyzed, while lignin-based biocomposites were prepared by melt injection. The results showed that lignin molecular weight was inversely proportional to the phenolic hydroxyl content and positively proportional to the alcohol hydroxyl group. The mechanical properties of the composites were also significantly affected by different molecular weights of lignin, indicating that the non-homogeneity of lignin affects its value-added utilization. In contrast to other performances of composites, the flexural and impact strengths of the materials prepared by acetone extracted lignin (AL) were improved by 18.2% and 28%, respectively, while the antibacterial properties against Staphylococcus aureus were up to 95%. The enhanced mechanical properties, antibacterial effect, and steady biocompatibility provide potential possibilities for lignin-based composites in biomedical applications.

The Effect of Ball Milling Time on the Isolation of Lignin in the Cell Wall of Different Biomass

Ball milling technology is the classical technology to isolate representative lignin in the cell wall of biomass for further investigation. In this work, different ball milling times were carried out on hardwood (poplar sawdust), softwood (larch sawdust), and gramineous material (bamboo residues) to understand the optimum condition to isolate the representative milled wood lignin (MWL) in these different biomass species. Results showed that prolonging ball milling time from 3 to 7 h obviously increased the isolation yields of MWL in bamboo residues (from 39.2% to 53.9%) and poplar sawdust (from 15.5% to 35.6%), while only a slight increase was found for the MWL yield of larch sawdust (from 23.4% to 25.8%). Importantly, the lignin substructure of ß-O-4 in the MWL samples from different biomasses can be a little degraded with the increasing ball milling time, resulting in the prepared MWL with lower molecular weight and higher content of hydroxyl groups. Based on the isolation yield and structure features, milling time with 3 and 7 h were sufficient to isolate the representative lignin (with yield over 30%) in the cell wall of bamboo residues and poplar sawdust, respectively, while more than 7 h should be carried out to isolate the representative lignin in larch sawdust.

Understanding the relationship between the structural properties of lignin and their biological activities

Due to the antioxidant properties of lignin, it has been demonstrated as an active substance for treating oxidation-related and inflammatory diseases. However, how the structural properties of lignin affect its biological activities is still ambiguous. In this study, Kraft lignin from wheat straw (KL-A) was used as the raw material to fractionate into three fractions (e.g., KL-B, KL-C, and KL-D) with different molecular weight by ultrafiltration, which possessed different physicochemical properties. The biocompatibility, in vivo and in vitro scavenging abilities for reactive oxygen species (ROS), and anti-apoptotic abilities of the lignin fractions were evaluated using SW1353 chondrocyte cell lines and were quantitatively fitted to their physicochemical properties. The results showed that lignin fractions with lower molecular weights, lower G/S ratios, and higher non-condensed phenolic OH contents endowed lignin with stronger ROS scavenging ability in vivo and in vitro, but was accompanied by increased cytotoxicity to cells. The half maximal inhibitory concentration (IC50) of KL-A, KL-B, KL-C, and KL-D were separately determined as 44.02, 33.43, 32.41, and 18.40 μg/mL. Furthermore, KL-D, with the lowest molecular weight and highest number of functional groups, showed the best antioxidant ability, while it performed poorly in inhibiting cellular apoptosis of chondrocytes. Compared to KL-D, KL-C with inverse structural properties, performed better in anti-apoptosis of SW1353 cells, which is the optimum lignin as promising active substances to be applied in the treatment of osteoarthritis in biomedical engineering.

Protective Effects of Lignin-Carbohydrate Complexes from Wheat Stalk against Bisphenol a Neurotoxicity in Zebrafish via Oxidative Stress

Lignin-carbohydrate complexes (LCCs) from different lignocellulosic biomass have shown biological qualities as antioxidant and immunostimulant. By contrast, the application of LCCs as protectant against neurotoxicity caused by different compounds is scarce. In this work, two kinds of LCCs with carbohydrate-rich and lignin-rich fractions were obtained from wheat stalk and used to protect against BPA-neurotoxicity in zebrafish. The results showed that BPA at a concentration of 500 µg/L results in neurotoxicity, including significant behavioral inhibition, and prevents the expression of central nervous system proteins in transgenic zebrafish models (Tg (HuC-GFP)). When the zebrafish was treated by LCCs, the reactive oxygen species of zebrafish decreased significantly with the change of antioxidant enzymes and lipid peroxidation, which was due to the LCCs' ability to suppress the mRNA expression level of key genes related to nerves. This is essential in view of the neurotoxicity of BPA through oxidative stress. In addition, BPA exposure had negative effects on the exercise behavior, the catalase (CAT) and superoxide dismutase (SOD) activity, and the larval development and gene expression of zebrafish larvae, and LCC preparations could recover these negative effects by reducing oxidative stress. In zebrafish treated with BPA, carbohydrate-rich LCCs showed stronger antioxidant activity than lignin-rich LCCs, showing their potential as a neuroprotective agents.

Insight in the Recent Application of Polyphenols From Biomass

Biomass polyphenols are bio-active macromolecules with distinct chemical structures in a variety of biomass. In recent years, the study of biomass polyphenols and their application in food and medicine fields has become a research hotspot, which predominantly focuses on the preparation, purification, structural identifications, and measurements of biological activities. Many studies describe methodologies for extraction and application of polyphenols, but comprehensive work to review its physiological activities like drugs and health products are lacking. This paper comprehensively unlocks the bioactivities of antioxidant, antibacterial, antitumor, anticancer, neuroprotection, control of blood sugar, regulation of blood fat, and promotion of gastrointestinal health functions of polyphenols from different biomass sources. This review will serve as an illuminating resource for the global scientific community, especially for those who are actively working to promote the advances of the polyphenols research field.

Effects of the Hofmeister anion series salts on the rheological properties of Sesbania cannabina galactomannan

Sesbania cannabina galactomannan (2%) solutions added with strongly hydrated ions (Na₂CO₃, NaH₂PO₄, NaCl) and weakly hydrated ions (NaNO₃) at different ionic strengths were rheologically characterized. The four selected salts dramatically decreased the intrinsic viscosity of galactomannan solution in the following order of effectiveness: Na₂CO₃ < NaH₂PO₄ < NaCl < NaNO₃. This conforms effectively to the Hofmeister anion series. Moreover, salt addition increased the viscosity of galactomannan solution when the ionic strength was 1 mmol/kg, which related to an increased occurrence of intermolecular interactions. As increasing ionic strength, galactomannan chains may tend to contract or expand due to the presence of strongly or weakly hydrated ions, thereby decreasing the viscosity. These phenomena were demonstrated by zeta potential measurement and again observed in dynamic viscoelasticity measurement. Overall, this property can be used to manipulate the rheological properties of galactomannan in food gums to obtain gums of high quality for enhancing consumer goods.