Antimicrobial Activity of Lignin and Lignin-Derived Cellulose and Chitosan Composites Against Selected Pathogenic and Spoilage Microorganisms

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.

Room Temperature Fabrication of Macroporous Lignin Membranes for the Scalable Production of Black Silicon

Rising global demand for biodegradable materials and green sources of energy has brought attention to lignin. Herein, we report a method for manufacturing standalone lignin membranes without additives for the first time to date. We demonstrate a scalable method for macroporous (∼100 to 200 nm pores) lignin membrane production using four different organosolv lignin materials under a humid environment (>50% relative humidity) at ambient temperatures (∼20 °C). A range of different thicknesses is reported with densely porous films observed to form if the membrane thickness is below 100 nm. The fabricated membranes were readily used as a template for Ni²⁺ incorporation to produce a nickel oxide membrane after UV/ozone treatment. The resultant mask was etched via an inductively coupled plasma reactive ion etch process, forming a silicon membrane and as a result yielding black silicon (BSi) with a pore depth of >1 μm after 3 min with reflectance <3% in the visible light region. We anticipate that our lignin membrane methodology can be readily applied to various processes ranging from catalysis to sensing and adapted to large-scale manufacturing.

Valorization of lignins from energy crops and agro-industrial byproducts as antioxidant and antibacterial materials

BACKGROUND

Developing eco-friendly antioxidant and antimicrobial substances originating from biomass residues has recently attracted considerable interest. In this study, two lignosulfonates and various oxidized water-soluble lignins were investigated for their antioxidant properties, as assessed by ABTS, DPPH and Folin-Ciocalteu methods, and their antimicrobial activity against some bacterial strains responsible for human pathologies.

RESULTS

The lignosulfonates showed the largest antiradical/antimicrobial capacity, whereas the other substrates were less effective. The observed antioxidant/antibacterial properties were positively correlated with lignin aromatic/phenolic content. The positive correlation between antiradical and antimicrobial activities suggests that lignin scavenging capacity was also involved in its antibacterial activity. A greater antimicrobial performance was generally observed against Gram-positive bacterial strains, and it was attributed to the intrinsic larger susceptibility of Gram-positive bacteria to lignin phenols. A significant though lesser inhibitory activity was also found against Escherichia coli.

CONCLUSION

Our results confirmed the dependence of lignin antioxidant/antibacterial power on its extraction method and chemical structure, as well as on the type of bacterial strains. Identifying the relationship between lignin molecular composition and its antioxidant/antibacterial features represents an advance on the potential future use of renewable and eco-compatible lignin materials in nutraceutical, pharmaceutical and cosmetic sectors. © 2021 Society of Chemical Industry.

Chitosan Film Functionalized with Grape Seed Oil—Preliminary Evaluation of Antimicrobial Activity

Although the fishing and wine industries undoubtedly contribute significantly to the economy, they also generate large waste streams with considerable repercussions on both economic and environmental levels. Scientific literature has shown products can be extracted from these streams which have properties of interest to the cosmetics, pharmaceutical and food industries. Antimicrobial activity is undoubtedly among the most interesting of these properties, and particularly useful in the production of food packaging to increase the shelf life of food products. In this study, film for food packaging was produced for the first time using chitosan extracted from the exoskeletons of red shrimp (Aristomorpha foliacea) and oil obtained from red grape seeds (Vitis vinifera). The antimicrobial activity of two films was analyzed: chitosan-only film and chitosan film with the addition of red grape seed oil at two different concentrations (0.5 mL and 1 mL). Our results showed noteworthy antimicrobial activity resulting from functionalized chitosan films; no activity was observed against pathogen and spoilage Gram-positive and Gram-negative bacteria, although the antimicrobial effects observed were species-dependent. The preliminary results of this study could contribute to developing the circular economy, helping to promote the reuse of waste to produce innovative films for food packaging.

Investigating the Antibacterial Characteristics of Japanese Bamboo

Natural materials, such as bamboo, is able to withstand the rough conditions posed by its environment, such as resistance to degradation by microorganisms, due to notable antibacterial characteristics. The methods of extraction exert a significant influence on the effectiveness of bamboo-derived antibacterial agents. In this study, the antibacterial characteristics of various types of Japanese bamboo, namely, Kyoto-Moso, Kyushu-Moso and Kyushu-Madake were investigated by considering an extraction and a non-extraction method. The characterization of the efficacy of antibacterial agents of various bamboo samples derived from both methods of extractions was conducted using an in vitro cultured bacteria technique consisting of E. coli and S. aureus. Antibacterial test results based on colony-forming units showed that antibacterial agents derived from the non-extraction method yielded better efficacy when tested against E. coli and S. aureus. Most specimens displayed maximum antibacterial efficacy following a 48-h period. The antibacterial agents derived from thermally modified bamboo powder via the non-extraction method showed improved antibacterial activity against S. aureus specifically. In contrast, absorbance results indicated that antibacterial agents derived from the extraction method yielded poor efficacy when tested against both E. coli and S. aureus. From FTIR analysis, characteristic bands assigned to the C-O and C-H functional groups in lignin were recognized as responsible for the antibacterial trait observed in both natural and thermally modified Japanese bamboo powder. Techniques to exploit the antibacterial characteristics present in bamboo by identification of antibacterial source and adoption of adequate methods of extraction are key steps in taking advantage of this attribute in numerous applications involving bamboo-derived products such as laminates and textile fabrics.

Antioxidant and Antimicrobial Properties of Mung Bean Phyto-Film Combined with Longkong Pericarp Extract and Sonication

Mung bean (Vigna radiata) flour serves as an excellent biopolymer and a potential material for producing antioxidant and antimicrobial phyto-films. In addition to mung bean flour, this study also combined the longkong (Aglaia dookkoo Griff.) pericarp extract (LPE, 1.5%) and ultrasonication process (0 (C1), 2 (T1), 4 (T2), 6 (T3), 8 (T4), and 10 (T5) min, sonicated at 25 kHz, 100% amplitude) in film emulsion production to improve the antioxidant and antimicrobial efficiency in the phyto-films. This study showed that sonication increased the phyto-films’ color into more lightness and yellowness, and the intensity of the color changes was in accordance with the increased sonication time. Alternatively, the thickness, water vapor permeability, and solubility of the films were adversely affected by extended sonication. In addition, elongation at break and tensile strength increased while the Young modulus decreased in the phyto-films with the extended sonication. Furthermore, the droplet size and polydispersity index of the phyto-films decreased with extended sonication. Conversely, the zeta potential of the film tended to increase with the treatments. Furthermore, phytochemicals such as total phenolic content and total flavonoid contents, and the radical scavenging ability of phyto-films against the DPPH radical, ABTS radical, superoxide radical, hydroxyl radical, and ferrous chelating activity, were significantly higher, and they were steadily increased in the films with the extended sonication time. Furthermore, the phyto-films showed a significant control against Gram (-) pathogens, followed by Gram (+) pathogens. A higher inhibitory effect was noted against L. monocytogens, followed by S. aureus and B. subtilis. Similarly, the phyto-films also significantly inhibited the Gram (-) pathogens, and significant control was noted against C. jejuni, followed by E. coli and P. aeruginosa. Regardless of the mung bean flour, this study found that longkong pericarp extract and the sonication process could also effectively be used in the film emulsions to enhance the efficiency of the antioxidant and antimicrobial properties of phyto-films.

Circular Hazelnut Protection by Lignocellulosic Waste Valorization for Nanopesticides Development

Hazelnut represents a relevant agro-food supply chain in many countries worldwide. Several biological adversities threaten hazelnut cultivation, but among them bacterial blight is one of the most feared and pernicious since its control can be achieved only by prevention through the observation of good agricultural practices and the use of cupric salts. The aim of this work was to evaluate the lignocellulosic biomasses obtained from hazelnut pruning and shelling residues as a renewable source of cellulose nanocrystals and lignin nanoparticles and to investigate their antimicrobial properties against hazelnut bacterial blight. Cellulose nanocrystals were obtained through an acid hydrolysis after a chemical bleaching, while lignin nanoparticles were synthesized by a solvent–antisolvent method after an enzymatic digestion. Both collected nanomaterials were chemically and morphologically characterized before being tested for their in vitro and in vivo antibacterial activity and biocompatibility on hazelnut plants. Results indicated the selected biomasses as a promising starting material for lignocellulosic nanocarriers synthesis, confirming at the same time the potential of cellulose nanocrystals and lignin nanoparticles as innovative tools to control hazelnut bacterial blight infections without showing any detrimental effects on the biological development of treated hazelnut plants.

How far is Lignin from being a biomedical material?

Lignin is a versatile biomass that possesses many different desirable properties such as antioxidant, antibacterial, anti-UV, and good biocompatibility. Natural lignin can be processed through several chemical processes. The processed lignin can be modified into functionalized lignin through chemical modifications to develop and enhance biomaterials. Thus, lignin is one of the prime candidate for various biomaterial applications such as drug and gene delivery, biosensors, bioimaging, 3D printing, tissue engineering, and dietary supplement additive. This review presents the potential of developing and utilizing lignin in the outlook of new and sustainable biomaterials. Thereafter, we also discuss on the challenges and outlook of utilizing lignin as a biomaterial.

Highly Functional Materials Based on Nano-Lignin, Lignin, and Lignin/Silica Hybrid Capped Silver Nanoparticles with Antibacterial Activities

Rice husk is one of the most abundant biomass resources in the world, yet it is not effectively used. This study focuses on the sustainably rice-husk-extracted lignin, nano-lignin (n-Lignin), lignin-capped silver nanoparticles (LCSN), n-Lignin-capped silver nanoparticles (n-LCSN), and lignin-capped silica-silver nanoparticles (LCSSN), and using them for antibacterial activities. The final n-Lignin-based products had a sphere-like structure, of which the size varied between 50 and 80 nm. We found that while n-Lignin and lignin were less effective against Escherichia coli than against Staphylococcus aureus, n-Lignin/lignin-based hybrid materials, i.e., n-LCSN, LCSN, and LCSSN, were better against E. coli than against S. aureus. Interestingly, the antimicrobial behaviors of n-LCSNs could be further improved by decreasing the size of n-Lignin. Considering the facile, sustainable, and eco-friendly method that we have developed here, it is promising to use n-Lignin/lignin-based materials as highly efficient antimicrobials without environmental concerns.

The SlHB8 Acts as a Negative Regulator in Stem Development and Lignin Biosynthesis

The stem is an important organ in supporting plant body, transporting nutrients and communicating signals for plant growing. However, studies on the regulation of stem development in tomato are rather limited. In our study, we demonstrated that SlHB8 negatively regulated tomato stem development. SlHB8 belongs to homeo domain-leucine zipper Class III gene family transcription factors and expressed in all the organs examined including root, stem, leaves, flower, and fruit. Among these tissues, SlHB8 showed stable high expression level during tomato stem development. Overexpression of SlHB8 gene decreased stem diameter with inhibited xylem width and xylem cell layers, while loss of function of SlHB8gene increased the stem diameter and xylem width. The contents of lignin were decreased both in leaves and stems of SlHB8 overexpression plants. RNA-seq analysis on the stems of wild type and SlHB8 transgenic plants showed that the 116 DEGs (differential expressed genes) with reversible expression profiles in SlHB8-ox and SlHB8-cr plants were significantly enriched in the phenylpropanoid biosynthesis pathway and plant-pathogen pathway which were related to lignin biosynthesis and disease resistance. Meanwhile, the key genes involved in the lignin biosynthesis pathway such as SlCCR (cinnamoyl-CoA reductase), SlCYP73A14/C4H (cinnamate 4-hydroxylase), SlC3H (coumarate 3-hydroxylase) and SlCAD (cinnamoyl alcohol dehydrogenase) were down-regulated in both stem and leaves of SlHB8 overexpression plants, indicating a negative regulatory role of SlHB8 in the lignin biosynthesis and stem development.

Chitosan for biomedical applications, promising antidiabetic drug delivery system, and new diabetes mellitus treatment based on stem cell

Since chitosan's excellent pharmacokinetic and chemical properties, it is an attractive and promising carbohydrate biopolymer in biomedical applications. Chitosan's beneficial function in the defense and propagation of pancreatic β cells, reducing hyperglycemia, and avoiding diabetes mellitus associated with impaired lipid metabolism has been demonstrated in several studies. Additionally, chitosan has also been used in various nanocarriers to deliver various antidiabetic drugs to reduce glucose levels. Herein, the first to provide the currently available potential benefits of chitosan in diabetes mellitus treatment focuses on chitosan-based nanocarriers for oral administration of various antidiabetic drugs nasal and subcutaneous passages. Moreover, chitosan is used to activate and deliver stem cells and differentiate them into cells similar to pancreatic beta cells as a new type of treatment for type one diabetes mellitus. The results of this review will be helpful in the development of promising treatments and better control of diabetes mellitus.

Injectable Lignin-co-Gelatin Cryogels with Antioxidant and Antibacterial Properties for Biomedical Applications

For several biomedical applications, it is essential to develop novel bioactive materials. Such biomaterials could potentially improve wound healing, prevent infections, or be used in immunoengineering. For example, bioactive materials that reduce oxidative stress without relying on antibiotics and other drugs could be beneficial. Hydrogel-based biomaterials, especially those derived from natural polymers, have been regarded as one of the most promising scaffolds for biomedical research. These multifunctional scaffolds can exhibit high water adsorption capacity, biocompatibility, and biomechanical properties that can match native tissues. Cryogels are a special type of hydrogels in which polymers are cross-linked around ice crystals. As a result, cryogels exhibit unique physical features, including a macroporous and interconnected network, flexibility, shape-memory properties, and syringe injectability. Herein, we developed a multifunctional, i.e., antibacterial, antioxidant, and injectable cryogel by combining lignin with gelatin. The cryogel with 0.2% lignin showed a compressive modulus of 25 kPa and a compressive stress of 140 kPa at 80% strain, which is, respectively, 1.8 and 7 times higher than those of the pure gelatin cryogels. Meanwhile, such a cryogel formulation could completely recover its shape after compression up to 90% and was needle-injectable. Additionally, the lignin-co-gelatin cryogel with 0.1-0.2 lignin showed 8-10 mm of inhibition zone against the most common surgical site infection-associated pathogenic bacteria. Furthermore, lignin-co-gelatin cryogel was found to scavenge free radicals and have good cytocompatibility, and the cryogels with up to 0.2% lignin minimally activate naïve mouse bone marrow-derived dendritic cells. Overall, the current approach shows great promise for the design of bioresource-based multifunctional cryogels for a wide range of biomedical applications.

Multifunctional lignin-based nanocomposites and nanohybrids

Significant progress in lignins valorization and development of high-performance sustainable materials have been achieved in recent years. Reports related to lignin utilization indicate excellent prospects considering green chemistry, chemical engineering, energy, materials and polymer science, physical chemistry, biochemistry, among others. To fully realize such potential, one of the most promising routes involves lignin uses in nanocomposites and nanohybrid assemblies, where synergistic interactions are highly beneficial. This review first discusses the interfacial assembly of lignins with polysaccharides, proteins and other biopolymers, for instance, in the synthesis of nanocomposites. To give a wide perspective, we consider the subject of hybridization with metal and metal oxide nanoparticles, as well as uses as precursor of carbon materials and the assembly with other biobased nanoparticles, for instance to form nanohybrids. We provide cues to understand the fundamental aspects related to lignins, their self-assembly and supramolecular organization, all of which are critical in nanocomposites and nanohybrids. We highlight the possibilities of lignin in the fields of flame retardancy, food packaging, plant protection, electroactive materials, energy storage and health sciences. The most recent outcomes are evaluated given the importance of lignin extraction, within established and emerging biorefineries. We consider the benefit of lignin compared to synthetic counterparts. Bridging the gap between fundamental and application-driven research, this account offers critical insights as far as the potential of lignin as one of the frontrunners in the uptake of bioeconomy concepts and its application in value-added products.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. Coli ATCC 25922 and MCR 1+ E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

Development and Characterization of Novel Cellulose Composites Obtained in 1-Ethyl-3-methylimidazolium Chloride Used as Drug Delivery Systems

Two polysaccharides (cellulose and chitosan) and polyurethane dissolved in 1-ethyl-3-methylimidazolium chloride represented the matrix for the obtainment of new composite formulations comprised of lignin, ferrite-lignin hybrid and ketoconazole. The mechanical performances (Young's modulus and compressive strength) increased with the filler addition. The nature of the filler used in the studied formulations influenced both bioadhesion and mucoadhesion parameters. It was found that the incorporation of lignin and ferrite-lignin hybrid into the matrix has influenced the in vitro rate of ketoconazole release, which is described by the Korsmeyer-Peppas model. All materials exhibited activity against Gram positive (Staphylococcus aureus ATCC 25923) and Gram negative (Escherichia coli ATCC 25922) bacteria.

Sinking Our Teeth in Getting Dental Stem Cells to Clinics for Bone Regeneration

Dental stem cells have been isolated from the medical waste of various dental tissues. They have been characterized by numerous markers, which are evaluated herein and differentiated into multiple cell types. They can also be used to generate cell lines and iPSCs for long-term in vitro research. Methods for utilizing these stem cells including cellular systems such as organoids or cell sheets, cell-free systems such as exosomes, and scaffold-based approaches with and without drug release concepts are reported in this review and presented with new pictures for clarification. These in vitro applications can be deployed in disease modeling and subsequent pharmaceutical research and also pave the way for tissue regeneration. The main focus herein is on the potential of dental stem cells for hard tissue regeneration, especially bone, by evaluating their potential for osteogenesis and angiogenesis, and the regulation of these two processes by growth factors and environmental stimulators. Current in vitro and in vivo publications show numerous benefits of using dental stem cells for research purposes and hard tissue regeneration. However, only a few clinical trials currently exist. The goal of this review is to pinpoint this imbalance and encourage scientists to pick up this research and proceed one step further to translation.

Can Sustainable Packaging Help to Reduce Food Waste? A Status Quo Focusing Plant-Derived Polymers and Additives

The promotion of sustainable packaging is part of the European Green Deal and plays a key role in the EU’s social and political strategy. One option is the use of renewable resources and biomass waste as raw materials for polymer production. Lignocellulose biomass from annual and perennial industrial crops and agricultural residues are a major source of polysaccharides, proteins, and lignin and can also be used to obtain plant-based extracts and essential oils. Therefore, these biomasses are considered as potential substitute for fossil-based resources. Here, the status quo of bio-based polymers is discussed and evaluated in terms of properties related to packaging applications such as gas and water vapor permeability as well as mechanical properties. So far, their practical use is still restricted due to lower performance in fundamental packaging functions that directly influence food quality and safety, the length of shelf life, and thus the amount of food waste. Besides bio-based polymers, this review focuses on plant extracts as active packaging agents. Incorporating extracts of herbs, flowers, trees, and their fruits is inevitable to achieve desired material properties that are capable to prolong the food shelf life. Finally, the adoption potential of packaging based on polymers from renewable resources is discussed from a bioeconomy perspective.

Potentials of polysaccharides, lipids and proteins in biodegradable food packaging applications

Bio-based packaging materials are gaining importance due to their biodegradability, sustainability and environmental friendliness. To control the food quality and improve the food safety standards, proteins polysaccharide and lipid-based packaging films are enriched with bioactive and functional substances. However, poor permeability and mechanical characteristics are the challenging areas in their commercialization. Scientists and researchers are using a combination of techniques i.e. hydrogels, crosslinking, etc. to improve the intermolecular forces between different components of the film formulation to counter these challenges More recently, biodegradable packaging materials, sometimes edible, are also used for the delivery of functional ingredients which reveals their potential for drug delivery to counter the nutrient deficiency problems. This study highlights the potentials of bio-based materials i.e. proteins, polysaccharides, lipids, etc. to develop biodegradable packaging materials. It also explores the additives used to improve the physicochemical and mechanical properties of biodegradable packaging materials. Furthermore, it highlights the novel trends in biodegradable packaging from a food safety and quality point of view.

Antimicrobial Polymer-Based Assemblies: A Review

An antimicrobial supramolecular assembly (ASA) is conspicuous in biomedical applications. Among the alternatives to overcome microbial resistance to antibiotics and drugs, ASAs, including antimicrobial peptides (AMPs) and polymers (APs), provide formulations with optimal antimicrobial activity and acceptable toxicity. AMPs and APs have been delivered by a variety of carriers such as nanoparticles, coatings, multilayers, hydrogels, liposomes, nanodisks, lyotropic lipid phases, nanostructured lipid carriers, etc. They have similar mechanisms of action involving adsorption to the cell wall, penetration across the cell membrane, and microbe lysis. APs, however, offer the advantage of cheap synthetic procedures, chemical stability, and improved adsorption (due to multipoint attachment to microbes), as compared to the expensive synthetic routes, poor yield, and subpar in vivo stability seen in AMPs. We review recent advances in polymer-based antimicrobial assemblies involving AMPs and APs.

Investigation of the biological activity, mechanical properties and wound healing application of a novel scaffold based on lignin-agarose hydrogel and silk fibroin embedded zinc chromite nanoparticles

Given the important aspects of wound healing approaches, in this work, an innovative biocompatible nanobiocomposite scaffold was designed and prepared based on cross-linked lignin-agarose hydrogel, extracted silk fibroin solution, and zinc chromite (ZnCr2O4) nanoparticles. Considering the cell viability technique, red blood cell hemolysis in addition to anti-biofilm assays, it was determined that after three days, the toxicity of the cross-linked lignin-agarose/SF/ZnCr2O4 nanobiocomposite was less than 13%. Moreover, the small hemolytic effect (1.67%) and high level of prevention in forming a P. aeruginosa biofilm with low OD value (0.18) showed signs of considerable hemocompatibility and antibacterial activity. Besides, according to an in vivo assay study, the wounds of mice treated with the cross-linked lignin-agarose/SF/ZnCr2O4 nanobiocomposite scaffold were almost completely healed in five days. Aside from these biological tests, the structural features were evaluated by FT-IR, EDX, FE-SEM, and TG analyses, as well as swelling ratio, rheological, and compressive mechanical study tests. Additionally, it was concluded that adding silk fibroin and ZnCr2O4 nanoparticles could enhance the mechanical tensile properties of cross-linked lignin-agarose hydrogel, and also an elastic network was characterized for this designed nanobiocomposite.

Proteomic reveals the influences of smoke-water and karrikinolide on the biosynthesis of salvianolic acids and lignins in Salvia miltiorrhiza hairy roots

The proteins related to the biosynthesis of salvianolic acids and lignins were regulated by smoke-water and karrikinolide in Salvia miltiorrhiza hairy roots. The effects of smoke-water (SW) and karrikinolide (KAR₁) on the biosynthesis of salvianolic acids and lignins in Salvia miltiorrhiza hairy roots have been studied using proteomic technology. The results showed that a total of 1290 and 1678 differentially expressed proteins were respectively obtained in SW and KAR₁ comparing to the control. Bioinformatics analysis indicated the differentially expressed proteins responding to SW and KAR₁ treatments mainly involved in macromolecule metabolic process, cell part, binding, etc., and most of the proteins were located at the cytoplasm and cell membrane, followed by nuclear. In addition, the proteins involved in salvianolic acids biosynthesis were up-regulated, including 4-coumarate-CoA ligase (EC 6.2.1.12) and shikimate O-hydroxycinnamoyl-transferase (EC 2.3.1.133). Enzymes involved in lignins biosynthesis were also identified, e.g. cinnamyl-alcohol dehydrogenase (EC 1.1.1.195) and peroxidase (EC 1.11.1.7). The results indicated that proteins related to the biosynthesis of salvianolic acids and lignins were regulated by SW and KAR₁ in S. miltiorrhiza hairy roots. This study will enhance our understanding of the mechanism by which SW and KAR₁ on the biosynthesis of salvianolic acids and lignins in S. miltiorrhiza hairy roots.

Material utilization of green waste: a review on potential valorization methods

Considering global developments like climate change and the depletion of fossil resources, the use of new and sustainable feedstocks such as lignocellulosic biomass becomes inevitable. Green waste comprises heterogeneous lignocellulosic biomass with low lignin content, which does not stem from agricultural processes or purposeful cultivation and therefore mainly arises in urban areas. So far, the majority of green waste is being composted or serves as feedstock for energy production. Here, the hitherto untapped potential of green waste for material utilization instead of conventional recycling is reviewed. Green waste is a promising starting material for the direct extraction of valuable compounds, the chemical and fermentative conversion into basic chemicals as well as the manufacturing of functional materials like electrodes for electro-biotechnological applications through carbonization. This review serves as a solid foundation for further work on the valorization of green waste.

Development of a light activatable lignin nanosphere based spray coating for bioimaging and antimicrobial photodynamic therapy

Many coating materials are commercially available to combat microbial infections. However, these coatings are difficult to synthesize, and are mostly composed of toxic chemicals. Lignin is an under-explored natural biopolymer with multifaceted potential. Lignin, with adhesive, UV resistant, and antimicrobial properties, is a suitable candidate to develop coating materials. Here we report a smart method to fabricate a sustainable nanospray coating from lignin which does not require any toxic chemicals or additives during synthesis. Initially, we have developed stable lignin nanospheres in a single step in aqueous medium, which were later utilized as a lignin nanospray (LNSR). The LNSR was characterized by dynamic light scattering, scanning electron microscopy, FTIR and other analytical techniques. This LNSR showed remarkable UV blocking, antioxidant and light-activated antimicrobial properties. Interestingly, for the first time, the LNSR demonstrated photoluminescence, making it useful for bioimaging. Moreover, singlet oxygen generation potential was observed in the LNSR, which could render it useful in phototheranostic applications (i.e. light assisted imaging and photodynamic therapy). Further, the LNSR was directly utilized to fabricate a sustainable coating. The nanospray coating exhibited maximum light-induced cell killing when applied to common microbes as detected by live-dead cell imaging. Taken together, the lignin nanospray coating developed via a direct pathway holds great promise to disinfect microbes in the presence of light.

Lignins Isolated via Catalyst-Free Organosolv Pulping from Miscanthus x giganteus, M. sinensis, M. robustus and M. nagara: A Comparative Study

As a low-input crop, Miscanthus offers numerous advantages that, in addition to agricultural applications, permits its exploitation for energy, fuel, and material production. Depending on the Miscanthus genotype, season, and harvest time as well as plant component (leaf versus stem), correlations between structure and properties of the corresponding isolated lignins differ. Here, a comparative study is presented between lignins isolated from M. x giganteus, M. sinensis, M. robustus and M. nagara using a catalyst-free organosolv pulping process. The lignins from different plant constituents are also compared regarding their similarities and differences regarding monolignol ratio and important linkages. Results showed that the plant genotype has the weakest influence on monolignol content and interunit linkages. In contrast, structural differences are more significant among lignins of different harvest time and/or season. Analyses were performed using fast and simple methods such as nuclear magnetic resonance (NMR) spectroscopy. Data was assigned to four different linkages (A: β-O-4 linkage, B: phenylcoumaran, C: resinol, D: β-unsaturated ester). In conclusion, A content is particularly high in leaf-derived lignins at just under 70% and significantly lower in stem and mixture lignins at around 60% and almost 65%. The second most common linkage pattern is D in all isolated lignins, the proportion of which is also strongly dependent on the crop portion. Both stem and mixture lignins, have a relatively high share of approximately 20% or more (maximum is M. sinensis Sin2 with over 30%). In the leaf-derived lignins, the proportions are significantly lower on average. Stem samples should be chosen if the highest possible lignin content is desired, specifically from the M. x giganteus genotype, which revealed lignin contents up to 27%. Due to the better frost resistance and higher stem stability, M. nagara offers some advantages compared to M. x giganteus. Miscanthus crops are shown to be very attractive lignocellulose feedstock (LCF) for second generation biorefineries and lignin generation in Europe.

Revisiting lignin: a tour through its structural features, characterization methods and applications

A pedagogical overview of the main extraction procedures and structural features, characterization methods and state-of-the-art applications.

Antioxidant, antibacterial and antitumoural activities of kraft lignin from hardwood fractionated by acid precipitation

Kraft lignin, so far useful for energy generation, has been gathering considerable attention as an alternative material to replace fossil-based resources mainly due to its high phenolic content. However, the wide molecular weight distribution and chemical composition heterogeneity led to the development of fractionation methods. Herein, to narrow such characteristics we used eucalypt kraft lignin fractionated at pH's 9, 7, 5 and 3 by sequential acid precipitation. These lignin fractions were first characterised by simultaneous pyrolysis and trimethylsilylation (SPyT) with N-Methyl-N-(trimethylsilyl) trifluoroacetamide with posterior tests of antioxidant, antibacterial, and antitumour activities. We observed higher ratio of syringyl/guaiacyl groups and increase in antioxidant activity in those fractions with lower molecular weight (precipitated at lower pH's). Fractions precipitated at pH's 9 and 7 have shown an outstanding antibacterial activity against five bacteria. Moreover, fractions 7 and 5 presented at cytotoxicity tests higher ability to inhibit the growth of U87MG and T98G glioma cells, while only a slight inhibition of adult human fibroblasts (non-tumour cells) was detected.

Lignin-Based Sunscreens—State-of-the-Art, Prospects and Challenges

This review covers the latest developments and challenges in the field of broad-spectrum sunscreens and how sunscreens based on lignin address their requirements in terms of sunlight protection, antioxidants, and preservatives.

Challenges and physiological implications of wood feeding in termites

Termites are fascinating insects for a number of reasons, one of which being their specialization on diets of wood lignocellulose. The goal of this review is to consider stress-inducing characteristics of wood and apparent molecular-physiological adaptations in termite guts to overcome these stressors. Defensive factors present in wood include extractive secondary plant metabolites, lignin and related phenolics, crystalline cellulose, and low nitrogen content. Molecular-physiological adaptations of the termite gut to deal with these factors include robust detoxification and antioxidant machinery, the production of a peritrophic matrix and a wide range of cellulases from host and symbiotic sources, and creation of niches available to nitrogen-fixing bacterial symbionts. Considering termite gut physiology and symbioses in the context of stress-response has applied implications. These outcomes can include development of efficient biomass breakdown strategies, protection of microbes during industrial processing applications, and safeguarding wooden structures from termite damage.

Encapsulation Systems for Antimicrobial Food Packaging Components: An Update

Antimicrobially active packaging has emerged as an effective technology to reduce microbial growth in food products increasing both their shelf-life and microbial safety for the consumer while maintaining their quality and sensorial properties. In the last years, a great effort has been made to develop more efficient, long-lasting and eco-friendly antimicrobial materials by improving the performance of the incorporated antimicrobial substances. With this purpose, more effective antimicrobial compounds of natural origin such as bacteriocins, bacteriophages and essential oils have been preferred over synthetic ones and new encapsulation strategies such as emulsions, core-shell nanofibres, cyclodextrins and liposomes among others, have been applied in order to protect these antimicrobials from degradation or volatilization while trying to enable a more controlled release and sustained antimicrobial action. On that account, this article provides an overview of the types of antimicrobials agents used and the most recent trends on the strategies used to encapsulate the antimicrobial agents for their stable inclusion in the packaging materials. Moreover, a thorough discussion regarding the benefits of each encapsulation technology as well as their application in food products is presented.

Synthesis and polymerization of bio-based acrylates: a review

Acrylates and polyacrylates have been produced massively due to their interesting applications like Plexiglas.

Antimicrobial Activity of Lignin-Derived Polyurethane Coatings Prepared from Unmodified and Demethylated Lignins

Due to global ecological and economic challenges that have been correlated to the transition from fossil-based to renewable resources, fundamental studies are being performed worldwide to replace fossil fuel raw materials in plastic production. One aspect of current research is the development of lignin-derived polyols to substitute expensive fossil-based polyol components for polyurethane and polyester production. This article describes the synthesis of bioactive lignin-based polyurethane coatings using unmodified and demethylated Kraft lignins. Demethylation was performed to enhance the reaction selectivity toward polyurethane formation. The antimicrobial activity was tested according to a slightly modified standard test (JIS Z 2801:2010). Besides effects caused by the lignins themselves, triphenylmethane derivatives (brilliant green and crystal violet) were used as additional antimicrobial substances. Results showed increased antimicrobial capacity against Staphylococcus aureus. Furthermore, the coating color could be varied from dark brown to green and blue, respectively.