Enzymatic modification of polysaccharides: Mechanisms, properties, and potential applications: A review

Engineered inulin-based hybrid biomaterials for augmented immunomodulatory responses

Modified biopolymers that are based on prebiotics have been found to significantly contribute to immunomodulatory events. In recent years, there has been a growing use of modified biomaterials and polymer-functionalized nanomaterials in the treatment of various tumors by activating immune cells. However, the effectiveness of immune cells against tumors is hindered by several biological barriers, which highlights the importance of harnessing prebiotic-based biopolymers to enhance host defenses against cancer, thus advancing cancer prevention strategies. Inulin, in particular, plays a crucial role in activating immune cells and promoting the secretion of cytokines. Therefore, this mini-review aims to emphasize the importance of inulin in immunomodulatory responses, the development of inulin-based hybrid biopolymers, and the role of inulin in enhancing immunity and modifying cell surfaces. Furthermore, we discuss the various approaches of chemical modification for inulin and their potential use in cancer treatment, particularly in the field of cancer immunotherapy.

Tailor-Made Polysaccharides for Biomedical Applications

Polysaccharides (PSAs) are carbohydrate-based macromolecules widely used in the biomedical field, either in their pure form or in blends/nanocomposites with other materials. The relationship between structure, properties, and functions has inspired scientists to design multifunctional PSAs for various biomedical applications by incorporating unique molecular structures and targeted bulk properties. Multiple strategies, such as conjugation, grafting, cross-linking, and functionalization, have been explored to control their mechanical properties, electrical conductivity, hydrophilicity, degradability, rheological features, and stimuli-responsiveness. For instance, custom-made PSAs are known for their worldwide biomedical applications in tissue engineering, drug/gene delivery, and regenerative medicine. Furthermore, the remarkable advancements in supramolecular engineering and chemistry have paved the way for mission-oriented biomaterial synthesis and the fabrication of customized biomaterials. These materials can synergistically combine the benefits of biology and chemistry to tackle important biomedical questions. Herein, we categorize and summarize PSAs based on their synthesis methods, and explore the main strategies used to customize their chemical structures. We then highlight various properties of PSAs using practical examples. Lastly, we thoroughly describe the biomedical applications of tailor-made PSAs, along with their current existing challenges and potential future directions.

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Extraction, purification, structural characteristic, health benefit, and product application of the polysaccharides from bamboo shoot: A review

Bamboo shoot is a kind of widely distributed natural green vegetable, which has a long history of consumption and cultivation, and has edible, nutritional and economic value. Bamboo shoot is nutrient-rich food with carbohydrates, fats, proteins, polysaccharides, flavonoids, alkaloids and other chemical components, can meet the body's needs. Notably, bamboo shoot polysaccharides are the most attractive saccharides, most of which are water-soluble polysaccharides, and their various biological activities have been paid more attention by researchers. With the deepening of research on bamboo shoot polysaccharides, they have been found to have anti-diabetic, anti-oxidant, anti-inflammatory, anti-complement activities, immunomodulatory, etc. Further research on bamboo shoot polysaccharides, their sources, molecular weights, chemical structures, monosaccharide compositions and structural characteristics are constantly explored. In order to better research and development of bamboo shoot polysaccharides, it is necessary to carry on a comprehensive arrangement. Here, the extraction and purification methods, structural characteristics, health benefits, structure-activity relationships and product applications of bamboo shoot polysaccharides were systematically reviewed. This article will deepen the understanding of bamboo shoot polysaccharides, provide knowledge base for further research on bamboo shoot polysaccharides, and expand the vision for developing related products.

Chemical structures, extraction and analysis technologies, and bioactivities of edible fungal polysaccharides from Poria cocos: An updated review

Poria cocos is a popular medicinal food. Polysaccharides are the key component of Poria cocos, forming 70-90 % of the dry sclerotia mass. Recent studies indicate that Poria cocos polysaccharides (PCP-Cs) have multiple beneficial functions and applications. A literature search was conducted using the Web of Science Core Collection and PubMed databases. For this review, we provided an updated research progress in chemical structures, various extraction and analysis technologies, bioactivities of PCP-Cs, and insights into the directions for future research. The main polysaccharides identified in Poria cocos are water-soluble polysaccharides and acidic polysaccharides. Hot water, alkali, supercritical fluid, ultrasonic, enzyme, and deep eutectic solvent-based methods are the most common methods for PCP-Cs extraction. Technologies such as near-infrared spectroscopy, high-performance liquid chromatography, and ultraviolet-visible spectrophotometry, are commonly used to evaluate the qualities of PCP-Cs. In addition, PCP-Cs have antioxidant, immunomodulatory, neuroregulatory, anticancer, hepatoprotective, and gut microbiota regulatory properties. Future research is needed to focus on scaling up extraction, enhancing quality control, elucidating mechanisms of bioactivities, and the utilisation of PCP-Cs in food industries. Overall, Poria cocos is a good source of edible fungi polysaccharides, which can be developed into functional foods with potential health benefits.

Laccases as Effective Tools in the Removal of Pharmaceutical Products from Aquatic Systems

This review aims to provide a comprehensive overview of the application of bacterial and fungal laccases for the removal of pharmaceuticals from the environment. Laccases were evaluated for their efficacy in degrading pharmaceutical substances across various categories, including analgesics, antibiotics, antiepileptics, antirheumatic drugs, cytostatics, hormones, anxiolytics, and sympatholytics. The capability of laccases to degrade or biotransform these drugs was found to be dependent on their structural characteristics. The formation of di-, oligo- and polymers of the parent compound has been observed using the laccase mediator system (LMS), which is advantageous in terms of their removal via commonly used processes in wastewater treatment plants (WWTPs). Notably, certain pharmaceuticals such as tetracycline antibiotics or estrogen hormones exhibited degradation or even mineralization when subjected to laccase treatment. Employing enzyme pretreatment mitigated the toxic effects of degradation products compared to the parent drug. However, when utilizing the LMS, careful mediator selection is essential to prevent potential increases in environment toxicity. Laccases demonstrate efficiency in pharmaceutical removal within WWTPs, operating efficiently under WWTP conditions without necessitating isolation.

State-of-the-art advancement in tara gum polysaccharide (Caesalpinia spinosa) modifications and their potential applications for drug delivery and the food industry

In preference to synthetic or petroleum-based materials, current research in food and pharmaceutical industries has focused on the development of biodegradable and sustainable materials due to their low toxicity, and biocompatibility. In particular, the natural water-soluble polysaccharide tara gum (Caesalpinia spinosa) has been widely used as a food-grade and drug-delivery agent due to its biodegradability, and biocompatibility. Moreover, owing to its easily modifiable hydroxy groups, tara gum, and its derivatives have been employed as food packaging films and pharmaceutical materials. In the present critical review, facile grafting methods of tara gum are reviewed, and an up-to-date comprehensive application of tara gum polysaccharides revealed their uses in pH-sensitive food packaging. In addition, modified tara gum materials exhibited improved drug delivery applications with biocompatible properties. The non-toxic nature and non-Newtonian, pseudoplastic rheological properties as well as the synergistic behavior of tara gum with other polysaccharides explore its further industrial applications in several fields. Additionally, several approaches for improving tara gum for use as a stabilizer and thickener for food items, and monitoring food spoilage, have provided notable customized characteristics. In brief, its many advantages make tara gum polysaccharide a promising material for applications in the food and pharmaceutical industries.

Role of carbohydrate binding modules, CBM3A and CBM3B in stability and catalysis by a β-1,4 endoglucanase, AtGH9C-CBM3A-CBM3B from Acetivibrio thermocellus ATCC 27405

A recombinant β-1,4 endoglucanase, AtGH9C-CBM3A-CBM3B from Acetivibrio thermocellus ATCC27405 was explored for biochemical properties and the role of its associated CBMs in catalysis. The gene expressing full-length multi-modular β-1,4-endoglucanase (AtGH9C-CBM3A-CBM3B) and its truncated derivatives (AtGH9C-CBM3A, AtGH9C, CBM3A and CBM3B) were independently cloned and expressed in Escherichia coli BL21(DE3) cells and purified. AtGH9C-CBM3A-CBM3B showed maximal activity at 55 °C and pH 7.5. AtGH9C-CBM3A-CBM3B exhibited highest activity against carboxy methyl cellulose (58.8 U/mg) followed by lichenan (44.5 U/mg), β-glucan (36.2 U/mg) and hydroxy ethyl cellulose (17.9 U/mg). Catalytic module, AtGH9C showed insignificant activity against the substrates, signifying the essential requirement of CBMs in catalysis. AtGH9C-CBM3A-CBM3B displayed stability in pH range, 6.0-9.0 and thermostability up to 60 °C for 90 min with unfolding transition midpoint (T_m) of 65 °C. The generation of cellotetraose and other higher oligosaccharides by AtGH9C-CBM3A-CBM3B confirmed it as an endo-β-1,4-glucanase. AtGH9C activity was partially recovered by the addition of equimolar concentration of CBM3A, CBM3B or CBM3A + CBM3B by 47 %, 13 % or 50 %, respectively. Moreover, the associated CBMs imparted thermostability to the catalytic module, AtGH9C. These results showed that the physical association of AtGH9C with its associated CBMs and the cross-talk between CBMs are necessary for AtGH9C-CBM3A-CBM3B in effective cellulose catalysis.

Nanosilver-functionalized polysaccharides as a platform for wound dressing

Polysaccharides that are naturally sourced have enormous promise as wound dressings, due to their wider availability and reasonable cost and good biocompatibility. Furthermore, nanosilver extensively applied in wound treatment is attributed to its broad spectrum of antimicrobial effects and lesser drug resistance. Consequently, wound dressings in corporating nanosilver have attracted wide-scale interest in wound healing, and nanosilver-functionalized polysaccharide-based wound dressings present an affordable option for healing of chronic wounds. This review encompasses preparation methods, classification, and antibacterial performances of nanosilver wound dressings. The prospective research arenas of nanosilver-based wound polysaccharide dressings are also elaborated. The review attempts to include a summary of the most recent advancements in silver nanotechnology as well as guidance for the investigation of nanosilver-functionalized polysaccharide-based wound dressings.

Current Advancements in Pectin: Extraction, Properties and Multifunctional Applications

Pectin is a heterogeneous hydrocolloid present in the primary cell wall and middle lamella in all dicotyledonous plants, more commonly in the outer fruit coat or peel as compared to the inner matrix. Presently, citrus fruits and apple fruits are the main sources for commercial extraction of pectin, but ongoing research on pectin extraction from alternate fruit sources and fruit wastes from processing industries will be of great help in waste product reduction and enhancing the production of pectin. Pectin shows multifunctional applications including in the food industry, the health and pharmaceutical sector, and in packaging regimes. Pectin is commonly utilized in the food industry as an additive in foods such as jams, jellies, low calorie foods, stabilizing acidified milk products, thickener and emulsifier. Pectin is widely used in the pharmaceutical industry for the preparation of medicines that reduce blood cholesterol level and cure gastrointestinal disorders, as well as in cancer treatment. Pectin also finds use in numerous other industries, such as in the preparation of edible films and coatings, paper substitutes and foams. Due to these varied uses of pectin in different applications, there is a great necessity to explore other non-conventional sources or modify existing sources to obtain pectin with desired quality attributes to some extent by rational modifications of pectin with chemical and enzymatic treatments.

Recent Advances in Lipases and Their Applications in the Food and Nutraceutical Industry

Lipases are efficient enzymes with promising applications in the nutraceutical and food industry, as they can offer high yields, pure products under achievable reaction conditions, and are an environmentally friendly option. This review addresses the production of high-value-added compounds such as fatty acid esters, with the potential to be used as flavoring agents or antioxidant and antimicrobial agents, as well as structured lipids that offer specific functional properties that do not exist in nature, with important applications in different food products, and pharmaceuticals. In addition, the most recent successful cases of reactions with lipases to produce modified compounds for food and nutraceuticals are reported.

Extraction, purification, structural features and biological activities of longan fruit pulp (Longyan) polysaccharides: A review

Dimocarpus longan Lour. (also called as longan) is a subtropical and tropical evergreen tree belonging to the Sapindaceae family and is widely distributed in China, Southeast Asia and South Asia. The pulp of longan fruit is a time-honored traditional medicinal and edible raw material in China and some Asian countries. With the advancement of food therapy in modern medicine, longan fruit pulp as an edible medicinal material is expected to usher in its rapid development as a functional nutrient. As one of the main constituents of longan fruit pulp, longan fruit pulp polysaccharides (LPs) play an indispensable role in longan fruit pulp-based functional utilization. This review aims to outline the extraction and purification methods, structural characteristics and biological activities (such as immunoregulatory, anti-tumor, prebiotic, anti-oxidant, anti-inflammatory and inhibition of AChE activity) of LPs. Besides, the structure-activity relationship, application prospect and patent application of LPs were analyzed and summarized. Through the systematic summary, this review attempts to provide a theoretical basis for further research of LPs, and promote the industrial development of this class of polysaccharides.

Current advances and potential trends of the polysaccharides derived from medicinal mushrooms sanghuang

For thousands of years, sanghuang is distinctive as a general designation for a group of precious and rare Chinese medicinal mushrooms. Numerous investigations have revealed that polysaccharide is one of the important biological active ingredients of sanghuang with various excellent biological activities, including antioxidant, anti-aging, anti-tumor, immunomodulatory, anti-inflammatory, anti-diabetic, hepatoprotective, and anti-microbial functionalities. For the past two decades, preparation, structural characterization, and reliable bioactivities of the polysaccharides from fruiting bodies, cultured mycelia, and fermentation broth of sanghuang have been arousing extensive interest, and particularly, different strains, sources, and isolation protocols might result in obvious discrepancies in structural features and bioactivities. Therefore, this review summarizes the recent reports on preparation strategies, structural features, bioactivities, and structure-activity relationships of sanghuang polysaccharides, which will enrich the knowledge on the values of natural sanghuang polysaccharides and support their further development and utilization as therapeutic agents, vaccines, and functional foods in tonic and clinical treatment.

Genipin-Crosslinking Effects on Biomatrix Development for Cutaneous Wound Healing: A Concise Review

Split skin graft (SSG), a standard gold treatment for wound healing, has numerous limitations such as lack of fresh skin to be applied, tedious process, severe scarring, and keloid formation followed by higher risks of infection. Thus, there is a gap in producing polymeric scaffolds as an alternative for wound care management. Bioscaffold is the main component in tissue engineering technology that provides porous three-dimensional (3D) microarchitecture for cells to survive. Upon skin tissue reconstruction, the 3D-porous structure ensures sufficient nutrients and gaseous diffusion and cell penetration that improves cell proliferation and vascularization for tissue regeneration. Hence, it is highly considered a promising candidate for various skin wound healing applications. To date, natural-based crosslinking agents have been extensively used to tailor the physicochemical and mechanical properties of the skin biomatrix. Genipin (GNP) is preferable to other plant-based crosslinkers due to its biological activities, such as antiinflammatory and antioxidant, which are key players to boost skin wound healing. In addition, it has shown a noncytotoxic effect and is biocompatible with human skin cells. This review validated the effects of GNP in biomatrix fabrication for skin wound healing from the last 7 years of established research articles and stipulated the biomaterial development-scale point of view. Lastly, the possible role of GNP in the skin wound healing cascade is also discussed. Through the literature output, it can be concluded that GNP has the capability to increase the stability of biomatrix and maintain the skin cells viability, which will contribute in accelerating wound healing.

Enzyme and microwave co-assisted extraction, structural characterization and antioxidant activity of polysaccharides from Purple-heart Radish

A novel method of simultaneous extraction and separation of diverse polysaccharides from Purple-heart Radish was developed by integrating EAE with MAATPE. The effects of different enzymes, the ATPS composition, extraction temperature, time etc. were investigated by single-factor experiments and RSM. Under the optimum conditions, the extraction yields of PTP, PBP and total polysaccharides were 9.107 ± 0.391%, 32.506 ± 0.046% and 41.613 ± 0.437%, respectively. By means of HPGPC and PMP-HPLC, Mw of PTP and Mw of PBP were 15935 Da and 27962 Da, respectively. PTP and PBP were mainly composed of mannose, glucuronic acid, aminogalactose, glucose, galactose and arabinose. Moreover, both polysaccharides exhibited stronger antioxidant activities for scavenging multiple radicals and anti-lipid peroxidation. Compared to the conventional extraction methods, EAE-MAATPE achieved higher extraction efficiency due to the synergistic effect between EAE and MAATPE leading to rupture and enzymolysis of cell. Thus, EAE-MAATPE provided an efficient alternative to simultaneous extraction of different polysaccharides from natural products.

Copolymers of starch, a sustainable template for biomedical applications: A review

The outstanding versatility of starch offers a source of inspiration for the development of high-performance-value-added biomaterials for the biomedical field, including drug delivery, tissue engineering and diagnostic imaging. This is because starch-based materials can be tailored to specific applications via facile grafting or other chemistries, introducing specific substituents, with starch being effectively the "template" used in all the chemical transformations discussed in this review. A considerable effort has been carried out to obtain specific tailored starch-based grafted polymers, taking advantage of its biocompatibility and biodegradability with appealing sustainability considerations. The aim of this review is to critically explore the latest research that use grafting chemistries on starch for the synthesis of products for biomedical applications. An effort is made in reviewing the literature that proposes synthetic "greener" approaches, the use of enzymes and their immobilized analogues and alternative solvent systems, including water emulsions, ionic liquids and supercritical CO₂.

Trends in "green" and novel methods of pectin modification - A review

Modification of hydrocolloids to alter their functional properties using chemical methods is well documented in the literature. There has been a recent trend of adopting eco-friendly and "green" methods for modification. Pectin, being a very important hydrocolloid finds its use in various food applications due to its gelling, emulsifying, and stabilizing properties. The adoption of various "green" methods can alter the properties of pectin and make it more suitable for incorporation in food products. The novel approaches such as microwave and pulsed electric field can also be utilized for solvent-free modification, making it desirable from the perspective of sustainability, as it reduces the consumption of organic chemicals. Pectic oligosaccharides (POSs) produced via novel approaches are being explored for their biological properties and incorporation in various functional foods. The review can help to set the perspective of potential scale-up and adoption by the food industry for modification of pectin.

Fabrication and biomedical applications of Arabinoxylan, Pectin, Chitosan, Soy protein, and Silk fibroin hydrogels via laccase - ferulic acid redox chemistry

The unique physiochemical properties and the porous network architecture of hydrogel seek the attention to be explored in broad range of fields. In the last decade, numerous studies on the development of enzymatically cross-linked hydrogels have been elucidated. Implementing enzyme based cross-linking for fabrication of biomaterials over other crosslinking methods harbor various advantages, especially hydrogels designed using laccase exhibits mild reaction environment, high cross-linking efficiency and less toxicity. To our knowledge this is the first report reviewing the formulation of laccase mediated cross-linking for hydrogel preparation. Here, laccase catalyzed synthesis of hydrogel using polysaccharide viz. arabinoxylan, sugar beet pectin, galactomannan, chitosan etc. and proteins namely soy protein, gelatin, silk fibroin were discussed on highlighting their mechanical properties and its possible field of application. We have summarized the role of phenolic acids in laccase mediated crosslinking particularly ferulic acid which is a component of lignocellulose, serving cell rigidity via crosslinkage. The review also discusses on various biomedical applications such as controlled protein release, tissue engineering, and wound healing. It is anticipated that this review will give a detailed information on different laccase mediated reaction strategies that can be applied for the synthesis of various new biomaterials with tailor made properties.

Recent advances in the enzymatic synthesis of lipophilic antioxidant and antimicrobial compounds

Due to the increase in the consumption of highly processed food in developed countries, as well as, a growing number of foodborne diseases, exploration of new food additives is an issue focusing on scientific attention and industrial interest. Functional compounds with lipophilic properties are remarkably desirable due to the high susceptibility to the deterioration of lipid-rich food products. This paper in a comprehensive manner provides the current knowledge about the enzymatic synthesis of lipophilic components that could act as multifunctional food additives. The main goal of enzymatic lipophilization of compounds intentionally added to food is to make these substances soluble in lipids and/or to obtain environmentally friendly surfactants. Moreover, lipase-catalyzed syntheses could result in changes in the antioxidant and antimicrobial activities of phenolic compounds, carbohydrates, amino acids (oligopeptides), and carboxylic acids. The review describes also the implementation of a new trend in green chemistry, where apart from simple and uncomplicated chemical compounds, the modifications of multi-compound mixtures, such as phenolic extracts or essential oils have been carried out.

Development of Starch-Based Materials Using Current Modification Techniques and Their Applications: A Review

Starch is one of the most common biodegradable polymers found in nature, and it is widely utilized in the food and beverage, bioplastic industry, paper industry, textile, and biofuel industries. Starch has received significant attention due to its environmental benignity, easy fabrication, relative abundance, non-toxicity, and biodegradability. However, native starch cannot be directly used due to its poor thermo-mechanical properties and higher water absorptivity. Therefore, native starch needs to be modified before its use. Major starch modification techniques include genetic, enzymatic, physical, and chemical. Among those, chemical modification techniques are widely employed in industries. This review presents comprehensive coverage of chemical starch modification techniques and genetic, enzymatic, and physical methods developed over the past few years. In addition, the current applications of chemically modified starch in the fields of packaging, adhesives, pharmaceuticals, agriculture, superabsorbent and wastewater treatment have also been discussed.

Laccase-Catalyzed Grafting of Lauryl Gallate on Chitosan To Improve Its Antioxidant and Hydrophobic Properties

Biografting is a promising and ecofriendly approach to meet various application requirements of products. Herein, a popular green enzyme, laccase, was adopted to graft a hydrophobic phenolic compound (lauryl gallate, LG) onto chitosan (CTS). The resultant chitosan derivate (Lac/LG-CTS) was systematically analyzed by Fourier transform infrared (FTIR), grafting efficiency, scanning probe microscopy (SPM), and X-ray diffraction (XRD). This grafting technique produced a multifunctional chitosan copolymer with remarkably enhanced antioxidant property, hydrophobicity, and moisture barrier property. Furthermore, the swelling capacity and acid solubility of the copolymer film decreased significantly, although the tensile strength and elongation were slightly weakened as compared to those of native chitosan. These results suggest that the Lac/LG-CTS holds great potential as a food-packaging material, preservative agent, or edible coating material.

Preparation, characterization, and antibiofilm activity of cinnamic acid conjugated hydroxypropyl chitosan derivatives

In this study, cinnamic acid (CA) conjugated hydroxypropyl chitosan (HPCS) derivatives (HPCS-CA) with different degrees of substitution (DS) were successfully synthesized. The reaction was divided into two steps: the first step was to modify chitosan (CS) to HPCS, and the second step was to graft CA onto HPCS. Structural characterization and properties were carried out employing elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The solubility test revealed the better water solubility of derivatives than CS. In addition, in vitro antibacterial and antibiofilm tests were performed. As expected, HPCS-CA derivatives exhibited good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The MIC and MBC of HPCS-CA derivatives could reach 256 μg/mL and 512 μg/mL, respectively. Confocal laser scanning microscopy (CLSM) analysis proved the inhibitory effect of HPCS-CA derivatives on S. aureus and E. coli biofilms by disrupting the formation of biofilms, reducing the thickness of biofilms, and the number of live bacteria. These results suggest the potential applicability of HPCS-CA derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of novel CS-based antibacterial materials.

Starch granule size: Does it matter?

Nature has developed starch granules varying in size from less than 1 μm to more than 100 μm. The granule size is an important factor affecting the functional properties and the applicability of starch for food and non-food applications. Within the same botanical species, the range of starch granule size can be up to sevenfold. This review critically evaluated the biological and environmental factors affecting the size of starch granules, the methods for the separation of starch granules and the measurement of size distribution. Further, the structure at different length scales and properties of starch-based on the granule size is elucidated by specifying the typical applications of granules with varying sizes. An amylopectin cluster model showing the arrangement of amylopectin from inside toward the granule surface is proposed with the hypothesis that the steric hindrance for the growth of lamellar structure may limit the size of starch granules.

Enzymatic crosslinking and food allergenicity: A comprehensive review

Food allergy has become a major global public health concern. In the past decades, enzymatic crosslinking technique has been employed to mitigate the immunoreactivity of food allergens. It is an emerging non-thermal technique that can serve as a great alternative to conventional food processing approaches in developing hypoallergenic food products, owing to their benefits of high specificity and selectivity. Enzymatic crosslinking via tyrosinase (TYR), laccase (LAC), peroxidase (PO), and transglutaminase (TG) modifies the structural and biochemical properties of food allergens that subsequently cause denaturation and masking of the antigenic epitopes. LAC, TYR, and PO catalyze the oxidation of tyrosine side chains to initiate protein crosslinking, while TG initiates isopeptide bonding between lysine and glutamine residues. Enzymatic treatment produces a high molecular weight crosslinked polymer with reduced immunoreactivity and IgE-binding potential. Crosslinked allergens further inhibit mast cell degranulation due to the lower immunostimulatory potential that assists in the equilibration of T-helper (Th)1/Th2 immunobalance. This review provides an updated overview of the studies carried out in the last decade on the potential application of enzymatic crosslinking for mitigating food allergenicity that can be of importance in the context of developing hypoallergenic/non-allergenic food products.

Development of Janus Cellulose Acetate Fiber (CA) Membranes for Highly Efficient Oil-Water Separation

A new type of Janus cellulose acetate (CA) fiber membrane was used to separate oil–water emulsions, which was prepared with plasma gas phase grafting by polymerizing octamethylcyclotetrasiloxane (D4) onto a CA fiber membrane prepared by centrifugal spinning. The Janus–CA fiber membrane was described in terms of chemical structure using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) analysis, energy dispersive X-ray spectroscopy (EDX) analysis and morphology by field emission scanning electron microscopy (FESEM). In this contribution, we examine the influence of spinning solution concentration, spinning speed and nozzle aperture on the centrifugal spinning process and the fiber morphology. Superhydrophobic/hydrophilic Janus–CA fiber membrane was used to separate water and 1,2-dibromoethane mixture and Toluene-in-water emulsion. Unidirectional water transfer Janus–CA fiber membrane was used to separate n-hexane and water mixture. The separation for the first-time interception rate was about 98.81%, 98.76% and 98.73%, respectively. Experimental results revealed that the Janus cellulose acetate (CA) fiber membrane gave a permeate flux of about 43.32, 331.72 and 275.27 L/(m²·h), respectively. The novel Janus–CA fiber membrane can potentially be used for sustainable W/O emulsion separation. We believe that this is a facile strategy for construction of filtration materials for practical oil–water separation.

Structural studies of Myceliophthora Thermophila Laccase in the presence of deep eutectic solvents

In this work, we elucidated the interactions between Myceliophthora thermophila laccase and deep eutectic solvent (DES) by crystallographic and kinetics analyses. Four types of DESs with different hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), including lactic acid: betaine, glycerol: choline chloride, lactic acid: choline chloride and glycerol: betaine was used. The results revealed that different DES have different effects on laccase activity. Lactic acid-betaine (2:1) DES has shown to enhance laccase activity up to 300 % at a concentration ranged from 2% to 8% v/v, while glycerol: choline chloride and lactic acid: choline chloride DES choline chloride-based DES have found to possess inhibitory effects on laccase under the same concentration range. Detailed kinetic study showed that glycerol: choline chloride DES is a S-parabolic-I-parabolic mixed non-competitive inhibitor, where conformational changes can occur. The crystal structures of laccase with lactic acid: choline chloride DES (LCDES) were obtained at 1.6 Å. Crystallographic analysis suggested that the addition of LCDES causes changes in the laccase active site, but the increase in water molecules observed in the resulting crystal prevented laccase from experiencing drastic structural change. Fluorescence and circular dichroism spectroscopies were also applied to determine the effects of DES on the structural conformation of laccase. The results have confirmed that the presence of DES can trigger changes in the local environments of the amino acids in the active site of laccase which contributes to the changes in its activity and stability.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

Industrial biotransformations catalyzed by microbial lipases: screening platform and commercial aspects

The successfulness of a lipase-catalyzed industrial process depends on a proper lipase selection. In this work, an alternative screening platform for industrially important biotransformations catalyzed by microbial lipases was proposed. Thus, the reactivity of sixty lipase activities from spore-forming microorganisms towards hydrolytic and transesterification reactions by using p-nitrophenyl palmitate as a chromogenic acyl donor substrate was explored. Only three biocatalysts were capable of catalyzing all reactions tested. Fourteen biocatalysts did not show hydrolytic activity at all; however, they displayed transesterification activities using ethanol, starch, low-methoxyl (LM) pectin, high-methoxyl (HM) pectin, or vitamin C as acyl acceptors. Using heat-treated biocatalysts, hydrolytic activities were not highly correlated with the corresponding transesterification activities using ethanol (r =  -0.058, p = 0.660), starch (r = 0.431, p = 0.001), LM pectin (r =  -0.010, p = 0.938), HM pectin (r = 0.167, p = 0.202), and vitamin C (r =  -0.048, p = 0.716) as acyl acceptor. In addition, to the best of our knowledge, several transesterification activities produced from microorganisms of the genus Bacillus, Brevibacillus, Lysinibacillus, Geobacillus, or Sporosarcina were reported for first time. Finally, the global lipase market was presented and segmented by date, application, geography and player highlighting the commercial contribution of microbial lipases.

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

Production and molecular characterization of tailored citrus pectin-derived compounds

In this study, tailored-made citrus pectin-derived compounds were produced through controlled enzymatic and/or chemical modifications of commercial citrus pectin with different degrees of methylesterification (DM) and similar average molecular weight (M_W). In the first treatment, degradation of the citrus pectin (CP) materials by endo-polygalacturonase (EPG) yielded pectins with average M_w's (between 2 and 60 kDa). Separation and identification of the oligosaccharide fraction present in these samples, revealed the presence of non-methylesterified galacturonic acid oligomers with degree of polymerization (DP) 1-5. In the second treatment, exploiting the combined effect of EPG and pectin lyase, compounds with M_W between 2 and 21 kDa, containing methylesterified and non-methylesterified polygalacturonans (DP 1-6), were generated. Finally, CP was sequentially modified by chemical saponification and the action of EPG. A sample of DM 11% and M_W 2.7 kDa, containing POS (DP 1-5), was produced. Diverse pectin-derived compounds were successfully generated for further studies exploring their functionality.

Natural microbial polysaccharides as effective factors for modification of the catalytic properties of fungal cellobiose dehydrogenase

Polysaccharides are biopolymers composed of simple sugars like glucose, galactose, mannose, fructose, etc. The major natural sources for the production of polysaccharides include plants and microorganisms. In the present work, four bacterial and two fungal polysaccharides (PS or EPS) were used for the modification and preservation of Pycnoporus sanguineus cellobiose dehydrogenase (CDH) activity. It was found that the presence of polysaccharide preparations clearly enhanced the stability of cellobiose dehydrogenase compared to the control value (4 °C). The highest stabilization effect was observed for CDH modified with Rh110EPS. Changes in the optimum pH in the samples of CDH incubated with the chosen polysaccharide modifiers were evidenced as well. The most significant effect was observed for Rh24EPS and Cu139PS (pH 3.5). Cyclic voltammetry used for the analysis of electrochemical parameters of modified CDH showed the highest peak values after 30 days of incubation with polysaccharides at 4 °C. In summary, natural polysaccharides seem to be an effective biotechnological tool for the modification of CDH activity to increase the possibilities of its practical applications in many fields of industry.

Starch chemical modifications applied to drug delivery systems: From fundamentals to FDA-approved raw materials

Starch derivatives are versatile compounds that are widely used in the pharmaceutical industry. This article reviews the advances in the research on hydrophilic and hydrophobic starch derivatives used to develop drug delivery systems over the last ten years, specifically microparticles, nanoparticles, nanocrystals, hydrogels, and scaffolds using these materials. The fundamentals of drug delivery systems, regulatory aspects, and chemical modifications are also discussed, along with the synthesis of starch derivatives via oxidation, etherification, acid hydrolysis, esterification, and cross-linking. The chemical modification of starch as a means to overcome the challenges in obtaining solid dosage forms is also reviewed. In particular, dialdehyde starches are potential derivatives for direct drug attachment; carboxymethyl starches are used for drug encapsulation and release, giving rise to pH-sensitive devices through electrostatic interactions; and starch nanocrystals have high potential as hydrogel fillers to improve mechanical properties and control drug release through hydrophilic interactions. Starch esterification with alginate and acidic drugs could be very useful for site-specific, controlled release. Starch cross-linking with other biopolymers such as xanthan gum is promising for obtaining novel polyelectrolyte hydrogels with improved functional properties. Surface modification of starch nanoparticles by cross-linking and esterification reactions is a potential approach to obtain novel, smart solid dosages.

Stearic acid esterified pectin: Preparation, characterization, and application in edible hydrophobic pectin/chitosan composite films

This work investigated the modification of low-methoxy pectin with stearic anhydride through microwave action with 4-dimethylaminopyridine as catalyst. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that stearic acid was grafted on the pectin through esterification reaction, with the maximum stearic acid grafting ratio (SGR) of 10.7% for the modified pectin. The introduction of stearic acid was shown to significantly improve the emulsifying activity and stability of pectin. Composite films were prepared by blending the modified pectins and chitosan, and compared with the contact angle of 65.3° for the film with native low-methoxy pectin (PC0), the films with modified pectins showed a significant angle increase, with the highest contact angle reaching 101.9°, indicating a hydrophobic surface. Moreover, an appropriate amount of aliphatic chains could improve the tensile strength and elongation at break of the composite films due to the "anchoring effect".

Strategies to Increase the Biological and Biotechnological Value of Polysaccharides from Agricultural Waste for Application in Healthy Nutrition

Nowadays, there is a growing interest in the extraction and identification of new high added-value compounds from the agro-food industry that will valorize the great amount of by-products generated. Many of these bioactive compounds have shown beneficial effects for humans in terms of disease prevention, but they are also of great interest in the food industry due to their effect of extending the shelf life of foods by their well-known antioxidant and antimicrobial activity. For this reason, an additional research objective is to establish the best conditions for obtaining these compounds from complex by-product structures without altering their activity or even increasing it. This review highlights recent work on the identification and characterization of bioactive compounds from vegetable by-products, their functional activity, new methodologies for the extraction of bioactive compounds from vegetables, possibly increasing their biological activity, and the future of the global functional food and nutraceuticals market.

A novel crystalline molecular salt of sulfamethoxazole and amantadine hybridizing antiviral-antibacterial dual drugs with optimal in vitro/vivo pharmaceutical properties

In order to exploit the advantages to the full of multidrug salification strategy in amending the pharmaceutical properties of drugs both in vitro and in vivo, and further to open up a new way for its applications in bacteria-virus mixed cross-infection drugs, a novel dual-drug crystalline molecular salt hybridizing antibacterial drug sulfamethoxazole (SFM) with antiviral ingredient amantadine (ATE), namely SFM-ATE, is successfully designed and synthesized via multidrug salification strategy oriented by proton exchange reaction. The crystal structure of the firstly obtained molecular salt is precisely identified by employing single-crystal X-ray diffraction and multiple other techniques. The results show that, in the crystal lattice of molecular salt SFM-ATE, the classical hydrogen bonds together with charge-assisted hydrogen bonds contribute to two- dimensional networks, between which the hydrophobic interaction plays an important role. The relevant in vitro/vivo pharmaceutical properties of the dual-drug molecular salt are carried out through a comparative investigation of theoretical and experimental methods. It has been found that SFM displays concurrent improvements over the bulk drug in its permeability and dissolution after forming the molecular salt, which is supported by the molecular electrostatic potential calculation and Hirshfeld surface analysis. Encouragingly, the perfected in vitro biopharmaceutical properties can effectually turn into the in vivo pharmacokinetic preponderances with the expedited peak plasma concentration, lengthened half-life and enhanced bioavailability. Better yet, the antibacterial activities of SFM from the molecular salt get stronger with enlargement in inhibition areas and reduction in values of minimum inhibitory concentrations against the tested bacterial strains. Consequently, the present contribution not only supplies an opportunity for widening applications for classical sulfa drugs via dual-drug salification strategy, but also offers an alternative approach in dealing with viral-bacterial coinfection even other complex diseases by drugs' hybridization at the molecular level.

Prospects of Using Biocatalysis for the Synthesis and Modification of Polymers

Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on the production of biodegradable, biocompatible and functional polymeric materials oriented to medical applications. The possibilities of using enzymes not only as catalysts for polymerization but also for the preparation of monomers for polymerization or oligomers for block copolymerization are considered. Special attention is paid to the prospects and existing limitations of biocatalytic production of new synthetic biopolymers based on natural compounds and monomers from biomass, which can lead to a huge variety of functional biomaterials. The existing experience and perspectives for the integration of bio- and chemocatalysis in this area are discussed.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Investigation of a Lipase-Catalyzed Reaction between Pectin and Salicylic Acid and Its Isomers and Evaluation of the Emulsifying Properties, Antioxidant Activities, and Antibacterial Activities of the Corresponding Products

This study presents a method for modifying pectin with phenolic acids catalyzed by lipase in a two-phase system of water/tetrahydrofuran. Salicylic acid (SA) and its isomers, including m-hydroxybenzoic acid (MHBA) and p-hydroxybenzoic acid (PHBA), were grafted onto pectin, and the products were characterized via UV-vis, Fourier transform infrared spectroscopy (FTIR), and ¹H NMR analyses to explore the reaction process and mechanism between pectin and the three phenolic acids. Results indicated that lipase played a dual role in the reaction, namely, catalyzing the hydrolysis of the methyl group in the aqueous phase and esterifying the carboxyl group of pectin with the phenolic hydroxyl group of the phenolic acids in tetrahydrofuran. The grafting ratio of SA-modified pectin, MHBA-modified pectin, and PHBA-modified pectin was 1.89, 10.58, and 20.32%, respectively, and it was affected by the position of phenolic hydroxyl. Moreover, the effects of phenolic acids on the emulsifying properties, antioxidant activities, and antibacterial activities of the native and modified pectins were evaluated. In several aspects, the emulsifying properties of the modified pectins were better than those of native pectin. Moreover, the grafting of phenolic acids only slightly affected the 1,1-diphenyl-2-picryl hydrazine (DPPH) clearance of the modified pectins but substantially improved their inhibition ratio in a β-carotene bleaching assay. Furthermore, the modified pectins exhibited better bacteriostatic activity against both Escherichia coli and Staphylococcus aureus than native pectin.

Characterization of three bacterial glycoside hydrolase family 9 endoglucanases with different modular architectures isolated from a compost metagenome

BACKGROUND

Environmental bacteria express a wide diversity of glycoside hydrolases (GH). Screening and characterization of GH from metagenomic sources provides an insight into biomass degradation strategies of non-cultivated prokaryotes.

METHODS

In the present report, we screened a compost metagenome for lignocellulolytic activities and identified six genes encoding enzymes belonging to family GH9 (GH9a-f). Three of these enzymes (GH9b, GH9d and GH9e) were successfully expressed and characterized.

RESULTS

A phylogenetic analysis of the catalytic domain of pro- and eukaryotic GH9 enzymes suggested the existence of two major subgroups. Bacterial GH9s displayed a wide variety of modular architectures and those harboring an N-terminal Ig-like domain, such as GH9b and GH9d, segregated from the remainder. We purified and characterized GH9 endoglucanases from both subgroups and examined their stabilities, substrate specificities and product profiles. GH9e exhibited an original hydrolysis pattern, liberating an elevated proportion of oligosaccharides longer than cellobiose. All of the enzymes exhibited processive behavior and a synergistic action on crystalline cellulose. Synergy was also evidenced between GH9d and a GH48 enzyme identified from the same metagenome.

CONCLUSIONS

The characterized GH9 enzymes displayed different modular architectures and distinct substrate and product profiles. The presence of a cellulose binding domain was shown to be necessary for binding and digestion of insoluble cellulosic substrates, but not for processivity.

GENERAL SIGNIFICANCE

The identification of six GH9 enzymes from a compost metagenome and the functional variety of three characterized members highlight the importance of this enzyme family in bacterial biomass deconstruction.

Characterization of the starch surface binding site on Bacillus paralicheniformis α-amylase

α-Amylase from Bacillus paralicheniformis (BliAmy), belonging to GH13_5 subfamily of glycoside hydrolases, was proven to be a highly efficient raw starch digesting enzyme. The ability of some α-amylases to hydrolyze raw starch is related to the existence of surface binding sites (SBSs) for polysaccharides that can be distant from the active site. Crystallographic studies performed on BliAmy in the apo form and of enzyme bound with different oligosaccharides and oligosaccharide precursors revealed binding of these ligands to one SBS with two amino acids F257 and Y358 mainly involved in complex formation. The role of this SBS in starch binding and degradation was probed by designing enzyme variants mutated in this region (F257A and Y358A). Kinetic studies with different substrates show that starch binding through the SBS is disrupted in the mutants and that F257 and Y358 contributed cumulatively to binding and hydrolysis. Mutation of both sites (F257A/Y358A) resulted in a 5-fold lower efficacy with raw starch as substrate and at least 5.5-fold weaker binding compared to the wild type BliAmy, suggesting that the ability of BliAmy to hydrolyze raw starch with high efficiency is related to the level of its adsorption onto starch granules.

Conjugation reaction with ferulic acid boosts the antioxidant property of arabinogalactan-protein and enhances its ability to form complex with β-lactoglobulin

Ferulic acid was chemically grafted onto the arabinogalactan protein of Aegle marmelos fruit gum using 1,1'-carbonyldiimidazole as coupling reagent. Thus, grafted polysaccharides with different degrees of substitution were prepared and then characterized by gas chromatography/mass spectrometry, size exclusion chromatography, and ultraviolet-visible, infra-red, and nuclear magnetic resonance spectroscopic investigations. Fluorescence spectroscopic investigation showed hydrophobic microdomain formation in grafted polymers. The antioxidant activities of the derivatives, as determined by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl radical assay, were strong and increases with increasing the degree of feruloylation. Compared to parental arabinogalactan protein (K = 2.38 × 10⁶ M^-1), these grafted polymers bind more strongly with β-lactoglobulin (K = 11.4 × 10⁶ M^-1 and 8.19 × 10⁶ M^-1). Given that gum polysaccharides are valuable component in functional foods, synthesis of antioxidative graft polymer possessing good compatibility with β-lactoglobulin may have important implication.