Recent development of lactoferrin-based vehicles for the delivery of bioactive compounds: Complexes, emulsions, and nanoparticles

Complexation of bovine lactoferrin with selected phenolic acids via noncovalent interactions: Binding mechanism and altered functionality

Noncovalent interactions of 4 selected phenolic acids, including gallic acid (GA), caffeic acid (CA), chlorogenic acid (CGA), and rosmarinic acid (RA) with lactoferrin (LF) were investigated. Compound combined with LF in the binding constant of CA > GA > RA > CGA, driven by van der Waals and hydrogen bonding for GA, and hydrophobic forces for others. Conformation of LF was affected at secondary and ternary structure levels. Molecular docking indicated that GA and CA located in the same site near the iron of the C-lobe, whereas RA and CGA bound to the C2 and N-lobe, respectively. Significantly enhanced antioxidant activity of complexes was found compared with pure LF, as demonstrated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(2-ethylbenzothiazoline-6-sulfonate) (ABTS), and ferric reducing antioxidant power (FRAP) models. Caffeic acid, CGA, and RA significantly decreased the emulsifying stability index and improved foam ability of LF, and the effect of CA and RA was the most remarkable, respectively.

Lactoferrin thermal stabilization and iron(II) fortification through ternary complex fabrication with succinylated sodium caseinate

A thermally stable co-delivery system for lactoferrin (LF) and iron(II) was developed to address iron deficiency anemia. Complexes were formed between LF, succinylated sodium caseinate (S.NaCas) and FeSO4 with high yield (∼85%). LF-S.NaCas-Fe complexes achieved loading capacities for iron(II) between 2.5 and 12 mg g-1and LF loading capacities between 250 and 690 mg g-1, depending upon initial Fe2+ concentrations and LF ratios. The LF-S.NaCas complex mixtures appeared as smooth cubic particles in SEM, and gradually aggregated to amorphous particles as th iron(II) concentration increased due to iron-facilitated cross-linking. The complexation significantly improved LF thermal stability and addressed the poor solubility of iron(II) under neutral pH. After thermal treatment (95 °C, 5 min), the rehydrated complexes retained 68%-90% LF, with <10% iron(II) release. Circular dichroism spectra showed the secondary structure of the complexed LF was well retained during thermal treatment. This thermally stable system showed great potential in LF thermal protection and iron(II) fortification.

Effects of ultrasound and thermal treatment on the interaction between hyaluronic acid and lactoferrin: Preparation, structures and functionalities

Complexes of polysaccharides and proteins have superior physicochemical and functional properties compared to single proteins or polysaccharides. In this study, lactoferrin-hyaluronic acid (LF-HA) complexes were prepared by both ultrasonic and thermal treatment. Appropriate preparation conditions, including ultrasonic and thermal treatment conditions, have been established. The complexes formed by different methods were structurally characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis, fourier transform infrared spectroscopy, and circular dichroism spectroscopy. Ultrasound formed non-covalent binding, while thermal treatment generated covalent bonding, altering the structure of LF. The LF-HA complexes showed improved heat stability, foaming stability, emulsifying activity and antioxidant capacity, but deceased foaming ability. Iron binding ability could only be improved by HA through thermal treatment. Moreover, the in vitro digestibility of LF-HA complexes decreased to below 80 % compared to LF.

Interaction between Dietary Lactoferrin and Gut Microbiota in Host Health

The gut microbiota are known to play an important role in host health and disease. Alterations in the gut microbiota composition can disrupt the stability of the gut ecosystem, which may result in noncommunicable chronic diseases (NCCDs). Remodeling the gut microbiota through personalized nutrition is a novel therapeutic avenue for both disease control and prevention. However, whether there are commonly used gut microbiota-targeted diets and how gut microbiota-diet interactions combat NCCDs and improve health remain questions to be addressed. Lactoferrin (LF), which is broadly used in dietary supplements, acts not only as an antimicrobial in the defense against enteropathogenic bacteria but also as a prebiotic to propagate certain probiotics. Thus, LF-induced gut microbiota alterations can be harnessed to induce changes in host physiology, and the underpinnings of their relationships and mechanisms are beginning to unravel in studies involving humans and animal models.

New Horizons of Covalent Complex of Plant-Derived Recombinant Human Lactoferrin (OsrhLF) Combined with Different Polyphenols: Formation, Physicochemical Properties, and Gastrointestinal Fate

Four typical dietary polyphenols ((-)-epigallocatechin gallate (EGCG), quinic acid (QA), caffeic acid (CA), and ferulic acid (FA)) were covalently prepared with rice recombinant human lactoferrin (OsrhLF) and bovine lactoferrin (bLF), and their structure and physicochemical properties were investigated, different lycopene emulsions were made by ultrasonic emulsification to analyze gastrointestinal fate. The results indicated that the covalent modification polyphenols changed the secondary/tertiary structure of LF, significantly improving the surface hydrophilicity, thermal stability, and antioxidant activity of LF. Compared with the bLF group, the OsrhLF group was more hydrophilic and the thermal denaturation temperature of the OsrhLF-CA reached 104.4 °C. LF-polyphenol emulsions significantly enhanced the photochemical stability and bioavailability of lycopene and achieved effective encapsulation and protection of lycopene compared to free lycopene, and the OsrhLF-EGCG reached 58.94% lycopene bioavailability. In short, OsrhLF does not differ much from bLF in terms of physicochemical properties and has a strong potential in the field of dietary supplements.

Ultrasonic treatment of rice bran protein-tannic acid stabilized oil-in-water emulsions: Focus on microstructure, rheological properties and emulsion stability

Rice bran protein (RBP)-tannic acid (TA) complex was prepared and the RBP-TA emulsions were subjected to ultrasonic treatment with different powers. Ultrasonic treatment has a positive effect on improving the properties of RBP-TA emulsion. This study investigated the influence of different ultrasonic power levels on the physicochemical properties, microstructure, rheological properties, and stability of emulsions containing RBP-TA. Under the ultrasonic treatment of 400 W, the particle size, zeta potential, and adsorbed protein content of the RBP-TA emulsion were 146.86 nm, -20.7 eV, and 61.91%, respectively. At this time, the emulsion had the best emulsifying properties, apparent viscosity, energy storage modulus and loss modulus. In addition, the POV and TBARS values of RBP-TA emulsions were 6.12 and 7.60 mmol/kg, respectively. The thermal, salt ion, pH and oxidative stability of the emulsions were investigated, and it was shown that ultrasonic treatment was effective in improving the stability of RBP-TA emulsions.

Investigation of bovine β-lactoglobulin-procyanidin complexes interactions and its utilization in O/W emulsion

Procyanidins are bioactive polyphenols that have a strong affinity to proteins. Beta-lactoglobulin (BLG) is widely used as an emulsifier in the food and other industries. This study evaluated the interaction between BLG and A-type procyanidin dimer (PA2) using the spectroscopic, thermodynamic, and molecular simulation. PA2 decreased the transmissivity and quenched the intrinsic fluorescence of BLG, suggesting that the two molecules formed a complex. The binding of PA2 reduced the surface hydrophobicity and altered the conformation of BLG with increasing the random coil regions. Thermodynamic and isothermal titration calorimetry analyses suggested that the main driving force of PA2-BLG interaction was hydrophobic attraction. Molecular docking simulations were used to identify the main interaction sites and forces in the BLG-PA2 complexes, which again indicated that hydrophobic interactions dominated. In addition, the influence of PA2 on the ability of BLG to form and stabilize O/W emulsions was analyzed. Emulsions formulated using BLG-PA2 complexes contained relatively small droplets (D_4,3 ≈ 0.7 μm) and high surface potentials (absolute value >50 mV). Compared to BLG alone, BLG-PA2 complexes improved the storage stability of the emulsions. This study provides valuable new insights into the formation, properties, and application of protein-polyphenol complexes as functional ingredients in foods.

Nanocarrier-Based Drug Delivery to Brain: Interventions of Surface Modification

Brain disorders are a prevalent and rapidly growing problem in the medical field as they adversely affect the quality of life of a human. With an increase in life expectancy, it has been reported that diseases like Alzheimer's, Parkinson's, stroke and brain tumors, along with neuropsychological disorders, are also being reported at an alarmingly high rate. Despite various therapeutic methods for treating brain disorders, drug delivery to the brain has been challenging because of a very complex Blood Brain Barrier, which precludes most drugs from entering the brain in effective concentrations. Nano-carrier-based drug delivery systems have been reported widely by researchers to overcome this barrier layer. These systems due to their small size, offer numerous advantages; however, their short residence time in the body owing to opsonization hinders their success in vivo. This review article focuses on the various aspects of modifying the surfaces of these nano-carriers with polymers, surfactants, protein, antibodies, cell-penetrating peptides, integrin binding peptides and glycoproteins such as transferrin & lactoferrin leading to enhanced residence time, desirable characteristics such as the ability to cross the blood-brain barrier (BBB), increased bioavailability in regions of the brain and targeted drug delivery.

Research Advances of Lactoferrin in Electrostatic Spinning, Nano Self-Assembly, and Immune and Gut Microbiota Regulation

Lactoferrin (LF) is a naturally present iron-binding globulin with the structural properties of an N-lobe strongly positively charged terminus and a cage-like structure of nano self-assembly encapsulation. These unique structural properties give it potential for development in the fields of electrostatic spinning, targeted delivery systems, and the gut-brain axis. This review will provide an overview of LF's unique structure, encapsulation, and targeted transport capabilities, as well as its applications in immunity and gut microbiota regulation. First, the microstructure of LF is summarized and compared with its homologous ferritin, revealing both structural and functional similarities and differences between them. Second, the electrostatic interactions of LF and its application in electrostatic spinning are summarized. Its positive charge properties can be applied to functional environmental protection packaging materials and to improving drug stability and antiviral effects, while electrostatic spinning can promote bone regeneration and anti-inflammatory effects. Then the nano self-assembly behavior of LF is exploited as a cage-like protein to encapsulate bioactive substances to construct functional targeted delivery systems for applications such as contrast agents, antibacterial dressings, anti-cancer therapy, and gene delivery. In addition, some covalent and noncovalent interactions of LF in the Maillard reaction and protein interactions and other topics are briefly discussed. Finally, LF may affect immunological function via controlling the gut microbiota. In conclusion, this paper reviews the research advances of LF in electrostatic spinning, nano self-assembly, and immune and gut microbiota regulation, aiming to provide a reference for its application in the food and pharmaceutical fields.

A review of sugar beet pectin-stabilized emulsion: extraction, structure, interfacial self-assembly and emulsion stability

In recent years, sugar beet pectin as a natural emulsifier has shown great potential in food and pharmaceutical fields. However, the emulsification performance depends on the molecular structure of sugar beet pectin, and the molecular structure is closely related to the extraction method. This review summarizes the extraction methods of pectin, structure characterization methods and the current research status of sugar beet pectin-stabilized emulsions. The structural characteristics of sugar beet pectin (such as degree of methylation, degree of acetylation, degree of blockiness, molecular weight, ferulic acid content, protein content, neutral sugar side chains, etc.) are of great significance to the emulsifying activity and stability of sugar beet pectin. Compared with traditional hot acid extraction method, ultrasonic-assisted extraction, microwave-assisted extraction, subcritical water-assisted extraction, induced electric field-assisted extraction and enzyme-assisted extraction can improve the yield of sugar beet pectin. At the same time, compared with harsh extraction conditions (too high temperature, too strong acidity, too long extraction time, etc.), mild extraction conditions can better preserve these emulsifying groups in sugar beet pectin molecules, which are beneficial to improve the emulsifying properties of sugar beet pectin. In addition, the interfacial self-assembly behavior of sugar beet pectin induced by the molecular structure is crucial to the long-term stability of the emulsion. This review provides a direction for extracting or modifying sugar beet pectin with specific structure and function, which is instructive for finding alternatives to gum arabic.

Improving foam performance using colloidal protein-polyphenol complexes: Lactoferrin and tannic acid

In this study, colloidal complexes were prepared from bovine lactoferrin (BLF) and tannic acid (TA) and then their ability to form and stabilize foams was characterized. The molecular interactions between BLF and TA were studied using fluorescence and molecular docking analysis, which suggested that hydrophobic forces were primarily involved in holding the complexes together. The production of colloidal BLF-TA complexes was supported by increases in turbidity and mean particle diameter, quenching of intrinsic fluorescence, decrease in surface hydrophobicity, and change in conformation. When used alone, BLF exhibited good foam formation but poor foam stability properties. In contrast, BLF-TA complexes exhibited good foam stability but poor foamability properties. The change in foaming properties of the proteins was closely related to their interactions with the polyphenols. These findings may be useful for the development of novel functional ingredients to construct food foams with good physicochemical and nutritional attributes.

Molecular modeling of lactoferrin for food and nutraceutical applications: insights from in silico techniques

Lactoferrin is a protein, primarily found in milk that has attracted the interest of the food industries due to its health properties. Nevertheless, the instability of lactoferrin has limited its commercial application. Recent studies have focused on encapsulation to enhance the stability of lactoferrin. However, the molecular insights underlying the changes of structural properties of lactoferrin and the interaction with protectants remain poorly understood. Computational approaches have proven useful in understanding the structural properties of molecules and the key binding with other constituents. In this review, comprehensive information on the structure and function of lactoferrin and the binding with various molecules for food purposes are reviewed, with a special emphasis on the use of molecular dynamics simulations. The results demonstrate the application of modeling and simulations to determine key residues of lactoferrin responsible for its stability and interactions with other biomolecular components under various conditions, which are also associated with its functional benefits. These have also been extended into the potential creation of enhanced lactoferrin for commercial purposes. This review provides valuable strategies in designing novel nutraceuticals for food science practitioners and those who have interests in acquiring familiarity with the application of computational modeling for food and health purposes.

Self-assembled nano-micelles of lactoferrin peptides: Structure, physicochemical properties, and application for encapsulating and delivering curcumin

Food-derived protein hydrolysate exhibits good bioactivity, compatibility, and low toxicity, etc. However, the information on protein hydrolysate-based micelles and their application as carriers for hydrophobic bioactive compounds is limited. In this study, an enzymatic partially hydrolyzed lactoferrin hydrolysate nano-micelle with the size within 50 nm was constructed, and its formation mechanism and delivery characteristics for curcumin (Cur) were studied. The results demonstrated that Cur was loaded into the micelles through hydrophobic interaction, and the encapsulation rate of Cur by nano-micelles was (93.44 ± 0.01)%. In addition, the nano-micelle system demonstrated excellent thermal stability, dilution stability, and storage stability. The in vitro simulated digestion proved that self-assembled nano-micelles could improve the transformation rate and bioaccessibility of Cur. This study revealed that lactoferrin hydrolysate self-assembled nano-micelle is a promising delivery system for hydrophobic bioactive compounds.

High internal phase emulsions stabilized by native and heat-treated lactoferrin-carboxymethyl chitosan complexes: Comparison of molecular and granular emulsifiers

While the high internal phase emulsions (HIPEs) have been formed by food-grade biopolymers and granules have been widely reported, it is not known which components are more effective. In this work, we first used heat-treated lactoferrin (LF)-carboxymethyl chitosan (CMCTS) granules and native LF-CMCTS physical mixtures as emulsifiers to form HIPEs. The results showed that the interfacial behavior and emulsifying properties of the two complexes were controlled by the ratio of LF-CMCTS and the optimal ratio of LF to CMCTS was 1:1. Heated LF-CMCTS granules anchored to the water-oil interface and formed an elastic shell to stabilize HIPEs, while unheated LF-CMCTS complexes formed a thick film layer to stabilize HIPEs. Both HIPEs could act as delivery systems loaded with curcumin, and they showed better protection of curcumin than Tween-80 under light. This study provides a new basis for the design of LF-based HIPEs systems loaded with lipophilic food functional ingredients.

Development of Encapsulation Strategies and Composite Edible Films to Maintain Lactoferrin Bioactivity: A Review

Lactoferrin (LF) is a whey protein with various and valuable biological activities. For this reason, LF has been used as a supplement in formula milk and functional products. However, it must be considered that the properties of LF can be affected by technological treatments and gastrointestinal conditions. In this article, we have revised the literature published on the research done during the last decades on the development of various technologies, such as encapsulation or composite materials, to protect LF and avoid its degradation. Multiple compounds can be used to conduct this protective function, such as proteins, including those from milk, or polysaccharides, like alginate or chitosan. Furthermore, LF can be used as a component in complexes, nanoparticles, hydrogels and emulsions, to encapsulate, protect and deliver other bioactive compounds, such as essential oils or probiotics. Additionally, LF can be part of systems to deliver drugs or to apply certain therapies to target cells expressing LF receptors. These systems also allow improving the detection of gliomas and have also been used for treating some pathologies, such as different types of tumours. Finally, the application of LF in edible and active films can be effective against some contaminants and limit the increase of the natural microbiota present in meat, for example, becoming one of the most interesting research topics in food technology.

Bovine lactoferrin and Lentinus edodes mycelia polysaccharide complex: The formation and the activity to protect islet β cells

The formation of complexes may be used for the development of delivery systems in foods field. The aim of this study was to explore the interaction mechanism between Lentinus edodes mycelia polysaccharide (LMP) and bovine lactoferrin (BLF), and the activity of LMP-BLF complex to inhibit oxidative stress in islet β cells. The interaction mechanisms of LMP with BLF were investigated with multi-spectroscopic techniques. The multi-spectroscopic analysis result showed that LMP bound with BLF by van der Waals force and hydrogen bond. The quenching mechanism of BLF with LMP was static quenching. Cell viability, reactive oxygen species (ROS) level, apoptosis and the related signaling pathways were detected with thiazolyl blue tetrazolium bromide (MTT) assay, 2,7-Dichlorofluorescin diacetate (DCFH-DA) staining, Hoechst 33258 staining and Western blot methods respectively. The complex alleviated apoptosis induced by hydrogen peroxide (H₂O₂), and inhibited oxidative stress via MAPK pathways in MIN6 cells. In addition, the complex was able to promote glucose uptake in HepG2 cells. These results will broaden our understanding of LMP-BLF complexes and the applications of polysaccharide-protein complexes in the foods field.

Recent Progress on Protein-Polyphenol Complexes: Effect on Stability and Nutrients Delivery of Oil-in-Water Emulsion System

Oil-in-water emulsions are widely encountered in the food and health product industries. However, the unsaturated fatty acids in emulsions are easily affected by light, oxygen, and heat, which leads to oxidation, bringing forward difficulties in controlling emulsion quality during transportation, storage, and retail. Proteins are commonly used as emulsifiers that can enhance the shelf, thermal and oxidation stability of emulsions. Polyphenols are commonly found in plants and members of the family have been reported to possess antioxidant, anticancer, and antimicrobial activities. Numerous studies have shown that binding of polyphenols to proteins can change the structure and function of the latter. In this paper, the formation of protein-polyphenol complexes (PPCs) is reviewed in relation to the latters' use as emulsifiers, using the (covalent or non-covalent) interactions between the two as a starting point. In addition, the effects polyphenol binding on the structure and function of proteins are discussed. The effects of proteins from different sources interacting with polyphenols on the emulsification, antioxidation, nutrient delivery and digestibility of oil-in-water emulsion are also summarized. In conclusion, the interaction between proteins and polyphenols in emulsions is complicated and still understudied, thereby requiring further investigation. The present review results in a critical appraisal of the relevant state-of-the-art with a focus on complexes' application potential in the food industry, including digestion and bioavailability studies.

Influence of iron binding in the structural stability and cellular internalization of bovine lactoferrin

Lactoferrin (Lf) is an iron-binding glycoprotein and a component of many external secretions with a wide diversity of functions. Structural studies are important to understand the mechanisms employed by Lf to exert so varied functions. Here, we used guanidine hydrochloride and high hydrostatic pressure to cause perturbations in the structure of bovine Lf (bLf) in apo and holo (unsaturated and iron-saturated, respectively) forms, and analyzed conformational changes by intrinsic and extrinsic fluorescence spectroscopy. Our results showed that the iron binding promotes changes on tertiary structure of bLf and increases its structural stability. In addition, we evaluated the effects of bLf structural change on the kinetics of bLf internalization in Vero cells by confocal fluorescence microscopy, and observed that the holo form was faster than the apo form. This finding may indicate that structural changes promoted by iron binding may play a key role in the intracellular traffic of bLf. Altogether, our data improve the comprehension of bLf stability and uptake, adding knowledge to its potential use as a biopharmaceutical.

Utilization of diverse protein sources for the development of protein-based nanostructures as bioactive carrier systems: A review of recent research findings (2010-2021)

Consumer awareness of the relationship between health and nutrition has caused a substantial increase in the demand for nutraceuticals and functional foods containing bioactive compounds (BACs) with potential health benefits. However, the direct incorporation of many BACs into commercial food and beverage products is challenging because of their poor matrix compatibility, chemical instability, low bioavailability, or adverse impact on food quality. Advanced encapsulation technologies are therefore being employed to overcome these problems. In this article, we focus on the utilization of plant and animal derived proteins to fabricate micro and nano-particles that can be used for the oral delivery of BACs such as omega-3 oils, vitamins and nutraceuticals. This review comprehensively discusses different methods being implemented for fabrications of protein-based delivery vehicles, types of proteins used, and their compatibility for the purpose. Finally, some of the challenges and limitations of different protein matrices for encapsulation of BACs are deliberated upon. Various approaches have been developed for the fabrication of protein-based microparticles and nanoparticles, including injection-gelation, controlled denaturation, and antisolvent precipitation methods. These methods can be used to construct particle-based delivery systems with different compositions, sizes, surface hydrophobicity, and electrical characteristics, thereby enabling them to be used in a wide range of applications.

Whey protein-polyphenol conjugates and complexes: Production, characterization, and applications

Whey proteins are widely used as functional ingredients in various food applications owing to their emulsifying, foaming, and gelling properties. However, their functional attributes are limited in some applications because of the dependence of their performance on pH, mineral levels, and temperature. Several approaches have been investigated to enhance the functional performance of whey proteins by interacting them with polyphenols via covalent bonds (conjugates) or non-covalent bonds (complexes). The interaction of the polyphenols to the whey proteins alters their molecular characteristics, techno-functional attributes, and biological properties. Analytical methods for characterizing the properties of whey protein-polyphenol complexes and conjugates are highlighted, and a variety of potential applications within the food industry are discussed, including as antioxidants, emulsifiers, and foaming agents. Finally, areas for future research are highlighted.

Eco-friendly synthesis of the Li/Al in nonionic surfactant-based vesicles (niosomes) modified with graphene oxide quantum dot nanostructures for controlled released of chlorpheniramine maleate

The aim of the present work was the preparation of Li/Al nanoparticles (NPs) functionalized with graphene oxide quantum dots (GOQDs) for the controlled release of chlorpheniramine maleate (CPAM). The role of lemon and egg white extracts as oxidation agents were investigated for the morphology and particle size of the products. GOQDs were synthesized using green, environmentally friendly, and cost-effective precursors. This work demonstrates that Li/Al NPs functionalized with graphene oxide as a nanolayer structure can be used as efficient nanocarriers for loading and delivery of CPAM as water-insoluble aromatic drugs The final products were identified with X-ray diffraction, scanning electron microscopy, atomic force microscopy, ultraviolet-visible spectroscopy, dynamic light scattering, thermogravimetric analysis, and transmission electron microscopy nitrogen adsorption [i.e. Brunauer-Emmett-Teller (BET) surface area analysis] techniques. The calibration curve for Li/Al nanoparticles functionalized with GOQDs for controlled released of CPAM was calculated as y = 0.0137x + 0.0103 with R²  = 0.9995. The data found through BET and Barrett-Joyner-Halenda analysis using the adsorption/desorption isotherm method demonstrated by total pore volumes and dead volume were calculated respectively as 0.162 nm² , 0.0439 cm³ g^-1 . The mean pore diameter was calculated as 20.33 nm using BET isotherm data.

Enzymatic and Nonenzymatic Conjugates of Lactoferrin and (-)-Epigallocatechin Gallate: Formation, Structure, Functionality, and Allergenicity

The impact of covalent attachment of (-)-epigallocatechin gallate (EGCG) to lactoferrin (LF) on the structure, morphology, functionality, and allergenicity of the protein was studied. These polyphenol-protein conjugates were formed using various enzymatic (laccase- and tyrosinase-catalyzed oxidation) and nonenzymatic (free radical grafting and alkali treatment) methods. The preparation conditions for forming the enzymatic conjugates were optimized by exploring the influence of order-of-addition effects: protein, polyphenols, and enzymes. The total phenol content of the LF-EGCG conjugates was quantified using the Folin-Ciocalteu method. The nature of the conjugates formed was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) spectroscopy analyses. These studies showed that enzymatic cross-linking was a highly effective means of forming LF-EGCG conjugates. Analysis of these conjugates using various spectroscopic methods showed that conjugation to EGCG changed the molecular structure of LF. Atomic force microscopy showed that the four covalent cross-linking methods affected the size and morphology of these LF-EGCG conjugates formed. The antioxidant activity and emulsifying stability of LF were significantly improved by conjugation to EGCG. Finally, an enzyme-linked immunosorbent assay (ELISA) and a western blot assay indicated that conjugation of EGCG reduced the binding capacity of LF to immunoglobulin E (IgE) and immunoglobulin G (IgG), which is consistent with a decrease in allergenicity. Overall, this study suggests that LF-EGCG conjugates formed using enzymatic or nonenzymatic methods have potential applications as functional ingredients in foods.

Lactoferrin-ginsenoside Rg3 complex ingredients: Study of interaction mechanism and preparation of oil-in-water emulsion

Revealing the interaction mechanism between bovine lactoferrin (LF) and 20(S)-ginsenoside Rg3 (Rg3), thereby introducing Rg3 to LF and even into stable emulsions will contribute significantly to food valorization and food industry. Adding Rg3 to LF caused slight absorbance increment and static fluorescence quench of LF, implying the successful combination. Synchronous fluorescence, three-dimensional fluorescence and circular dichroism spectroscopy indicated the conformation changing of LF after binding with Rg3. Thermodynamic analysis showed that the binding happened spontaneously to form a LF-Rg3 complex with a molar ratio of 1:1, which was mainly driven by hydrogen bonding and van der Waals force. Molecular docking simulation provided extensive information about the optimized binding sites and the involved interactions. Finally, we prepared stable LF-Rg3 oil-in-water emulsion, showing great potential in foods and beverages. This work prepares all-natural functional ingredients, and also diversifies the effective food molecule-based delivery systems for LF and Rg3.

Development of astaxanthin-loaded layer-by-layer emulsions: physicochemical properties and improvement of LPS-induced neuroinflammation in mice

Astaxanthin (AST) has been shown to have neuroprotective effects; however, its bioavailability in vivo is low due to its hydrophobic properties. In this study, lactoferrin (LF) was prepared by heat-treatment at different temperatures, and on this basis, a layer-by-layer self-assembly method was used to construct double-layer emulsions with LF as the inner layer and polysaccharide (beet pectin, BP or carboxymethyl chitosan, CMCS) as the outer layer. Then AST was encapsulated in the emulsions and their physiochemical properties and function were investigated. The results indicated that high temperature heated LF (95 °C) showed a more stable structure than the lower temperature one, and the exposed internal nonpolar groups of LF could give the emulsion an enhanced stability. The rheology results showed that compared with CMCS, the double-layer emulsion formed by BP had a higher viscosity. In addition, the 95 °C LF-AST-BP emulsion showed the best stability among all the bilayer emulsions. The best emulsion was then used as a model drug to investigate its effects on lipopolysaccharide (LPS)-induced neuroinflammation and learning-memory loss in C57BL/6J mice. Through animal behavioral experiments, it was found that dietary supplementation with the AST emulsion could effectively improve the brain cognitive and learning memory impairment caused by inflammation. Transmission electron microscopy, mRNA and western blotting results also illustrated that the AST emulsion could alleviate neuroinflammation caused by LPS. This study provides a feasible scheme for exploring an AST loaded system and may be suitable for food and drug applications.

Oral fate and stabilization technologies of lactoferrin: a systematic review

Lactoferrin (Lf), a bioactive protein initially found in many biological secretions including milk, is regarded as the nutritional supplement or therapeutic ligand due to its multiple functions. Research on its mode of action reveals that intact Lf or its active peptide (i.e., lactoferricin) shows an important multifunctional performance. Oral delivery is considered as the most convenient administration route for this bioactive protein. Unfortunately, Lf is sensitive to the gastrointestinal (GI) physicochemical stresses and lactoferricin is undetectable in GI digesta. This review introduces the functionality of Lf at the molecular level and its degradation behavior in GI tract is discussed in detail. Subsequently, the absorption and transport of Lf from intestine into the blood circulation, which is pivotal to its health promoting effects in various tissues, and some assisting labeling methods are discussed. Stabilization technologies aiming at preserving the structural integrity and functional properties of orally administrated Lf are summarized and compared. Altogether, this work comprehensively reviews the structure-function relationship of Lf, its oral fate and the development of stabilization technologies for the enhancement of the oral bioavailability of Lf. The existing limitations and scope for future research are also discussed.

Assessment of binding interaction dihydromyricetin and myricetin with bovine lactoferrin and effects on antioxidant activity

The binding interactions of bovine lactoferrin (BLF) with two flavonoids dihydromyricetin (DMY) and myricetin (MY) were investigated by the multi-spectroscopic, microscale thermophoresis (MST) techniques, molecular docking, and then their antioxidant activities were studied by detection of free radical scavenging activity against DPPH. Results of UV-vis and fluorescence spectroscopies showed that DMY/MY and BLF formed the ground state complex through the static quenching mechanism. Moreover, MY with more planar stereochemical structure had higher affinity for BLF than DMY with twisted stereochemical structure, according to the binding constant (K_b), free energy change (ΔG°), dissociation constant (K_d) and donor-acceptor distance (r). Thermodynamic parameters revealed that hydrogen bond and van der Waals force were major forces in the formation of BLF-DMY complex, while hydrophobic interactions played major roles in the formation of BLF-DMY complex. The circular dichroism (CD) study indicated that MY induced more conformational change in BLF than DMY. Furthermore, molecular modeling provided insights into the difference of binding interactions between BLF and two flavonoids. Finally, the radical scavenging activity assays indicated the presence of BLF delayed the decrease in antioxidant capacities of two flavonoids. These results were helpful to understand the binding mechanism and biological effects of non-covalent BLF-flavonoid interaction.

Simultaneous Ultrasound and Heat Enhance Functional Properties of Glycosylated Lactoferrin

Protein-polysaccharide covalent complexes exhibit better physicochemical and functional properties than single protein or polysaccharide. To promote the formation of the covalent complex from lactoferrin (LF) and beet pectin (BP), we enhanced the Maillard reaction between LF and BP by using an ultrasound-assisted treatment and studied the structure and functional properties of the resulting product. The reaction conditions were optimized by an orthogonal experimental design, and the highest grafting degree of 55.36% was obtained by ultrasonic treatment at 300 W for 20 min and at LF concentration of 20 g/L and BP concentration of 9 g/L. The formation of LF-BP conjugates was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) spectroscopy. Ultrasound-assisted treatment can increase the surface hydrophobicity, browning index, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals scavenging activity of LF due to the changes in the spatial configuration and formation of Maillard reaction products. The thermal stability, antioxidant activity and emulsifying property of LF were significantly improved after combining with BP. These findings reveal the potential application of modified proteins by ultrasonic and heat treatment.

Glycation mechanism of lactoferrin-chitosan oligosaccharide conjugates with improved antioxidant activity revealed by high-resolution mass spectroscopy

Glycosylation has a great effect on the antioxidant ability of proteins, which is due to the structural conformational change of peptides in the protein. In this study, a chitosan oligosaccharide (COS) was selected as the saccharide for glycation with lactoferrin (LF) by a wet-heat method, and a new stripe at a higher molecular zone in the gel of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and a change in the bond revealed by Fourier transform infrared (FT-IR) and fluorescence spectroscopy analyses were used to confirm that the chitosan oligosaccharide was successfully covalently bound to lactoferrin. The ABTS and oxygen radical absorbance capacity (ORAC) assays indicated that lactoferrin exhibited a stronger antioxidant activity after glycation with the chitosan oligosaccharide. High-resolution mass spectroscopy further illuminated the relationship of enhanced antioxidant capacity and structural conformational change of peptides in lactoferrin at a molecular level.

Towards Green Nanoscience: From extraction to nanoformulation

The use of nanotechnology has revolutionized many biotechnological sectors, from bioengineering to medicine, passing through food and cosmetic fields. However, their clinic and industrial application has been into the spotlight due to their safety risk and related side effects. As a result, Green Nanoscience/Nanotechnology emerged as a strategy to prevent any associated nanotoxicity, via implementation of sustainable processes across the whole lifecycle of nanoformulation. Notwithstanding its success across inorganic nanoparticles, the green concept for organic nanoparticle elaboration is still at its infancy. This, coupled with the organic nanoparticles being the most commonly used in biomedicine, highlights the need to implement specific green principles for their elaboration. In this review, we will discuss the possible green routes for the proper design of organic nanoparticles under the umbrella of Green Nanoscience: from the extraction of nanomaterials and active compounds to their final nanoformulation.

Utilization of plant-based protein-polyphenol complexes to form and stabilize emulsions: Pea proteins and grape seed proanthocyanidins

Plant-based proteins and polyphenols are increasingly being explored as functional food ingredients. Colloidal complexes were prepared from pea protein (PP) and grape seed proanthocyanidin (GSP) and the ability of the PP/GSP complexes to form and stabilize oil-in-water emulsions were investigated. The main interactions between PP and GSP were hydrogen bonding. The stability of PP-GSP complexes to environmental changes were studied: pH (2-9); ion strength (0-0.3 M); and temperature (30-90 °C). Emulsions produced using PP-GSP complexes as emulsifiers had small mean droplet diameters (~200 nm) and strongly negative surface potentials (~-60 mV). Compared to PP alone, PP-GSP complexes slightly decreased the isoelectric point, thermostability, and salt stability of the emulsions, but increased their storage stability. The presence of GSP gave the emulsions a strong salmon (red-yellow) color, which may be beneficial for some specific applications. These results may assist in the creation of more efficacious food-based strategies for delivering proanthocyanidins.

Protein-polyphenol functional ingredients: The foaming properties of lactoferrin are enhanced by forming complexes with procyanidin

The solution turbidity and intrinsic fluorescence quenching increased after procyanidin was mixed with lactoferrin. The addition of procyanidin also caused a reduction in the surface hydrophobicity of the lactoferrin, suggesting procyanidin bound to non-polar patches on lactoferrin's surfaces. Moreover, the binding interaction caused an appreciable alteration in the structure of both the polyphenol and protein. Thermodynamic analysis indicated the interaction was spontaneous and mainly driven by entropy changes, suggesting that hydrophobic interactions dominated. A computational docking simulation provided insights into the location of the most-likely binding sites on the protein, as well as the nature of the interaction forces involved. In particular, both hydrophobic and hydrogen bonding were found to be important. The binding of the procyanidin to the lactoferrin enhanced its foaming properties. These results may lead to the development of a new class of natural functional ingredients that can be used in food products to improve their quality attributes.

Spectroscopic and Molecular Modeling Investigation on the Interaction between Folic Acid and Bovine Lactoferrin from Encapsulation Perspectives

The impact of thermal treatment on the ability of lactoferrin (FL) to bind folic acid (FA) was investigated by employing fluorescence spectroscopy, molecular dynamics and docking tests. The structural and conformational particularities of LF upon heating at 80 °C and 100 °C were first estimated based on the intrinsic fluorescence changes in respect to the native protein. The emission spectra indicated gradual unfolding events accompanied by Trp exposure with increasing temperature. In agreement with the experimental results, molecular modeling investigations showed that the secondary and tertiary structure of LF are slightly affected by the thermal treatment. Some minor unfolding events related particularly to the α-helical regions of LF were observed when the temperature increased to 100 °C. The LF fluorescence quenching upon FA addition indicated that a static mechanism stands behind LF-FA complex formation. Regardless of the simulated temperature, the hydrogen bonds played an important role in regulating the interaction between the protein and ligand. FA binding to LF equilibrated at different temperatures occurred spontaneously, and all complexes displayed good thermodynamic stability. The obtained results support the suitability of LF as biocompatible material, for obtaining micro- and nanoparticles for delivery of dietary supplements or for enhancing the functionality of target delivery systems.