Characterization of resveratrol–milk protein interaction

Targeting Human Papillomavirus 33 E2 DNA Binding Domain With Polyphenols: Unveiling Interactions Through Biophysical and In Silico Methods

The human papillomavirus (HPV) 33 is a high-risk strain that causes lesions with potential cancerous outcomes. Its E2 protein regulates the viral protein transcription and life cycle maintenance. The DNA binding domain (DBD) of the E2 protein plays a crucial role in the viral life cycle. The DBD region of the E2 protein is particularly interesting for targeting and finding potential inhibitors to inhibit its function or dimerization. Given the limited research on HPV 33 and its proteins, the present work delved into the interaction of two natural polyphenolic compounds, resveratrol, and baicalein, with the E2 DBD of HPV 33 using biophysical and in silico studies. Fluorescence studies of the E2 DBD-polyphenol complexes showed fluorescence quenching with a binding constant of the order of 106 M-1. Circular dichroism data reveal conformational changes upon binding with the polyphenols, possibly due to distinct binding sites of the E2 DBD. Differential scanning calorimetry exhibited higher melting temperatures for the two complexes than alone DBD, suggesting the complexes' stability. ITC experiment suggested favorable binding reactions with k d values in the micromolar range. Molecular docking and dynamic simulation studies revealed that the resveratrol binds to the helical region and baicalein near the central dimeric interface of E2 DBD with a good binding affinity, forming a stable protein-ligand complex during the run of 100 ns simulation. Therefore, the current study identifies both polyphenolic compounds as promising candidates for potential antiviral drug development.

Unraveling the binding mechanism between soybean protein isolate and selected bioactive compounds

The present study was aimed to investigate the interactions between soybean protein isolate (SPI) with resveratrol (RESV) and lutein (LUT). The binding forces, molecular interactions and functional properties were explored by multi-spectroscopic analysis, molecular docking and functional property indexes between SPI and RESV/LUT. The RESV/LUT quenched SPI chromophore residues with static mechanism and the endothermic reaction. The SPI- RESV/LUT complexes were formed through hydrogen bond, electrostatic and hydrophobic interactions. Molecular docking confirmed van-der-Waals force as one of the important forces. The interaction of RESV/LUT led to SPI's secondary structure alterations with a decrease in α-helix and random coil and an increase in β-sheet and β-turns. RESV/LUT developed foaming and emulsifying properties of SPI and showed a significant decrease of the surface hydrophobicity with RESV/LUT concentrations increase attributed to SPI's partial unfolding. Our study exposed molecular mechanisms and confirmations to understand the interactions in protein- RESV/LUT complexes for protein industrial base promotion.

The mechanism of resveratrol stabilization and degradation by synergistic interactions between constituent proteins of whey protein

Whey protein isolate (WPI) is mainly composed of β-lactoglobulin (β-LG), α-lactalbumin (α-LA) and bovine serum albumin (BSA). The aim of this study was to compare and analyze the influence of WPI and its three main constituent proteins, as well as proportionally reconstituted WPI (R-WPI) on resveratrol. It was found that the storage stability of resveratrol was protected by WPI, not affected by R-WPI, but reduced by individual whey proteins at 45°C for 30 days. The rank of accelerated degradation of resveratrol by individual whey proteins was BSA > α-LA > β-LG. The antioxidant activity, localization of resveratrol and oxidation of carrier proteins were determined by ABTS, H2O2 assay, synchronous fluorescence, carbonyl and circular dichroism. The non-covalent interactions and disulfide bonds between constituent proteins improved the antioxidant activity of the R-WPI-resveratrol complex, the oxidation stability of the carrier and the solvent shielding effect on resveratrol, which synergistically inhibited the degradation of resveratrol in R-WPI system. The results gave insight into elucidating the interaction mechanism of resveratrol with protein carriers.

Stability, Digestion, and Cellular Transport of Soy Isoflavones Nanoparticles Stabilized by Polymerized Goat Milk Whey Protein

Soy isoflavones (SIF) are bioactive compounds with low bioavailability due to their poor water solubility. In this study, we utilized polymerized goat milk whey protein (PGWP) as a carrier to encapsulate SIF with encapsulation efficiency of 89%, particle size of 135.53 nm, and zeta potential of -35.16 mV. The PGWP-SIF nanoparticles were evaluated for their stability and in vitro digestion properties, and their ability to transport SIF was assessed using a Caco-2 cell monolayer model. The nanoparticles were resistant to aggregation when subjected to pH changes (pH 2.0 to 8.0), sodium chloride addition (0-200 mM), temperature fluctuations (4 °C, 25 °C, and 37 °C), and long-term storage (4 °C, 25 °C, and 37 °C for 30 days), which was mainly attributed to the repulsion generated by steric hindrance effects. During gastric digestion, only 5.93% of encapsulated SIF was released, highlighting the nanoparticles' resistance to enzymatic digestion in the stomach. However, a significant increase in SIF release to 56.61% was observed during intestinal digestion, indicating the efficient transport of SIF into the small intestine for absorption. Cytotoxicity assessments via the MTT assay showed no adverse effects on Caco-2 cell lines after encapsulation. The PGWP-stabilized SIF nanoparticles improved the apparent permeability coefficient (Papp) of Caco-2 cells for SIF by 11.8-fold. The results indicated that using PGWP to encapsulate SIF was an effective approach for delivering SIF, while enhancing its bioavailability and transcellular transport.

The association of resveratrol and AFPI did not enhance the cryoresistance of ram sperm

Cryoprotectants are required to reduce damage caused to the cells due to low temperatures during the cryopreservation. Antifreeze proteins (AFP) have a well-known role in cell membrane protection, while resveratrol is a potent antioxidant. This study assessed the effect of the association of resveratrol concentrations and AFP I in a ram semen extender. Pooled semen of four rams was allocated into six treatments in a factorial arrangement: (CONT, only the semen extender); only AFP I (ANT: 0.1 µg/mL of AFP I), only resveratrol, one treatment with two levels (10 µM/mL or 50 µM/mL of resveratrol); and two treatments with the interactions, with one AFP I and one of the two levels of resveratrol (0.1 µg/mL of AFP I with 10 µM/mL resveratrol; 0.1 µg/mL of AFP I with 50 µM/mL resveratrol). No interaction between factors was observed on sperm kinetics, plasma membrane integrity, hypo-osmotic test, and mitochondrial activity parameters. There was a high probability (P = 0.06) of reducing sperm cells with functional membrane percentage in the hypo-osmotic test and increasing the percentage of sperm with high mitochondrial activity (P = 0.07) was observed in AFP presence. An interaction of AFP and resveratrol was observed in non-capacitated sperm (P = 0.009), acrosomal reaction (P = 0.034), and sperm binding (P = 0.04). In conclusion, the association of resveratrol and AFP did not improve the quality of frozen-thawed semen and even promoted deleterious effects compared to their single addition in the semen extender. The supplementation of 50 µM/mL of resveratrol improved the outcomes of frozen-thawed ram sperm, being a potential cryoprotectant.

Brassica oleracea L. var. italica Aquaporin Reconstituted Proteoliposomes as Nanosystems for Resveratrol Encapsulation

Aquaporins (AQPs), membrane proteins responsible for facilitating water transport, found in plant membrane vesicles (MV), have been related to the functionality and stability of MV. We focused on AQPs obtained from broccoli, as they show potential for biotechnological applications. To gain further insight into the role of AQPs in MV, we describe the heterologous overexpression of two broccoli AQPs (BoPIP1;2 and BoPIP2;2) in Pichia pastoris, resulting in their purification with high yield (0.14 and 0.99 mg per gram cells for BoPIP1;2 and BoPIP2;2). We reconstituted AQPs in liposomes to study their functionality, and the size of proteoliposomes did not change concerning liposomes. BoPIP2;2 facilitated water transport, which was preserved for seven days at 4 °C and at room temperature but not at 37 °C. BoPIP2;2 was incorporated into liposomes to encapsulate a resveratrol extract, resulting in increased entrapment efficiency (EE) compared to conventional liposomes. Molecular docking was utilized to identify binding sites in PIP2s for resveratrol, highlighting the role of aquaporins in the improved EE. Moreover, interactions between plant AQP and human integrin were shown, which may increase internalization by the human target cells. Our results suggest AQP-based alternative encapsulation systems can be used in specifically targeted biotechnological applications.

Structural, Binding and Functional Properties of Milk Protein-Polyphenol Systems: A Review

Polyphenols (PP) are linked to health benefits (e.g., prevention of cancer, cardiovascular disease and obesity), which are mainly attributed to their antioxidant activity. During digestion, PP are oxidised to a significant degree reducing their bio-functionality. In recent years, the potential of various milk protein systems, including β-casein micelles, β-lactoglobulin aggregates, blood serum albumin aggregates, native casein micelles and re-assembled casein micelles, to bind and protect PP have been investigated. These studies have yet to be systematically reviewed. The functional properties of the milk protein-PP systems depend on the type and concentration of both PP and protein, as well as the structure of the resultant complexes, with environmental and processing factors also having an influence. Milk protein systems protect PP from degradation during digestion, resulting in a higher bioaccessibility and bioavailability, which improve the functional properties of PP upon consumption. This review compares different milk protein systems in terms of physicochemical properties, PP binding performance and ability to enhance the bio-functional properties of PP. The goal is to provide a comprehensive overview on the structural, binding, and functional properties of milk protein-polyphenol systems. It is concluded that milk protein complexes function effectively as delivery systems for PP, protecting PP from oxidation during digestion.

Resveratrol production for the valorisation of lactose-rich wastes by engineered industrial Saccharomyces cerevisiae

Resveratrol is an antioxidant with applications in the food and cosmetic industries. Its biosynthesis can side the hindrances of its extraction from plants. The dairy industry generates tonnes of lactose-rich wastes, which can be a carbon source. Saccharomyces cerevisiae is an industrial workhorse for biotechnological processes, being unable to naturally metabolise lactose. Here, an S. cerevisiae strain was engineered for de novo production of resveratrol from lactose. A resveratrol titre of 210 mg/L from 100 g/L of lactose in synthetic media was achieved. Process optimization increased by 35% the production by a two-stage process, one favouring ethanol production and a subsequent one with stronger agitation favouring ethanol and lactose consumption with conversion into resveratrol. Resveratrol production from cheese whey was further attained. To the best knowledge of the authors, this is the first report on resveratrol production from lactose, relevant in dairy wastes, establishing grounds for future resveratrol-producing lactose-based processes.

Functionalization of Fe3O4/rGO magnetic nanoparticles with resveratrol and in vitro DNA interaction

Based on the previous research, we found that the magnetic nanocomposite Fe₃O₄/rGO (reduced graphene oxide) has a good drug loading effect. Therefore, in this paper, we studied the positive role of Fe₃O₄/rGO as a drug carrier in the interaction between resveratrol (RES) and calf-thymus DNA (ct-DNA). The fluorescence experiment is used to evaluate by the Stern-Volmer equation, the quenching constant of RES - ct-DNA system with and without Fe₃O₄/rGO decreases with the increasing temperature. It was found the quenching mode of RES - ct-DNA and Fe₃O₄/rGO - RES - ct-DNA systems were all static quenching, but the binding constant of RES -ct-DNA increased from 4.14 ± 0.21 × 10⁴ L mol^-1 to 10.12 ± 0.02 × 10⁴ L mol^-1. It was found that Fe₃O₄/rGO formed a ternary complex with RES and ct-DNA by ultraviolet spectrum (UV-vis), resonance light scattering experiments (RLS) and scanning electron microscope (SEM). Meanwhile, Fourier transform infrared (FT-IR) and circular dichroism (CD) experiments show that Fe₃O₄/rGO and Fe₃O₄/rGO loaded with RES have effect on the secondary structure of ct-DNA and change the conformation of ct-DNA. On the cellular level, the comet assay shows that Fe₃O₄/rGO and Fe₃O₄/rGO - RES could not cause DNA strand break to the mouse hepatocytes after 24 co-incubation. These results confirm that Fe₃O₄/rGO nanocomposites have good application potential, which can be used as a good drug carrier in a wide range of therapeutic methods.

Chemical aspects of polyphenol-protein interactions and their antibacterial activity

The hunt for novel antibiotics has become a global public health imperative due to the rise in multidrug-resistant microorganisms, untreatable infection cases, overuse, and inefficacy of modern antibiotics. Polyphenols are getting much attention in research due to their multiple biological effects; their use as antimicrobial agents is attributed to their activity and that microbes have a hard time developing resistance to these natural compounds. Polyphenols are secondary metabolites produced in higher plants. They are known to possess various functional properties in the human body. Polyphenols also exhibit antibacterial activities against foodborne pathogens. Their antibacterial mechanism is based on inhibiting bacterial biofilm formation or inactivating enzymes. This review focused on polyphenol-protein interactions and the creation of this complex as a possible antibacterial agent. Also, different phenolic interactions on bacterial proteins, efflux pump, cell membrane, bacterial adhesion, toxins, and other bacterial proteins will be explored; these interactions can work in a synergic combination with antibiotics or act alone to assure bacterial inhibition. Additionally, our review will focus on polyphenol-protein interaction as a possible strategy to eradicate bacteria because polyphenols have shown a robust enzyme-inhibitory characteristic and a high tendency to complex with proteins, a response that neutralizes any bactericidal potential.

Inorganic food additive nanomaterials alter the allergenicity of milk proteins

While inorganic nanomaterials are copiously incorporated in food products, their impact on the allergenicity food proteins is largely unknown. This study analyzed the effect of widely used food additive nanomaterials (silica and titania) on the antigenicity and allergenicity of milk proteins (β-lactoglobulin and casein) and skimmed milk. Changes in the antigenicity of milk proteins in the presence of dietary nanomaterials were identified using an indirect-ELISA assay, while the change in allergenicity was studied using mast cell (LAD2) sensitized using allergic human sera. Results showed an enhancement in the allergenicity of milk proteins/skimmed milk interacted with particles (both silica and titania). Similarly, mast cell degranulation (a proxy for allergenicity) was higher when exposed to particle interacted skim milk where nanomaterials of titania showed the highest effect, and this tendency was retained even after subjecting to simulated gut digestion. Particles induced alterations in the structure of milk proteins, as evidenced by our studies, are reasoned to expose epitopes that increase allergenicity of milk proteins.

Casein Micelles as an Emerging Delivery System for Bioactive Food Components

Bioactive food components have potential health benefits but are highly susceptible for degradation under adverse conditions such as light, pH, temperature and oxygen. Furthermore, they are known to have poor solubilities, low stabilities and low bioavailabilities in the gastrointestinal tract. Hence, technologies that can retain, protect and enable their targeted delivery are significant to the food industry. Amongst these, microencapsulation of bioactives has emerged as a promising technology. The present review evaluates the potential use of casein micelles (CMs) as a bioactive delivery system. The review discusses in depth how physicochemical and techno-functional properties of CMs can be modified by secondary processing parameters in making them a choice for the delivery of food bioactives in functional foods. CMs are an assembly of four types of caseins, (α_s1, α_s2, β and κ casein) with calcium phosphate. They possess hydrophobic and hydrophilic properties that make them ideal for encapsulation of food bioactives. In addition, CMs have a self-assembling nature to incorporate bioactives, remarkable surface activity to stabilise emulsions and the ability to bind hydrophobic components when heated. Moreover, CMs can act as natural hydrogels to encapsulate minerals, bind with polymers to form nano capsules and possess pH swelling behaviour for targeted and controlled release of bioactives in the GI tract. Although numerous novel advancements of employing CMs as an effective delivery have been reported in recent years, more comprehensive studies are required to increase the understanding of how variation in structural properties of CMs be utilised to deliver bioactives with different physical, chemical and structural properties.

Interactions between caseins and food-derived bioactive molecules: A review

Caseins are recognized as safe for consumption, abundant, renewable and have high nutritional value. Casein molecules are found in different aggregation states and their multiple binding sites offer the potential for delivering biomolecules with nutritional and/or health benefits, such as vitamins, phytochemicals, fibers, lipids, minerals, proteins, peptides, and pharmaceutical compounds. In the present review, we highlight the interactions between caseins and food-derived bioactive molecules, with a special focus on the aggregation states of caseins and the techniques used to produce and study the particles used for delivering. Research on interactions between caseins-minerals and casein-pharmaceutical molecules are not included here. This review aims to support the development of new and innovative functional foods in which caseins can be used as designed delivery systems.

Interface Compositions as Determinants of Resveratrol Stability in Nanoemulsion Delivery Systems

The incorporation of hydrophobic ingredients, such as resveratrol (a fat-soluble phytochemical), in nanoemulsions can increase the water solubility and stability of these hydrophobic ingredients. The nanodelivery of resveratrol can result in a marked improvement in the bioavailability of this health-promoting ingredient. The current study hypothesized that resveratrol can bind to caprine casein, which may result in the preservation of the biological properties of resveratrol. The fluorescence spectra provided proof of this complex formation by demonstrating that resveratrol binds to caprine casein in the vicinity of tryptophan amino acid residues. The caprine casein/resveratrol complex is stabilized by hydrophobic interactions and hydrogen bonds. Hence, to study the rate of resveratrol degradation during processing/storage, resveratrol losses were determined by reversed-phase high performance liquid chromatography (RP-HPLC) in nanoemulsions stabilized by bovine and caprine caseins individually and in combination with polysorbate-20. At 48 h oxidation, 88.33% and 89.08% was left of resveratrol in the nanoemulsions stabilized by caprine casein (α_s1-I)/polysorbate-20 complex and caprine (α_s1-II)/polysorbate-20 complex, while there was less resveratrol left in the nanoemulsions stabilized by bovine casein/polysorbate-20 complex, suggesting that oxygen degradation was involved. The findings of this study are crucial for the food industry since they imply the potential use of caprine casein/polysorbate-20 complex to preserve the biological properties of resveratrol.

Preparation and Characterization of Soy Isoflavones Nanoparticles Using Polymerized Goat Milk Whey Protein as Wall Material

Soy isoflavones (SIF) are a group of polyphenolic compounds with health benefits. However, application of SIF in functional foods is limited due to its poor aqueous solubility. SIF nanoparticles with different concentrations were prepared using polymerized goat milk whey protein (PGWP) as wall material. The goat milk whey protein was prepared from raw milk by membrane processing technology. The encapsulation efficiencies of all the nanoparticles were found to be greater than 70%. The nanoparticles showed larger particle size and lower zeta potential compared with the PGWP. Fourier Transform Infrared Spectroscopy indicated that the secondary structure of goat milk whey protein was changed after interacting with SIF, with transformation of α-helix and β-sheet to disordered structures. Fluorescence data indicated that interactions between SIF and PGWP decreased the fluorescence intensity. All nanoparticles had spherical microstructure revealed by Transmission Electron Microscope. Data indicated that PGWP may be a good carrier material for the delivery of SIF to improve its applications in functional foods.

Kinetic interactions of nanocomplexes between astaxanthin esters with different molecular structures and β-lactoglobulin

The influence of different fatty acid carbon chains on the kinetic interactions of nanocomplexes between esterified astaxanthin (E-Asta) and β-lactoglobulin (β-Lg) were investigated by multi-spectroscopy and molecular modeling techniques. We synthesized ten different E-Asta bound to β-Lg and formed nanocomplexes (< 300 nm). Fluorescence spectroscopy showed moderate affinities (binding constants Ka = 10³-10⁴ M^-1). Docosahexaenoic acid astaxanthin monoester (Asta-C22:6) had the strongest binding affinity towards β-Lg (Ka = 3.77 × 10⁴ M^-1). The fluorescence quenching of β-Lg upon binding of E-Asta displayed a static mechanism, with binding sites (n) equal to 1. Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectroscopy revealed that E-Asta might enter the β-Lg hydrophobic cavity, leading to unfolding of the peptide chain skeleton. In summary, β-Lg and E-Asta can form stable nanocomplex emulsions to achieve an effective delivery process for E-Asta.

Fibrinogen Increases Resveratrol Solubility and Prevents it from Oxidation

The French paradox describes a lower incidence of cardiovascular problems despite a high intake of saturated fats. This phenomenon was associated with higher consumption of red wine, as it was later discovered that the presence of antioxidants, including resveratrol, have beneficial effects. We hypothesized that resveratrol may have a more direct role in protection from harmful oxidation, presumably through binding to important proteins of the blood coagulation process. Spectrofluorimetry demonstrated that resveratrol is capable of binding to fibrinogen, the main protein in the coagulation process, which is also important as a food additive. Various spectroscopic methods determined that binding does not cause fibrinogen unfolding or destabilization since protein melting temperature remains unchanged. A mutually protective effect against the free radical-induced oxidation of polyphenol and fibrinogen was found. The presence of fibrinogen caused only a negligible masking effect of the antioxidative abilities of resveratrol, measured by a reduction of hexacyanoferrate (III), while greatly increasing its solubility in an aqueous environment, thus increasing its potential bioavailability. Due to its interaction with fibrinogen, resveratrol may serve as an antioxidant at the site of injury. The antioxidative effect of resveratrol may also protect and thus keep the desired characteristics of fibrinogen during the application of this protein as a food additive.

Coencapsulation and Stability Evaluation of Hydrophilic and Hydrophobic Bioactive Compounds in a Cagelike Phytoferritin

Enrichment of multiple bioactive components with different characters into one food substrate simultaneously is a challenge. In this study, the hydrophilic epigallocatechin gallate (EGCG) and the hydrophobic quercetin were simultaneously enriched in the cavity of phytoferritin from red bean seed deprived of iron (apoRBF), a cagelike protein. The interactions of apoRBF with EGCG and quercetin were evaluated by UV/visible absorption, fluorescence, and circular dichroism technologies. By combination of the reversible assembly and urea induced approaches, both EGCG and quercetin were successfully coencapsulated in apoRBF to fabricate four kinds of apoRBF-EGCG-quercetin nanocomplexes FEQ (FEQ1, FEQ2, FEQ3, and FEQ4) with good solubility in aqueous solution. All FEQ samples maintained the typically spherical morphology of ferritin cage with a diameter around 12 nm. Among the four FEQ samples, the FEQ1 prepared by involving a pH 2.0/6.7 transition scheme was more effective in encapsulating EGCG and quercetin molecules than that by the urea induced method. Furthermore, all FEQs facilitated the stability of EGCG and quercetin molecules relative to free ones, and simultaneous coencapsulation of EGCG and quercetin could significantly improve the quercetin stability as compared with that of the free one and quercetin-loaded ferritin (p < 0.05), respectively. This work provides a new scheme to design and fabricate the ferritin based carrier for encapsulation of multiple bioactive components, and it is beneficial for the intensification of multifunction in one food substrate.

Encapsulation of Lutein in Nanoemulsions Stabilized by Resveratrol and Maillard Conjugates

Lutein is incorporated into foods as a natural yellow pigment and nutraceutical. The introduction of lutein into many foods and beverages, however, is problematic because of its strong hydrophobicity and poor chemical stability. In this research, lutein-loaded nanoemulsions were prepared to overcome this problem. Casein-dextran Maillard conjugates or physical complexes were utilized as emulsifiers, while either medium chain triglycerides (MCT) or grape seed oil (GSO) were used as carrier oils. The impact of resveratrol addition on nanoemulsion stability was also examined. The influence of storage temperature, pH, and CaCl₂ concentration on the chemical and physical stability of the nanoemulsions was measured. The casein-dextran conjugates were highly effective at improving the physical resistance of the nanoemulsions to environmental stresses, but had a detrimental effect on their color stability. Conversely, nanoemulsions prepared from casein-dextran physical complexes were unstable around the protein's isoelectric point (pH 4.6), as well as upon addition of CaCl₂ . Incorporation of resveratrol and GSO into the nanoemulsions decreased lutein degradation and color fading at all temperatures. This study shows that casein-dextran conjugates are highly effective at improving the physical stability of lutein-loaded nanoemulsions, while resveratrol and GSO are effective at improving their chemical stability. PRACTICAL APPLICATION: Lutein can be used by the food industry to create "clean label" and functional food products. The major challenges in incorporating lutein in foods are its poor chemical stability and its high hydrophobicity, which makes it difficult to incorporate. Emulsion-based delivery systems assembled from natural ingredients may address these challenges. In this study, the impact of Maillard conjugates fabricated from caseinate and dextran, as well as resveratrol addition, on the formation and stability of lutein-enriched nanoemulsions was determined. The information obtained from this study will help the formulation of more effective functional foods and beverage products.

Enterodiol is Actively Transported by Rat Liver Cell Membranes

The interaction of enterodiol and the well-described polyphenol epigallocatechin gallate (EGCG) with hepatic membranes has been matter of interest in the last few years. On one hand, EGCG is only able to bind to the phospholipid polar head groups, as it has been already described in synthetic lipid bilayers and erythrocyte membranes but cannot get inserted into the hydrophobic core or be transported into the lumen of membrane vesicles. On the other, enterodiol has no interaction with non-energized membranes either, but it is able to interact and even be transported upon addition of ATP. In fact, the ATPase activity undergoes a twofold increase in the presence of enterodiol but not in the presence of EGCG. This is the first report on the transport of enterodiol by liver membranes, and it may help explain the rather high blood concentrations of this estrogenic enterolignan compared to EGCG, which is extensively metabolized by the intestine and the liver. The present results suggest that a fraction of enterodiol may escape the liver inactivation by being pumped out from the hepatocytes to the bloodstream.

Enhanced pH and thermal stability, solubility and antioxidant activity of resveratrol by nanocomplexation with α-lactalbumin

The health-promoting benefits of resveratrol (RES) have attracted significant attention.

Functional and conformational changes to soy proteins accompanying anthocyanins: Focus on covalent and non-covalent interactions

The present study was aimed to evaluate the interaction between anthocyanins from black rice and soybean protein isolate (SPI) via non-covalent and covalent bindings and the impact of these interactions on the functional and conformational changes of soybean protein. The conformational changes of the protein structure with different concentrations of anthocyanins (0.05, 0.1%, and 0.2%) were analyzed using three-dimensional fluorescence and Fourier transform infrared spectroscopy. The anthocyanins were more likely to form covalent interactions with SPI instead of non-covalent interactions. The addition of anthocyanins changed the secondary structure of SPI with a decrease in β-sheets and an increase in β-turns and random coils. The emulsifying and foaming properties of SPI were improved after complexation with anthocyanins. This study might be useful for elucidating the mechanisms behind the binding of anthocyanins with SPI and the possible uses of SPI-anthocyanin complexes in food formulations.

Influence of quercetin on the interaction of gliclazide with human serum albumin - spectroscopic and docking approaches

Protein-binding interactions are displacement reactions which have been implicated as the causative mechanisms in many drug-drug interactions. Thus, the aim of presented study was to analyse human serum albumin-binding displacement interaction between two ligands, hypoglycaemic drug gliclazide and widely distributed plant flavonoid quercetin. Fluorescence analysis was used in order to investigate the effect of substances on intrinsic fluorescence of human serum albumin (HSA) and to define binding and quenching properties of ligand-albumin complexes in binary and ternary systems, respectively. Both ligands showed the ability to bind to HSA, although to a different extent. The displacement effect of one ligand from HSA by the other one has been described on the basis of the quenching curves and binding constants comparison for the binary and ternary systems. According to the fluorescence data analysis, gliclazide presents a substance with a lower binding capacity towards HSA compared with quercetin. Results also showed that the presence of quercetin hindered the interaction between HSA and gliclazide, as the binding constant for gliclazide in the ternary system was remarkably lower compared with the binary system. This finding indicates a possibility for an increase in the non-bound fraction of gliclazide which can lead to its more significant hypoglycaemic effect. Additionally, secondary and tertiary structure conformational alterations of HSA upon binding of both ligands were investigated using synchronous fluorescence, circular dichroism and FT-IR. Experimental data were complemented with molecular docking studies. Obtained results provide beneficial information about possible interference upon simultaneous co-administration of the food/dietary supplement and drug.

Formation of a Multiligand Complex of Bovine Serum Albumin with Retinol, Resveratrol, and (-)-Epigallocatechin-3-gallate for the Protection of Bioactive Components

Clarification of the interaction mechanisms between proteins and bioactive components is important to develop effective carriers for encapsulation and protection of bioactive components. Bovine serum albumin (BSA), a globular protein in serum and milk, contains multiple sites to bind a variety of low-molecular-weight molecules, forming protein-monoligand complexes. In this study, the interactions of BSA with retinol, resveratrol, and/or (-)-epigallocatechin-3-gallate (EGCG) were investigated by using fluorescence, circular dichroism, and molecular docking techniques. BSA-triligand complexes were successfully formed when added in the sequence of retinol, resveratrol, and EGCG. The stability of these bioactive components was improved in the complexes relative to free ones. The complexes provided a better protective effect on retinol and resveratrol than did BSA-monoligand complexes, in which the presence of EGCG played an important role.