Interaction between Curcumin and β-Casein: Multi-Spectroscopic and Molecular Dynamics Simulation Methods

Encapsulation of three different types of polyphenols in casein using a customized pH-driven method: Preparation and characterization

Phenolic compounds represent natural compounds endowed with diverse biological functionalities. However, their inherent limitations, characterized by poor water solubility and low oral bioavailability, limit their broader applications. Encapsulation delivery systems are emerging as a remedy, able to ameliorate these limitations by enhancing the stability and solubility of phenolic compounds. In this study, a novel, customized pH-driven approach was developed by determining the optimal deprotonation and protonation points of three different types of polyphenols: ferulic acid, resveratrol, and rhein. The polyphenols were successfully encapsulated in a casein carrier. The solubility, stability, LogD, and LogS curves of the three polyphenols at different pH values were analyzed to identify the optimal deprotonation points for ferulic acid (pH 9), resveratrol (pH 11), and rhein (pH 10). Based on these findings, three different nanoparticles were prepared. The encapsulation efficiencies of the three phenolic compounds were 95.86%, 94.62%, and 94.18%, respectively, and the casein nanoparticles remained stable at room temperature for seven days. FTIR spectroscopy, fluorescence spectroscopy, and molecular docking study substantiated the encapsulation of phenolic compounds within the hydrophobic core of casein-based complexes, facilitated by hydrogen bonding interactions and hydrophobic interactions. Furthermore, the analysis of antioxidant activity elucidated that casein nanoparticles heightened both the water solubility and antioxidant efficacy of the phenolic compounds. This customized encapsulation technique, by establishing a transitional pH value, resolves the challenges of chemical instability and facile degradation of polyphenols under alkaline conditions in the application process of pH-driven methods. It presents novel insights for the application of polyphenols in the domains of food and biomedical fields.

New Perspective on the Interaction Behavior Between Riboflavin and β Lactoglobulin-β Casein Complex by Biophysical Techniques

Riboflavin (RF) is a vitamin that only exists in plants and microorganisms and must be procured externally by humans. On the other hand, there are two major allergic factors in cow's milk, including β-lactoglobulin (βLG) and β-casein (βCN), while their allergic properties can be eliminated by binding to micronutrients. In this regard, we examined the binding process of RF to βLG and βCN in the binary and ternary systems by different spectroscopies such as zeta potential, electric conductivity, and molecular modeling. According to the result of the fluorescence spectrum regarding the interaction of RF with βLG and βCN in binary and ternary systems, an increase in RF concentration declined the fluorescence intensity of three systems and also caused the quenching of proteins. Static quenching plays a pivotal role in the formation of stable interactions. The obtained thermodynamic parameters by Van't Hoff equation ascertained the predominance of hydrogen bonds and van der Waals interaction in all the systems. Considering how the negative value of ΔH0 resulted in the negative value of ΔG0, the systems were assumed to be enthalpy driven. The outcomes of circular dichroism (CD) disclosed that the attachment of RF to the targets of systems increased their a-helix content, which particularly included the binding of RF to βLG that led to the conversion of β-sheet to α-helix content. As indicated by the results of zeta potential, the low concentration of RF contained the dominance of hydrophobic forces in the interactions, whereas the enlargement of this concentration prevailed electrostatic forces. Moreover, conductometry measurements showed an extension in the rate of ionizable groups due to the addition of RF to the systems, which may increase the probability of an interaction between RF, βCN, and βLG in binary and ternary systems. In consistency with the outcomes of molecular dynamics simulation, the data of molecular docking approved the capability of RF in forming strong and stable interactions with βCN and βLG.

Exploring thyroxine binding globulin structural changes and its release from human hepatoblastoma cells upon interaction with silica particles: A prelude to unrevealing the mechanism of thyroid hormone dysregulation

Endocrine dysregulation in the presence of environmental chemical risk factors is a global adverse health concern. The aim of this investigation was to explore the structural changes and binding affinity of thyroxine (T4) binding protein (TBG) upon interaction with SiO2 particles as the second largest mineral in the Earth's crust and one of the most important constituents of rock, soil, and dust. Therefore, the interaction of TBG with SiO2 particles was assessed by fluorescence quenching, molecular docking, ANS and synchronous fluorescence, and far-UV CD analyses. Also, the release of TBG from human hepatoblastoma cell line, Hep G2, was assessed by ELISA assay. The results displayed that the value of stoichiometry of binding site (n) of TBG for T4 was approximately equal to one, which was reduced to 0.36 in the presence of SiO2 particles. Also, the binding affinity (Kb) values revealed that the binding affinity between T4 and TBG was strong (97.90 × 105 L/mol), while the presence of SiO2 particles resulted in the calculation of a Kb around 0.00159 × 105 L/mol, which was significantly lower than that of the absence of SiO2 particles. This data was also verified by molecular docking analyses which indicated that SiO2 particles interacted with the T4 binding pocket of TBG. Moreover, further studies exhibited that although the equimolar concentration of T4 to TBG resulted in the superior stability of TBG-T4 complex relative to free TBG, the presence of SiO2 particles with the same concentration led to denaturation of the secondary structure of TBG. Furthermore, it was seen that the amount of released TBG in the cell culture medium of Hep G2 was about 2.21 ng/mL protein, whereas this amount in SiO2 particles-treated cell group was significantly reduced to 1.71 ng/mL protein (*P < 0.05). In conclusion, this study implies that SiO2 particles show the potential to result in inhibition of TBG release, TBG denaturation, and interfere with TBG binding affinity which may lead to dysregulation of the thyroid hormone transport and associated signaling pathways.

Protein-polysaccharide-based delivery systems for enhancing the bioavailability of curcumin: A review

In recent years, a wide attention has been paid to curcumin in medicine due to its excellent physiological activities, including anti-inflammatory, antioxidant, antibacterial, and nerve damage repair. However, the low solubility, poor stability, and rapid metabolism of curcumin make its bioavailability low, which affects its development and application. As a unique biopolymer structure, protein-polysaccharide (PRO-POL)-based delivery system has the advantages of low toxicity, biocompatibility, biodegradability, and delayed release. Many scholars have investigated PRO-POL -based delivery systems to improve the bioavailability of curcumin. In this paper, we focus on the interactions between different proteins (e.g. casein, whey protein, soybean protein isolate, pea protein, zein, etc.) and polysaccharides (chitosan, sodium alginate, hyaluronic acid, pectin, etc.) and their effects on complexes diameter, surface charge, encapsulation drive, and release characteristics. The mechanism of the PRO-POL-based delivery system to enhance the bioavailability of curcumin is highlighted. In addition, the application of PRO-POL complexes loaded with curcumin is summarized, aiming to provide a reference for the construction and application of PRO-POL delivery systems.

Current Understanding of Polyphenols to Enhance Bioavailability for Better Therapies

In recent years, plant polyphenols have become a popular focus for the development of novel functional foods. Polyphenols, a class of bioactive compounds, including flavonoids, phenolic acids, and lignans, are commonly found in plant-based diets with a variety of biological actions, including antioxidant, anti-inflammatory, and anticancer effects. Unfortunately, polyphenols are not widely used in nutraceuticals since many of the chemicals in polyphenols possess poor oral bioavailability. Thankfully, polyphenols can be encapsulated and transported using bio-based nanocarriers, thereby increasing their bioavailability. Polyphenols' limited water solubility and low bioavailability are limiting factors for their practical usage, but this issue can be resolved if suitable delivery vehicles are developed for encapsulating and delivering polyphenolic compounds. This paper provides an overview of the study of nanocarriers for the enhancement of polyphenol oral bioavailability, as well as a summary of the health advantages of polyphenols in the prevention and treatment of several diseases.

Polyphenols: a route from bioavailability to bioactivity addressing potential health benefits to tackle human chronic diseases

Chronic pathologies or non-communicable diseases (NCDs) include cardiovascular diseases, metabolic syndrome, neurological diseases, respiratory disorders and cancer. They are the leading global cause of human mortality and morbidity. Given their chronic nature, NCDs represent a growing social and economic burden, hence urging the need for ameliorating the existing preventive strategies, and for finding novel tackling therapies. NCDs are highly correlated with unhealthy lifestyle habits (such as high-fat and high-glucose diet, or sedentary life). In general, lifestyle approaches that might improve these habits, including dietary consumption of fresh vegetables, fruits and fibers, may contrast NCD symptoms and prolong life expectancy of affected people. Polyphenols (PPLs) are plant-derived molecules with demonstrated biological activities in humans, which include: radical scavenging and anti-oxidant activities, capability to modulate inflammation, as well as human enzymes, and even to bind nuclear receptors. For these reasons, PPLs are currently tested, both preclinically and clinically, as dietary adjuvants for the prevention and treatment of NCDs. In this review, we describe the human metabolism and bioactivity of PPLs. Also, we report what is currently known about PPLs interaction with gastro-intestinal enzymes and gut microbiota, which allows their biotransformation in many different metabolites with several biological functions. The systemic bioactivity of PPLs and the newly available PPL-delivery nanosystems are also described in detail. Finally, the up-to-date clinical studies assessing both safety and efficacy of dietary PPLs in individuals with different NCDs are hereby reported. Overall, the clinical results support the notion that PPLs from fruits, vegetables, but also from leaves or seeds extracts, are safe and show significant positive results in ameliorating symptoms and improving the whole quality of life of people with NCDs.

Strategies for Improving Bioavailability, Bioactivity, and Physical-Chemical Behavior of Curcumin

Curcumin (CCM) is one of the most frequently explored plant compounds with various biological actions such as antibacterial, antiviral, antifungal, antineoplastic, and antioxidant/anti-inflammatory properties. The laboratory data and clinical trials have demonstrated that the bioavailability and bioactivity of curcumin are influenced by the feature of the curcumin molecular complex types. Curcumin has a high capacity to form molecular complexes with proteins (such as whey proteins, bovine serum albumin, β-lactoglobulin), carbohydrates, lipids, and natural compounds (e.g., resveratrol, piperine, quercetin). These complexes increase the bioactivity and bioavailability of curcumin. The current review provides these derivatization strategies for curcumin in terms of biological and physico-chemical aspects with a strong focus on different type of proteins, characterization methods, and thermodynamic features of protein–curcumin complexes, and with the aim of evaluating the best performances. The current literature review offers, taking into consideration various biological effects of the CCM, a whole approach for CCM-biomolecules interactions such as CCM-proteins, CCM-nanomaterials, and CCM-natural compounds regarding molecular strategies to improve the bioactivity as well as the bioavailability of curcumin in biological systems.