The interaction mechanism of oligopeptides containing aromatic rings with β-cyclodextrin and its derivatives

Encapsulation of 4-terpineol with β-cyclodextrin: Inclusion mechanism, characterization and relative humidity-triggered release

4-Terpineol (4-TA), a typical monocyclic monoterpene essential oil compound with important biological activities, poor stability and solubility severely hamper its biological activities. To date, β-cyclodextrin (β-CD) encapsulating essential oil to form inclusion complexes (ICs) is considered as a satisfactory treatment. Nevertheless, the detailed inclusion mechanism of β-CD for 4-TA especially the behavior of 4-TA during inclusion formation have not available yet. Herein, 4-TA/β-CD ICs were successfully synthesized by the co-precipitation method, and hydrogen bonds and hydrophobic interactions played a key role in the formation of ICs, and the isopropyl of 4-TA entered the cavity through the wide rim of β-CD. Moreover, the release profile demonstrated that high RH (85 % and 99 %) triggered the release of TA from ICs. This study suggests the great potential of cyclodextrin inclusion strategy for improving the stability and sustained release of 4-TA in food preservation application.

Exploring novel lead scaffolds for SGLT2 inhibitors: Insights from machine learning and molecular dynamics simulations

Sodium-glucose cotransporter 2 (SGLT2) plays a pivotal role in mediating glucose reabsorption within the renal filtrate, representing a well-known target in type 2 diabetes and heart failure. Recent emphasis has been directed toward designing SGLT2 inhibitors, with C-glycoside inhibitors emerging as front-runners. The architecture of SGLT2 has been successfully resolved using cryo-electron microscopy. However, comprehension of the pharmacophores within the binding site of SGLT2 remains unclear. Here, we use machine learning and molecular dynamics simulations on SGLT2 bound with its inhibitors in preclinical or clinical development to shed light on this issue. Our dataset comprises 1240 SGLT2 inhibitors amalgamated from diverse sources, forming the basis for constructing machine learning models. SHapley Additive exPlanation (SHAP) elucidates the crucial fragments that contribute to inhibitor activity, specifically Morgan_3, 162, 310, 325, 366, 470, 597, 714, 926, and 975. Furthermore, the computed binding free energies and per-residue contributions for SGLT2-inhibitor complexes unveil crucial fragments of inhibitors that interact with residues Asn-75, His-80, Val-95, Phe-98, Val-157, Leu-274, and Phe-453 in the binding site of SGLT2. This comprehensive investigation enhances understanding of the binding mechanism for SGLT2 inhibitors, providing a robust framework for evaluating and discovering novel lead scaffolds within this domain.

Difference in the complexation of cholesterol with β-cyclodextrin derivatives: A combined theoretical and experimental study

This study aimed to compare differences in interactions between cholesterol and β- cyclodextrin and its derivatives for selecting a suitable β-cyclodextrin derivative to efficiently remove cholesterol from high-melting-point foods. First, the formation of cholesterol/β-cyclodextrin derivative complexes was investigated using Fourier transform infrared spectroscopy and thermogravimetric analysis. Secondly, the conformations of β-cyclodextrin derivatives were determined from experimental and calculated 1H NMR spectra, and the weak interactions between cholesterol and β-cyclodextrin derivatives were studied by computational approach. Cholesterol/hydroxypropyl-β-cyclodextrin complex had the lowest complexation energy. Besides, two moderate hydrogen bonds were formed between cholesterol and hydroxypropyl-β-cyclodextrin and between cholesterol and sulfobutyl ether-β-cyclodextrin, while one weak hydrogen bond was formed between cholesterol and methyl-β-cyclodextrin. Finally, the efficiency of cholesterol removal by hydroxypropyl-β-cyclodextrin was 5.47% higher than that by β-cyclodextrin at their optimal temperature. This work provided a theoretical basis for selecting a competent adsorbent to effectively remove cholesterol from high-melting-point foods.

Unravelling the interaction between α-SOH and myofibrillar protein based on spectroscopy and molecular dynamics simulation

This work systematically investigated the dose-response interaction between hydroxy-α-sanshool (α-SOH) and pork myofibrillar proteins (MPs) via spectroscopy, molecular docking, and molecular dynamics simulation methods. Results showed that MPs bound with low α-SOH can enhance the surface hydrophobicity and particle size of MPs, whereas high concentrations were exactly the opposite. The main interaction force in α-SOH/MPs complex changed from hydrophobic to hydrogen bonding with increased α-SOH. α-SOH causes tryptophan quenching and bring about a red shift at low concentration, as well as to promote α-helix conversion into β-sheet in MPs. Simultaneously, molecular docking and dynamics simulations verified that hydrogen bonding and hydrophobic forces were the main contributors to α-SOH/MPs complex, indicating that the binding of α-SOH with MPs proceeded spontaneously with high intensity, in which TYR286 contributed the most significant energy. Therefore, revealing the binding mechanism of α-SOH and MPs can contribute to the deep processing of numbing meat products.

Green Synthesis of Magnetic Supramolecules β-Cyclodextrin/Iron Oxide Nanoparticles for Photocatalytic and Antibacterial Applications

Iron oxide nanoparticles (Fe3O4NPs) are a fascinating field of study due to their wide range of practical applications in environmental and medical contexts. This study presents a straightforward, environmentally friendly method for producing Fe3O4NPs utilizing β-cyclodextrin (β-CD) as a reducing and capping agent. This approach results in the rapid and effective eco-friendly synthesis of β-CD/Fe3O4NPs. The properties and characteristics of β-CD/Fe3O4NPs were investigated using various methods, including ultraviolet-visible (UV/vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA), and vibrating-sample magnetometry (VSM). The absorption of β-CD/Fe3O4NPs caused a distinct peak at 349 nm, as evidenced by the results of UV/vis studies. This peak was attributed to the absorption of surface plasmon resonance. The crystalline nature of β-CD/Fe3O4NPs was confirmed through XRD analysis. The SEM and TEM analyses have verified the geometry and structural characteristics of β-CD/Fe3O4NPs. The β-CD/Fe3O4NPs exhibited remarkable effectiveness in the decomposing efficiency (%) of methylene blue (MB) dye with 52.2, 94.1, and 100% for 0.2, 0.4, and 0.6 g β-CD/Fe3O4NPs, respectively. In addition, the highest efficiency in hunting radicals was observed (347.2 ± 8.2 mg/g) at 100 mg/mL β-CD/Fe3O4NPs; the combination of β-CD/Fe3O4NPs exhibited remarkable effectiveness in inhibiting the growth of some bacteria that cause infections. The capabilities of β-CD/Fe3O4NPs for various applications showed that these materials could be used in photocatalytic, antioxidants, and antibacterial. Additionally, the eco-friendly synthesis of these materials makes them a promising option for the remediation of harmful pollutants and microbes.

Application of Molecular Simulation Methods in Food Science: Status and Prospects

Molecular simulation methods, such as molecular docking, molecular dynamic (MD) simulation, and quantum chemical (QC) calculation, have become popular as characterization and/or virtual screening tools because they can visually display interaction details that in vitro experiments can not capture and quickly screen bioactive compounds from large databases with millions of molecules. Currently, interdisciplinary research has expanded molecular simulation technology from computer aided drug design (CADD) to food science. More food scientists are supporting their hypotheses/results with this technology. To understand better the use of molecular simulation methods, it is necessary to systematically summarize the latest applications and usage trends of molecular simulation methods in the research field of food science. However, this type of review article is rare. To bridge this gap, we have comprehensively summarized the principle, combination usage, and application of molecular simulation methods in food science. We also analyzed the limitations and future trends and offered valuable strategies with the latest technologies to help food scientists use molecular simulation methods.

Stability, Antioxidant Activity and Intestinal Permeation of Oleuropein Inclusion Complexes with Beta-Cyclodextrin and Hydroxypropyl-Beta-Cyclodextrin

Compared to beta-cyclodextrins (beta-CD), hydroxypropyl-beta-cyclodextrins (HP-beta-CD) are a more popular material used to prepare inclusion complexes due to their superior solubility and intestinal absorption. In this study, oleuropein (OL) inclusion complexes with beta-CD (beta-CD:OL) and HP-beta-CD (HP-beta-CD:OL) were prepared and the formation of inclusion complexes was validated by IR, PXRD, and DSC. A phase solubility test showed that the lgK (25 °C) and binding energy of beta-CD:OL and HP-beta-CD:OL was 2.32 versus 1.98, and −6.1 versus −24.66 KJ/mol, respectively. Beta-CD:OL exhibited a more powerful effect than HP-beta-CD:OL in protecting OL from degradation upon exposure to light, high temperature and high humidity. Molecular docking, peak intensity of carbonyls in IR, and ferric reducing power revealed that beta-CD:OL formed more hydrogen bonds with the unstable groups of OL. Both inclusion complexes significantly enhanced the solubility, intestinal permeation and antioxidant activity of OL (p < 0.05). Though HP-beta-CD:OL had higher solubility and intestinal absorption over beta-CD:OL, the difference was not significant (p > 0.05). The study implies that lower binding energy is not always associated with the higher stability of a complex. Beta-CD can protect a multiple-hydroxyl compound more efficiently than HP-beta-CD with the intestinal permeation comparable to HP-beta-CD complex.

Spray-Drying of Hydroxypropyl β-Cyclodextrin Microcapsules for Co-Encapsulation of Resveratrol and Piperine with Enhanced Solubility

The synergistic therapeutic benefits of resveratrol (RES) and piperine (PIP) have been proven for the treatment of various diseases. This study reports, for the first time, spray-drying of hydroxypropyl β-cyclodextrin (HP-β-CD) microcapsules for combined delivery of resveratrol and piperine. Phase solubility studies indicated that there was a strong interaction between the active ingredients and HP-β-CD, and both active ingredients can bind stably to HP-β-CD. The results of FTIR, XRD, and DSC demonstrated that RES-PIP/HP-β-CD inclusion complexes were successfully formed, with the RES and PIP encapsulated into the hollow spherical cavity of HP-β-CD. The results of SEM showed that the spray-dried microcapsules displayed a smooth surface and uniform particle size. Upon the formation of the spray-dried microcapsules, both RES and PIP presented significantly enhanced solubility. The results of DPPH and ABTS+ scavenging activity assays showed that the spray-drying process did not adversely influence the antioxidant activity of the bioactives, and the addition of PIP increased the antioxidation performance of RES.

Computational Methods for the Interaction between Cyclodextrins and Natural Compounds: Technology, Benefits, Limitations, and Trends

Cyclodextrins (CDs) have a hollow structure with a hydrophobic interior and hydrophilic exterior. Forming inclusion complexes with CDs will maximize the bioavailability of natural compounds and enable active components to be processed into functional foods, medicines, additives, and so forth. However, experimental methods cannot explain CD-guest binding at the atomic level. Different models have been recently developed to simulate the interaction between CDs and guests to study the binding conformation and analyze noncovalent forces. This review paper summarizes modeling methods of CD-natural compound complexes. The methods include quantitative structure-activity relationships, molecular docking, molecular dynamics simulations, and quantum-chemical calculations. The applications of these methods to enhance the solubility and bioactivities of guest molecules, assist material transportation, and promote compound extraction are also discussed. The purpose of this review is to explore interaction mechanisms of CDs and guests and to help expand new applications of CDs.

Application of molecular docking in elaborating molecular mechanisms and interactions of supramolecular cyclodextrin

The cyclodextrin (CD)-based supramolecular nanomedicines have attracted growing interest because of their superior characteristics, including desirable biocompatibility, low toxicity, unique molecular structure and easy functionalization. The smart structures of CD impart host-guest interaction for meeting the multifunctional needs of disease therapy. However, it faces challenges in formulation design and inclusion mechanism clarification of the functional supramolecular assemblies owing to the complicated structures and mechanisms. Fortunately, molecular docking helps the researchers to comprehend the interaction between the drug and the target molecule for achieving high-through screening from the database. In this review, we summarized the category and characteristics of molecular docking along with the properties and applications of CD. Significantly, we highlighted the application of molecular docking in elaborating molecular mechanisms and simulating complex structures at molecular levels. The issues and development of CD and molecular docking were also presented to provide beneficial reference and new insights for supramolecular nano-systems.

Cyclodextrins as carriers for volatile aroma compounds: A review

Cyclodextrins (CDs) are edible and biocompatible natural cyclic compounds that can encapsulate essential oils, flavours, volatile aroma compounds, and other substances. Complexation with CD-based materials improves the solubility and stability of volatile compounds and protects the bioactivity of the core materials. Therefore, the development of CD/volatile compound nanosystems is a key research area in the food, cosmetic, and pharmaceutical industries. This review briefly introduces the main types of natural CD; preparation methods of CD-based materials as carriers for aromatic substances or essential oils; characterisation methods used to calculate the interaction between CDs and volatile aroma compounds; molecular docking and simulation methods; and the application of CD-based nanosystems in different industries. The review aims to provide guidance for relevant practitioners in selecting appropriate CD materials and characterisation methods.

Formononetin/methyl-β-cyclodextrin inclusion complex incorporated into electrospun polyvinyl-alcohol nanofibers: Enhanced water solubility and oral fast-dissolving property

Improving solubility and administration route of isoflavone formononetin (FMN) are critical factors to improve its bioavailability in the oral cavity. This study fabricated fast-dissolving nanofibers containing FMN/methyl-β-cyclodextrin (FMN/Me-β-CD) inclusion complex. The solubility of FMN could be increased by approximately 50 times at 20 mM aqueous Me-β-CD. Interactions and thermodynamic parameters of the host-guest inclusion complex were studied by a fluorescence quenching method. The structure and mechanisms of the complex were further studied by molecular docking and molecular dynamics. Finally, polyvinyl-alcohol (PVA) nanofibrous webs containing the FMN/Me-β-CD inclusion complex were fabricated by electrospinning. The dissolution test demonstrated that the FMN/Me-β-CD/PVA nanofibers can be dissolved in artificial saliva within approximately 2 s. This study shows the potential of Me-β-CD inclusion and electrospinning to improve solubility and administration route of isoflavones.

Fabrication of food-grade Pickering high internal phase emulsions stabilized by the mixture of β-cyclodextrin and sugar beet pectin

Food-grade Pickering high internal phase emulsions (HIPEs) stabilized by a mixture of β-cyclodextrin (β-CD) and sugar beet pectin (SBP) were fabricated for the first time. The factors affecting the microstructures, mechanical properties, and stabilities of the Pickering HIPEs were systematically investigated. The corresponding hybrid particles were also separated and characterized to reveal the formation mechanism. The results indicated that the mixture could induce the formation of HIPEs with an oil phase volume fraction (φ) of 75% using a one-step high-speed shearing process at room temperature. The composition (the mass ratio of β-CD to SBP, R_c/s) and concentration (W) of the mixture had significant effects on the formation and properties of HIPEs. When W ≥ 1.0% and R_c/s = 2:2 or 3:1, HIPEs had smaller oil droplets, higher gel strengths, better centrifugation stabilities and lutein protection effects. The spectral analysis suggested that SBP could adhere to the surface of β-CD particles to form hybrid particles during the homogenization. Compared with native β-CD particles, these hybrid particles had higher ζ-potential absolute values, and the SBP could also increase the viscosity of the aqueous phase, which contributed to the formation and properties of these HIPEs.

Obtaining and Investigation of the β-Cyclodextrin Inclusion Complex with Vitamin D 3 Oil Solution

Background. The research results of fat-soluble vitamin D 3 (cholecalciferol) encapsulation with β-cyclodextrin have been presented in this work. The vitamin D 3 inclusion complex with β-cyclodextrin was obtained under microwave radiation. The surface morphology of obtained clathrate inclusion complexes was described with the help of a scanning electron microscope. The thermographic measurement results on a differential scanning calorimeter have been presented. The activation energy of the β-cyclodextrin : vitamin D 3 clathrate complex thermal oxidative destruction reaction was calculated. The clathrate thermal destruction kinetic parameters were determined. The inclusion complex spectral properties were characterized by IR-Fourier and 1H and 13C NMR spectroscopy. The existence of β-cyclodextrin inclusion complex with vitamin D 3 in a 2 : 1 ratio was confirmed by the experimental results. The activation energy of thermal destruction of the inclusion complex of β-cyclodextrin with vitamin D 3 was calculated using four different methods.

Immobilization of β-CD on a Hyper-Crosslinked Polymer for the Enhanced Removal of Amines from Aqueous Solutions

In this paper, we adopted a simple and efficient strategy to prepare a β-cyclodextrin (β-CD)-modified hyper-crosslinked polymer (CDM-HCP). The structures and physicochemical properties of the as-synthesized polymer were also evaluated. It was applied to the removal of anilines from aqueous solutions. The introduction of β-CD into the hyper-crosslinked polymer significantly enhanced adsorption properties for the removal of various amines. The adsorption kinetics agreed with the pseudo-second-order mode very well. The adsorption isotherm data of p-methylaniline (p-MA) and p-aminobenzoic acid (p-ABC) were in agreement with the Langmuir isotherm, whereas aniline and p-chloroaniline (p-CA) were fitted best with the Freundlich model. The maximum adsorption capacities (q_max) determined by adsorption isotherms were 148.97 mg/g for aniline, 198.45 mg/g for p-MA, 293.71 mg/g for p-CA, and 622.91 mg/g for p-ABC, respectively. It had higher adsorption capacities than those of some commercial polymeric resins, such as XAD-4, PA66, and AB-8. The interaction mechanism was investigated by FTIR, XPS, and the ONIOM2 method. A CDM-HCP can be regenerated efficiently and used repeatedly, indicating its potential technological applications in removing organic pollutants from actual industrial effluents.

Proteome-based identification of chicken egg yolk proteins associated with antioxidant activity on the Qinghai-Tibetan Plateau

In this study, a proteome analysis of Tibetan chicken egg yolk as well as the comparison to that of lowland chicken were performed by label-free quantitative proteomics. A total of 135 proteins were identified and abundances of 19 of these proteins were significantly different between these two groups. These differential proteins were mainly associated with oxidative stress, defense, energy metabolism and tissue development through bioinformatics analysis. To further verify the species-specific diversity of the antioxidant capacity, the antioxidative activities of egg yolk proteins were further invested in vitro and in Caco-2 cells. It was observed that both Tibetan and lowland chicken egg yolk proteins showed antioxidant activities, but the former exerted a much stronger effect. PIT54 and glutathione peroxidase 3 were considered to be antioxidant-related candidate proteins. These results provide substantial evidence for the molecular mechanisms of enhancing physical activity levels of egg yolk proteins, especially with regard to the cross-species protective mechanisms against oxidative stress.

Preparation and Characterization of Octenyl Succinate β-Cyclodextrin and Vitamin E Inclusion Complex and Its Application in Emulsion

Vitamin E (VE) and β-cyclodextrin (β-CD) can form an inclusion complex; however, the inclusion rate is low because of the weak interaction between VE and β-CD. The results of a molecular docking study showed that the oxygen atom in the five-membered ring of octenyl succinic anhydride (OSA) formed a strong hydrogen bond interaction (1.89 Å) with the hydrogen atom in the hydroxyl group of C-6. Therefore, β-CD was modified using OSA to produce octenyl succinic-β-cyclodextrin (OCD). The inclusion complexes were then prepared using OCD with VE. The properties of the inclusion complex were investigated by Fourier-transform infrared spectroscopy (FT-IR), ¹³C CP/MAS NMR, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results demonstrated that VE had been embedded into the cavity of OCD. Furthermore, the emulsifying properties (particle size distribution, ζ-potential, and creaming index) of the OCD/VE inclusion-complex-stabilized emulsion were compared with that stabilized by β-CD, OCD, and an OCD/VE physical mixture. The results showed that the introduction of the OS group and VE could improve the physical stability of the emulsion. In addition, the OCD/VE inclusion complex showed the strongest ability to protect the oil in the emulsion from oxidation. OCD/VE inclusion complex was able to improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry.

Biodegradable Redox-Sensitive Star Polymer Nanomicelles for Enhancing Doxorubicin Delivery

A typical amphiphilic star polymer adamantane-[poly(lactic-co-glycolic acid)-bis(2-carboxyethyl) sulfide-poly(ethylene glycol) monomethyl ether)]₄ with a specific hydrophilic/redox-sensitive/hydrophobic structure was designed and synthesized through ring opening and esterification reactions. The self-assembled nanomicelles were used as doxorubicin (DOX) delivery vehicles with suitable critical micelle concentrations (5.0 mg/L). After the drug being loaded, drug-loaded micelles showed good drug-loading efficiency (10.39%), encapsulation efficiency (58.1%), and drug release (up to 60%) under simulated biological environment conditions. In addition, the backbone structure of the biodegradable polymer was easily hydrolyzed by the action of biological enzymes. As expected, cell-based studies showed that the designed polymer micelles possessed good biocompatibility (a survival rate of 85% for NH-3T3 cells). Moreover, the drug (DOX) still maintained good anti-cancer effects after being loaded, which caused 40% of MCF-7 cells to survive. These redox-sensitive micelles showed anti-tumor therapeutic potential.