Structure-antioxidant activity relationship of β-cyclodextrin inclusion complexes with olive tyrosol, hydroxytyrosol and oleuropein: Deep insights from X-ray analysis, DFT calculation and DPPH assay

Investigations of Antioxidant and Anti-Cancer Activities of 5-Aminopyrazole Derivatives

To further extend the structure-activity relationships (SARs) of 5-aminopyrazoles (5APs) and identify novel compounds able to interfere with inflammation, oxidative stress, and tumorigenesis, 5APs 1-4 have been designed and prepared. Some chemical modifications have been inserted on cathecol function or in aminopyrazole central core; in detail: (i) smaller, bigger, and more lipophilic substituents were introduced in meta and para positions of catechol portion (5APs 1); (ii) a methyl group was inserted on C3 of the pyrazole scaffold (5APs 2); (iii) a more flexible alkyl chain was inserted on N1 position (5APs 3); (iv) the acylhydrazonic linker was moved from position 4 to position 3 of the pyrazole scaffold (5APs 4). All new derivatives 1-4 have been tested for radical scavenging (DPPH assay), anti-aggregating/antioxidant (in human platelets) and cell growth inhibitory activity (MTT assay) properties. In addition, in silico pharmacokinetics, drug-likeness properties, and toxicity have been calculated. 5APs 1 emerged to be promising anti-proliferative agents, able to suppress the growth of specific cancer cell lines. Furthermore, derivatives 3 remarkably inhibited ROS production in platelets and 5APs 4 showed interesting in vitro radical scavenging properties. Overall, the collected results further confirm the pharmaceutical potentials of this class of compounds and support future studies for the development of novel anti-proliferative and antioxidant agents.

Cyclodextrin Inclusion Complexes for Improved Drug Bioavailability and Activity: Synthetic and Analytical Aspects

Many active pharmaceutical ingredients show low oral bioavailability due to factors such as poor solubility and physical and chemical instability. The formation of inclusion complexes with cyclodextrins, as well as cyclodextrin-based polymers, nanosponges, and nanofibers, is a valuable tool to improve the oral bioavailability of many drugs. The microencapsulation process modifies key properties of the included drugs including volatility, dissolution rate, bioavailability, and bioactivity. In this context, we present relevant examples of the stabilization of labile drugs through the encapsulation in cyclodextrins. The formation of inclusion complexes with drugs belonging to class IV in the biopharmaceutical classification system as an effective solution to increase their bioavailability is also discussed. The stabilization and improvement in nutraceuticals used as food supplements, which often have low intestinal absorption due to their poor solubility, is also considered. Cyclodextrin-based nanofibers, which are polymer-free and can be generated using environmentally friendly technologies, lead to dramatic bioavailability enhancements. The synthesis of chemically modified cyclodextrins, polymers, and nanosponges based on cyclodextrins is discussed. Analytical techniques that allow the characterization and verification of the formation of true inclusion complexes are also considered, taking into account the differences in the procedures for the formation of inclusion complexes in solution and in the solid state.

Computer-based identification of olive oil components as a potential inhibitor of neirisaral adhesion a regulatory protein

In silico methods such as molecular docking and molecular dynamic (MD) simulations have significant interest due to their ability to identify the protein-ligand interactions at the atomic level. In this work, different computational methods were used to elucidate the ability of some olive oil components to act as Neisseria adhesion A Regulatory protein (NadR) inhibitors. The frontier molecular orbitals (FMOs) and the global properties such as global hardness, electronegativity, and global softness of ten olive oil components (α-Tocopherol, Erythrodiol, Hydroxytyrosol, Linoleic acid, Apigenin, Luteolin, Oleic acid, Oleocanthal, Palmitic acid, and Tyrosol) were reported using Density Functional Theory (DFT) methods. Among all investigated compounds, Erythrodiol, Apigenin, and Luteolin demonstrated the highest binding affinities (-8.72, -7.12, and -8.24 kcal/mol, respectively) against NadR, compared to -8.21 kcal/mol of the native ligand based on molecular docking calculations. ADMET properties and physicochemical features showed that Erythrodiol, Apigenin, and Luteolin have good physicochemical features and can act as drugs candidate. Molecular dynamics (MD) simulations demonstrated that Erythrodiol, Apigenin, and Luteolin show stable binding affinity and molecular interaction with NadR. Further Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) analyses using the MD trajectories also demonstrated the higher binding affinity of Erythrodiol, Apigenin and Luteolin inside NadR protein. The overall study provides a rationale to use Erythrodiol, Apigenin, and Luteolin in the drug development as anti-adhesive drugs lead. Communicated by Ramaswamy H. Sarma.

The Contribution of Theoretical Prediction Studies to the Antioxidant Activity Assessment of the Bioactive Secoiridoids Encountered in Olive Tree Products and By-Products

Assessment of the antioxidant activity of different types of natural compounds is a complex research area that encompasses various in vitro tests and in vivo studies. Sophisticated modern analytical tools permit the unambiguous characterization of the compounds present in a matrix. The contemporary researcher, knowing the chemical structure of the compounds present, can carry out quantum chemical calculations that provide important physicochemical information assisting the prediction of antioxidant potential and the mechanism behind the activity of target compounds before further experimentation. The efficiency of calculations is steadily improved due to the rapid evolution of both hardware and software. It is possible, consequently, to study compounds of medium or even larger size, incorporating also models that simulate the liquid phase (solution). This review contributes to the establishment of theoretical calculations as an inherent part of the antioxidant activity assessment process, having as a case study the complex mixtures of olive bioactive secoiridoids (oleuropein, ligstroside, and related compounds). The literature indicates great variability in theoretical approaches and models used so far for only a limited number of this group of phenolic compounds. Proposals are made for standardization of methodology (reference compounds, DFT functional, basis set size, and solvation model) to facilitate comparisons and communication of findings.

Interactions between plant-derived antioxidants and cyclodextrins and their application for improving separation, detection, and food quality issues

Plant-derived antioxidants (PD-AOs) are important for food preservation, as well as for human health and nutrition. However, the poor chemical stability and water solubility of many PD-AOs currently limit their application as functional ingredients in foods and pharmaceuticals. Moreover, it is often difficult to isolate and detect specific antioxidants in multi-component systems, which again limits their potential in the food and medical industries. In this review, we highlight recent advances in the use of cyclodextrins (CDs) to overcome these limitations by forming simple, modified and competitive host-guest interactions with PD-AO. The host-guest properties of CDs can be used to enhance the separation efficiency of PD-AOs, as well as to improve their dispersion and stability in food systems. Moreover, the competitive complexation properties of CDs with target molecules can be used to selectively isolate PD-AOs from multi-component systems and develop detection technologies for PD-AOs. Overall, CD-antioxidant interactions have great potential for addressing isolation, detection, and food quality issues.

Inside the Mechanism of Action of Three Pyrazole Derivatives in Human Platelets and Endothelial Cells

In the effort to obtain multitarget compound interfering with inflammation, oxidative stress, and tumorigenesis, we synthesized a small library of pyrazole compounds, selecting 4a, 4f, and 4g as the most noteworthy being IC₅₀ against platelet ROS production induced by thrombin of about 10 µM. The in vitro antioxidant potential of the three molecules was evaluated, and since they show a remarkable antioxidative activity, their effect on several parameter indicative of oxidative status and on the efficiency of the aerobic metabolism was tested. The three molecules strongly inhibit superoxide anion production, lipid peroxidation, NADPH oxidase activity and almost restore the oxidative phosphorylation efficiency in thrombin-stimulated platelet, demonstrating a protective effect against oxidative stress. This effect was confirmed in endothelial cell in which 4a, 4f, and 4g show an interesting inhibition activity on H₂O₂-stimulated EA.hy926 cells. At last, antiproliferative activity of 4a, 4f, and 4g was submitted to a large screening at the NCI. The molecules show interesting anticancer activity, among them the most remarkable is 4g able to strongly inhibit the proliferation of both solid tumor and leukemia cells lines. In conclusion, all the three newly synthetized pyrazoles show remarkable antioxidant and antiproliferative effect worthy of further study.

In Search of Preferential Macrocyclic Hosts for Sulfur Mustard Sensing and Recognition: A Computational Investigation through the New Composite Method r2SCAN-3c of the Key Factors Influencing the Host-Guest Interactions

Sulfur mustard (SM) is a harmful warfare agent that poses a serious threat to human health and the environment. Thus, the design of porous materials capable of sensing and/or capturing SM is of utmost importance. In this paper, the interactions of SM and its derivatives with ethylpillar[5]arene (EtP[5]) and the interactions between SM and a variety of host macrocycles were investigated through molecular docking calculations and non-covalent interaction (NCI) analysis. The electronic quantum parameters were computed to assess the chemical sensing properties of the studied hosts toward SM. It was found that dispersion interactions contributed significantly to the overall complexation energy, leading to the stabilization of the investigated systems. DFT energy computations showed that SM was more efficiently complexed with DCMP[5] than the other hosts studied here. Furthermore, the studied macrocyclic containers could be used as host-based chemical sensors or receptors for SM. These findings could motivate experimenters to design efficient sensing and capturing materials for the detection of SM and its derivatives.

Current Status of Quantum Chemical Studies of Cyclodextrin Host-Guest Complexes

This article aims to review the application of various quantum chemical methods (semi-empirical, density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2)) in the studies of cyclodextrin host-guest complexes. The details of applied approaches such as functionals, basis sets, dispersion corrections or solvent treatment methods are analyzed, pointing to the best possible options for such theoretical studies. Apart from reviewing the ways that the computations are usually performed, the reasons for such studies are presented and discussed. The successful applications of theoretical calculations are not limited to the determination of stable conformations but also include the prediction of thermodynamic properties as well as UV-Vis, IR, and NMR spectra. It has been shown that quantum chemical calculations, when applied to the studies of CD complexes, can provide results unobtainable by any other methods, both experimental and computational.

Valorization and Potential Antimicrobial Use of Olive Mill Wastewater (OMW) from Italian Olive Oil Production

The production of olive oil generates olive mill wastewater (OMW) which essentially derives from the processing, treatment and pressing of olives in mills. Traditional milling processes require a quantity of water varying between 40 and 120 L per quintal of pressed olives, generating a considerable amount of wastewater. It is thus necessary to reduce process water and enhance its use to implement the concept of a circular economy. To this end, our preliminary work was dedicated to water purification by means of suitable and efficient filtration systems. The microfiltered OMW was firstly concentrated through reverse osmosis. Then, an additional concentration step was carried out via vacuum membrane distillation using hydrophobic hollow fiber membranes. The application of the membrane-based processes allowed the recovery of a purified water and the concentration of valuable polyphenols in a smaller volume. The different fractions obtained from the purification have been tested for the determination of the antioxidant power (DPPH assay) and dosage of polyphenols (Folin–Ciocalteu assay) and were characterized using IR spectroscopy. All samples showed relevant antioxidant activity (percentage range: 10–80%) and total phenolic content in the 1.5–15 g GAE/L range. The obtained fractions were tested for their antimicrobial effect on numerous clinical isolates of Gram-positive and Gram-negative species, resistant and multi-resistant to current antibiotic drugs. OMW samples showed widespread activity against the considered (phyto)pathogens (MIC range 8–16 mg/mL) thus supporting the value of this waste material in the (phyto)pharmaceutical field.

Inclusion Scenarios and Conformational Flexibility of the SSRI Paroxetine as Perceived from Polymorphism of β-Cyclodextrin–Paroxetine Complex

Depression, a global mental health problem, is prevalent during the coronavirus disease 2019 (COVID-19) pandemic and can be efficiently treated by selective serotonin reuptake inhibitors (SSRIs). Our study series aims at forwarding insights on the β-cyclodextrin (β-CD)–SSRI inclusion complexes by X-ray crystallography combined with density functional theory (DFT) calculation. Here, we report a new crystal form (II) of the 1:1 β-CD–paroxetine (PXT) complex, which is inspired by the reported 2:1 β-CD–PXT complex (crystal form I), reflecting an elusive phenomenon of the polymorphism in CD inclusion complexes. The β-CD–PXT polymorphism stems from the PXT conformational flexibility, which is defined by torsion angles κ, ε around the -CH2–O- group bridging the A- and C–D-rings, of which those of PXT in I and II are totally different. While PXT (II) in an open V-shaped conformation that has the B-ring shallowly inserted in the β-CD cavity, PXT (I) in a closed U-shaped structure is mostly entirely embedded in the β-CD dimeric cavity, of which the A-ring is deeply inserted in the main β-CD cavity. However, PXT molecules in both crystal forms are similarly maintained in the CD cavity via host–guest N–H···O5/O6 H-bonds and C/O–H···π(B/C) interactions and β-CDs have similar 3D arrangements, channel (II) vs. screw-channel (I). Further theoretical explorations on the β-CD–PXT thermodynamic stabilities and the PXT conformational stabilities based on their potential energy surfaces (PESs) have been completed by DFT calculations. The 2:1 β-CD–PXT complex with the greater presence of dispersion interactions is more energetically favorable than the unimolar complex. Conversely, whereas free PXT, PXT (II) and PXT in complex with serotonin transporter are more energetically stable, PXT (I) is least stable and stabilized in the β-CD cavity. As SSRIs could lessen the COVID-19 severity, the CD inclusion complexation not only helps to improve the drug bioavailability, but also promotes the use of antidepressants and COVID-19 medicines concurrently.

Cyclodextrin as Functional Carrier in Development of Mucoadhesive Tablets Containing Polygoni cuspidati Extract with Potential for Dental Applications

Polygoni cuspidati root is a resveratrol-rich source with anti-inflammatory, angiogenic and neuroprotective effects. The raw material was standardized for the content of resveratrol, for which there is a special justification for administration within the oral mucosa. To improve the solubility of resveratrol and to assure its high content in plant material, an ultrasound-assisted extraction method was applied. The addition of cyclodextrin was found to increase the extraction efficiency of resveratrol (from 13 to 297 µg per 1 g of plant material in case of 50% ethanol extracts) and enhanced its antioxidant activity as compared to pure Polygoni cuspidati extract/resveratrol. Cyclodextrin plays the role of a functional extract regarding technological properties (increasing the extraction of resveratrol from the extract, improving mucoadhesive properties). Therefore, the aim of this study was to develop mucoadhesive tablets containing combinations of the Polygoni cuspidati extract with a cyclodextrin carrier for buccal delivery. The tests sequentially included extract preparation and characterization of its physical and biological properties and then formulation studies with a broad description of the prototype properties. The test results indicate that cyclodextrin increases the efficiency of resveratrol extraction from Polygoni cuspidati rhizome, which is a rich source of resveratrol, and its extract enclosed in a mucoadhesive tablet guarantees prolonged action at the site of administration.

β-Cyclodextrin Inclusion Complexes with Catechol-Containing Antioxidants Protocatechuic Aldehyde and Protocatechuic Acid-An Atomistic Perspective on Structural and Thermodynamic Stabilities

Protocatechuic aldehyde (PCAL) and protocatechuic acid (PCAC) are catechol derivatives and have broad therapeutic effects associated with their antiradical activity. Their pharmacological and physicochemical properties have been improved via the cyclodextrin (CD) encapsulation. Because the characteristics of β-CD inclusion complexes with PCAL (1) and PCAC (2) are still equivocal, we get to the bottom of the inclusion complexation by an integrated study of single-crystal X-ray diffraction and DFT full-geometry optimization. X-ray analysis unveiled that PCAL and PCAC are nearly totally shielded in the β-CD wall. Their aromatic rings are vertically aligned in the β-CD cavity such that the functional groups on the opposite side of the ring (3,4-di(OH) and 1-CHO/1-COOH groups) are placed nearby the O6–H and O2–H/O3–H rims, respectively. The preferred inclusion modes in 1 and 2 help to establish crystal contacts of OH⋅⋅⋅O H-bonds with the adjacent β-CD OH groups and water molecules. By contrast, the DFT-optimized structures of both complexes in the gas phase are thermodynamically stable via the four newly formed host–guest OH⋯O H-bonds. The intermolecular OH⋅⋅⋅O H-bonds between PCAL/PCAC 3,4-di(OH) and β-CD O6–H groups, and the shielding of OH groups in the β-CD wall help to stabilize these antioxidants in the β-CD cavity, as observed in our earlier studies. Moreover, PCAL and PCAC in distinct lattice environments are compared for insights into their structural flexibility.

Buccal Resveratrol Delivery System as a Potential New Concept for the Periodontitis Treatment

The health benefits of resveratrol have been proven to inhibit the development of numerous diseases. A frequent limitation in its use is a low bioavailability stemming from a poor solubility and fast enterohepatic metabolism. Thus, the aim of the research was to investigate the possibility to formulate mucoadhesive cyclodextrin- and xanthan gum-based buccal tablets in order to increase the solubility of resveratrol and to eliminate bypass enterohepatic metabolism. Systems of resveratrol with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) prepared by the dry mixing method (ratio 1:1) were selected for the of tablets where xanthan gum was used as a mucoadhesive agent. They were identified on the basis of PXRD, FT-IR analysis. Tablets F1 (with α-CD), F2 (with β-CD) and F3 (with γ-CD) were characterized by the highest compactibility as well as by favorable mucoadhesive properties. Resveratrol release from these tablets was delayed and controlled by diffusion. The tablets prepared in the course of this study appear to constitute promising resveratrol delivery systems and are recommended to increase the effectiveness of the treatment in many diseases, particularly periodontitis.

Strategies to Broaden the Applications of Olive Biophenols Oleuropein and Hydroxytyrosol in Food Products

Oleuropein (OLE) and hydroxytyrosol (HT) are olive-derived phenols recognised as health-promoting agents with antioxidant, anti-inflammatory, cardioprotective, antifungal, antimicrobial, and antitumor activities, providing a wide range of applications as functional food ingredients. HT is Generally Recognised as Safe (GRAS) by the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA), whereas OLE is included in EFSA daily consumptions recommendations, albeit there is no official GRAS status for its pure form. Their application in food, however, may be hindered by challenges such as degradation caused by processing conditions and undesired sensorial properties (e.g., the astringency of OLE). Among the strategies to overcome such setbacks, the encapsulation in delivery systems and the covalent and non-covalent complexation are highlighted in this review. Additionally, the synthesis of OLE and HT derivatives are studied to improve their applicability. All in all, more research needs however to be carried out to investigate the impact of these approaches on the sensory properties of the final food product and its percussions at the gastrointestinal level, as well as on bioactivity. At last limitations of these approaches at a scale of the food industry must also be considered.

Nanoformulations to Enhance the Bioavailability and Physiological Functions of Polyphenols

Polyphenols are micronutrients that are widely present in human daily diets. Numerous studies have demonstrated their potential as antioxidants and anti-inflammatory agents, and for cancer prevention, heart protection and the treatment of neurodegenerative diseases. However, due to their vulnerability to environmental conditions and low bioavailability, their application in the food and medical fields is greatly limited. Nanoformulations, as excellent drug delivery systems, can overcome these limitations and maximize the pharmacological effects of polyphenols. In this review, we summarize the biological activities of polyphenols, together with systems for their delivery, including phospholipid complexes, lipid-based nanoparticles, protein-based nanoparticles, niosomes, polymers, micelles, emulsions and metal nanoparticles. The application of polyphenol nanoparticles in food and medicine is also discussed. Although loading into nanoparticles solves the main limitation to application of polyphenolic compounds, there are some concerns about their toxicological safety after entry into the human body. It is therefore necessary to conduct toxicity studies and residue analysis on the carrier.

Analytical techniques to recognize inclusion complexes formation involving monoterpenes and cyclodextrins: A study case with (-) borneol, a food ingredient

Monoterpenes are non-polar secondary metabolites widely used by industry due to their excellent therapeutic, food-ingredient and cosmetic properties. However, their low solubility in water limits their use. In this sense, cyclodextrins (CDs) have been widely used to solve these technological challenges. Thus, this study aims to use (-)-borneol as a monoterpene model to prepare inclusion complexes between β-CD and hydroxypropyl-β-CD (HP-β-CD) through different ways and characterize them in order to choose the best inclusion method to improve physicochemical properties of monoterpenes. To achieve this goal, the samples were prepared by physical mixture (PM), paste complex (PA) and freeze-drying complex (FD) and then, extensively characterized by thermal analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, size particle, X-ray diffraction and nuclear magnetic resonance. The physicochemical results showed that freeze-drying was more effective to form inclusion complexes between (-)-borneol with both CDs. This research highlights the importance of recognizing the best method to prepare inclusion complexes, including food additives as (-)-borneol, to achieve better results in food preparations.

Extrapolation of hydroxytyrosol and its analogues as potential anti-inflammatory agents

Discovery of potential lead molecule is a challenging, and complex process which require lots of money, patience, and manpower. Human beings are using natural products, predominantly secondary metabolites, for this purpose since ancient time and they are still working on them as a potent source for drug discovery due to their wide structural diversity. Phenolic phytochemicals such as hydroxytyrosol and tyrosol are natural antioxidant and involved in many biological disease cure. Herein, we have carried out the quantum chemical calculations for conformational analysis, geometry optimization and computation of electronic as well as optical properties of hydroxytyrosol and its analogues (1a-1k) in terms of density functional theory by using Gaussian 09 program suite. The eventual charge transfer within the molecules has been confirmed by the analysis of frontier molecular orbitals. The molecular docking studies of 1a-1k with cyclooxygenase-2 showed the noticeable binding affinity as compared to other nonsteroidal anti-inflammatory drugs viz. aspirin, naproxen and celecoxib. Computation of pharmacokinetics and pharmacological properties confirmed the lead/drug like potential of these screened molecules. Furthermore, the molecular dynamics simulation of best three docked ligands (1f, 1h and 1k)-receptor complex and their binding free energy calculations reveals that these molecules bind in the catalytic cavity of cyclooxygenase-2 and found stable during the 100 ns of simulation. Communicated by Ramaswamy H. Sarma.

Electrospun anti-inflammatory patch loaded with essential oils for wound healing

Wound healing is a complex process that consists of three overlapping phases: inflammation, proliferation, and remodeling. A bacterial infection can increase inflammation and delay this process. Microorganisms are closely related to the innate immune system, such as macrophages and neutrophils, as they can start an inflammatory cascade. Essential oils play an important role in the inhibition and prevention of bacterial growth due to their ability to reduce antimicrobial resistance. The possibility to find a strategy that combines antimicrobial and anti-inflammatory properties is particularly appealing for wound healing. In this work, we showcase a variety of patches based on electrospun polycaprolactone (PCL) nanofibers loaded with natural compounds derived from essential oils, such as thymol (THY) and tyrosol (TYR), to achieve reduced inflammation. In addition, we compared the effect these essential oils have on activated macrophages when incorporated into the PCL patch. Specifically, we demonstrate that PCL-THY resulted in more efficient down-regulation of pro-inflammatory genes related to the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κb) pathway when compared to PCL-TYR and the combination patch containing TYR and THY (i.e., PCL-TYR-THY). Furthermore, PCL-THY displayed low affinity for cell attachment, which may hinder wound adherence and integration. Overall, our results indicate that THY-loaded patches could serve as promising candidates for the fabrication of dressings that incorporate bactericidal and anti-inflammatory properties while simultaneously avoiding the limitations of traditional antibiotic-loaded devices.

β-Cyclodextrin encapsulation of nortriptyline HCl and amitriptyline HCl: Molecular insights from single-crystal X-ray diffraction and DFT calculation

The β-CD encapsulation of two tricyclic antidepressants (TCAs), nortriptyline (NRT) HCl and amitriptyline (AMT) HCl (most widely used TCA), has been thoroughly investigated by single-crystal X-ray diffraction and DFT calculation for insights into the inclusion complexation. X-ray analysis reveals that both drugs insert the A-ring moiety vertically from the β-CD O2H/O3H-side and are kept in position by C5H⋯π interactions, yielding thermodynamically favorable complexes. In the β-CD cavity, NRT and AMT are less open as their butterfly angles are ~10° smaller than those in free HCl salt forms and in complex with proteins. The effect of HCl salt on both complexes is evaluated by DFT full-geometry optimization. When Cl^- is directly linked with the NRT NH₂Me⁺ group, the inclusion complex formed gains stability by 3.65 kcal mol^-1 through N5'H⋯Cl⋯HO26 H-bond chain, compared to the complex of NRT base. The addition of HCl to N5' of the side chain marginally affects the structures of β-CD-TCA complexes. This study provides a rigorous crystallographic evidence for the β-CD-TCA complexation and a theoretical view on the improved stability of TCA in the CD cavity, supporting the pharmacological benefit of CD encapsulation in reducing the TCA side effects.

Enhanced Solubility and Anticancer Potential of Mansonone G By β-Cyclodextrin-Based Host-Guest Complexation: A Computational and Experimental Study

Mansonone G (MG), a plant-derived compound isolated from the heartwood of Mansonia gagei, possesses a potent antitumor effect on several kinds of malignancy. However, its poor solubility limits the use for practical applications. Beta-cyclodextrin (βCD), a cyclic oligosaccharide composed of seven (1→4)-linked α-D-glucopyranose units, is capable of encapsulating a variety of poorly soluble compounds into its hydrophobic interior. In this work, we aimed to enhance the water solubility and the anticancer activity of MG by complexation with βCD and its derivatives (2,6-di-O-methyl-βCD (DMβCD) and hydroxypropyl-βCD). The 90-ns molecular dynamics simulations and MM/GBSA-based binding free energy results suggested that DMβCD was the most preferential host molecule for MG inclusion complexation. The inclusion complex formation between MG and βCD(s) was confirmed by DSC and SEM techniques. Notably, the MG/βCDs inclusion complexes exerted significantly higher cytotoxic effect (~2–7 fold) on A549 lung cancer cells than the uncomplexed MG.

Understanding structures and thermodynamics of β-cyclodextrin encapsulation of chlorogenic, caffeic and quinic acids: Implications for enriching antioxidant capacity and masking bitterness in coffee

Green coffee beans are rich in polyphenol chlorogenic acids (CGAs), which are decomposed to give caffeic acid (CFA) and quinic acid (QNA) upon roasting. CGA, CFA and QNA primarily confer the bitterness, astringency and acidity to the coffee brew. Aiming at the structural and thermodynamic insights into the β-cyclodextrin (β-CD) encapsulation of key compounds in coffee (CGA 1, CFA 2, and QNA 3), a systematic, comprehensive study using single-crystal X-ray diffraction and DFT calculation has been undertaken. Scrutinizing the X-ray-derived inclusion structures of 1-3 reveals that the CFA moiety plays a determinant role in complexation, in agreement with the DFT-derived relative thermodynamic stabilities. The guest molecules gain stability through OH⋯O hydrogen bonding with β-CD and are well shielded in the β-CD wall. The three stable β-CD inclusion complexes with coffee key compounds suggest the implications of CDs as encapsulating agents for improving bioactivities and masking bitter taste in foods.

Inclusion complex of β-cyclodextrin with coffee chlorogenic acid: new insights from a combined crystallographic and theoretical study

This work reports the elusive structural evidence for the [4]pseudorotaxane of β-cyclodextrin (β-CD) with coffee chlorogenic acid (CGA), a conjugate of caffeic acid (CFA) and quinic acid (QNA). A single-crystal X-ray structure analysis of the inclusion complex β-cyclodextrin-chlorogenic acid-water (2/2/17), 2C₄₂H₇₀O₃₅·2C₁₆H₁₈O₉·17H₂O, reveals that CGA threads through β-CD and assembles via O-H...O hydrogen bonds and parallel-displaced π-π interactions in the twofold symmetry-related dimer yielding a [4]pseudorotaxane, which is crystallographically observed for the first time in CD inclusion complexes. The encapsulation of the aromatic ring and C=C-C(=O)O chain in the β-CD dimeric cavity indicates that the CFA moiety plays a determinant role in complexation. This is in agreement with the DFT-derived relative thermodynamic stabilities of the trimodal β-CD-CGA inclusion complexes, that is, β-CD complexed with different CGA components: C=C-C(=O)O chain > cyclohexane ring > aromatic ring. The complexation stability is further enhanced in the dimeric β-CD-CGA complex, with the CFA moiety totally enclosed in the β-CD dimeric cavity.