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

A strategy to reduce the bitterness of green tea extract: Preparation of cyclodextrin inclusion and assessment of its antioxidant activity and stability

Green tea extract (GTE) is rich in polyphenols that are the main body of functional activity, but the natural bitterness greatly restricts its applications in food areas. In this study, the effect of β-cyclodextrin (β-CD) on the bitterness and properties of GTE were investigated. The bitterness intensity was evaluated by determination of catechin content and the electronic tongue analysis. It was found that the bitterness of GTE decreased significantly by complexing with 20 % β-CD. Subsequently, the physicochemical properties were determined, including the determination of functional substances by high performance liquid chromatography, as well as the assessment of antioxidant activity and stability under different conditions (heat, acid/base, time). It was found that β-CD inclusion of active substances in GTE protected its functional components and delayed the deactivation rate. Additionally, the formation of a complex between β-CD and components of GTE was confirmed by UV-vis, FT-IR, thermogravimetric analysis, and scanning electron microscope. Therefore, the findings of the present work suggest that the masking of bitter substances and the protection of functional components of GTE through preparing the β-CD inclusion is a feasible way to expand its applications.

Colloidal Nanoparticles of a β-Cyclodextrin/L-Tryptophan Inclusion Complex for Use as Pickering Emulsion Stabilizers

Inclusion complexes of β-cyclodextrin (β-CD) and tryptophan (Trp) were synthesized using an antisolvent approach, and fully characterized. Scanning electron microscope images proved the formation of the β-CD/Trp NPs and the powder X-ray diffraction pattern indicated the formation of a crystalline channel-like structure for the β-CD/Trp nanoparticles (NPs). The NPs of a β-CD/Trp inclusion complex were used as a natural stabilizer at the oil/water interface of a Pickering emulsion. Pickering emulsions with an oil to water ratio of 1:1 (v:v) were obtained under high-speed homogenization and different mass ratios of the β-CD to Trp (1:0, 1:0.1, 1:0.25, 1:0.5, 1:1), and at different pH levels (3, 5, 7, 9). At pH 9, when the β-CD:Trp mass ratio was 1:0.1, the β-CD/Trp NPs were hydrophilic, and the oil-in-water Pickering emulsions stabilized by those nanoparticles showed the highest storage stability: 180 days at room temperature. In contrast, when the emulsions were prepared at pH 5 with the weight ratios of either 1:0.1 or 1:1, β-CD:Trp, the nanoparticles were hydrophobic and could be used to stabilize water-in-oil Pickering emulsions.

Studies on inhibition of α-glucosidase using debittered formulation of Bacopa monnieri juice: Enzyme inhibition kinetics, interaction strategy, and molecular docking approach

Bacopa monnieri juice (BMJ) is traditionally used, reported, and scientifically validated for memory enhancement. However, its efficacy against diabetes is less explored. The extreme bitterness of BMJ restricts its commercial applications. This study investigates the reduction of bitterness of BMJ followed by evaluation for its α-glucosidase inhibitory activity. Initially, debittering of 30 % (v/v) BMJ using ZnSO4 (15 mM) was optimized by time-intensity analysis and molecular docking of ZnSO4 as well as bacoside A3, the main active compound in BMJ, with TAS2R14 taste receptor. The study indicated 5 hydrogen bonds to be involved in binding with bacoside A3 with binding energy of -11.82 Kcal/mol, while hydrogen bond, salt bridges and metal complexes were involved in binding of ZnSO4 with binding energy of -6.65 Kcal/mol. Subsequently, BMJ, ZnSO4 and BMJ + ZnSO4 (debittered juice) were also found to be potent inhibitors of α-glucosidase in dose-dependent manner. These inhibitors showed parabolic mixed inhibition of α-glucosidase, altered the secondary structure, and quenching of fluorescence. In silico studies revealed hydrogen bonding and hydrophobic interactions between inhibitors and α-glucosidase with lowest binding energy of -15.53 and -7.54 Kcal/mol being recorded for bacoside A3 and ZnSO4, respectively. Molecular docking of other bioactive compounds in BMJ such as apigenin, luteolin, quercetin and bacopasaponin C also showed lower binding energy than the standard drug, acarbose (-5.84). This study inferred the binding of bacoside A3 at the active site of α-glucosidase and of ZnSO4 with other sites on the protein. The study proposes a debittered BMJ formulation to control hyperglycemia.

Refermentation with yeast and lactic acid bacteria isolates: a strategy to improve the flavor of green coffee beans

BACKGROUND

Yeast and lactic acid bacteria (LAB) play an important part in the post-harvest fermentation of coffee. This study applied lab-scale fermentation to commercial green coffee beans using dry coffee pulp as the substrate, with the aim of modifying coffee-bean flavor. In addition to spontaneous fermentation, yeast and LAB isolated from coffee beans and dried coffee pulp were added during fermentation.

RESULTS

Co-inoculation of yeast and LAB showed a significant effect on the chlorogenic acid content after between 24 and 72 h of fermentation. Acetic, citric, malic, lactic, and quinic acids were shown to be affected significantly (P < 0.05) by fermentation and inoculation. Gas chromatography detected that esters, alcohols, aldehydes, furans, and pyrazines were the primary compounds in the coffee beans. Certain volatile groups were present in greater concentrations and broader varieties within the inoculated beans. The highest cupping scores were given to beans that had been co-inoculated with yeast and LAB.

CONCLUSION

Overall, the use of yeasts and LAB starters showed potential to create coffee beverages with desirable characteristics by standardized fermentation. © 2024 Society of Chemical Industry.

Supramolecular deep eutectic solvents: Current advances and critical evaluation of cyclodextrins from solute to solvent in emerging functional food

The acceptance of nonconventional solvents as viable substitutes for traditional organic solvents has been widely recognized in order to comply with food-safety and sustainability regulations. Cyclodextrins (CDs), derived from starch, are cyclic oligosaccharides with the ability to form inclusion complexes with a variety of functional substances as the result of their distinctive structure, which enables them to effectively encapsulate bioactive compounds, rendering them highly sought after for use in food applications. In the implementing plan to achieve carbon-neutral emissions by 2050, the novel generation of supramolecular deep eutectic solvents (SUPRADES) has garnered increased attention and interest. The approach of utilizing SUPRADES as emerging solvents was just beginning to be applied to food studies. This review summarizes a revision of the current advances and critical evaluation of cyclodextrin-based SUPRADES (CD-based SUPRADES) as promising solvents for the enhancement of the extraction efficiency, solubilization and stability of bioactive compounds, adsorption and separation of food components, packaging materials, and modification of biopolymers. To meet the sustainable processing needs of the food industry, the emerging categories of CD-based SUPRADES need to be further fabricated. Herein, our review will sort out the potential application of CD-based SUPRADES in the food industry, aiming to provide a better understanding of CD-based SUPRADES within the viewpoint of food science. Formulation intricacies and scalability issues in real functional foods using CD-based SUPRADES as media need more efforts.

One of the major challenges of masking the bitter taste in medications: an overview of quantitative methods for bitterness

Objective

The aim of the present study was to carry out a systematic research on bitterness quantification to provide a reference for scholars and pharmaceutical developers to carry out drug taste masking research. Significance: The bitterness of medications poses a significant concern for clinicians and patients. Scientifically measuring the intensity of drug bitterness is pivotal for enhancing drug palatability and broadening their clinical utility.

Methods

The current study was carried out by conducting a systematic literature review that identified relevant papers from indexed databases. Numerous studies and research are cited and quoted in this article to summarize the features, strengths, and applicability of quantitative bitterness assessment methods.

Results

In our research, we systematically outlined the classification and key advancements in quantitative research methods for assessing drug bitterness, including in vivo quantification techniques such as traditional human taste panel methods, as well as in vitro quantification methods such as electronic tongue analysis. It focused on the quantitative methods and difficulties of bitterness of natural drugs with complex system characteristics and their difficulties in quantification, and proposes possible future research directions.

Conclusion

The quantitative methods of bitterness were summarized, which laid an important foundation for the construction of a comprehensive bitterness quantification standard system and the formulation of accurate, efficient and rich taste masking strategies.

Effect of Encapsulated Phenolic Compounds of Cocoa on Growth of Lactic Acid Bacteria and Antioxidant Activity of Fortified Drinking Yogurt

The aim of this study was to obtain drinking yogurts enriched with ACTICOA cocoa powder (ACTICOA), its extract (EACTICOA) and pure phenolics, as well as their inclusion complexes with cyclodextrins and alginate-chitosan (A-Ch) capsules, and to evaluate the effects of these additives on the viability of lactic acid bacteria (LAB) and antioxidant properties of fresh yogurts and yogurts stored for 14 days at 4 °C. The application of cocoa phenolic compounds in free form and in the form of EACTICOA to yogurts resulted in the greatest increase in the concentration of phenolic compounds and a significant improvement in the antioxidant properties of the fortified products. The highest TPC was found in yogurts enriched with free quercetin (107.98 mg CE/g). Yogurt fortified with free gallic acid showed the highest ability to neutralize free radicals (EC50 = 2.74 mg/mg DPPH, EC50 = 5.40 mg/mg ABTS) and reduce ferric ions (183.48 µM Trolox/g). The enrichment of yogurts with the tested phenolic compounds preparations, especially in the form of encapsulates, did not affect the viability of LAB during storage.

The health benefits of dietary polyphenols on pediatric intestinal diseases: Mechanism of action, clinical evidence and future research progress

Pediatric intestinal development is immature, vulnerable to external influences and produce a variety of intestinal diseases. At present, breakthroughs have been made in the treatment of pediatric intestinal diseases, but there are still many challenges, such as toxic side effects, drug resistance, and the lack of more effective treatments and specific drugs. In recent years, dietary polyphenols derived from plants have become a research hotspot in the treatment of pediatric intestinal diseases due to their outstanding pharmacological activities such, as anti-inflammatory, antibacterial, antioxidant and regulation of intestinal flora. This article reviewed the mechanism of action and clinical evidence of dietary polyphenols in the treatment of pediatric intestinal diseases, and discussed the influence of physiological characteristics of children on the efficacy of polyphenols, and finally prospected the new dosage forms of polyphenols in pediatrics.

Development of Potential Therapeutic Agents from Black Elderberries (the Fruits of Sambucus nigra L.)

Elderberry (Sambucus nigra L.) is a widespread deciduous shrub, of which the fruits (elderberries) are used in the food industry to produce different types of dietary supplement products. These berries have been found to show multiple bioactivities, including antidiabetic, anti-infective, antineoplastic, anti-obesity, and antioxidant activities. An elderberry extract product, Sambucol®, has also been used clinically for the treatment of viral respiratory infections. As the major components, phenolic compounds, such as simple phenolic acids, anthocyanins and other flavonoids, and tannins, show promising pharmacological effects that could account for the bioactivities observed for elderberries. Based on these components, salicylic acid and its acetate derivative, aspirin, have long been used for the treatment of different disorders. Dapagliflozin, an FDA-approved antidiabetic drug, has been developed based on the conclusions obtained from a structure-activity relationship study for a simple hydrolyzable tannin, β-pentagalloylglucoside (β-PGG). Thus, the present review focuses on the development of therapeutic agents from elderberries and their small-molecule secondary metabolites. It is hoped that this contribution will support future investigations on elderberries.

Microencapsule delivery systems of functional substances for precision nutrition

Microencapsulation, a typical core-shell structure technology, encapsulates functional active ingredients for protection, controlled release, and targeted delivery. In precise nutrition, the focus is on utilizing microcapsule delivery systems for personalized dietary supplements and disease intervention. This chapter outlines the morphological structure of microcapsules, common wall materials, and preparation techniques. It discusses the characteristics of different hydrophilic and lipophilic functional factors and their function as dietary supplements. The role of microencapsulation on the controlled release, odor masking, and enhanced bioavailability of functional factors is explored. Additionally, the application of microcapsule delivery systems in nutritional interventions for diseases like inflammatory bowel disease, alcoholic/fatty liver disease, diabetes, and cancer is introduced in detail. Lastly, the chapter proposes the future developments of anticipation in responsive wall materials for precise nutrition interventions, including both challenges and opportunities.

Alterations in pH of Coffee Bean Extract and Properties of Chlorogenic Acid Based on the Roasting Degree

Factors influencing the sour taste of coffee and the properties of chlorogenic acid are not yet fully understood. This study aimed to evaluate the impact of roasting degree on pH-associated changes in coffee bean extract and the thermal stability of chlorogenic acid. Coffee bean extract pH decreased up to a chromaticity value of 75 but increased with higher chromaticity values. Ultraviolet-visible spectrophotometry and structural analysis attributed this effect to chlorogenic and caffeic acids. Moreover, liquid chromatography-mass spectrometry analysis identified four chlorogenic acid types in green coffee bean extract. Chlorogenic acid isomers were eluted broadly on HPLC, and a chlorogenic acid fraction graph with two peaks, fractions 5 and 9, was obtained. Among the various fractions, the isomer in fraction 5 had significantly lower thermal stability, indicating that thermal stability differs between chlorogenic acid isomers.

Effects of the Taste Substances and Metal Cations in Green Tea Infusion on the Turbidity of EGCG-Mucin Mixtures

Astringency has an important impact on the taste quality of tea infusion, a process which occurs when polyphenols complex with salivary proteins to form an impermeable membrane. (-)-Epigallocatechin gallate (EGCG) is the main astringent compound found in green tea and mucin is the main protein present in saliva. Determining the turbidity of EGCG-mucin mixtures is an effective method to quantify the astringency intensity of EGCG solutions. In this study, the effects of taste-related, substances present during green tea infusion, on the turbidity of EGCG-mucin mixtures was investigated under the reacting conditions of a pH value of 5.0, at 37 °C, and for 30 min. The results showed that epicatechins, caffeic acid, chlorogenic acid, and gallic acid reduced the turbidity of EGCG-mucin mixtures, while rutin increased turbidity. Metal ions increased the turbidity of EGCG-mucin mixtures. These can be arranged by effectiveness as Al3+ > K+ > Mg2+ > Ca2+. Caffeine, theanine, and sodium glutamate all decreased the turbidity values of EGCG-mucin mixtures, but sucrose had a weak effect. Further experiments confirmed that the turbidity of green tea infusion-mucin mixture indicated the astringent intensity of green tea infusion, and that the turbidity was significantly correlated with the contents of tea polyphenols and EGCG.

Sustained release of chlorogenic acid by co-encapsulation of sodium alginate binding to the Northern pike (Esox Lucius) liver ferritin

Ferritin has a unique hollow spherical structure, which makes it a promising nanocarrier for food functional substances. In this study, a new ferritin was successfully extracted from the liver of Northern pike, purified, and identified. We used the reversible self-assembly characteristics of ferritin to fabricate chlorogenic acid (CA)-loaded apoferritin (Apo) complex (Apo-CA) and sodium alginate (SA)-apoferritin (Apo) co-encapsulate system. Apo-CA was encapsulated into the SA system to form SA-Apo-CA. The fabricated composites were analyzed using particle size, UV-Vis absorption spectroscopy, fluorescence spectroscopy, flourier transform infrared spectroscopy and transmission electron microscope. Physicochemical property of analysis confirmed th successful preparation of Apo-CA/SA-Apo-CA and improved thermal and UV radiation stability. The effect of sustained-release of CA were tested in vitro of simulated gastrointestinal tract digestion. SA-Apo-CA exhibited greater release ability than unencapsulated CA and Apo-CA. This study provides a new strategy for designing a multilayer delivery system with improved stability and sustained-release property.

Influence of Complexation with β- and γ-Cyclodextrin on Bioactivity of Whey and Colostrum Peptides

Dairy protein hydrolysates possess a broad spectrum of bioactivity and hypoallergenic properties, as well as pronounced bitter taste. The bitterness is reduced by complexing the proteolysis products with cyclodextrins (CDs), and it is also important to study the bioactivity of the peptides in inclusion complexes. Hydrolysates of whey and colostrum proteins with extensive hydrolysis degree and their complexes with β/γ-CD were obtained in the present study, and comprehensive comparative analysis of the experimental samples was performed. The interaction of CD with peptides was confirmed via different methods. Bioactivity of the initial hydrolysates and their complexes were evaluated. Antioxidant activity (AOA) was determined by fluorescence reduction of fluorescein in the Fenton system. Antigenic properties were studied by competitive enzyme immunoassay. Antimutagenic effect was estimated in the Ames test. According to the experimental data, a 2.17/2.78-fold and 1.45/2.14-fold increase in the AOA was found in the β/γ-CD interaction with whey and colostrum hydrolysates, respectively. A 5.6/5.3-fold decrease in the antigenicity of whey peptides in complex with β/γ-CD was detected, while the antimutagenic effect in the host-guest systems was comparable to the initial hydrolysates. Thus, bioactive CD complexes with dairy peptides were obtained. Complexes are applicable as a component of specialized foods (sports, diet).

Quality Assessment of Ground Coffee Samples from Greek Market Using Various Instrumental Analytical Methods, In Silico Studies and Chemometrics

Coffee is one of the most widely consumed beverages worldwide due to its sensory and potential health-related properties. In the present comparative study, a preparation known as Greek or Turkish coffee, made with different types/varieties of coffee, has been investigated for its physicochemical attributes (i.e., color), antioxidant/antiradical properties, phytochemical profile, and potential biological activities by combining high-throughput analytical techniques, such as infrared spectroscopy (ATR-FTIR), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and in silico methodologies. The results of the current study revealed that roasting degree emerged as the most critical factor affecting these parameters. In particular, the L* color parameter and total phenolic content were higher in light-roasted coffees, while decaffeinated coffees contained more phenolics. The ATR-FTIR pinpointed caffeine, chlorogenic acid, diterpenes, and quinic esters as characteristic compounds in the studied coffees, while the LC-MS/MS analysis elucidated various tentative phytochemicals (i.e., phenolic acids, diterpenes, hydroxycinnamate, and fatty acids derivatives). Among them, chlorogenic and coumaric acids showed promising activity against human acetylcholinesterase and alpha-glucosidase enzymes based on molecular docking studies. Therefore, the outcomes of the current study provide a comprehensive overview of this kind of coffee preparation in terms of color parameters, antioxidant, antiradical and phytochemical profiling, as well as its putative bioactivity.

How cyclodextrin encapsulation improves molecular stability of apple polyphenols phloretin, phlorizin, and ferulic acid: Atomistic insights through structural chemistry

Phloretin (PRT), phlorizin (PRZ), and ferulic acid (FEA) prevalent in apples are unstable and less soluble in water, which can be improved by cyclodextrin (CD) encapsulation. This study aimed to provide atomistic insights of β-CD-PRT (1), β-CD-PRZ (2), and α-CD-FEA (3) complexes. Single-crystal X-ray diffraction (XRD) revealed that one PRZ (2) and one FEA (3) insert the aromatic B-ring and C=C-C=O(O) group respectively into the β-CD (2) and α-CD (3) cavities, whereas a half-occupied PRT (1) inserts the B-ring across the β-CD cavity. The induced-fit process yielded thermodynamically stable complexes 2 > 1 > 3, in agreement with the density functional theory (DFT)-optimized structures with the corresponding number of intermolecular OH···O H-bonds (7 > 3 > 1). Perpendicular conformations of the pharmaceutically active forms of PRT (1) and PRZ (2) are first observed crystallographically. This study confirmed the potential applications of CDs as molecular stabilizers and aqueous solubilizers for the improved bioavailability and efficient delivery of food bioactive compounds.

Possible role of polypeptide-chlorogenic acid interaction in the physicochemical and sensory characteristics of quinoa-modified coffee beverage

The effect of quinoa protein hydrolysate (QPH) beverage on the physicochemical and sensory characteristics of coffee was investigated. The scores of sensory properties of coffee-quinoa beverage revealed that the unpleasant sensory characteristics, such as extreme bitterness and astringency, were covered up by the addition of quinoa beverage; while smooth mouthfeel and sweetness were enhanced. On the other hand, the introduction of coffee into quinoa beverage significantly retarded oxidation characterized by TBARS. When treated with chlorogenic acid (CGA), significant structural changes and improved functionalities of QPH were detected. CGA induced the unfolding structure of QPH and decreased surface hydrophobicity. The interaction between QPH and CGA was shown by the changes of sulfydryl content and the pattern of SDS-PAGE. Besides, neutral protease treatment increased the equilibrium oil-water interfacial pressure value of QPH, revealing improved stability of emulsions. Synergistic antioxidant effect between QPH and CGA was revealed by increased ABTS^+· scavenging rate.

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.

Cyclodextrin-Based Delivery Systems and Hydroxycinnamic Acids: Interactions and Effects on Crucial Parameters Influencing Oral Bioavailability-A Review

Hydroxycinnamic acids (HCAs) are a subclass of phenolic acids presenting caffeic acid (CA), chlorogenic acid (CGA), coumaric acid (COA) isomers, ferulic acid (FA), and rosmarinic acid (RA) as the major representants, being broadly distributed into vegetal species and showing a range of biological potentials. Due to the low oral bioavailability of the HCAs, the development of delivery systems to promote better administration by the oral route is demanding. Among the systems, cyclodextrin (CD)-based delivery systems emerge as an important technology to solve this issue. Regarding these aspects, in this review, CD-based delivery systems containing HCAs are displayed, described, and discussed concerning the degree of interaction and their effects on crucial parameters that affect the oral bioavailability of HCAs.

Strategies for Taste Masking of Orodispersible Dosage Forms: Time, Concentration, and Perception

Orodispersible dosage forms, characterized as quick dissolving and swallowing without water, have recently gained great attention from the pharmaceutical industry, as these forms can satisfy the needs of children, the elderly, and patients suffering from mental illnesses. However, poor taste by thorough exposure of the drugs' dissolution in the oral cavity hinders the effectiveness of the orodispersible dosage forms. To bridge this gap, we put forward three taste-masking strategies with respect to the intensity of time, concentration, and perception. We further investigated the raw material processing, the composition of auxiliary material, formulation techniques, and process control in each strategy and drew conclusions about their effects on taste masking.

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.

Host-guest inclusion complexes of hydroxytyrosol with cyclodextrins: Development of a potential functional ingredient for food application

Hydroxytyrosol (HT), a potent phenolic phytochemical, exerts positive health effects due to its antioxidant properties. However, it is highly reactive to oxygen, light, and heat and presents high instability. Alpha- and beta-cyclodextrin (α-CD, β-CD) have structures that allow them to encapsulate a variety of hydrophobic molecules. The aim of this study was to examine the outcomes of the inclusion of HT into α-CD and β-CD. Aqueous solutions of HT and either α-CD or β-CD were prepared and freeze-drying was applied for the encapsulation, in 1:1 and 2:1 molar ratios. The produced solid complexes were studied and characterized using NMR spectroscopy, differential scanning calorimetry (DSC) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Encapsulation efficiency (EE%), stability, and in vitro release of the encapsulated complexes under simulated digestion conditions were also evaluated. In both DSC thermograms and FTIR spectra of the inclusion complexes, absence of the characteristic peaks of HT and shifts of the CDs peaks were observed, showing an interaction between the molecules. NMR suggested a stronger complex formed between β-CD and HT. The EE% of β-CD/HT (1:1 and 2:1) complexes and α-CD/HT (1:1) complex was found to be higher (83%, 76%, 78%, respectively), compared to α-CD/HT (2:1) (51%). Data obtained support the encapsulation of HT in both CDs, revealing a potential interaction between them and an improvement in HT's thermal stability. Regarding the in vitro release study, both CD complexes had similar behavior and a controlled release of HT in the intestinal site was observed. PRACTICAL APPLICATION: The encapsulation of hydroxytyrosol in cyclodextrins resulted in white amorphous food-grade powders with no aroma and taste. Incorporation of these powders in foods could lead to an increase in their antioxidant content and offer an additional nutritional value.

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.

Degradation of organophosphorus flame retardants in heterogeneous photo-Fenton system driven by Fe(III)-based metal organic framework: Intermediates and their potential interference on bacterial metabolism

Organophosphorus flame retardants (OPFRs) have been regarded as one of the most rebarbative classes of emerging contaminants due to their persistence and toxicity. In the current study, Fe-based metal organic framework (MIL-88A) was synthesized and employed as photo-Fenton catalyst for the degradation of tris-(2-chloroisopropyl) phosphate (TCPP), a typical representative of OPFRs. The observations indicated that visible light could boost the reduction of ≡Fe^III to ≡Fe^II in Fe-O clusters of MIL-88A during the photo-Fenton system and consequently induce the transformation of H₂O₂ to OH, which realized efficient degradation of TCPP. Due to the excellent function of MIL-88A, the effective pH application range of photo-Fenton system was extended in comparison with traditional Fenton system. The degradation efficiency of TCPP was visibly influenced in presence of humic acid (HA). MIL-88A exhibited a commendable reusability and stability after 3 times cycle. As the photo-Fenton reaction proceeded, TCPP was disintegrated to several kinds of carboxylated, dechlorinated and hydroxylated products. The observations of metabolomics endorsed that the interference of intermediate products mixture on E. coli weakened to a certain extent. In conclusion, carboxylation, dechlorination, hydroxylation and oxidation of TCPP were likewise effective for its detoxification, revealing that heterogeneous photo-Fenton system driven by Fe-based metal organic framework will be an attractive and safe treatment technique for OPFRs control.

Recent advances in cyclodextrin-based films for food packaging

Cyclodextrins are garnering increasing attention because they offer several benefits. For instance, cyclodextrins can form several complexes and supramolecular structures not only for food packaging but also for applications in other fields of science. In this review, we discussed the physical and chemical properties of cyclodextrins and the mechanism of their inclusion complex formation. The use of cyclodextrins in various types of food packaging is elaborated upon. We also explain the effects of cyclodextrins on the packaging of fruits, vegetables, meat, fish, and processed foods. Furthermore, some feasible suggestions for future applications are provided. In addition to the positive attributes of cyclodextrins, there are some limitations and drawbacks, which are discussed briefly in this review. In summary, this review can serve as a guide for researchers exploring cyclodextrins for the development of various packaging films.

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.

Quantification of Caffeine and Chlorogenic Acid in Green and Roasted Coffee Samples Using HPLC-DAD and Evaluation of the Effect of Degree of Roasting on Their Levels

Chlorogenic acid and caffeine are among the important components in coffee beans, determining the taste and aroma. In addition, phenols and antioxidants content possess vital health values. The main aim of this study is to determine the levels of caffeine and chlorogenic acid in several coffee samples of different origins and degrees of roasting. The coffee samples were extracted using hot water. The levels of caffeine and chlorogenic acid were quantified using high-performance liquid chromatography (HPLC) equipped with a diode array detector, a reverse phase system, and an ODS column (C18). Total phenol and antioxidant contents were previously determined for the same samples. The results showed that the highest content of caffeine was found in the medium roasted coffee (203.63 mg/L), and the highest content of chlorogenic acid content was found in the green coffee (543.23 mg/L). The results demonstrated a negative correlation between the chlorogenic acid levels with the degree of roasting, while it showed a positive correlation between the caffeine levels with the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. The origin of coffee samples did not show any effect on any of the measured variables. Antioxidant effects of coffee samples were largely determined by chlorogenic acid content.

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.

Interaction between caffeic acid/caffeic acid phenethyl ester and micellar casein

Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) are bioactive molecules with poor solubility. We investigated the interaction between CA/CAPE and micellar casein (MC), and the physico-chemical and antioxidant properties of the complexes. Fluorescence spectroscopy analysis showed that both CA and CAPE formed complexes with MC via hydrophobic interactions. The binding constant was higher for CAPE than for CA at each temperature. The complexes were confirmed by FTIR and XRD. The secondary structure of MC was not affected by CAPE, but its morphology changed. CA/CAPE did not induce the dissociation of casein micelles. CA and CAPE increased and decreased, respectively, the bulk and tapped densities of MC. The complexes had higher thermal stability and DPPH radical scavenging capacity than free MC or CA/CAPE.

Green Extracts from Coffee Pulp and Their Application in the Development of Innovative Brews

Coffee pulp, a by-product of coffee production, contains valuable compounds such as caffeine and chlorogenic acid with high antiradical activity. In this study, aqueous solutions of β-cyclodextrin (β-CD) were used as a non-conventional solvent for the extraction of targeted compounds from coffee pulp. The parameters of β-CD concentration (Cβcd), liquid-to-solid ratio (L/S), and temperature (T) were evaluated based on the antiradical activity (AAR) and the caffeine content (CCaf). The optimum operational conditions were found to be Cβcd: 9.25 mg/mL, L/S: 30 mL/g and T: 80 °C. The sensory profiles of brews prepared with coffee and coffee pulp with or without cyclodextrin were studied with quantitative descriptive analysis. The brew from the by-product had fruity, botanic, sweet and sourness sensory properties, and cyclodextrin was found to be able to affect the overall taste of the brew.

Supramolecular Complexes of β-Cyclodextrin with Clomipramine and Doxepin: Effect of the Ring Substituent and Component of Drugs on Their Inclusion Topologies and Structural Flexibilities

Depression is a global threat. Tricyclic antidepressants (TCAs) are still efficacious in treating depression, albeit with more side effects. Cyclodextrins (CDs) with a suitable nanocavity are potential drug carriers and can enhance the drug bioavailability. Aiming for an atomistic understanding of the CD encapsulation facilitating the improvement of drug stability and the reduction of side effects, a comprehensive study series of the β-CD-TCA inclusion complexes through single crystal X-ray diffraction and density functional theory (DFT) calculation was undertaken. This work reports the supramolecular complexes of β-CD with two pivotal TCAs, clomipramine (CPM; 1) and doxepin (DXP; 2). The different inclusion topologies of the β-CD-TCA complexes were notable. X-ray analysis revealed that, in 1, the CPM B-ring (without chloro group) was entrapped in the β-CD cavity, whereas, in 2, the E-DXP A-ring and the Z-DXP B-ring were disordered in the cavity, yielding energetically favorable complexes primarily maintained by intermolecular C-H⋯π interactions, as indicated by DFT calculation. Because both wings of TCAs were similar, an alternative inclusion scenario of the A-ring was evidenced crystallographically in four other TCA complexes. The enhanced TCA thermodynamic stabilities via CD inclusion complexation helped to reduce the side effects and to increase the bioavailability. Moreover, the scrutinization of six TCAs in different lattice circumstances revealed the greater TCA structural flexibilities for their optimum pharmacological activity while binding with proteins.

β-Cyclodextrin Inclusion Complexation With Tricyclic Antidepressants Desipramine and Imipramine: A Structural Chemistry Perspective

Single-crystal X-ray diffraction and DFT calculation have been carried out for an atomic-level understanding of β-cyclodextrin (β-CD) inclusion complexation with 2 tricyclic antidepressants (TCAs), desipramine and imipramine. X-ray analysis discloses that the A-C-rings are buried in the β-CD cavity and the side chain is mostly outside the cavity, nearby the O2-H/O3-H side. Hence, the inclusion structures of both complexes are stabilized by host-guest C5-H∙∙∙π interaction and N5'-H∙∙∙O5/O6 H-bonds of twofold-screw-symmetry-related molecules, which are similar to those of the reported complexes of nortriptyline and amitriptyline. The DFT full-geometry optimization in the gas phase reveals an alternative inclusion scenario with the TCA side chain that is embedded in the β-CD cavity and stabilized by intermolecular O6-H∙∙∙N5' H-bond and O2-H/O3-H∙∙∙π interactions. The β-CD encapsulation of the TCA side chain is more energetically stable by 10.76 and 4.70 kcal mol^-1 than that of the aromatic moiety for the respective complexes of DPM and IPM, based on the relative stabilization energies (ΔΔE_stb). This suggests the existence of the bimodal β-CD-TCA inclusion complexes as spectroscopically observed in solution, thus explaining the controversy in the inclusion mode and the improvement of TCA therapeutic effect by CD encapsulation.

Thermo- and redox-responsive dumbbell-shaped copolymers: from structure design to the LCST–UCST transition

Redox- and thermo-responsive dumbbell-shaped copolymers and their self-assembly and stimuli-responsive properties were investigated.

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.