Inclusion complexation of catechins-rich green tea extract by β-cyclodextrin: Preparation, physicochemical, thermal, and antioxidant properties

The role of glutathione in stabilizing aromatic volatile organic compounds in Rougui Oolong tea: A comprehensive study from content to mechanisms

Chinese Oolong tea is widely known for its intricate aroma. However, the degradation of volatile organic compounds (VOCs) poses significant challenges for the tea products. In this study, glutathione (GSH) has an excellent preservation effect on VOCs in both the VOCs extract and the tea infusion during storage, specifically slowing the degradation of hexanal (by 66.39% and 35.09%) and heptanal (by 67.46% and 63.50%). Additionally, the addition of GSH maintained higher levels of active ingredients in tea infusion, including epigallocatechin, procyanidin B1, glutamic acid, and L-(+)-arginine, with respective increases of 184.09, 2.92, 4.10, and 6.35 times. The sulfhydryl group of GSH formed a covalent bond with hexanal and 2-methylbutanal, therefore improving the stability of VOCs. These findings provided a valuable insight for developing effective VOC preservation techniques for water-based tea products.

Evaluate the effect of β-cyclodextrin on the sensory and physicochemical properties of bitter gourd extract during thermal processing

This study aims to evaluate the impact of β-cyclodextrin (β-CD) on the properties of the bitter gourd extract (BGE) under various heating conditions. In this work, the BGE and BGE supplemented with β-CD (0.75%) were heated at 60, 90, and 121 °C for 20 min before measuring the changes of bitterness, total saponin, polyphenol, antioxidant capacity, free amino acid, 5-hydroxymethylfurfural, browning intensity, and pH. It was found that β-CD mitigated the effect of heat treatment on the BGE, especially on saponins and color. Results also showed the debittering ability of β-CD was still preserved after heating duration. The bitter-masking and defensive mechanism of β-CD was also demonstrated using FTIR, thermogravimetric analysis, and molecular docking stimulation. These findings illustrated the addition of β-CD improved the thermal stability of the BGE, opening up the opportunities to incorporate BGE, which is promising in diabetes treatment but thermolabile, into heat-processed products.

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).

The effect of carboxymethyl cellulose and β-cyclodextrin as debittering agents on bitterness and physicochemical properties of bitter gourd extract

Bitter gourd extract (BGE) is rich in antioxidants and anti-diabetic components that promote good human health; however, its bitter taste makes it challenging to use in food. In this study, the effect of carboxymethyl cellulose and β-cyclodextrin (β-CD) on the bitterness and properties of BGE were investigated. The bitterness intensity was evaluated by the trained sensory panel, and the physicochemical properties were also determined, including viscosity, total saponin, polyphenol content, antioxidant capacity, and α-amylase inhibition activity. It was found that the bitterness of BGE with 0.75%, w/v β-cyclodextrin decreased significantly by more than 90%. Additionally, FTIR, 1 H-NMR, and thermogravimetric analysis of BGE supplemented with β-CD confirmed the formation of a complex between β-CD and components of BGE. The findings of the current study also reveal that debittering agents did not inhibit the bioactivities of BGE.

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.

Preparation and Characterization of Clopidogrel Bisulfate-hydroxypropyl-β-Cyclodextrin Mixed Inclusion Complex for Improved Intestinal Solubility and Anti-Thrombotic Efficacy

The study aimed to increase the intestinal solubility and absorption of orally bioavailable clopidogrel-bisulfate (CPB) by complexing with hydroxypropyl-β-cyclodextrin (HCD) to form a binary inclusion complex that was stabilized by Tween 80 (T80) resulting into mixed inclusion complex. The results of phase solubility studies and molecular docking of CPB with β-cyclodextrin (β-CD) and HCD suggested higher solubility and binding energy of the stable CPB: HCD complex in the presence of T80 as compared to the CPB: β-CD complex. The D-Optimal mixture design was used to optimize the formulation containing the CPB: HCD: T80 mixed inclusion complex. The results suggest the enhanced stability of the CPB: HCD inclusion complex in the presence of T80. The spectral attributes confirmed the inclusion complexation and pointed out the central position of CPB in a hydrophilic cavity of HCD. Further, the prepared soft gelatin capsule successfully confirmed the importance of obliterating the intestinal precipitation associated problem of CPB through an in-vitro release study. The anticoagulant activity in rabbits confirmed that soft gelatin capsules showed 1.2 folds and 1.3 folds increase in clotting time, 1.2 fold and 1.5 folds increase in bleeding time when compared to marketed formulation and pure drug, respectively. Conclusively, soft gelatin capsules exhibit the potential to enhance the oral bioavailability of CPB, leading to reduction of the dose and dose-related side effects.

β-cyclodextrin microencapsulation enhanced antioxidant and antihyperlipidemic properties of Tunisian Periploca angustifolia roots condensed tannins in rats

This study aimed to investigate the microencapsulation of novel condensed tannins isolated from Periploca angustifolia roots, using β-cyclodextrin macrocyclic oligosaccharides, in order to enhance their antioxidant and antihyperlipidemic potentials. Scanning electron microscopy and Fourier transform infrared spectroscopy results revealed that tannin fraction was successfully included into β-cyclodextrin cavities proved with an encapsulation efficacy of 70%. Our in vitro findings highlighted that both pure and encapsulated tannins have efficient inhibition capacities of pancreatic lipase activity. However, the inclusion complex has the greatest, in vivo, antioxidant, and antihyperlipidemic effects. In fact, results showed that complexed tannins had markedly restored serum lipid biomarkers, lipid peroxidation, protein carbonyl oxidation, and antioxidant enzyme defense. These findings were additionally confirmed by aortic and myocardial muscle sections of histological examination. Consequently, β-cyclodextrin microencapsulation may be considered as an effective and promising technique for tannin delivery with improved antioxidant and antihyperlipidemic activities.

Controlled release and antibacterial properties of PEO/casein nanofibers loaded with Thymol/β-cyclodextrin inclusion complexes in beef preservation

There are still many limitations in the application of natural active compounds in meat preservation. Herein, thymol was first inserted into the cavity of β-cyclodextrin (β-CD) to form a stable inclusion complex (THY/β-CD-IC). The computational investigation showed that the optimized complexation energy for THY/β-CD-IC was -12.95 kcal mol^-1. It contributed to the improvement of the thermal stability of thymol in the inclusion compound. Furthermore, the functionalized nanofibers (THY/β-CD-IC-NFs) loaded with THY/β-CD-IC were successfully fabricated by electrospinning of the mixture of casein and polyethylene oxide. When dealing with protease-producing bacteria, controllable release of thymol from THY/β-CD-IC-NFs was achieved through the response of casein to the hydrolysis of bacterial protease. The application results indicated that the prepared THY/β-CD-IC-NFs had a long-term antimicrobial activity for chilled beef preservation during 7-days storage. The information from this study presents a feasible strategy for the development of natural extracts for use in meat preservation.

The challenge of flavonoid/cyclodextrin complexation in a complex matrix of the quercetin, luteolin, and 3-O-methylquercetin

The complexation of herbal constituents with cyclodextrin has been a useful tool to improve their aqueous solubility. However, the simultaneous complexation of these compounds still lacks detailed studies. The present study investigated the multicomplexation of quercetin (QCT), luteolin (LUT), and 3-O-methylquercetin (3OMQ) with (2-hydroxypropyl)-β-cyclodextrin (HPβCD), when they are simultaneously contained in a flavonoid-enriched fraction (FEF) of Achyrocline satureioides. The phase-solubility diagram revealed a linear correlation between the flavonoids solubility and the HPβCD concentration, demonstrating the formation of complexes with a 1:1 stoichiometric ratio, which was confirmed by ESI-MS. Negative ΔG⁰ values indicated that complexation was spontaneous. Flavonoids/HPβCD interactions were evidenced by FT-IR, DSC, SEM, and 1D and 2D NMR. The last one showed the formation of inclusion complexes by insertion of the B-ring of the flavonoids into the cavity of HPβCD. Unexpectedly, the FEF/HPβCD complex showed a radical scavenger potential lower than the FEF. The HPLC analysis revealed that the complex contained different flavonoid ratio than the fraction. Thus, the antioxidant capacity of the samples was demonstrated to be related to the ratio among the flavonoids, rather than to the total flavonoids. These new findings are very useful for developing herbal cyclodextrin-based products from A. satureioides or other herbal products.

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.

Integrating diverse plant bioactive ingredients with cyclodextrins to fabricate functional films for food application: a critical review

The popularity of plant bioactive ingredients has become increasingly apparent in the food industry. However, these plant bioactive ingredients have many deficiencies, including low water solubility, poor stability, and unacceptable odor. Cyclodextrins (CDs), as cyclic molecules, have been extensively studied as superb vehicles of plant bioactive ingredients. These CD inclusion compounds could be added into various film matrices to fabricate bioactive food packaging materials. Therefore, in the present review, we summarized the extraction methods of plant bioactive ingredients, the addition of these CD inclusion compounds into thin-film materials, and their applications in food packaging. Furthermore, the release model and mechanism of active film materials based on various plant bioactive ingredients with CDs were highlighted. Finally, the current challenges and new opportunities based on these film materials have been discussed.

Novel β-Cyclodextrin and Catnip Essential Oil Inclusion Complex and Its Tick Repellent Properties

Cyclodextrin inclusion complexes have been successfully used to encapsulate essential oils, improving their physicochemical properties and pharmacological effects. Besides being well-known for its effects on cats and other felines, catnip (Nepeta cataria) essential oil demonstrates repellency against blood-feeding pests such as mosquitoes. This study evaluates the tick repellency of catnip oil alone and encapsulated in β-cyclodextrin, prepared using the co-precipitation method at a 1:1 molar ratio. The physicochemical properties of this inclusion complex were characterized using GC-FID for encapsulation efficiency and yield and SPME/GC-MS for volatile emission. Qualitative assessment of complex formation was done by UV-Vis, FT-IR, ¹H NMR, and SEM analyses. Catnip oil at 5% (v/v) demonstrated significant tick repellency over time, being comparable to DEET as used in commercial products. The prepared [catnip: β-CD] inclusion complex exerted significant tick repellency at lower concentration of the essential oil (equivalent of 1% v/v). The inclusion complex showed that the release of the active ingredient was consistent after 6 h, which could improve the effective repellent duration. These results demonstrated the effective tick repellent activity of catnip essential oil and the successful synthesis of the inclusion complex, suggesting that β-CDs are promising carriers to improve catnip oil properties and to expand its use in repellent formulations for tick management.

Encapsulation of Phenolic Compounds from a Grape Cane Pilot-Plant Extract in Hydroxypropyl Beta-Cyclodextrin and Maltodextrin by Spray Drying

Grape canes, the main byproducts of the viticulture industry, contain high-value bioactive phenolic compounds, whose application is limited by their instability and poorly solubility in water. Encapsulation in cyclodextrins allows these drawbacks to be overcome. In this work, a grape cane pilot-plant extract (GC_PPE) was encapsulated in hydroxypropyl beta-cyclodextrin (HP-β-CD) by a spray-drying technique and the formation of an inclusion complex was confirmed by microscopy and infrared spectroscopy. The phenolic profile of the complex was analyzed by LC-ESI-LTQ-Orbitrap-MS and the encapsulation efficiency of the phenolic compounds was determined. A total of 42 compounds were identified, including stilbenes, flavonoids, and phenolic acids, and a complex of (epi)catechin with β-CD was detected, confirming the interaction between polyphenols and cyclodextrin. The encapsulation efficiency for the total extract was 80.5 ± 1.1%, with restrytisol showing the highest value (97.0 ± 0.6%) and (E)-resveratrol (32.7 ± 2.8%) the lowest value. The antioxidant capacity of the inclusion complex, determined by ORAC-FL, was 5300 ± 472 µmol TE/g DW, which was similar to the value obtained for the unencapsulated extract. This formulation might be used to improve the stability, solubility, and bioavailability of phenolic compounds of the GC_PPE for water-soluble food and pharmaceutical applications.

Zinc oxide nanoparticles conjugated with clinically-approved medicines as potential antibacterial molecules

At present, antibiotic resistance is one of the most pressing issues in healthcare globally. The development of new medicine for clinical applications is significantly less than the emergence of multiple drug-resistant bacteria, thus modification of existing medicines is a useful avenue. Among several approaches, nanomedicine is considered of potential therapeutic value. Herein, we have synthesized Zinc oxide nanoparticles (ZnO-NPs) conjugated with clinically-approved drugs (Quercetin, Ceftriaxone, Ampicillin, Naringin and Amphotericin B) with the aim to evaluate their antibacterial activity against several Gram-positive (Methicillin resistant Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) and Gram-negative (Escherichia coli K1, Serratia marcescens and Pseudomonas aeruginosa) bacteria. The nanoparticles and their drug conjugates were characterized using UV-visible spectrophotometry, dynamic light scattering, Fourier transform infrared spectroscopy and atomic force microscopy. Antibacterial activity was performed by dilution colony forming unit method and finally 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed to determine their cytotoxic effects against human cell lines. ZnO-NPs revealed maxima surface plasmon resonance band at 374 and after conjugation with beta-cyclodextrin at 379 nm, polydispersity with size in range of 25–45 nm with pointed shaped morphology. When conjugated with ZnO-NPs, drug efficacy against MDR bacteria was enhanced significantly. In particular, Ceftriaxone- and Ampicillin-conjugated ZnO-NPs exhibited potent antibacterial effects. Conversely, ZnO-NPs and drugs conjugated NPs showed negligible cytotoxicity against human cell lines except Amphotericin B (57% host cell death) and Amphotericin B-conjugated with ZnO-NPs (37% host cell death). In conclusion, the results revealed that drugs loaded on ZnO-NPs offer a promising approach to combat increasingly resistant bacterial infections.

Synthesis and Characterization of β-Cyclodextrin-Essential Oil Inclusion Complexes for Tick Repellent Development

Essential oils (EOs) are used in several pest management applications. Due to their volatility, EOs may experience bioactivity reduction, thus requiring protection to extend their properties. In the present study, we investigated the inclusion complex formation (IC) of β-cyclodextrin (β-CD) with selected EOs with known tick repellent activity using two co-precipitation methods. ICs were characterized by evaluating EO mass concentration and inclusion efficiency (% IE) and other instrumental methods. Co-precipitation method 2 yielded the highest EO mass concentration (88 ± 6 μg/mg β-CD) for the 1:1 molar ratio geranium Egyptian EO IC. The EO volatile release over time from the ICs was investigated by headspace SPME/GC-MS analysis. ICs were also tested in tick repellency bioassays. ICs reported significant tick repellent activity, with lemongrass IC performing best overall. Method 1 showed the best combination of high mass concentration EO, controlled volatile release, and tick repellency with lemongrass EO. The results demonstrated that β-CD had selectively encapsulated different EOs. Moreover, the formation of ICs may improve EO tick repellent properties protecting the active ingredients and providing a better, long-lasting repellent action. These findings will allow the development of more effective naturally derived repellent products to protect individuals from tick bites and prevent tick-borne illnesses.

Phenolome of Asian Agrimony Tea (Agrimonia asiatica Juz., Rosaceae): LC-MS Profile, α-Glucosidase Inhibitory Potential and Stability

Functional beverages constitute the rapidly increasing part of the functional food section and represent an area with a wide range of products including herbal-based beverages. We carried out screening investigations of the extracts of 85 Rosaceous tea plants. Among the extracts analyzed Agrimonia asiatica herb extract demonstrated the highest inhibitory activity against the enzyme α-glucosidase (20.29 µg/mL). As a result of chromato-mass-spectrometric profiling of A. asiatica herb with high-performance liquid chromatography with photodiode array and electrospray triple quadrupole mass-spectrometric detection (HPLC-PDA-ESI-tQ-MS) 60 compounds were identified, including catechins, ellagitannins, flavones, flavonols, gallotannins, hydroxycinnamates, procyanidins, most for the very first time. The analysis of the seasonal variation of metabolites in A. asiatica herb demonstrated that the phenolic content was highest in summer samples and lower in spring and autumn. HPLC activity-based profiling was utilized to identify compounds of A. asiatica herb with the maximal α-glucosidase inhibitory activity. The most pronounced inhibition of α-glucosidase was observed for agrimoniin, while less significant results of inhibition were revealed for ellagic acid and isoquercitrin. The evaluation of phenolic content in A. asiatica herbal teas with the subsequent determination of α-glucosidase inhibiting potential was discovered. Maximum inhibition of α-glucosidase was observed for hot infusion (75.33 µg/mL) and the minimum for 30 min decoction (159.14 µg/mL). Our study demonstrated that A. asiatica herbal tea is a prospective functional beverage in which dietary intake may help to reduce blood glucose.

β-Cyclodextrin Inclusion Complex Containing Litsea cubeba Essential Oil: Preparation, Optimization, Physicochemical, and Antifungal Characterization

Litsea cubeba essential oil (LCEO), as naturally plant-derived products, possess good antimicrobial activities against many pathogens, but their high volatility and poor water solubility limit greatly the application in food industry. In this research, inclusion complex based on β-cyclodextrin (β-CD) and LCEO, was prepared by saturated aqueous solution method. An optimum condition using the response surface methodology (RSM) based on Box–Behnken design (BBD) was obtained with the inclusion time of 2 h and β-CD/LCEO ratio of 4.2 at 44 °C. Under the condition, the greatest yield of 71.71% with entrapment efficiency of 33.60% and loading capacity of 9.07% was achieved. In addition, the structure and characteristic of LCEO/β-CD inclusion complex (LCEO/βCD-IC) were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR), which indicated that LCEO/βCD-IC was successfully formed. The particle size of LCEO/βCD-IC was determined to be 17.852 μm. Thermal properties of LCEO/βCD-IC evaluated by thermogravimetric-differential scanning calorimetry (TG-DTA) illustrated better thermal stability of the aimed product compared with the physical mixture. Furthermore, the tests of antifungal activity showed that LCEO/βCD-IC was able to control the growth of Penicillium italicum, Penicillium digitatum, and Geotrichum citri-aurantii isolated from postharvest citrus. Our present study confirmed that LCEO/βCD-IC might be further applied as an alternative to chemical fungicides for protecting citrus fruit from postharvest disease.