Inclusion interactions of cyclodextrins and crosslinked cyclodextrin polymers with linalool and camphor in Lavandula angustifolia essential oil

Molecular dynamics simulation techniques and their application to aroma compounds/cyclodextrin inclusion complexes: A review

Homeostatic technologies play a crucial role in maintaining the quality and extending the service life of aroma compounds (ACs). Commercial cyclodextrins (CDs) are commonly used to form inclusion complexes (ICs) with ACs to enhance their solubility, stability, and morphology. The selection of suitable CDs and ACs is of paramount importance in this process. Molecular dynamics (MD) simulations provide an in-depth understanding of the interactions between ACs and CDs, aiding researchers in optimising the properties and effects of ICs. This review offers a systematic discussion of the application of MD simulations in ACs/CDs ICs, covering the establishment of the simulation process, parameter selection, model evaluation, and various application cases, along with their advantages and disadvantages. Additionally, this review summarises the major achievements and challenges of this method while identifying areas that require further exploration. These findings may contribute to a comprehensive understanding of the formation and stabilization mechanisms of ACs/CDs ICs and offer guidance for the selection and computational characterisation of CDs in the AC steady state.

Encapsulation of Rosmarinus officinalis essential oil and of its main components in cyclodextrin: application to the control of the date moth Ectomyelois ceratoniae (Pyralidae)

BACKGROUND

Synthetic insecticides are the most useful tools for preventing losses caused by insect pest's infestation during storage. However, the use of pesticides should be limited because of the development of insect resistance and their adverse effects on human health and environment. In the last decades, natural insecticidal products, principally essential oils (EOs) and their active components, exhibited potential alternatives for pest control. Nevertheless, due to their volatile nature, encapsulation could be considered as the most appropriate solution. Therefore, this work aims to investigate the fumigant ability of inclusion complexes of Rosmarinus officinalis EO and its major constituents (1,8-cineole, α-pinene and camphor) with 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) against Ectomyelois ceratoniae (Pyralidae) larvae.

RESULTS

The encapsulation within HP-β-CD reduced greatly the release rate of the encapsulated molecules. Therefore, free compounds were more toxic than those encapsulated. Moreover, results revealed that encapsulated volatiles exhibited interesting insecticidal toxicity towards E. ceratoniae larvae. In fact, after 30 days mortality rates were 53.85, 94.23, 3.85 and 42.31% for α-pinene, 1,8-cineole, camphor and EO, respectively, encapsulated within HP-β-CD. In addition, results showed also that 1,8-cineole free and encapsulated was more effective toward E. ceratoniae larvae than the other tested volatiles. Additionally, the HP-β-CD/volatiles complexes exhibited best persistence compared to the volatiles components. The half-life of the encapsulated α-pinene, 1,8-cineole, camphor and EO (7.83, 8.75, 6.87 and 11.20 days) was significantly longer than that of the free ones (3.46, 5.02, 3.38 and 5.58 days).

CONCLUSION

These results sustain the utility of R. officinalis EO and its main components encapsulated in CDs as treatment to stored-date commodities. © 2023 Society of Chemical Industry.

A review of the bioactive components and pharmacological properties of Lavandula species

Lavandula species is a flowering plant that is common in Europe and across the Mediterranean. Lavender has many health benefits for humans. In addition to its use in herbal medicine, it is widely used in the fields of cosmetics, perfumes, foods, and aromatherapy. Google Scholar, PubMed, Scopus, and Web of Science were used to search for relevant material on the phytochemical ingredients, the pharmacologic effects of the ingredients, and the mechanism of action of the Lavandula species identified. These materials were reviewed in order to have access to important updates about the Lavandula species. Lavender as referred to in English contains essential oils, anthocyanins, phytosterols, sugars, minerals, coumaric acid, glycolic acid, valeric acid, ursolic acid, herniarins, coumarins, and tannins. It has been used to treat colic and chest ailments, worrisome headaches, and biliousness, and in cleaning wounds. It has antifungal, antibacterial, neurologic, antimicrobial, anti-parasitic, anti-diabetic, and analgesic effects among others. Lavandula species has prospects for various biological applications, especially with its dermatological application. Advances in drug development would enable characterization of various bioactive constituents; thus, its development and application can have a more positive impact on humanity. Here, we highlighted updated information on the history, distribution, traditional uses, phytochemical components, pharmacology, and various biological activities of Lavandula species.

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

A simple method for the preparation of β-cyclodextrin derivatives containing covalently bonded aldehydes via an imine bond was developed and used to prepare a series of derivatives from 6I-amino-6I-deoxy-β-cyclodextrin and the following volatile aldehydes – cinnamaldehyde, cyclamen aldehyde, lilial, benzaldehyde, anisaldehyde, vanillin, hexanal, heptanal, citral, and 5-methylfurfural. Subsequently, the rate of release of the volatile compound from selected pro-fragrances, as a function of the environment (solvent, pH), was studied by 1H NMR spectroscopy (for benzaldehyde) and static headspace-gas chromatography (for benzaldehyde, heptanal, and 5-methylfurfural). The aldehyde release rate from the imine was shown to depend substantially on the pH from the solution and the air humidity from the solid state.

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.

History of cyclodextrin-based polymers in food and pharmacy: a review

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

Optimization and Validation of HS-GC/MS Method for the Controlled Release Study of Microencapsulated Specific Bioattractants for Target-Plaguicide Production

Insect plagues are a problem often hard to solve due to the harmful effects caused by the pesticides used to combat them. Consequently, the pesticide market is increasingly trying to develop new technologies to prevent the unwanted effects that common plague treatments usually bring with them. In this work, four specific bioattractants of Musca domestica, extracted from fungi (β-ocimene, phenol, p-cresol, and indole) were microencapsulated with β-cyclodextrin in order to produce an economically and environmentally sustainable bait containing biocides in the near future. Cyclodextrins will retain these volatile compounds until their use by the consumer when the product comes into contact with water. Then, the bioattractants will be released in the medium in a controlled manner. An analytical methodology based on headspace extraction coupled to gas chromatography and mass spectrometry (HS-GC/MS) has been developed and validated following Environmental Protection Agency (EPA) and European Commission Directorate General for Health and Food Safety guidelines for the bioattractants controlled release study from the microencapsulated product. The analytical method has been shown to be accurate and precise and has the sensitivity required for controlled release studies of the four bioattractants analyzed. The release of the bioattractants from microencapsulated products achieved the “plateau” after 3 h in all cases.

Comprehensive Characterization of Linalool-HP-β-Cyclodextrin Inclusion Complexes

The objective of the present study is to obtain linalool- cyclodextrin (CDs) solid complexes for possible applications in the food industry. For this purpose, a detailed study of linalool complexation was carried out at different pH values, to optimize the type of CDs and reaction medium that support the highest quantity of encapsulated linalool. Once demonstrated the ability of hydroxypropyl-β-cyclodextrin (HP-β-CDs), to form inclusion complexes with linalool (K_C = 921 ± 21 L mol⁻¹) and given their greater complexation efficacy (6.788) at neutral pH, HP-β-CDs were selected to produce solid inclusion complexes by using two different energy sources, ultrasounds and microwave irradiation, subsequently spraying the solutions obtained in the Spray Dryer. To provide scientific solidity to the experimental results, the complexes obtained were characterized by using different instrumental techniques in order to confirm the inclusion of linalool in the HP-β-CDs hydrophobic cavity. The linalool solid complexes obtained were characterized by using ¹H nuclear magnetic resonance (¹H-NMR) and 2D nuclear magnetic resonance (ROSEY), differential scanning calorimetry, thermogravimetry and Fourier transform infrared spectrometry. Moreover, the structure of the complex obtained were also characterized by molecular modeling.

Anti-Arrhythmic Effects of Linalool via Cx43 Expression in a Rat Model of Myocardial Infarction

BACKGROUND

Lavender is a traditional therapy for different heart symptoms including palpitation, which comprises an important symptom of cardiac arrhythmias. This experiment was designed to evaluate the antiarrhythmic effects of linalool using an experimental model of arrhythmia following myocardial infarction in rats. The underlying electrophysiological mechanism through cardiac connexin 43 (Cx43) expression was also investigated.

METHODS

Fifty male Sprague-Dawley rats were divided into five equal groups. The first group was considered as the normal control group; MI was induced by ligation of the left anterior descending artery (LAD) in the second group. The other three groups received metoprolol (100 mg/kg/day) or linalool (50 or 100 mg/kg/day) for seven days before LAD ligation. The arrhythmia score, isolated myocyte resting potential, histological changes, and cardiac Cx43 expression levels were evaluated.

RESULTS

In the MI group, there was a significant increase in the arrhythmia score but a marked decrease in resting membrane potential relative to the control; these changes were prevented by the administration of metoprolol or linalool. The histological changes were also minimized in the groups treated with these substances compared to the untreated MI group. The western blot and real-time PCR results showed that the protein expression of Cx43 in the infarct zone of the rat hearts was significantly higher in the MI groups receiving metoprolol or linalool compared with the untreated MI group.

CONCLUSION

Linalool was shown to be able to dose-dependently decrease the incidence of arrhythmias in a rat model of myocardial infarction. We propose that the key mechanism behind this antiarrhythmic effect is probably the prevention of decreased Cx43 expression following MI.

A facile synthesis of silver nanowires and their evaluation in the mitochondrial membrane potential

Silver nanowires (AgNWs) with a high-aspect-ratio were successfully synthesized by a green method using Lavandula angustifolia plant extract. The morphology of the AgNWs was evaluated as a function of the concentration of precursor salt and nucleating agent. Furthermore, AgNWs were analyzed in a biological model using rat liver mitochondria by measuring their effect on membrane potential. The scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques structurally characterized the nanowires obtained. Also, ultraviolet-visible spectroscopy (UV-Vis) investigated the optical properties of AgNWs. Structural studies show AgNWs fcc with lengths up to 100 μm and diameters ranging from 60 to 130 nm growing in the [110] orientation. Both the CuSO₄ nucleating agent and the centrifugation process are essential for the growth of nanowires. Furthermore, inhibition of mitochondrial membrane potential (MMP) depends on the concentration of the nanowires (NWs), suggesting dissipation of the electron transport chain. In this way, AgNWs can be used as a potential tool to verify biological reactions, such as modulation of metabolic pathways, together with the evaluation of a possible influence of biotic or abiotic factors in organisms.

Nanoencapsulation of Polyphenols towards Dairy Beverage Incorporation

Phenolic compounds, while widely recognized for their biological potential, when added into food matrixes may interact with food constituents. One example of this is the interaction between phenolic compounds and proteins, that may result in the formation of complexes and alter the bioavailability of both phenolic compounds and the nutrient availability. Moreover, when adding compounds to improve the functionality of a food matrix, these interactions may compromise the perceived benefits of the additions. Nanoencapsulation has been considered one of the means to circumvent these interactions, as they may function as a physical barrier between the phenolic compounds and the matrix (preventing not only the loss of bioactivity, but eventual sensorial alterations of the foods), protect phenolic compounds through the gastrointestinal tract, and may enhance phenolic absorption through cellular endocytosis. However, despite these advantages the food industry is still limited in its nanotechnological solutions, as special care must be taken to use food-grade encapsulants which will not pose any deleterious effect towards human health. Therefore, this review aims to provide an encompassing view of the existing advantages and limitations of nanotechnology, associated with the inclusion of phenolic compounds in dairy beverages.

Characterization of Cyclodextrin/Volatile Inclusion Complexes: A Review

Cyclodextrins (CDs) are a family of cyclic oligosaccharides that constitute one of the most widely used molecular hosts in supramolecular chemistry. Encapsulation in the hydrophobic cavity of CDs positively affects the physical and chemical characteristics of the guests upon the formation of inclusion complexes. Such a property is interestingly employed to retain volatile guests and reduce their volatility. Within this scope, the starting crucial point for a suitable and careful characterization of an inclusion complex is to assess the value of the formation constant (K_f), also called stability or binding constant. This task requires the application of the appropriate analytical method and technique. Thus, the aim of the present paper is to give a general overview of the main analytical tools used for the determination of K_f values for CD/volatile inclusion complexes. This review emphasizes on the advantages, inconvenients and limits of each applied method. A special attention is also dedicated to the improvement of the current methods and to the development of new techniques. Further, the applicability of each technique is illustrated by a summary of data obtained from the literature.

Methyl-β-cyclodextrin Inclusion Complex with β-Caryophyllene: Preparation, Characterization, and Improvement of Pharmacological Activities

β-Caryophyllene (BCP) is a sesquiterpene that shows high potential in pharmacological applications. However, these have been drastically limited by the respective volatility and poor water solubility. The present study investigates the formation of inclusion complexes between BCP and methyl-β-cyclodextrin (MβCD) and shows that these complexes promote a significant improvement of the anti-inflammatory, gastric protection, and antioxidant activities relative to neat BCP. It is shown that the solubility of BCP is significantly increased through complexation in phase solubility studies. Inclusion complexes with MβCD in solid state were prepared by three different methods, kneading, rotary evaporation, and lyophilization, with the latter confirmed by differential scanning calorimetry, Fourier transformed infrared spectroscopy, scanning electron microscopy, ¹H NMR spectroscopy, and molecular dynamics studies. This study provides for the first time a full characterization of inclusion complexes between BCP and MβCD and highlights the impact of complex formation upon pharmacological activity.

Electrospinning of cyclodextrin/linalool-inclusion complex nanofibers: Fast-dissolving nanofibrous web with prolonged release and antibacterial activity

The volatility and limited water solubility of linalool is a critical issue to be solved. Here, we demonstrated the electrospinning of polymer-free nanofibrous webs of cyclodextrin/linalool-inclusion complex (CD/linalool-IC-NFs). Three types of modified cyclodextrin (HPβCD, MβCD, and HPγCD) were used to electrospin CD/linalool-IC-NFs. Free-standing CD/linalool-IC-NFs facilitate maximum loading of linalool up to 12% (w/w). A significant amount of linalool (45-89%) was preserved in CD/linalool-IC-NFs, due to enhancement in the thermal stability of linalool by cyclodextrin inclusion complexation. Remarkably, CD/linalool-IC-NFs have shown fast-dissolving characteristics in which these nanofibrous webs dissolved in water within two seconds. Furthermore, linalool release from CD/linalool-IC-NFs inhibited growth of model Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria to a great extent. Briefly, characteristics of liquid linalool have been preserved in a solid nanofiber form and designed CD/linalool-IC-NFs confer high loading capacity, enhanced shelf life and strong antibacterial activity of linalool.

Polydisperse methyl β-cyclodextrin-epichlorohydrin polymers: variable contact time (13)C CP-MAS solid-state NMR characterization

The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state (13)C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices.

Enhanced analgesic activity by cyclodextrins - a systematic review and meta-analysis

INTRODUCTION

Analgesics can be ineffective in treating some types of pain, hence, improved drug delivery systems could optimize their efficacy.

AREA COVERED

The authors conducted a systematic review to evaluate the analgesic activity of compounds complexed in cyclodextrins, analyzing whether these complexes improved analgesic efficacy. The search terms 'analgesics', 'cyclodextrins' and 'drug effects' were used to retrieve articles in SCOPUS, PUBMED and EMBASE. A total of 22 papers were identified. In the clinical studies, there was greater efficacy in the complexed drug when compared with control groups, with differences ranging from 25 to 83%. Through a meta-analysis, the preclinical studies showed that the complexed drug had a significantly (p < 0.01) greater effect than the non-complexed drug.

EXPERT OPINION

The use of cyclodextrins can improve the efficacy of analgesic compounds, and they are an important tool in the search for greater analgesic effect. They may also be a way to reduce the therapeutic doses, and hence increasing the potential of the drug.

Complexation of estragole as pure compound and as main component of basil and tarragon essential oils with cyclodextrins

Inclusion complexes of estragole (ES) as pure compound and as main component of basil and tarragon essential oils (EOs) with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), randomly methylated-β-cyclodextrin (RAMEB), a low methylated-β-cyclodextrin (CRYSMEB) and γ-cyclodextrin (γ-CD) were characterized. Formation constants (Kf) of the complexes were determined in aqueous solution by nonlinear regression analysis using static headspace gas chromatography (SH-GC) and UV-visible spectroscopy. Solid inclusion complexes were prepared by the freeze-drying method for different CD:ES molar ratios and were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Inclusion complexes formation allowed the controlled release of ES. Moreover, increased DPPH radical scavenging activity and photostability of ES and ES containing EOs (ESEOs) were observed in the presence of CDs. These findings suggest that encapsulation with CDs could be an efficient tool to improve the use of ES and ESEOs in aromatherapy, cosmetic and food fields.

Inclusion and functionalization of polymers with cyclodextrins: current applications and future prospects

The numerous hydroxyl groups available in cyclodextrins are active sites that can form different types of linkages. They can be crosslinked with one another, or they can be derivatized to produce monomers that can form linear or branched networks. Moreover, they can form inclusion complexes with polymers and different substrates, modifying their physicochemical properties. This review shows the different applications using polymers with cyclodextrins, either by forming inclusion complexes, ternary complexes, networks, or molecularly imprinted polymers (MIPs). On one hand, the use of cyclodextrins enhances the properties of each polymer, and on the other the use of polymers decreases the amount of cyclodextrins required in different formulations. Both cyclodextrins and polymers contribute synergistically in several applications such as pharmacological, nutritional, environmental, and other industrial fields. The use of polymers based on cyclodextrins is a low cost easy to use potential tool with great future prospects.

Essential oils loaded in nanosystems: a developing strategy for a successful therapeutic approach

Essential oils are complex blends of a variety of volatile molecules such as terpenoids, phenol-derived aromatic components, and aliphatic components having a strong interest in pharmaceutical, sanitary, cosmetic, agricultural, and food industries. Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, and other medicinal properties such as analgesic, sedative, anti-inflammatory, spasmolytic, and locally anaesthetic remedies. In this review their nanoencapsulation in drug delivery systems has been proposed for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano- and microemulsions. Furthermore, molecular complexes such as cyclodextrin inclusion complexes also represent a valid strategy to increase water solubility and stability and bioavailability and decrease volatility of essential oils.

Improvement of thymol properties by complexation with cyclodextrins: in vitro and in vivo studies

Thymol, an effective agent for microbial diseases, has a low aqueous solubility and a strong bitter/irritating taste. These physicochemical characteristics need to be improved to develop pharmaceutical preparations. This study evaluates whether β-cyclodextrin and a copolymer based on dimethylaminoethyl methacrylate (DMAEMA) interact with thymol in order to control powderization, solubilization, and taste-masking properties. The thymol-β-cyclodextrin complex was prepared by co-precipitation and sealed-heating methods. The DMAEMA copolymer was mixed with the complex using a new approach, instead of spray coating, to decrease thymol volatility. In vivo studies were performed. Sealed-heating is a suitable method for including thymol in β-cyclodextrin with a good loading efficiency; thymol volatility control is achieved by mixing the complex with the DMAEMA copolymer. β-Cyclodextrin accelerates the in vivo thymol absorption rate compared with the free drug; the thymol half-life is still long. Therefore, a low number of administrations per day are required. Although bioavailability is unchanged with respect to free thymol, high doses could be administered of a selected formulation without compromising the compliance. Furthermore, thymol that is not absorbed is held along the intestine, where it can useful in the treatment and/or prevention of intestinal bacterial diseases.

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

The inclusion of volatile derivatives of benzene and cyclohexane in β-cyclodextrin (β-CD), hydroxypropyl-β-CD, and hydrophilic β-CD-thioethers was investigated by static headspace gas chromatography (HS-GC) and molecular modelling. The obtained binding constants strongly increase with the amount of space filling of the CD cavity and the salt concentration. β-CD thioethers show a 3–10 times higher binding potential than native β-CD.

Retention of aroma compounds from Mentha piperita essential oil by cyclodextrins and crosslinked cyclodextrin polymers

In this paper, the controlled release of aroma compounds from cyclodextrins (CDs) and CD polymers was studied by multiple headspace extraction (MHE) experiments. Mentha piperita essential oil was obtained by Soxhlet extraction and identification of the major compounds was performed by GC-MS analysis. Menthol, menthone, pulegone and eucalyptol were identified as the major components. Retention of standard compounds in the presence of different CDs and CD polymers has been realised by static headspace gas chromatography (SH-GC) at 25 °C in the aqueous or gaseous phase. Stability constants for standard compounds and for compounds in essential oil have been also determined with monomeric CD derivatives. The obtained results indicated the formation of a 1:1 inclusion complex for all the studied compounds. Molecular modelling was used to investigate the complementarities between host and guest. This study showed that β-CDs were the most versatile CDs and that β-CD polymers could perform the controlled release of aroma compounds.