Nicoleta G. Hădărugă

Thermal and oxidative stability of the Ocimum basilicum L. essential oil/β-cyclodextrin supramolecular system.

Summary Ocimum basilicum L. essential oil and its β-cyclodextrin (β-CD) complex have been investigated with respect to their stability against the degradative action of air/oxygen and temperature. This supramolecular system was obtained by a crystallization method in order to achieve the equilibrium of complexed–uncomplexed volatile compounds in an ethanol/water solution at 50 °C. Both the raw essential oil and its β-CD complex have been subjected to thermal and oxidative degradation conditions in order to evaluate the protective capacity of β-CD. The relative concentration of the O. basilicum L. essential oil compounds, as determined by GC–MS, varies accordingly with their sensitivity to the thermal and/or oxidative degradation conditions imposed. Furthermore, the relative concentration of the volatile O. basilicum L. compounds found in the β-CD complex is quite different in comparison with the raw material. An increase of the relative concentration of linalool oxide from 0.3% to 1.1%, in addition to many sesquiterpene oxides, has been observed. β-CD complexation of the O. basilicum essential oil modifies the relative concentration of the encapsulated volatile compounds. Thus, linalool was better encapsulated in β-CD, while methylchavicol (estragole) was encapsulated in β-CD at a concentration close to that of the raw essential oil. Higher relative concentrations from the degradation of the oxygenated compounds such as linalool oxide and aromadendren oxide were determined in the raw O. basilicum L. essential oil in comparison with the corresponding β-CD complex. For the first time, the protective capability of natural β-CD for labile basil essential oil compounds has been demonstrated.

Ficaria verna Huds. extracts and their β-cyclodextrin supramolecular systems.

BackgroundObtaining new pharmaceutical materials with enhanced properties by using natural compounds and environment-friendly methods is a continuous goal for scientists. Ficaria verna Huds. is a widespread perennial plant with applications in the treat of haemorrhoids and to cure piles; it has also anti-inflammatory, astringent, and antibiotic properties. The goal of the present study is the obtaining and characterization of new F. verna extract/β-cyclodextrin complexes by using only natural compounds, solvents, and environment-friendly methods in order to increase the quality and acceptability versus toxicity indicator. Thus, the flavonoid content (as quercetin) of Ficaria verna Huds. flowers and leaves from the West side of Romania was determined and correlated with their antioxidant activity. Further, the possibility of obtaining β-cyclodextrin supramolecular systems was studied.ResultsF. verna flowers and leaves extracts were obtained by semi-continuous solid-liquid extraction. The raw concentrated extract was spectrophotometrically analyzed in order to quantify the flavonoids from plant parts and to evaluate the antioxidant activity of these extracts. The F. verna extracts were used for obtaining β-cyclodextrin complexes; these were analyzed by scanning electron microscopy and Karl Fischer water titration; spectrophotometry was used in order to quantifying the flavonoids and evaluates the antioxidant activity. A higher concentration of flavonoids of 0.5% was determined in complexes obtained by crystallisation method, while only a half of this value was calculated for kneading method. The antioxidant activity of these complexes was correlated with the flavonoid content and this parameter reveals possible controlled release properties.ConclusionsThe flavonoid content of F. verna Huds. from the West side of Romania (Banat county) is approximately the same in flowers and leaves, being situated at a medium value among other studies. β-Cyclodextrin complexes of F. verna extracts are obtained with lower yields by crystallisation than kneading methods, but the flavonoids (as quercetin) are better encapsulated in the first case most probably due to the possibility to attain the host-guest equilibrium in the slower crystallisation process. F. verna extracts and their β-cyclodextrin complexes have antioxidant activity even at very low concentrations and could be used in proper and valuable pharmaceutical formulations with enhanced bioactivity.

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin.

Summary The thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) as well as its β-cyclodextrin (β-CD) complexation ability has been verified for the first time. The main omega-3 fatty acids, EPA and DHA, were significantly degraded, even at 50 °C. Their relative concentrations decrease from 6.1% for EPA and 4.1% for DHA to 1.7% and 1.5% after degradation at 150 °C, respectively. On the other hand, the relative concentrations of monounsaturated and saturated fatty acids remained constant or slightly increased by a few percent after degradation (e.g., from 10.7% to 12.9% for palmitic acid). Co-crystallization of ASO with β-CD at a host–guest ratio of 1:1 and 3:1 from an ethanol–water mixture and kneading methods has been used for the preparation of β-CD/ASO complexes. The analysis of the complexes by thermogravimetry, differential scanning calorimetry (DSC), and Karl Fischer titration (KFT) as well as the decrease of the “strongly-retained” water content confirm the formation of the inclusion compound. Furthermore, the DSC parameters correlate well with the KFT kinetic data for β-CD/ASO complexes.

Cyclodextrins as encapsulation material for flavors and aroma

Abstract Encapsulation with cyclodextrins (CDs) is among the most efficient technologies for preserving flavors and aromas in food systems. CDs are nontoxic naturally occurring oligosaccharides derived from starch. They are available in large scale, low price, food quality, and have been included in the GRAS (generally recognized as safe) list of the FDA. CDs offer many technical advantages in food processing. Encapsulation could be performed both in solution and solid state using various techniques. Evidence for flavors and aroma encapsulation (stability of interactions, encapsulation efficiency, estimation of optimal preparation ratios, etc.) could be obtained through a wide range of analytical methods. Encapsulation in CDs overcomes the requirements for neutrality in terms of odor and taste, additional costs, and the complexity of other encapsulation procedures. CDs offer as well a protective effect, ensure controlled release and reduce loss and volatility of encapsulated compounds. Release of encapsulated products from CDs could be activated by the presence of moisture. Consequently, CDs could be applied to food packaging. They could also be regarded as a promising tool for “liquisolid” technique, which provides better dissolution and facilitates dosing and handling of oily substances. Besides acting as carriers of flavors and aroma, CDs could also prevent discoloration of food and reduce off-flavors.

Thermal Analyses of Cyclodextrin Complexes

Human health is the most important issue in the society. There are many compounds such as food additives and ingredients or medicinal compounds that can alter human health. Cyclodextrins can protect these compounds against light and oxidative degradation by molecular encapsulation. Moreover, cyclodextrins can also enhance properties of biologically active compounds such as better water solubility and bioavailability, and controlled release. Cyclodextrins are cyclic oligosaccharides comprising of six to eight α-(1→4)-linked d-glucopyranose units corresponding to the natural α-, β- and γ-cyclodextrin, respectively. Cyclodextrins have a truncated cone-like structure, with a hydrophobic inner cavity and highly hydrophilic exterior. This property allows molecular encapsulating of geometrically compatible hydrophobic compounds for obtaining host-guest supramolecular systems. Among many characterization methods that are applicable in both solution and solid state, thermal techniques were widely used for analysis and stability evaluation of cyclodextrin complexes.

Moisture evaluation of β-cyclodextrin/fish oils complexes by thermal analyses: A data review on common barbel (Barbus barbus L.), Pontic shad (Alosa immaculata Bennett), European wels catfish (Silurus glanis L.), and common bleak (Alburnus alburnus L.) living in Danube river

The moisture content of β-cyclodextrin/Danube fish oils complexes (common barbel, Pontic shad, European wels catfish, common bleak) was evaluated by thermal methods. Saturated and monounsaturated fatty acids were the most concentrated in fish oils (25.3-30.8% and 36.1-45.0%). ω-3 And ω-6 fatty acids were identified in low concentrations of 2.8-12.1% and 4.1-7.1%. The moisture content was significantly lowered after β-CD complexation, as revealed by thermogravimetric (TG) analysis (13.3% for β-CD, 2.5-6.5% for complexes). These results are consistent with the differential scanning calorimetry (DSC) data for the peaks corresponding to dissociation of water (calorimetric effect of 536Jg-1 for β-cyclodextrin and 304-422.5Jg-1 for complexes). Furthermore, both TG and DSC results support the formation of inclusion complexes. This is the first study on the nanoencapsulation of Danube fish oils in β-cyclodextrin.

Comparative study of Juniperus communis and Juniperus virginiana essential oils: TLC and GC analysis

We report a comparative study of Juniperus virginiana and Juniperus communis essential oils (obtained by hydrodistillation of plant parts from the west of Romania or obtained commercially in Europe) by thin layer chromatographic and gas chromatographic-mass spectrometric analysis. Concentrations of cineole and guaiazulene, key compounds with insect repellent and anti-inflammatory activity, were evaluated. Monoterpenes were more abundant in essential oils from berries (40.2% in J. virginiana essential oil and 34.4% in J. communis essential oil), followed by sesquiterpene alcohols, but the latter were more abundant in essential oils from leaves (26.9% in J. virginiana and 16.9% in J. communis). We also discovered substantial amounts of monoterpene alcohols (8.9–9.5% and 6.4–11.6% for J. virginiana and J. communis, respectively) and sesquiterpenes (more abundant in J. communis essential oils: 21.1% in berries and 12.4% in leaves; in J. virginiana essential oils amounts of sesquiterpenes were only 5.9–6.8%). The key compounds cineole and guaiazulene were present at low absolute concentrations. The first was more abundant in J. communis essential oils (2.6–3.5 µg mL−1); guaiazulene was identified in J. virginiana essential oil only (0.7 µg mL−1 in essential oil from the leaves). Thinlayer chromatographic analysis of Juniperus essential oils revealed the importance of the monoterpenes, sesquiterpenes, and their corresponding alcohols in these mixtures. Cineole and guaiazulene spots from essential oils from autochthonous J. virginiana berries and leaves were very small, and were obscured by more abundant mono and sesquiterpenes (for example limonene) in the upper half of the chromatogram or mono and sesquiterpene alcohols (for example terpinen-4-ol) in the lower half of chromatograms. Similar results were also obtained for J. communis essential oils.

A review on thermal analyses of cyclodextrins and cyclodextrin complexes

Cyclodextrins are valuable natural or synthetically modified cyclic oligosaccharides that are widely used for ameliorating properties of biologically active compounds such as food additives and ingredients or medicinal compounds. They protect these compounds against light and oxidative degradation and provide host–guest supramolecular complexes having controlled release properties by molecular encapsulation, enhancing the water solubility and bioavailability. Among many characterization methods that are applicable in both solution and solid state, thermal techniques were widely used for analysis and stability evaluation of cyclodextrins and cyclodextrin complexes. This updated review deals with the use of thermal methods for analysis of cyclodextrins and cyclodextrin complexes. Classical and modern thermal techniques used for evaluation of inclusion compound formation were reviewed. Special attention was gave for thermogravimetry–differential thermogravimetry, differential thermal analysis, differential scanning calorimetry, hot stage microscopy, as well as for the more recent techniques thermogravimetry–mass spectrometry, gas chromatography-time-of-flight-mass spectrometry and isothermal titration calorimetry. In order to evaluate the cyclodextrin complexation capability by thermal methods, we grouped for the first time the guest compound as drugs by anatomical therapeutic chemical classification (ATC), as well as odorants, essential oils and vegetable extracts, antioxidants, fatty acids, oils, fatty acid-based derivatives, other organic, organometallic and inorganic compounds. The formation of cyclodextrin inclusion complexes was emphasized by disappearance of the signal corresponding to the melting or boiling points of the guest compound and the behavior of the hydration water molecules in the complex in comparison with the raw host and guest compounds. The thermal stability of the guest compound after cyclodextrin complexation was also discussed. It was emphasized that thermal methods are some of the most valuable techniques for analyzing cyclodextrin complexes and together with other methods can complete the information related to the host–guest molecular inclusion process and the specific properties of these cyclodextrin complexes.

Titanocene / cyclodextrin supramolecular systems: a theoretical approach

BackgroundRecently, various metallocenes were synthesized and analyzed by biological activity point of view (such as antiproliferative properties): ruthenocenes, cobaltoceniums, titanocenes, zirconocenes, vanadocenes, niobocenes, molibdocenes etc. Two main disadvantages of metallocenes are the poor hydrosolubility and the hydrolytic instability. These problems could be resolved in two ways: synthetically modifying the structure or finding new formulations with enhanced properties. The aqueous solubility of metallocenes with cytostatic activities could be enhanced by molecular encapsulation in cyclodextrins, as well as the hydrolytic instability of these compounds could be reduced.ResultsThis study presents a theoretical approach on the nanoencapsulation of a series of titanocenes with cytotoxic activity in α-, β-, and γ-cyclodextrin. The HyperChem 5.11 package was used for building and molecular modelling of titanocene and cyclodextrin structures, as well as for titanocene/cyclodextrin complex optimization. For titanocene/cyclodextrin complex optimization experiments, the titanocene and cyclodextrin structures in minimal energy conformations were set up at various distances and positions between molecules (molecular mechanics functionality, MM+). The best interaction between titanocene structures and cyclodextrins was obtained in the case of β- and γ-cyclodextrin, having the hydrophobic moieties oriented to the secondary face of cyclodextrin. The hydrophobicity of titanocenes (logP) correlate with the titanocene-cyclodextrin interaction parameters, especially with the titanocene-cyclodextrin interaction energy; the compatible geometry and the interaction energy denote that the titanocene/β- and γ-cyclodextrin complex can be achieved. Valuable quantitative structure-activity relationships (QSARs) were also obtained in the titanocene class by using the same logP as the main parameter for the in vitro cytotoxic activity against HeLa, K562, and Fem-x cell lines.ConclusionsAccording to our theoretical study, the titanocene/cyclodextrin inclusion compounds can be obtained (high interaction energy; the encapsulation is energetically favourable). Further, the most hydrophobic compounds are better encapsulated in β- and γ-cyclodextrin molecules and are more stable (from energetically point of view) in comparison with α-cyclodextrin case. This study suggests that the titanocene / β- and γ-cyclodextrin complexes (or synthetically modified cyclodextrins with higher water solubility) could be experimentally synthesized and could have enhanced cytotoxic activity and even lower toxicity.