Silvia Porcedda

Chemical characterization and biological activity of essential oils from Daucus carota L. subsp. carota growing wild on the Mediterranean coast and on the Atlantic coast

The essential oils and supercritical CO(2) extracts of wild Daucus carota L. subsp. carota growing spontaneously in Sardinia and in Portugal were investigated. The main components in the Sardinian essential oil of flowering and mature umbels with seeds are beta-bisabolene (17.6-51.0%) and 11-alpha-(H)-himachal-4-en-1-beta-ol (9.0-21.6%); instead, the oils from Portuguese samples are predominantly composed of geranyl acetate (5.2-65.0%) and alpha-pinene (3.5-37.9%). Supercritical extracts contain lower amounts of monoterpenes and higher amounts of sesquiterpene hydrocarbons. Antifungal activities of the Sardinian oils were the highest, particularly for dermatophytes and Cryptococcus neoformans, with MIC values of 0.16-0.64 microL mL(-1).

Thermodynamics of binary mixtures containing linear or cyclic alkanones + n-alkanes or + cycloalkanes☆

Abstract Marongiu, B., Pittau, B., Porcedda, S., and Tine, M.R., 1994. Thermodynamics of binary mixtures containing linear or cyclic alkenes + n -alkanes or cyclohexane. Fluid Phase Equilibria 93; 249-276. A head-space technique has been used to determine vapor-phase equilibria for binary mixtures of linear or cyclic mono- and polyalkenes + n-alkanes or + cyclohexane. Excess molar Gibbs energies GE for the mixtures investigated were obtained by a least-squares treatment of the equilibrium results. These data the previously measured excess enthalpies HE and the data available in the literature on GE HE activity coefficients at infinite dilution γi∞ and molar excess enthalpies at infinite dilution hiE,∞ are examined on the basis of the DISQUAC group contribution model. The model provides a fairly consistent description of the phase equilibria and the related excess functions using a unique set of structure-dependent dispersive parameters.

Isolation of eucalyptus oil by supercritical fluid extraction

Eucalyptus volatile oil was isolated by supercritical CO2 extraction with a fractional separation technique. GC–MS analysis of the various fractions obtained at different extraction and fractionation conditions allowed the identification of the best operating conditions to isolate the volatile oil. A good extraction performance was obtained by operating at 90 bar and 50°C for 510 min. The optimum fractionation was achieved by operating at 90 bar and −10°C in the first separator and at 15 bar and 15°C in the second one. The influence of the extraction pressure and of the extraction time on the oil composition were also evaluated. A comparison with the hydrodistilled oil is also given. Copyright

Evaluation of the Antimicrobial Properties of the Essential Oil of Myrtus communis L. against Clinical Strains of Mycobacterium spp.

Mycobacterium tuberculosis is the etiological agent of tuberculosis. The World Health Organization has estimated that 8 million of people develop active TB every year and the situation is complicated by an increase of Mycobacterium tuberculosis strains resistant to drugs used in antitubercular therapy: MDR and XDR-TB. Myrtle leaf extracts, used as an antiseptic in Sardinian traditional medicine, have strong antibacterial activity as several investigations showed. In this study we investigated the antimicrobial properties of the essential oil of Myrtus communis against clinical strains of M. tuberculosis and M. paratuberculosis.

Chemical and biological comparisons on supercritical extracts of Tanacetum cinerariifolium (Trevir) Sch. Bip. with three related species of chrysanthemums of Sardinia (Italy)

In this manuscript, the authors compare the chemical composition and the biological effects of extracts of some Sardinian plant species: Glebionis coronaria (L.) Spach [=Chrysanthemum coronarium L.], locally known as ‘caragantzu’, Glebionis segetum (L.) Fourr. [=Chrysanthemum segetum L.], known as ‘caragantzu masedu’, and Sardinian endemic species Plagius flosculosus (L.) Alavi and Heywood [=Chrysanthemum flosculosus L.], known as ‘caragantzu burdu’. In addition, the authors compare the pyrethrins contained in these species with an extract of Tanacetum cinerariifolium (Trevir.) Sch. Bip. [=Chrysanthemum cinerariifolium (Trevir.) Vis.], a commercial species rich in pyrethrins. The volatile fractions from chrysanthemum flowers were obtained by supercritical fluid extraction (SFE) with CO2 at 90 bar and 50°C and by hydrodistillation. Pyrethrins were extracted, together with other high molecular mass compounds, by SFE at high pressure, 300 bar and 40°C. The composition of the volatile oils is determined by GC–MS analysis and the amount of pyrethrins by HPLC analysis. Moreover, the antibacterial and antimycotic activities of volatile fractions were investigated in order to compare to their traditional uses.

The effect of the molecular shape on the enthalpic behaviour of liquid mixtures : cyclic hydrocarbons in heptane and tetrachloromethane

Excess enthalpies HE at 298.15 K have been determined by flow microcalorimetry for binary mixtures of heptane or tetrachloromethane + a cyclic hydrocarbon (cycloheptane, cyclooctane, cyclodecane, 1,2,3,4-tetrahydronaphthalene, cis-decahydronaphthalene, trans-decahydronaphthalene, bicyclohexyl). With the exception of tetrahydronaphthalene + tetrachloromethane and of trans-decahydronaphtalene + heptane, all mixtures examined exhibit positive deviations. HEs have been analysed in terms of the DISQUAC model. Partial molar excess enthalpies at infinite dilution as well as standard enthalpies of solvation, ΔHo, have been evaluated for cycloalkanes in the two solvents and compared with those of linear and branched alkanes. The effect of cyclization upon ΔHo has been discussed and the contributions to ΔHo of the cavity and of the interaction terms have been estimated through the scaled particle theory.

Antimicrobial activity of Inula helenium L. essential oil against Gram-positive and Gram-negative bacteria and Candida spp.

In this work we report results regarding the in vitro antimicrobial activity of Inula helenium L. dried root extracts obtained by stepwise supercritical fluid extraction (SFE) and by hydrodistillation (HD). Inula helenium L. (Compositae family) is a perennial plant widely occurring in Europe and East Asia. Its oil is one of the richest sources of sesquiterpenoid lactones, which have strong anthelminthic activity and have the potential to induce detoxifying enzymes. Inula helenium L. roots (C-040705130905) were purchased from Minardi (Bagnacavallo-Ravenna, Italy). Supercritical CO 2 extraction was performed in a laboratory apparatus equipped with a 400 cm3 extraction vessel operated in the single-pass mode of passing CO 2 through the fixed bed of charged vegetable particles. Extraction was carried out in a semibatch mode: batch charging of vegetable matter and continuous flow solvent. HD was performed for 4 h in a circulatory Clevenger-type apparatus up to exhaustion of the oil contained in the matrix, which was the same material as used in the SFE.

Extraction and Separation of Volatile and Fixed Oils from Seeds of Myristica fragrans by Supercritical CO2: Chemical Composition and Cytotoxic Activity on Caco-2 Cancer Cells

UNLABELLED Isolation of volatile and fixed oils from nutmeg have been obtained by supercritical fractioned extraction with carbon dioxide. Extraction experiments were carried out at pressures of 90 and 250 bar and temperature of 40 °C. The extraction step performed at 90 bar produced a volatile fraction mainly formed by myristicin (32.8%), sabinene (16.1%), α-pinene (9.8%), β-pinene (9.4%), β-phellandrene (4.9%), safrole (4.1%) and terpinen-4-ol (3.6%). The oil yield relative to this step of the process was 1.4% by weight of the charge. The last extraction step at 250 bar produced a butter-like material (nutmeg butter). The yield of this step was 14.4% by weight. The most represented fatty acids of fixed oil from nutmeg were 14:0 (79.2%), 18:1 n-9 (7.4%) and 16:0 (6.1%), and in particular the unsaturated fatty acids 18:1 n-9 averaged 32.96 μg/mg of oil. The level of myristicin in the nutmeg essential and fixed oils was also directly quantified by reversed HPLC-DAD. Moreover, the essential oil obtained from nutmeg, as well as myristicin, showed a significant in vitro inhibitory effect on the growth of a colon cancer cell line (undifferentiated Caco-2 cells). PRACTICAL APPLICATION In this study, the chemical characterization and the anticancer activity of nutmeg oils obtained by supercritical extraction with carbon dioxide were investigated. This is important for their potential application in food and pharmaceutical industries.

Extraction of Oil from Wheat Germ by Supercritical CO2

This study examined the supercritical fluid extraction of wheat germ oil. The effects of pressure (200-300 bar at 40 °C) and extraction time on the oil quality/quantity were studied. A comparison was also made between the relative qualities of material obtained by SFE and by organic solvent extraction. The extracts were analyzed for α-tocopherol and polyunsaturated fatty acid content. The maximum wheat germ oil yield at about 9% was obtained with supercritical carbon dioxide extraction at 300 bar, while fatty acid and α-tocopherol composition of the extracts was not remarkable affected by either pressure or the extraction method.

Extraction of Santolina insularis essential oil by supercritical carbon dioxide : influence of some process parameters and biological activity

Santolina insularis was used to obtain its essential oil by means of supercritical fluid extraction with carbon dioxide, CO2. The choice of the proper value of CO2 density is the crucial point influencing solvent power and selectivity, the main factors determining oil composition. In circuit to obtain a pure essential oil deprived of cuticular waxes, the extraction products were fractionated in two separators operated in series. A good process performance was obtained working at 90 bar and 50 °C in the extraction vessel, at 90 bar and −12 °C in the first separator and at 20 bar and 15 °C in the second separator. The extraction time proved to be another parameter that determines the composition of the essential oil extracted. Indeed, lower molecular weight and less polar compounds were more readily extracted, since the other families of compounds exhibit higher diffusion times. The oil extracted also contained small quantities of water. The water yield was measured and the possible role of water in the extraction process is discussed. A comparison with the oil obtained by hydrodistillation is also given. Finally, the cytotoxic and antimicrobial activity of the various extracts has been assayed. Copyright