Ana M. Mainar

Composition and antioxidant activity of Thymus vulgaris volatiles: Comparison between supercritical fluid extraction and hydrodistillation

Supercritical fluid extraction (SFE) of the volatile oil from Thymus vulgaris L. aerial flowering parts was performed under different conditions of pressure, temperature, mean particle size and CO(2) flow rate and the correspondent yield and composition were compared with those of the essential oil isolated by hydrodistillation (HD). Both the oils were analyzed by GC and GC-MS and 52 components were identified. The main volatile components obtained were p-cymene (10.0-42.6% for SFE and 28.9-34.8% for HD), gamma-terpinene (0.8-6.9% for SFE and 5.1-7.0% for HD), linalool (2.3-5.3% for SFE and 2.8-3.1% for HD), thymol (19.5-40.8% for SFE and 35.4-41.6% for HD), and carvacrol (1.4-3.1% for SFE and 2.6-3.1% for HD). The main difference was found to be the relative percentage of thymoquinone (not found in the essential oil) and carvacryl methyl ether (1.0-1.2% for HD versus t-0.4 for SFE) which can explain the higher antioxidant activity, assessed by Rancimat test, of the SFE volatiles when compared with HD. Thymoquinone is considered a strong antioxidant compound.

Enrichment of the thymoquinone content in volatile oil from Satureja montana using supercritical fluid extraction

Supercritical fluid extraction (SFE) of the volatile oil from Satureja montana L. was performed under different conditions of pressure (90 and 100 bar), temperature (40 and 50 degrees C), mean particle sizes (0.4, 0.6 and 0.8 mm) and CO(2) flow rate (0.8, 1.1 and 1.3 kg/h) to understand the influence of these parameters on the composition and yield of this oil. The results were compared with those obtained for the essential oil isolated by hydrodistillation (HD). The volatile and the essential oil were analysed by GC and GC-MS. The main compounds are carvacrol (52.2-62.0% for HD vs. 41.7-64.5% for SFE), thymol (8.6-11.0% for HD vs. 6.0-11.3% for SFE), p-cymene (6.9-12.8% for HD vs. 6.0-17.8% for SFE), gamma-terpinene (6.4-9.4% for HD vs. 2.3-6.0% for SFE) and beta-bisabolene (2.0-2.7% for HD vs. 2.2-3.5% for SFE). The major difference between SFE and HD was the relative amount of thymoquinone, an oxygenated monoterpene with important biological activities, which can be ten-fold higher in volatile oil (1.6-3.0 for SFE vs. 0.2% for HD). The morphology of the glandular trichomes of S. montana and the effect of the grinding process on them was also evaluated by SEM.

Extraction of Volatile Oil from Aromatic Plants with Supercritical Carbon Dioxide: Experiments and Modeling

An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal (Mentha pulegium L.), fennel seeds (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.), savory (Satureja fruticosa Béguinot), winter savory (Satureja montana L.), cotton lavender (Santolina chamaecyparisus) and thyme (Thymus vulgaris), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of cuticular waxes and the relative amount of thymoquinone, an oxygenated monoterpene with important biological properties, which is present in the oils from thyme and winter savory. On the other hand, the modeling of our data on supercritical extraction of volatile oil from pennyroyal is discussed using Sovová’s models. These models have been applied successfully to the other volatile oil extractions. Furthermore, other experimental studies involving supercritical CO2 carried out in our laboratories are also mentioned.

Antioxidant activities of the supercritical and conventional Satureja montana extracts.

The antioxidant activities of the volatile and the nonvolatile fractions from Satureja montana obtained by supercritical fluid extraction (SFE) and by conventional techniques, hydrodistillation (HD) and soxhlet extraction (SE), were compared. A good agreement between DPPH and rancimat methods was obtained showing that the extracts were able to scavenge free radicals and to inhibit lipid oxidation. The volatile oil (obtained by SFE at 90 bar/40 degrees C) was the most effective extract, presenting the lowest EC(50) (0.06 g/L) and the highest protector factor (PF = 2.03). These results demonstrated the advantages of SFE over conventional techniques by avoiding thermodegradation and hydrolysis reactions. Furthermore, volatile oil is 15 times richer in thymoquinone than the essential oil (HD). This compound is of great importance due to its antioxidant, neuroprotective, and anti-cancer activities. The combination of carvacrol + thymol + thymoquinone in volatile oil may be responsible for the increase in the antioxidant activity when compared to HD, which demonstrates that, in this case, SFE improves value to the final product.

Acute toxicological effects on the earthworm Eisenia fetida of 18 common pharmaceuticals in artificial soil.

Following soil applications of recycled water and biosolids, pharmaceutical residues can eventually enter the terrestrial environment. In vitro and in vivo assays have largely focused on the acute ecotoxicity of these compounds in aquatic systems. However, studies on the ecotoxicological effects of pharmaceuticals in soil biota are especially scarce. The aim of this study was to investigate the acute toxicity of 18 pharmaceuticals (4 NSAIDs, 5 blood lipid-lowering agents, 6 β-blockers and 3 antibiotics) that are usually found in the environment by using an Eisenia fetida bioassay. In addition, the presence of these pharmaceuticals in artificial soil was verified at the end of the test. Our results indicate that seven of the studied drugs cause acute adverse effects in E. fetida, in particular, the NSAIDs and the blood lipid-lowering agents. Ibuprofen (LC50=64.80 mg/kg) caused the highest acute toxicity for all tested compounds, followed by diclofenac (LC50=90.49 mg/kg) and simvastatin (LC50=92.70 mg/kg). Other tested pharmaceuticals from NSAIDs and blood lipid-lowering families have toxicity effects, from a LC50=140.87 mg/kg for gemfibrozil to 795.07 mg/kg for lovastatin. Atorvastatin, bezafibrate, β-blockers and antibiotics showed no detectable lethality in E. fetida. The four NSAIDs showed evidence of modification of their original chemical structure after 14 days so the detected toxicity may be due to the original product as well as their degradation products. The three blood lipid-lowering agents seem to be more stable in soil. From an environmental perspective, the lethal concentrations of the tested drugs are much greater than those reported in wastewater and biosolids, therefore acute toxic effects may be improbable. However, little is known about the accumulation of these substances in soils after regular applications, so accumulative and chronic effects cannot be excluded. Moreover, more studies are needed to determine the role of the degradation products of these pharmaceuticals on terrestrial toxicity.

Solvent effects on Diels-Alder reactions. The use of aqueous mixtures of fluorinated alcohols and the study of reactions of acrylonitrile

Rate, endo/exo, regio- and diastereo-facial selectivities of several Diels–Alder reactions were measured in a series of fluorinated alcohol–water mixtures, whose solvophobicity has been determined by means of the solvophobic power (Sp) parameter. Solvophobicity is the main factor influencing the reaction rate, although in some reactions hydrogen bond donating (HBD) ability may also play a role. Both solvophobicity and HBD ability are important to account for changes in endo/exo selectivity. HBD ability is the main factor responsible for the changes in regio- and diastereo-facial selectivities, induced by the reaction medium. On the other hand, the kinetic rate constants and endo/exo selectivity of the reaction of acrylonitrile with cyclopentadiene, as well as the regioselectivity of the reaction of acrylonitrile with isoprene, have been determined in 23 reaction media. The analysis of the results using empirical solvent parameters show that the reaction rate depends on solvophobic, HBD and dipolarity interactions, whereas endo/exo selectivity is influenced by solvophobic and dipolarity interactions, and the regioselectivity only by HBD effects.

Densities and excess molar volumes of the ternary mixture (1-butanol+n-hexane+1-chlorobutane) at 298.15 and 313.15 K. Application of the ERAS model

Abstract Densities of the liquid mixtures (n-hexane+1-chlorobutane) and (1-butanol+n-hexane+1-chlorobutane) have been measured by the vibrating tube technique at 298.15 K and 313.15 K. With these densities, excess molar volumes were calculated. An extended version of the so-called ERAS model has been used for describing VE of the complete ternary system at 298.15 K. Qualitatively the ERAS-model gives an adequate representation of this system, being similar the shapes of both the experimental and the predicted curves.

Supercritical fluid extraction of the volatile oil from Santolina chamaecyparissus

Supercritical fluid extraction (SFE) of the volatile oil from Santolina chamaecyparissus L. flower heads was performed under different conditions of pressure, temperature, mean particle size and CO(2) flow rate. This oil was compared with the essential oil isolated by hydrodistillation (HD). The SFE volatile and essential oils were analysed by GC and GC-MS. The range of the main volatile components obtained with HD and SFE were, respectively: 1,8-cineole (25-30% and 7-48%), camphor (7-9% and 8-14%), borneol (7-8% and 2-11%), terpinen-4-ol (6-7% and 1-4%), terpinolene (1-4% and 1-7%) and isobornyl acetate (1-2% and 1-11%). The chemical composition of the extracts was greatly influenced by the conditions of pressure and temperature used. In fact, it was possible to enrich the sesquiterpene fraction by increasing the pressure from 8 to 9 MPa, while changing the temperature from 50 to 40 degrees C at 9 MPa enriched the volatiles in n-alkanes [corrected].

Supercritical methodologies applied to the production of biopesticides: a review

Supercritical technologies are new, environmentally friendly, advanced separation techniques that have attracted the attention of both industry and academy in their aspirations of producing safer products with cleaner processes. In the field of biopesticides, supercritical fluids are being used in different stages, from the extraction of active ingredients from natural matrices to the encapsulation of blends during the formulation of the final commercial pesticide. This review summarizes different supercritical processes that arise in literature comprising supercritical fluid extraction, supercritical antisolvent fractionation or extraction, supercritical assisted atomization, particle from gas saturated solutions and supercritical solvent impregnation among others. The aim of this work is to give a general view of supercritical fluids in the field of biopesticides production, optimization and formulation, emphasizing in the extraction, fractionation and encapsulation and highlighting their importance when green, solvent free processes have to be designed.

Solubility of gases in butanols: IV. Solubilities of nonpolar gases in 2-methyl-2-propanol at 303.15 K and 101.33 kPa partial pressure of gas

Abstract Solubilities of 15 nonpolar gases (He, Ne, Ar, Kr, Xe, H 2 , D 2 , N 2 , O 2 , CH 4 , C 2 H 4 , C 2 H 6 , CF 4 , SF 6 , and CO 2 ) in 2-methyl-2-propanol ( tert -butanol) have been measured at the temperature 303.15 K and 101.33 kPa partial pressure of gas. Standard changes of the Gibbs energy of solution have been also determined from experimental data. The Lennard–Jones 6,12 pair potential parameters have been estimated for that solvent using the Scaled Particle Theory (SPT) and these parameters have been compared with those corresponding to the other isomers of butanol. It can be concluded that the derived energy parameters provide a measurement of the association of the alkanol. A version of the UNIFAC model has been applied and the corresponding interaction parameters for alkanes and alkanols have been determined.