José S. Urieta

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.

Herbicidal activity of volatiles from coriander, winter savory, cotton lavender, and thyme isolated by hydrodistillation and supercritical fluid extraction.

The volatiles from Coriandrum sativum L., Satureja montana L., Santolina chamaecyparissus L., and Thymus vulgaris L. were isolated by hydrodistillation (essential oil) and supercritical fluid extraction (volatile oil). Their effect on seed germination and root and shoot growth of the surviving seedlings of four crops ( Zea mays L., Triticum durum L., Pisum sativum L., and Lactuca sativa L.) and two weeds ( Portulaca oleracea L. and Vicia sativa L.) was investigated and compared with those of two synthetic herbicides, Agrocide and Prowl. The volatile oils of thyme and cotton lavender seemed to be promising alternatives to the synthetic herbicides because they were the least injurious to the crop species. The essential oil of winter savory, on the other hand, affected both crop and weeds and can be appropriate for uncultivated fields.

Hydrogen bonding. Part 25. The solvation properties of methylene iodide

Ostwald solubility coefficients, L, have been determined for 37 gases and vapours in methylene iodide at 298 K, and have been correlated through equation (i), where the solute explanatory log L=–0.74 + 0.32R2+ 1.34π2H+ 0.83α2H+ 1.19β2H+ 0.87 log L16(i) variables are R2 an excess molar refraction, π2H the solute dipolarity/polarisability, α2H and β2H the solute hydrogen-bond acidity and basicity, and log L16 where L16 is the solute Ostwald solubility coefficient on hexadecane at 298 K. Similar equations have been constructed for solvation of solutes in tetrachloromethane, trichloromethane and 1,2-dichloroethane using literature data. It is shown that polarisability effects favour solvation in methylene iodide, through the R2 term, but that such effects enhance the solubility of polarisable solutes only moderately: thus the R2 term contributes 0.4 log units more in methylene iodide than in trichloromethane for the solute benzene. Examination of ΔG°, ΔH° and ΔS° for solvation of gaseous solutes suggests also that polarisability effects in methylene iodide are not very much larger than in the other halogenated solvents.

Phytochemical Profile and Anticholinesterase and Antimicrobial Activities of Supercritical versus Conventional Extracts of Satureja montana

Winter savory Satureja montana is a medicinal herb used in traditional gastronomy for seasoning meats and salads. This study reports a comparison between conventional (hydrodistillation, HD, and Soxhlet extraction, SE) and alternative (supercritical fluid extraction, SFE) extraction methods to assess the best option to obtain bioactive compounds. Two different types of extracts were tested, the volatile (SFE-90 bar, second separator vs HD) and the nonvolatile fractions (SFE-250 bar, first and second separator vs SE). The inhibitory activity over acetyl- and butyrylcholinesterase by S. montana extracts was assessed as a potential indicator for the control of Alzheimers disease. The supercritical nonvolatile fractions, which showed the highest content of (+)-catechin, chlorogenic, vanillic, and protocatechuic acids, also inhibited selectively and significantly butyrylcholinesterase, whereas the nonvolatile conventional extract did not affect this enzyme. Microbial susceptibility tests revealed the great potential of S. montana volatile supercritical fluid extract for the growth control and inactivation of Bacillus subtilis and Bacillus cereus, showing some activity against Botrytis spp. and Pyricularia oryzae. Although some studies were carried out on S. montana, the phytochemical analysis together with the biological properties, namely, the anticholinesterase and antimicrobial activities of the plant nonvolatile and volatile supercritical fluid extracts, are described herein for the first time.

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.

Viscosities of the ternary mixture (2-butanol+n-hexane+1-butylamine) at 298.15 and 313.15 K

Abstract Viscosities of the ternary mixture (2-butanol+ n -hexane+1-butylamine) and of the binary mixtures (2-butanol+ n -hexane) at 298.15 and 313.15 K, and (2-butanol+1-butylamine) at 313.15 K have been measured at atmospheric pressure. Viscosity deviations and excess Gibbs energy of activation of viscous flow for the binary and ternary systems were fitted to Redlich–Kisters and Cibulkas equations, respectively. To correlate experimental data of ternary system from binary ones, different empirical and semiempirical equations have been used (Nissan and Grunberg, Hind, Frenkel, McAllister, Katti and Chaudhri, Heric and Iulan) and their parameters have been calculated. The “viscosity-thermodynamic” model (UNIMOD) has been applied to correlate experimental data for the binary mixtures and to predict the viscosity for the ternary system. The Group Contribution-Thermodynamic Viscosity model (GC-UNIMOD), and the group contribution method proposed by Wu have been employed to predict the viscosity for the binary and ternary systems.

Viscosities of the ternary mixture (1-butanol + n-hexane + 1-butylamine) at the temperatures 298.15 and 313.15 K

Abstract Viscosities of the ternary mixture {1-butanol + n -hexane + 1-butylamine} and the binary mixtures {1-butanol + n -hexane}, {1-butanol + 1-butylamine} and { n -hexane + 1-butylamine} have been measured at 298.15 and 313.15 K. Viscosity deviations for the binary and ternary systems were fitted to Redlich-Kisters and Cibulkas equations, respectively. The “viscosity-thermodynamic” model (UNIMOD) has been used to correlate experimental data for the binary mixtures and to predict the viscosities for the ternary system. The Group-Contribution Thermodynamic-Viscosity model (GC-UNIMOD), and the group contribution method proposed by Wu have been used to predict the viscosity of the binary and ternary systems.

Speed of sound and isentropic compressibility of the ternary mixture (2-Butanol + n-Hexane + 1-Butylamine) and the constituent binary mixtures at 298.15 K and 313.15 K

Abstract Densities and speeds of sound for (2-Butanol + n -Hexane + 1-Butylamine) at 298.15K and 313.15 K, and the constituent binary mixtures (2-Butanol + n -Hexane), (2-Butanol + 1-Butylamine) at 298.15 K and 313.15 K, and ( n -Hexane + 1-Butylamine), at 313.15 K have been measured. The isentropic compressibilities, the excess isentropic compressibilities, and the speeds of sound deviations have been calculated for both the binary and the ternary systems, from the experimental data. The isentropic compressibilities have been compared with calculated values from the Free Length Theory (FLT) and Collision Factor Theory (CFT).

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.