Supercritical extraction of thyme (Thymus vulgaris L.)

Summary Chromatographic methods for the qualitative and quantitative analysis of thyme (Thymus vulgaris L.) extracts (essential oil obtained by steam distillation and extracts obtained by carbon dioxide supercritical fluid extraction and methylene chloride) are described. The composition of extracts obtained at different pressures (from 80 bar to 400 bar) and constant temperature (40°C) is discussed. The extraction system thyme— supercritical carbon dioxide was modelled by empirical equations defining the dependence of the total extract (TE) solubility and thymol solubility in CO₂ on the density of carbon dioxide.     

Supercritical Carbon Dioxide Extraction of Salidroside from Rhodiola rosea L var. rosea Root

Salidroside from the root of Rhodiola rosea L var. rosea was extracted by supercritical carbon dioxide with and without methanol as modifier. Three parameters, i.e. temperature, pressure and different concentrations of methanol were optimized. Salidroside determinations were carried out using high‐performance liquid chromatography (HPLC) with UV‐Vis detector. An experimental design of response surface methodology (RSM) was used to map the effect of pressure (at 200, 300 and 400 bar), temperature (at 50, 60 and 70 °C) and percentage of methanol modifier (at 80, 90 and 100%) on the extraction yield of the active compound and to determine the optimal conditions for the extraction of salidroside from the root of plant. The results showed that supercritical carbon dioxide failed to extract salidroside from the plant material without a methanol as modifier. The yield obtained after 1.5 h extraction with the rate of modifier 0.4 mL/min and 300 bar, 70 °C, and 80 percent of methanol modifier condition was the highest (17.15 mg/g). The optimum conditions were 70 °C, 295.49 bar and 80 percent of methanol as modifier with the yield of 16.17 mg/g. In addition, the yield obtained with supercritical fluid extraction (SFE) was compared with the Soxhlet extraction, whose yield was 8.64 mg/g.     

Comparative analysis of the oil and supercritical CO2 extract of Ridolfia segetum (L.) Moris

Supercritical carbon dioxide extraction allowed to obtain the volatile oil of different aerial parts of Ridolfia segetum (L.) Moris. Extraction conditions were as follows: pressure, 90 bar; temperature, 50°C and carbon dioxide flow, Φ?=?1.0?kg?h^?1. Waxes were entrapped in the first separator set at 90?bar and ?10°C. The oil was recovered in the second separator working at 15?bar and 10°C. The main components of the flower oil were α-phellandrene (19.4%), terpinolene (20.5%), piperitenone oxide (11.6%), β-phellandrene (8.2%), (Z)-β-ocimene (7.8%), myristicin (7.5%) and p-cymene (4.4%). The comparison with the hydrodistilled (HD) oil reveal that the significative difference was the content of sesquiterpenes which are higher in the supercritical fluid extraction (SFE) products. Collection of samples at different extraction times during supercritical extraction, allowed to monitor the change of the oil composition. Lighter compounds, as hydrocarbon monoterpenes, were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes. The oil from the steams was characterized by a high content of α-phellandrene (12.9%), terpinolene (11.6%), myristicin (11.0%), p-cymene (9.9%), β-phellandrene (8.2%) and (Z)-β-ocimene (6.0%) while the main components of the fruits were found to be myristicin (70.8%), piperitenone oxide (19.9%) and dill apiole (4.2%).     

Supercritical extraction of phloroglucinol and benzophenone derivatives from Hypericum carinatum: quantification and mathematical modeling

The aerial parts of Hypericum carinatum (Guttiferae) were extracted with supercritical carbon dioxide under constant temperature (40, 50 or 60°C) and gradual pressure increase (90, 120, 150 and 200 bar) aiming at the recovery of enriched fractions containing uliginosin B, cariphenone A and cariphenone B, compounds of pharmaceutical interest. The yields of these substances were determined by high‐performance liquid chromatography and compared with those obtained with n‐hexane maceration. The supercritical‐fluid extraction showed higher selectivity than the conventional solvent extraction method. After defining 40°C and 90 bar as the best conditions to obtain the target compounds, a mathematical model was used for the extraction process and a good correlation was achieved with the experimental data.     

Investigation of the chemical composition–antibacterial activity relationship of essential oils by chemometric methods

The antibacterial effects of Thymus vulgaris (Lamiaceae), Lavandula angustifolia (Lamiaceae), and Calamintha nepeta (Lamiaceae) Savi subsp. nepeta var. subisodonda (Borb.) Hayek essential oils on five different bacteria were estimated. Laboratory control strain and clinical isolates from different pathogenic media were researched by broth microdilution method, with an emphasis on a chemical composition–antibacterial activity relationship. The main constituents of thyme oil were thymol (59.95%) and p-cymene (18.34%). Linalool acetate (38.23%) and β-linalool (35.01%) were main compounds in lavender oil. C. nepeta essential oil was characterized by a high percentage of piperitone oxide (59.07%) and limonene (9.05%). Essential oils have been found to have antimicrobial activity against all tested microorganisms. Classification and comparison of essential oils on the basis of their chemical composition and antibacterial activity were made by utilization of appropriate chemometric methods. The chemical principal component analysis (PCA) and hierachical cluster analysis (HCA) separated essential oils into two groups and two sub-groups. Thyme essential oil forms separate chemical HCA group and exhibits highest antibacterial activity, similar to tetracycline. Essential oils of lavender and C. nepeta in the same chemical HCA group were classified in different groups, within antibacterial PCA and HCA analyses. Lavender oil exhibits higher antibacterial ability in comparison with C. nepeta essential oil, probably based on the concept of synergistic activity of essential oil components.     

Supercritical CO2 Extract from Microalga Tetradesmus obliquus: The Effect of High-Pressure Pre-Treatment

High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO₂) extraction (300 bar, 40 °C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-high-performance liquid chromatography–high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO₂ on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO₂ extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO₂ can potentially be used as a safe and important source of organic compounds.     

Valorization of Fermented Shrimp Waste with Supercritical CO2 Conditions: Extraction of Astaxanthin and Effect of Simulated Gastrointestinal Digestion on Its Antioxidant Capacity

Lactic acid fermentation increases the bioactive properties of shrimp waste. Astaxanthin is the principal carotenoid present in shrimp waste, which can be found esterified in the liquid fraction (liquor) after its lactic acid fermentation. Supercritical CO₂ technology has been proposed as a green alternative to obtain astaxanthin from fermented shrimp waste. This study aimed to optimize astaxanthin extraction by supercritical CO₂ technology from fermented liquor of shrimp waste and study bioaccessibility using simulated gastrointestinal digestion (GD) of the optimized extract. A Box–Behnken design with three variables (pressure, temperature, and flow rate) was used to optimize the supercritical CO₂ extraction. The optimized CO₂ extract was obtained at 300 bar, 60 °C, and 6 mL/min, and the estimated characteristics showed a predictive extraction yield of 11.17%, antioxidant capacity of 1.965 mmol of Trolox equivalent (TE)/g, and astaxanthin concentration of 0.6353 µg/g. The experiment with optimal conditions performed to validate the predicted values showed an extraction yield of 12.62%, an antioxidant capacity of 1.784 mmol TE/g, and an astaxanthin concentration of 0.52 µg/g. The astaxanthin concentration decreased, and the antioxidant capacity of the optimized extract increased during gastrointestinal digestion. In conclusion, our optimized supercritical CO₂ process is suitable for obtaining astaxanthin from shrimp by-products after lactic acid fermentation.     

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 CO₂ 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 40 to 50°C at 90 bar enriched of the volatiles in n‐alkanes.     

Characterization of secondary volatile profiles in Nigella sativa seeds from two different origins using accelerated solvent extraction and gas chromatography-mass spectrometry

The extraction and identification of bioactive compounds from herbs is of great interest. In this study, accelerated solvent extraction (ASE) technique was used to analyze the secondary volatile profiles in Nigella sativa seeds obtained from two different origins, Egypt and Bangladesh. The main extraction parameters, including extraction temperature, pressure and static extraction time, were investigated and optimized. Identification and quantification of the major constituents in nonpolar extracts (hexane) were achieved by means of GC‐FID/GC‐MS analysis with external standards. The two seeds showed a similar variety of chemical composition; however, the secondary volatiles profile of Bangladesh seed was higher than that of the Egyptian seed. A total of 25 compounds were identified from the ASE extract under the following optimum extraction conditions: 100°C, 1500 psi and 5 min, for extraction temperature, pressure and static time, respectively. The proposed technique can be used for the characterization of N. sativa varieties or cultivars. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparative analysis of the oil and supercritical CO(2) extract of Cymbopogon citratus Stapf

Dried and ground leaves of lemon grass (Cymbopogon citratus Stapf.) were used as a matrix for supercritical extraction of essential oil with CO(2). The objective of this study was to analyze the influence of pressure on the supercritical extraction. A series of experiments were carried out, for 360 min, at 50 degrees C and at different pressures: 90, 100, 110 and 120 bar. Extraction conditions were chosen to maximize citral content in the extract oil. The collected extracts were analysed by GC-MS and their composition was compared with that of the essential oil isolated by hydrodistillation and by steam distillation. At higher solvent density the extract aspect changes passing from a characteristic yellow essential oil to yellowish semi-solid mass because of the extraction of high molecular mass compounds. The optimum conditions for citral extraction were 90 bar and 50 degrees C, at these conditions citral represent more than 68% of the essential oil and the extraction yield was 0.65% while the yield obtained from hydrodistillation was 0.43% with a content of citral of 73%.     

Optimization of extraction of evodiamine and rutaecarpine from fruit of Evodia rutaecarpa using modified supercritical CO(2)

Evodiamine and rutaecarpine have been intensively studied due to their pharmacological actions and clinical applications. In this report, supercritical fluid was used to extract evodiamine and rutaecarpine from the unripe fruit of Evodia rutaecarpa. Response surface methodology using Box-Behnken experimental design was utilized to optimize parameters for supercritical carbon dioxide extraction with methanol as co-solvent. The effect of various values of dynamic extraction time (30-90min), temperature (50-70°C) and pressure (200-400bar) on extraction yields of the two compounds was evaluated. Determinations of the extracts were performed by high-performance liquid chromatography. The experimental data obtained were fitted to second-order polynomial equations and analyzed by analysis of variance. The highest yields predicted were 1.217mg/g for evodiamine and 0.969mg/g for rutaecarpine at the optimal values (time 78min, temperature 62°C, pressure 280bar and co-solvent flow rate 0.4mL/min), based on the selected range of experimental conditions.     

Effects of process parameters on supercritical CO2 extraction of total phenols from strawberry (Arbutus unedo L.) fruits: An optimization study

The aim of this work was to optimize total phenolic yield of Arbutus unedo fruits using supercritical fluid extraction. A Box–Behnken statistical design was used to evaluate the effect of various values of pressure (50–300 bar), temperature (30–80°C) and concentration of ethanol as co‐solvent (0–20%) by CO₂ flow rate of 15 g/min for 60 min. The most effective variable was co‐solvent ratio (p<0.005). Evaluative criteria for both dependent variables (total phenols and radical scavenging activity) in the model were assigned maximum. Optimum extraction conditions were elicited as 60 bar, 48°C and 19.7% yielding 25.72 mg gallic acid equivalent (GAE) total phenols/g extract and 99.9% radical scavenging capacity, which were higher than the values obtained by conventional water (24.89 mg/g; 83.8%) and ethanol (15.12 mg/g; 95.8%) extractions demonstrating challenges as a green separation process with improved product properties for industrial applications.     

Identification of volatile compounds of Atractylode lancea Rhizoma using supercritical fluid extraction and GC–MS

Supercritical fluid was used to extract volatile components from the rhizoma of Atractylode lancea (A. lancea). An orthogonal array design (OAD), L₉ (3)⁴, was employed as a chemometric method for the optimization of the supercritical fluid extraction (SFE) of volatile compounds from the herbal medicine. Four parameters, namely, pressure, temperature, dynamic extraction time, and flow rate of CO₂, were studied and optimized by a three‐level OAD in which the interactions between the parameters were neglected. These compounds were identified according to their retention times and mass spectra by GC–MS. A total of 30 compounds of SFE extracts were identified. Atractylon (8.63%), hinesol (1.44%), β‐eudesmol (6.64%), elemol (0.42%), and atractydin (13.92%) were the major sesquiterpenes identified in A. lancea SFE extracts.     

Lippia origanoides chemotype differentiation based on essential oil GC‐MS and principal component analysis

Chromatographic (GC/flame ionization detection, GC/MS) and statistical analyses were applied to the study of essential oils and extracts obtained from flowers, leaves, and stems of Lippia origanoides plants, growing wild in different Colombian regions. Retention indices, mass spectra, and standard substances were used in the identification of 139 substances detected in these essential oils and extracts. Principal component analysis allowed L. origanoides classification into three chemotypes, characterized according to their essential oil major components. α‐ and β‐phellandrenes, p‐cymene, and limonene distinguished chemotype A; carvacrol and thymol were the distinctive major components of chemotypes B and C, respectively. Pinocembrin (5,7‐dihydroxyflavanone) was found in L. origanoides chemotype A supercritical fluid (CO₂) extract at a concentration of 0.83±0.03 mg/g of dry plant material, which makes this plant an interesting source of an important bioactive flavanone with diverse potential applications in cosmetic, food, and pharmaceutical products.     

Effect of the pre-treatment of the samples on the natural substances extraction from Helianthus annuus L. using supercritical carbon dioxide

The extraction of bioactive compounds from sunflowers (Helianthus annuus L.) with supercritical carbon dioxide has been studied. The samples were treated in four different ways and the effects of two factors (pressure and temperature) were investigated at 100, 500 bar and 35, 50 °C. The best yields were obtained using a high temperature and a high pressure (50 °C and 500 bar). The dry samples produced better extraction yields than the moist samples. The bioactivities of the extracts were compared for the samples treated in different ways. The best activity profiles were obtained for the moist samples extracted at 35 °C and 500 bar.     

High temperature treatment allows the detection of episesamin in paulownia wood extractives

Abstract

The composition and the relative variation of secondary metabolites of Paulownia tomentosa S. wood under thermal effect is a little explored area. Wood material was previously thermo-treated at 210?°C for 3?hours using a press vacuum technology. Extractives of untreated and thermo-treated wood material achieved with Soxhlet extraction techniques were obtained. Then the extracts were chromatographed by using thin layer chromatography. Component groups in extracts were determined by gas chromatography in combination with mass spectrometry. In terms of wood change the thermo-treatment of wood induces a darkening of wood color surface (ΔL* = 28.3), an increase of mass loss (3.5%) and an increase of the amount of extractives and lignin content as well as an increase of the chloroform soluble fraction. This work mainly describes the chemical exploration of the extract from paulownia wood, leading to the isolation and identification of episesamin.     

Thermoplastic blend demixing by a high‐pressure,high‐temperature process

The analysis of a thermoplastic polymer blend requires a precise separation of the blend components, which is usually performed by selective solvent extraction. However, when the components are high‐molecular‐weight polymers, a complete separation is very difficult. The use of fluids in near critical and supercritical conditions becomes a promising alternative to reach a much more precise separation. In this work, a method to separate reactive and physical blends from high‐molecular‐weight commercial polymers is proposed. Polyethylene (PE)/polystyrene (PS) blends were separated into their components with n‐propane, n‐pentane, and n‐heptane at near critical and supercritical conditions. The selectivity of each solvent was experimentally studied over a wide range of temperatures for assessing the processing windows for the separation of pure components. The entire PE phase was solubilized by n‐pentane and n‐heptane at similar temperatures, whereas propane at supercritical conditions could not dissolve the fraction of high‐molecular‐weight PE. The influence of the blend morphology and composition on the efficiency of the polymer separation was studied. In reactive blends, the in situ copolymer formed was solubilized with the PE phase by chemical affinity. The method proposed for blend separation is easy, rapid, and selective and seems to be a promising tool for blend separation, particularly for reactive blends, for which the isolation of the copolymer is essential for characterization © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2361–2369, 2005     

烟叶中油分的萃取方法研究

比较了烟叶中油分的萃取方法,分别采用超声、索氏、ASE加速溶剂和CO2超临界萃取方法萃取烟叶中的油分,萃取物再经硅胶氧化铝柱分离成3种不同极性的馏分,馏分使用气相色谱分离,质谱鉴定结构.在同时考虑萃取率和萃取物组成成分的基础上最终选择索氏萃取.通过对萃取溶剂和萃取时间进行单因素试验,确定了最佳萃取条件为:萃取溶剂三氯甲烷,萃取时间16 h.方法所得组分全面,有利于后期卷烟配方的调整与设计.     

Supercritical carbon dioxide extraction and gas chromatography–mass spectrometry analysis of Gymnema sylvestre R.Br. roots

Supercritical fluid extraction (SFE) achieves a wide range of applications since the past decade as a sustainable green technology. The present study investigates the process for producing high yield by supercritical carbon dioxide (Sc-CO₂) extraction form Gymnema sylvestre R.Br. roots. The effect of temperature and pressure on the percentage of accumulative yield is demonstrated. It is found that the highest yield is obtained at the temperature of 60°C and the pressure of 10?MPa. A proper review showed that there is a lack in the study of Sc-CO₂ extraction of this plant especially for optimization of SFE process which makes this study useful and valuable. For more benefit, the extract which achieves highest percentage is subjected to gas chromatography–mass spectrometry to study its chemical composition and detect the active principle compounds which present with high concentration and expected to be responsible of the pharmaceutical properties of the extract.     

Supercritical fluid extraction of kava lactones from Piper methysticum (kava) herb

Supercritical fluid extraction of kava lactones from Piper methysticum Forst. herb is described here. The extraction was performed with supercritical carbon dioxide alone and supercritical carbon dioxide modified with 15% ethanol, and the extracts were analyzed by gas chromatography/mass spectrometry. Seven lactones including: 7,8-dihydrokavain; kavain; 5,6-dehydrokavain; 5, 6, 7, 8-tetrahydroyangonin; dihydromethysticin; yangonin; and methysticin were the major constituents in the SFE extract.