Supercritical CO2 extraction of Persea indica: Effect of extraction parameters, modelling and bioactivity of its extracts

The objective of the work was to optimize the extraction of Persea indica L. bioactive compounds by means of supercritical fluid extraction (SFE) and analyze their insecticidal effects. P. indica L. is one of the dominant species of the Canarian laurel forest, a relict of the Tertiary flora. Different extraction conditions (pressure, plant material particle size, temperature, CO₂ flow) and the influence of entrainer were tested and the evolution of the extracted compounds was screened by HPLC-MS. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, four CO₂ densities ranging from 628.61 kg/m³ to 839.81 kg/m³ were studied in the range of 10.0-20.0 MPa and 40-50 °C. The extracts contained insecticidal ryanodanes of great interest, previously described as insecticidal components of P. indica. The insecticidal antifeedant activity of selected extracts was inspected. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Extraction of the essential oil of abajeru (Chrysobalanus icaco) using supercritical CO2

Abajeru (Chrysobalanus icaco) is a plant that has hypoglycemic properties and is often used in Brazilian popular medicine. In order to identify the flavoring and hypoglycemic substances present in this plant, this work has an objective for the extraction of the essential oil presented in the leaves of abajeru using the supercritical fluid extraction (SFE). The supercritical solvent used is CO₂, because of its moderate critical temperature and pressure, atoxicity, low cost and volatility. The experiments were conducted using dried leaves in an apparatus containing a high-pressure pump, a stainless steel extractor of 42 mL of volume and a micrometric valve for sampling. Different operational conditions were tested, varying mainly the temperature (313.15-353.15 K) and the pressure (10.5-20 kPa) in order to investigate the efficiency of the process. The results showed that the best operational condition was at 20 kPa and 353.15 K. To compare the supercritical carbon dioxide results, the essential oil was also extracted by hydrodistillation and soxhlet, using ethanol as solvent. The chromatographic analysis showed that the different technologies studied extracted the same classes of compounds but the SFE obtained the extract with potential hypoglycemic activity with the presence of lupenol.     

Supercritical fluid extraction of piceid, resveratrol and emodin from Japanese knotweed

In the present study, the use of supercritical fluid extraction was investigated for selected compounds from the plant Japanese knotweed (Polygonum cuspidatum Siebold & Zucc.). The effects of parameters such as type of modifier, pressure, temperature and time on the extraction efficiency of piceid, resveratrol and emodin were studied. The optimal conditions were found as follows: modifier acetonitrile, 40 MPa, 100 °C and 45 min. SFE results were compared with those obtained by conventional Soxhlet extraction carried out for 4 h. The extracts obtained using these two techniques were analysed by liquid chromatography coupled with UV detection. LiChrospher^® 100, RP-18 column (125 mm × 4 mm, 5 μm) coupled with gradient elution acetonitrile in acidified water was used for the separation of compounds at flow rate 0.5 mL min⁻¹. Detection was carried out at 306 nm. Limits of detection were 21, 8 and 52 μg L⁻¹ for piceid, resveratrol and emodin, respectively. The linear range was 0.5-10 mg L⁻¹ for piceid and resveratrol, and 1-50 mg L⁻¹ for emodin with correlation coefficients above 0.9981. Based on the comparison of both methods extracted amount of piceid by Soxhlet extraction is approximately 10 times higher than by SFE method, while the extraction yield of emodin by Soxhlet extraction in approx. 2.5 times lower than by SFE. The advantage of SFE over Soxhlet extraction method is more than 5 times shorter extraction time period.     

SFE from Bidens pilosa Linné to obtain extracts rich in cytotoxic polyacetylenes with antitumor activity

Bidens pilosa L. is a plant considered medicinal by some South American cultures. It contains polyacetylenes which may be the constituents responsible for its antitumor activity. Extracts obtained by hydroethanol maceration (HCE) and supercritical fluid extraction (SFE) were monitored for antitumor activity and the presence of polyacetylenes in the constitution. Both extracts killed concentration-dependently the MCF-7 cells in culture, although the SFE extract presented superior cytotoxic activity. The SFE presented IC₅₀ = 437 (428-446) μg/mL in 24 h of incubation, decreasing to IC₅₀ = 291 (282-299) μg/mL at 48 h. The HCE started causing DNA cleavage at 160 μg/mL while the SFE extract started at 40 μg/mL, a concentration enough to initiate the in vitro cleavage. The presence of polyacetylenes as the major compounds in SFE was confirmed by TL chromatography combined with UV-vis analyses. Ehrlich ascites carcinoma-bearing mice were used for the antitumor study. Animals were divided in five groups: normal, negative control, positive control (Doxorubicin 0.06 mg/kg), test group HCE and test group SFE (100 mg/kg b.w. per day). After 9 days of treatment, 50% of randomly chosen animals from each group were sacrificed for the study. The parameters evaluated were: body weight, abdominal circumference, volume of ascitic fluid and tumor cells, viable and nonviable tumor cell count, determination of mean survival time and increased life-span. Both extracts presented antitumor activity, but SFE reduced more the volumes of ascites fluid and the tumor cells (4 ± 1 and 1 ± 0.4 mL, respectively), while caused higher mean survival time (17 days) and increased life span (∼31%). The results suggest the importance of the polyacetylenes from B. pilosa as leader molecules to contribute to a new anticancer drug by using the supercritical technology.     

Extraction of sage (Salvia officinalis L.) by supercritical CO2: Kinetic data, chemical composition and selectivity of diterpenes

The supercritical carbon dioxide (SFE) extraction of Dalmatian sage (Salvia officinalis L.) was investigated and compared to extraction performed by Soxhlet ethanol-water (70:30) mixture extraction (SE) and hydrodistillation (HD). The supercritical extraction allowed isolation of wide spectrum of phytochemicals, while other applied methods were limited to either volatiles (HD) or high molecular compounds isolation (SE). The kinetics of the supercritical extraction and fractionation within the pressure range of 10-30 MPa at 50 °C were also analyzed as well as the chemical compositions of total extract and partial or differential fractions isolated at different CO₂ consumption. Volatile fraction could be isolated at low pressure and low CO₂ consumption, whereby the pressures between 10 and 15 MPa followed by increased CO₂ consumption were favourable for obtaining desired selectivity of diterpenes which contain compounds with expressed antioxidative characteristics.     

Supercritical CO2 extraction of Helichrysum italicum: Influence of CO2 density and moisture content of plant material

Kinetics and selectivity of supercritical carbon dioxide (SC CO₂) extraction of Helichrysum italicum flowers were analyzed at pressures in the range of 10-20 MPa and temperatures of 40 °C and 60 °C (density of SC CO₂ from 290 to 841 kg/m³) and also at 10 MPa and 40 °C using flowers with different moisture contents (10.5% and 28.4%). Increased moisture content of H. italicum flowers resulted in enchased solubility of solute enabling decrease of SC CO₂ consumption necessary for achieving desired extraction yield. The most abundant compounds in the supercritical extracts are sesquiterpenes and waxes while monoterpenes and sesquiterpenes are the main constituents of essential oil obtained by hydrodistillation. The optimal set of working parameters with respect to extraction yield, SC CO₂ consumption and chemical composition of extract were defined related to moisture content of raw material and SC CO₂ density.     

Supercritical fluid extraction of volatile oil from Lippia alba (Mill.) cultivated in Aragón (Spain)

The objective of this study is the supercritical extraction of the volatile oil from Lippia alba (Mill.) cultivated in Aragón. The influence of extraction pressure and temperature and cosolvent percentage on overall yield and volatile oil composition was studied. The supercritical extraction conditions were optimized using the 2007 crop; operating at 35.0 MPa, 40 °C and 5% of ethanol as cosolvent, 2009 and 2011 crops were also tested. Supercritical fluid extract compositions and overall yields were compared with the extracts obtained by conventional extraction techniques such as hydrodistillation (HD) and organic solvent extraction (OSE). Four terpenoids (linalool, 1,8-cineole, β-caryophyllene and β-caryophyllene oxide) were selected as target compounds and their content in the different extracts was monitored by gas chromatography. Linalool was selected as indicator of the plant adaptation to the commercial purposes. HD is the technique that provides the highest percentage of linalool in all the extracts, but showed always the lowest overall yields; whereas, SFE extracts provides a good balance between the overall yield and presence of the four target compounds.     

Extraction of phenolic fraction from guava seeds (Psidium guajava L.) using supercritical carbon dioxide and co-solvents

In this work the supercritical fluid extraction (SFE) with carbon dioxide (CO₂) and with ethyl acetate (EtAc) and ethanol (EtOH) as co-solvents was applied to obtain the phenolic fraction from guava seeds (Psidium guajava L.). The extraction was explored at various operating conditions, using 10, 20 and 30 MPa and 40, 50 and 60 °C. The use of EtAc and EtOH as co-solvents in SFE was also studied. The supercritical process was compared with traditional techniques such as Soxhlet extraction using EtAc and EtOH as solvents. The quality of the different extracts, obtained using SFE and Soxhlet methods and different solvents, was evaluated through the antioxidant activity, obtained by the collection methods of scavenging DPPH and bleaching of β-carotene, and also through the total phenolic content (TPC) of the samples, by the Folin-Ciocalteu method. The antioxidant potential indicates the use of ethanol as co-solvent as the best modifier in SFE, used in concentration of 10% (w/w) at 50 °C and 30 MPa. The quality of the extracts obtained by SFE with EtOH varied with the operating conditions of temperature and pressure, with higher values obtained at 10 and 20 MPa for TPC results and also antioxidant methods. The process yield of the phenolic fraction was also evaluated for all the extraction procedures studied (SFE and Soxhlet), with results varying from 0.380 to 1.738% (w/w).     

Supercritical fluid extraction combined with dispersive liquid-liquid microextraction as a sensitive and efficient sample preparation method for determination of organic compounds in solid samples

The supercritical fluid extraction (SFE) followed by the dispersive liquid-liquid microextraction (DLLME) has been developed for extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. PAHs were employed as model compounds to assess the extraction procedure and were determined by gas chromatography-flame ionization detection (GC-FID). SFE of PAHs was performed at 313 K and 253.2 bar, at static and dynamic times 10 and 30 min, respectively. The extracted PAHs were collected in 1 mL of acetonitrile. Subsequently, 16 μL of chlorobenzene (as extraction solvent) was added to collecting solvent (1.0 mL of acetonitrile). Then, the resulted mixture was injected into 5.0 mL of aqueous solution, rapidly. After centrifugation, the PAHs in the sedimented phase were analyzed by GC-FID. Effects of significant parameters on the extraction in SFE and DLLME methods were investigated. Under the optimum conditions, the calibration plots were linear in the range of 0.4-41.6 mg kg⁻¹ and the limits of detection (LODs) were 0.2 mg kg⁻¹ for all of the analytes. Analysis of PAHs in different solid samples showed that the improved technique has great potential for PAHs analysis in marine sediments. SFE-DLLME leads to high preconcentration factor, easy use of DLLME in solid samples and solving the main problem of SFE that is the extra step (vaporization of large volume of toxic organic solvent) after extraction needed prior to final analysis.     

The analysis of simultaneous clove/oregano and clove/thyme supercritical extraction

The goal of present work was to investigate and explain kinetics and mass transfer phenomena occurring during the SFE from the mixture of two plants with different initial composition. The extractions from pure clove, oregano and thyme as well as from clove/oregano (C/O) and clove/thyme (C/T) mixtures with various initial compositions of plant material were carried out using supercritical CO₂ at 10 MPa and 40 °C. The results indicated that presence of light compounds in supercritical CO₂ originated from the oregano leaves or thyme at the beginning of extraction process increases the extraction rate of compounds from clove bud. Only small added amounts of oregano or thyme to clove bud (C/O - 90:10%, w/w; or C/T - 84:16%, w/w) in the starting plant mixture had the same effect resulted in the similar and the highest increase of the extraction rate and had negligible influence on total extraction yield compared to extract isolated from pure clove. Different mathematical models were used for simulation of experimental data which showed that the highest increase of the solubility of extractable compounds in supercritical CO₂ as well as the highest mass transfer rate in the solid phase during extractions existed during extraction from C/O (90:10, w/w) and C/T (84:16, w/w) mixtures. Decrease of SC CO₂ consumption or shorter time of extraction necessary for achieving desired extract yield in the case of SFE of the clove buds could be important for industrial-scale application.     

Bioactive extracts of orange (Citrus sinensis L. Osbeck) pomace obtained by SFE and low pressure techniques: Mathematical modeling and extract composition

The objective of this study was to obtain orange (Citrus sinensis L. Osbeck) pomace extract using supercritical fluid extraction (SFE) with CO₂ and with CO₂ and co-solvent. In order to evaluate the high pressure method in terms of process yield, extract composition and biological activity, low pressure methods were also applied to obtain orange extracts, such as ultrasound (UE) and soxhlet (SOX), with different organic solvents, and hydrodistillation (HD). The SFE conditions were temperatures of 313.15 K and 323.15 K and pressures from 100 to 300 bar. The SFE kinetics and mathematical modeling of the overall extraction curves (OEC) were also investigated. The antioxidant potential of the extracts was evaluated by the DPPH method, by the Folin-Ciocalteau method and by the β-carotene/linoleic acid bleaching method. The antimicrobial activity of the extracts was also studied. The main compounds identified were l-limonene, palmitic and oleic acids, n-butyl benzenesulfonamide and β-sitosterol.     

Guava (Psidium guajava L.) seed oil obtained with a homemade supercritical fluid extraction system using supercritical CO2 and co-solvent

In this work we designed and built a homemade supercritical fluid extraction (HM-SFE) system, in which pure CO₂ and CO₂ with co-solvents were used. The HM-SFE was made by means of thermal dilatation-contraction (TDC). This HM-SFE system was used for obtaining guava (Psidium guajava L.) seed oil, using supercritical CO₂ adding ethanol as co-solvent (CO₂ SC/EtOH), extractions were performed at 313 K and different pressures (10, 20 and 30 MPa), each one in four stages of 30 min, the extract with higher yield was subjected to transesterification and high-resolution gas chromatography (HRGC) analysis. The highest extraction yield was obtained at 30 MPa (17.30% w/w), this yield was higher than one observed in a previous work using SC-CO₂, and near to the one obtained by Soxhlet extraction (20.2% w/w). HRGC enabled the identification of components of the derivatized extract as methyl esters of palmitic, oleic, linoleic, and stearic fatty acids. The results obtained with HM-SFE system was compared with a commercial SFE system, obtained very similar results. In this work was possible to construct a low cost and simple manner HM-SFE system which was employed for obtaining guava seed oil, using CO₂ SC/EtOH.     

Supercritical extraction of grape seed oil at industrial-scale: Plant and process design,modeling, economic feasibility

The aim of this paper is to present the results of a study on the possible use of exhausted grape marc for obtaining grape seed oil by means of the supercritical technology. An industrial-scale supercritical extraction plant (three extractors in series working in the counter-current mode) has been designed based on the availability of grape seeds of a region in the north of Italy, namely 3000 ton/year (3 × 10⁶ kg/year). The process has been analyzed in depth and modeled and the results indicate that the proposed industrial application could be economically interesting: the breakeven point, which makes the process economically sustainable, is a value of 5.9 €/kg for the supercritical extracted grape seed oil.     

Brazilian Ginseng extraction via LPSE and SFE: Global yields, extraction kinetics, chemical composition and antioxidant activity

Brazilian Ginseng extracts of two species, Pfaffia paniculata and Pfaffia glomerata, were obtained by supercritical fluid extraction (SFE) with CO₂ and by low-pressure solvent extraction (LPSE) with methanol, hexane and ethanol. The SFE assays were conducted at pressures of 100, 200 and 300 bar, and temperatures of 30 and 50 °C. The qualitative chemical compositions of the extracts were determined by thin layer chromatography (TLC). One of the active principles of interest from P. glomerata extract, β-ecdysone, was identified and quantified by HPLC. The antioxidant activities of Brazilian Ginseng extracts were determined by the coupled reaction of linolenic acid and β-carotene. For P. paniculata, the highest SFE yield was obtained at 200 bar/50 °C (0.22%, dry basis—d.b.), while the best extraction condition for P. glomerata was obtained at 200 bar/30 °C (0.18%, d.b.). The higher extract yields obtained by LPSE were 2.0% and 5.8% (w/w, d.b.) for P. paniculata and P. glomerata, respectively, both obtained with methanol as extraction solvent. From the overall extraction curve of P. glomerata, it was possible to obtain the kinetic parameters of extraction; the duration of the CER (constant extraction rate) period was determined as 134 min. The TLC plates showed the possible presence of flavonoids in the ethanolic extract for both Pfaffia species. The antioxidant activity analysis detected that LPSE extracts had higher activity than SFE extracts.     

Radical-scavenging activity of extracts from Cordia verbenacea DC obtained by different methods

The possibility of using the leaves of Cordia verbenacea as a new source of natural antioxidant compounds was investigated. In the present work, extracts from C. verbenacea were obtained using different extraction methods: supercritical fluid extraction (SFE), Soxhlet (SE), hydrodistillation and maceration, with the objective to evaluate the methods in terms of yield and antioxidant potential. The high-pressure technique was applied using pure CO₂ and CO₂ with co-solvent at different temperatures and pressures (30, 40 and 50 °C and 100, 200, and 300 bar). Organic solvents with different polarities were used to obtain extracts by low-pressure extraction processes. The extracts were evaluated according to their antioxidant activity using total phenolic content, scavenging abilities on DPPH radical, total antioxidant activities (ABTS^•+), superoxide anion radical-scavenging (O₂^•) and protection against lipid peroxidation in vitro (LPO). Ethyl acetate fraction obtained by maceration and extract isolated by SE using 25% aqueous mixture of ethanol possessed the highest scavenger activity against DPPH radical (IC₅₀ = 9.2 ± 0.4 μg/ml, IC₅₀ = 27.4 ± 0.1 μg/ml, respectively). The SFE with 8% ethanol as a co-solvent produced extracts with distinguished increase in the antioxidant activity. The Soxhlet extract with ethyl acetate exhibited a strong reduction of lipid peroxidation (IC₅₀ = 209 ± 3 μg/ml) value comparable to the standard rutin (IC₅₀ = 203 ± 2 μg/ml). The results indicate that extracts of C. verbenacea have important potential as a source of bioactive compounds with antioxidant activity.     

Optimization of ethanol modified supercritical carbon dioxide on the extract yield and antioxidant activity from Biebersteinia multifida DC

Essential oil of Biebersteinia multifida DC cultivated in Iran was obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE) methods. The oil was analyzed by capillary gas chromatography using flame ionization and mass spectrometric detections. The effects of different parameters such as temperature, pressure, static extraction time, dynamic extraction time, and mole fraction of modifier on the supercritical fluid extraction (SFE) and radical scavenging activity of B. multifida oil were optimized using central composite design. Fifty two compounds were identified in the HD oil. The major components of B. multifida were (E)-Nerolidol (31.45%), Hexadecanoic acid (11.84%), Phytol (17.1%), and 6,10,14-trimethyl-2-pentadecanone (15.4%). However, by using supercritical carbon dioxide in optimum conditions, obtained only four components contain more than 91.74% of the essential oil. The optimum extraction yield and DPPH EC₅₀ via SFE method were 96% (w/w) and 27.19, respectively.     

Production of polyphenol extracts from grape bagasse using supercritical fluids: Yield,extract composition and economic evaluation

The objective of this work was to determine the economic feasibility of large-scale operations of supercritical fluid extraction (SFE) for the recovery of phenolics using grape bagasse from Pisco residues. Experimental data were used to estimate the extraction kinetic parameters, as well as the cost of manufacturing the extracts. Experimental data were obtained using supercritical CO₂ containing 10% ethanol (w/w) at 313 K and 20–35 MPa. The supercritical CO₂/ethanol extraction process produced extracts with higher concentrations of phenolics than extracts produced using conventional techniques. The compounds identified in the extracts were syringic, vanillic, gallic, p-hydroxybenzoic, protocatechuic and p-coumaric acids, as well as quercetin. An evaluation of the economics of the process indicated the feasibility of an industrial SFE plant with a capacity of 0.5 m³ for producing an extract with an expected phenolics concentration of approximately 23 g/kg of extract at an estimated cost of manufacturing of US$ 133.16/kg.     

Supercritical fluid extraction of flavonoids from Maydis stigma and its nitrite-scavenging ability

Supercritical fluid carbon dioxide (SF-CO₂) extraction (SFE) of flavonoids from Maydis stigma and its nitrite-scavenging ability were investigated. The effects of extraction time, particle size and co-solvent composition in terms of water content in ethanol were first optimized. Then, a Box-Behnken design combined with response surface methodology (RSM) was employed to study the effects of three independent variables (temperature, pressure and co-solvent amount) on the extraction yield of flavonoids. A maximal extraction yield of flavonoids of approximately 4.24 mg/g of M. stigma by SFE was obtained under optimal conditions (a temperature of 50.88 °C, a pressure of 41.80 MPa, a co-solvent amount of 2.488 mL/g and an extraction time of 120 min with 0.4-mm particle sizes and 20% aqueous ethanol as the co-solvent). Furthermore, the nitrite-scavenging ability of the flavonoid-enriched SFE extracts was assessed using the Griess reagent. The flavonoid-enriched SFE extracts exhibited the highest scavenging ability on nitrite (88.1 ± 3.04%) at the concentration of 500 μg/mL and at pH 3.0. The nitrite-scavenging ability of the extracts appeared to be concentration dependent but negatively correlated with the pH.     

Determination of sudan dyes in food samples using supercritical fluid extraction-capillary liquid chromatography

Determination of sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples has been developed by several and different methods. However, sample treatment continues being the most important problem to determine these compounds in real samples. A rapid, sensitive and selective method for the extraction, separation and quantification of sudan dyes in commercial food samples has been developed. The method is based on the combination of a supercritical fluid extraction (SFE) procedure, followed by the analysis of the extracted plug by capillary liquid chromatography (CLC) with diode array detection (DAD). The entire procedure was optimized for the extraction of the samples, separation and detection of the analytes. For the SFE, the effect of CO₂ flow rate, extraction pressure, extraction temperature, equilibration and extraction time and methanol modifier content were studied. Linear responses in the range from 50 to 1000 ng mL⁻¹ with average relative standard deviation lower than 11.6, and detection limits ranging from 23.2 to 42.0 ng mL⁻¹ were obtained for the different sudan dyes. The recoveries were in the range of 91-109% for dyes powder samples.     

A green separation process for recovery of healthy oil from pumpkin seed

In this study, pumpkin seeds, called as “Ürgüp Sivrisi” and grown in Cappadocia region, were used as plant materials because of high aroma contents. In the supercritical fluid extraction of pumpkin seed oil, the effect of main process parameters as the particle size (250-2360 μm), the volumetric flow rate of supercritical solvent (0.06-0.30 L/h), the operating pressure (20-50 MPa), the operating temperature (40-70 °C), the type of entrainer (ethanol and n-hexane) and those concentrations (0-10 vol.%) on the extraction yield, the oil solubility and the initial extraction rate were investigated. A cross-over effect for the extraction of pumpkin seed oil using supercritical CO₂ was determined at the operating pressure of 20-30 MPa. The maximum extraction yield obtained with entrainer free was reached 0.50 g oil/g dry seed at 600-1180 μm, 0.12 L/h, 50 MPa and 70 °C for the operation time of 5 h. The maximum extraction yield obtained with ethanol as an entrainer in the experiments was reached 0.54 g oil/g dry seed at the conditions of 600-1180 μm, 0.12 L/h, 30 MPa, 40 °C and 8 vol.% for the operating time of 2 h. The oil compositions were determined by gas chromatography analysis and the results showed that the compositions of pumpkin seed oil which were obtained by means of organic solvent extraction and supercritical fluid extraction were similar. The average oil compositions determined as 9.3 (±0.43)% palmitic acid, 7.5 (±0.6)% stearic acid, 32.3 (±0.6)% oleic acid, 48.1 (±0.6)% linoleic acid and 0.7 (±0.3)% linolenic acid. The morphological changes in the seeds were determined by the scanning electron microscopy analysis.