Extraction of oil and silybin compounds from milk thistle seeds using supercritical carbon dioxide

Facilitated on-line supercritical fluid extraction - supercritical fluid chromatography for nonpolar and polar compounds from milk thistle seeds

Plant seeds, as those from milk thistle (Silybum marianum), are a valuable source of nonpolar and polar compounds with potentially interesting biological activity. The main nonpolar compounds are triglycerides, which are also the main components of all vegetable oils. In addition, specific polar compounds - flavonolignans, called silymarin, have been found in large amounts in milk thistle seeds extract. These flavonoids derivatives have different biological activity, for instance hepatoprotective effects. In order to extract and analyze both nonpolar (triglycerides) and polar compounds (flavonolignans) from milk thistle seeds through a sequential methodology, an on-line supercritical fluid extraction - supercritical fluid chromatography (SFE-SFC) method was developed. Different ways of transferring the extracts from SFE to SFC (i.e. direct on-column transfer and loop transfer) were compared, and particularly for their effect on chromatographic quality. In this respect, nonpolar and polar compounds caused different issues, especially as polar compounds required a significant portion of co-solvent in the extraction step, favoring early elution in the chromatographic column. First, on-line SFE-SFC was used for triglycerides analysis and allowed the comparison of transfer modes. Then, on-line kinetics were performed to measure defatting time before polar molecules extraction. Finally, the eventual benefit of loop transfer was also investigated for the analysis of flavonolignans, polar molecules whose analysis can be difficult by on-line SFE-SFC. The aim of this paper is to discuss the versatility of on-line SFE-SFC and how challenging the coupling can be, especially when both non-polar and polar molecules must be analyzed independently in a single sample.

Milk Thistle Oil Extracted by Enzyme-Mediated Assisted Solvent Extraction Compared with n-Hexane and Cold-Pressed Extraction

Silymarin and milk thistle oil have unique biological benefits; however, applying silymarin to milk thistle oil remains a challenge. In this research, the content of silymarin in milk thistle oil conditions using enzyme-mediated solvent extraction was investigated and optimized by response surface methodology. The optimal extraction conditions using enzyme-mediated solvent extraction were as follows: the enzyme-added content was 3.06 mg/mL, the enzymatic hydrolysis temperature was 55.09 °C, and the enzymatic hydrolysis time was 66.28 min. Oil extracted by the enzyme-mediated assisted solvent was further compared with those extracted with n-hexane and cold pressing. Results indicated that the oil extraction using the enzyme-mediated assisted solvent had a lower acid value (2.20 ± 0.01 mg/g) and the highest α-tocopherol content (0.62 ± 0.00 mg/g), total phenols (7.67 ± 0.01 mg/g), and flavonoids (1.06 ± 0.13 mg/g). Furthermore, the antioxidant capacity of milk thistle oils was further investigated. The results showed that the enzyme-mediated assisted solvent-extracted oil had the strongest antioxidant capacity with lower lipid oxide content. Therefore, enzyme-mediated solvent extraction is an excellent method for extracting milk thistle oil.

Fatty Acid Composition of Pseudocereals and Seeds Used as Functional Food Ingredients

In recent times, the popularity of seeds, other than cereals, in the diet has systematically grown. The fat contained in these products significantly affects their energy value as well as their biological and physicochemical properties, including their susceptibility to oxidation. The objective of this study is to evaluate the fat concentration and fatty acid (FA) composition of popular non-spice seeds used in food as a substitute for cereals or a functional additive. The research material consisted of thirteen groups of seeds derived from the following plants: amaranth, blue poppy, buckwheat, chia, flax, hemp, canihua, milk thistle, pumpkin, plantago, quinoa, sesame, and sunflower. The fat contents and fatty acid profiles differed significantly between the tested products and were dependent on the plant species. In all products, polyunsaturated fatty acids (PUFAs, 40-80% of total FAs) dominated. Linoleic acid was the main FAs in most tested seeds. The exceptions were chia and flax seeds, which were characterized by very high contents of α-linolenic acid, respectively, 62.0 and 51.4% of the total FAs. The share of monounsaturated FAs (mainly oleic acid) in the total FAs content was between 6 and 40%. All tested seeds (especially flax, chia, and hemp) have favorable values for their indexes of atherogenicity and thrombogenicity as well as the hypocholesterolemic/hypercholesterolemic ratio.

Pilot-Plant-Scale Extraction of Antioxidant Compounds from Lavender: Experimental Data and Methodology for an Economic Assessment

The techno-economic feasibility of lavender essential oil supercritical CO2 extraction was studied. The process was scaled up to a pilot plant, and the extraction yield, composition, and antioxidant potential of the extracts were evaluated at 60 °C and 180 bar or 250 bar, achieving a maximum yield of 6.9% and a percentage inhibition of the extracts of more than 80%. These results drove the development of a business plan for three scenarios corresponding to different extraction volumes (20, 50, and 100 L) and annual production. The SWOT matrix showed that this is a promising business idea. The COM was calculated and an investment analysis was performed. The profitability of this process was demonstrated by means of a financial analysis for 8 years, considering a selling price of 1.38 EUR/g for the extract from the 20 L plant and 0.9 EUR/g for industrial-scale plants, supported by the price curve. The sensitivity analysis showed that the price of the equipment was the factor that could most influence the robustness of the project and the business strategy, and the financial ratios evaluation resulted in a ROE value above 57% in all cases, indicating the economic attractiveness of the process.

One-step sustainable extraction of Silymarin compounds of wild Algerian milk thistle (Silybum marianum) seeds using Gas Expanded Liquids

This work reports the application of Gas Expanded Liquid (GXL) extraction to concentrate the flavonolignan fraction (silymarin) and taxifolin from Silybum marianum seeds, which have proven to be highly valuable health-promoting compounds. GXL using green solvents was used to isolate silymarin with the objective of replacing conventional methods. In one hand, the effect of different compositions of solvents, aqueous ethanol (20%, 50% or 80% (v/v)) at different CO2/liquid (25, 50 and 75%) ratios, on the GXL extraction was investigated. The obtained extracts have been chemically and functionally characterized by means of UHPLC-ESI-MS/MS (triple quadrupole) and in-vitro assays such as anti-inflammatory, anti-cholinergic and antioxidant. Results revealed that the operating conditions influenced the extraction yield, the total phenolic content and the presence of the target compounds. The best obtained yield was 55.97% using a ternary mixture of solvents composed of CO2:EtOH:H2O (25:60:15) at 40 °C and 9 MPa in 160 min. Furthermore, the results showed that obtained extracts had significant antioxidant and anti-inflammatory activities (with best IC50 value of 8.80 µg/mL and 28.52 µg/mL, respectively) but a moderate anti-cholinesterase activity (with best IC50 value of 125.09 µg/mL). Otherwise, the concentration of silymarin compounds in extract can go up to 59.6% using the present one-step extraction method without further purification, being silybinA+B the predominant identified compound, achieving value of 545.73 (mg silymarin/g of extract). The obtained results demonstrate the exceptional potential of GXL to extract high-added values molecules under sustainable conditions from different matrices.

Berberis Vulgaris Fruit: Determination of Phenolic Compounds in Extracts Obtained by Supercritical CO2 and Soxhlet Methods Using HPLC

Recently, research studies on nutraceutically important polyphenolic substances have attracted intensive attention. Berberis vulgaris is an important source of polyphenolic compounds and is often used in traditional medicine. In this study, the extraction of rutin and apigenin rich oil from Berberis vulgaris fruits was evaluated by supercritical carbon dioxide (Sc-CO₂) extraction method with and without co-solvent. As valuable antioxidants, rutin and apigenin content of extracts were analyzed by HPLC, and their amounts were maximized via parametric optimization. The rutin compound studied in this research has the potential to be a drug against the COVID-19 virus. The operating conditions were considered in the range of 35–70 °C temperatures, 140–240 bar of pressures, 0.35–1.00 mm of mean particle sizes, 3–7 l/min of CO₂ flow rates, and 0–8% w/w co-solvent. As a result of Sc-CO₂ extractions, the amounts of rutin and apigenin were found as 173 ± 14.97 µg/g and 2.91 ± 0.11 µg/g, respectively, with the 8% (w/w) co-solvent addition. The amounts of rutin and apigenin obtained by Soxhlet extractions were found as 208.81 ± 8.48 µg/g and 6.55 ± 0.21 µg/g, respectively. When the Sc-CO₂ method was compared with the Soxhlet method, it was seen that the fast and eco-friendly Sc-CO₂ method was an ideal extraction method by providing 76.89% rutin and 44.53% apigenin recoveries. As a result of this study, the maximum extraction conditions for rutin and apigenin were obtained as 160 bar, 40 °C, 0.35 mm particle size, 3 l/min CO₂, 8% w/w co-solvent ratio, and 120 min extraction period.

Extraction and quantification of some valuable flavonoids from pinecone of Pinus brutia via Soxhlet and Supercritical CO2 extraction: a comparison study

In this study, the extraction of oil from pinecone of Pinus brutia was evaluated by supercritical CO₂ (Sc-CO₂) and Soxhlet extraction methods. The quercetin, rutin and kaempferol (QRK) contents of oil were analyzed one by one via HPLC. The rutin compound investigated in this study has the potential to be a drug against the COVID 19 virus. SEM and BET analysis were performed to observe the structural change and increase in surface area after Sc-CO₂ extraction. The operating conditions were investigated in the range of 35–65 °C temperatures, 140–220 bar of pressures, 0.30–1.00 mm of mean particle sizes, 3–7 l/min of CO₂ flow rates, 0–8% w/w co-solvent and 30–150 min extraction periods. When the results obtained by the Sc-CO₂ method were compared with the results of Soxhlet extraction method, the maximum recovery of total QRK was found 4.18% in co-solvent-free studies and 30.94% in co-solvent-added Sc-CO₂ studies. Sc-CO₂ extraction results of Q, R, and K were found as 14.75 ± 1.08 µg/g, 14.23 ± 1.27 µg/g, and 15.70 ± 1.13 µg/g pinecone, respectively. Soxhlet extraction results of Q, R, and K were found as 36.43 ± 2.26 μg/g, 57.19 ± 3.81 μg/g, and 50.80 ± 2.79 μg/g pinecone, respectively. The maximum amount of QRK was found as 44.68 ± 2.89 μg/g pinecone by Sc-CO₂ method via adding 8% ethanol by mass and as 144.42 ± 5.39 μg/g pinecone by Soxhlet method. According to the reference Soxhlet method efficiency, the Sc-CO₂ extraction recovery was found as 30.94%.

Supercritical carbon dioxide extraction of plant phytochemicals for biological and environmental applications - A review

Recently, supercritical fluid CO₂ extraction (SFE) has emerged as a promising and pervasive technology over conventional extraction techniques for various applications, especially for bioactive compounds extraction and environmental pollutants removal. In this context, temperature and pressure regulate the solvent density and thereby effects the yield, selectivity, and biological/therapeutic properties of the extracted components. However, the nature of plant matrices primarily determines the extraction mechanism based on either density or vapor pressure. The present review aims to cover the recent research and developments of SFE technique in the extraction of bioactive plant phytochemicals with high antioxidant, antibacterial, antimalarial, and anti-inflammatory activities, influencing parameters, process conditions, the investigations for improving the yield and selectivity. In another portion of this review focuses on the ecotoxicology and toxic metal recovery applications. Nonpolar properties of Sc-CO₂ create strong solvent strength via distinct intermolecular interaction forces with micro-pollutants and toxic metal complexes. This results in efficient removal of these contaminants and makes SFE technology as a superior alternative for conventional solvent-based treatment methods. Moreover, a compelling assessment on the therapeutic, functional, and solvent properties of SFE is rarely focused, and hence this review would add significant value to the SFE based research studies. Furthermore, we mention the limitations and potential of future perspectives related to SFE applications.

Milk thistle flour effect on dough rheological properties

The influence of the addition of partially defatted milk thistle seed flour was studied by analyzing the rheological properties of dough in order to further exploit the functionality of partially defatted milk thistle flour in bakery products. The rheological properties of dough were monitored using Mixolab 2 (Chopin Technologies, France). A rheofermentometer F4 (Chopin Technologies, France) was used to check the dough fermentation, and for the baking trials wheat flour, rye flour, and milk thistle flour were kept in the portion: 50:50:0 (control flour); 50:45:5; 50:40:10 and 50:35:15. The addition of different milk thistle flour in the mixtures resulted in a difference in the viscoelastic properties of the dough. The results showed a weakening of the gluten network in all trial mixtures evaluated. The dough development time values of the control flour were 1.20 min, while an addition of milk thistle flour in portions of 5, 10, and 15% increased these values to 1.30 min, 1.90 min, and 2,80 min, respectively. In addition to higher dough development time values, all trial mixtures exhibited also higher stability (5.07 min; 6.25 min and 8.03 min), when compared to the control flour (4.63 min). The trial mixture with 15% milk thistle flour had different characteristics of gelatinization and retrogradation. The rheofermentometer measured the dough characteristics during proofing, and the trial mixtures with the addition of MTF had a retention volume at approximately the same level as the control flour (WRF). The Volscan profiler was used to determine the bread volume and other parameters. All breads had high volume and specific volume values and can be rated as good, with good porosity and ratio. Mixtures containing 5%, 10% and 15% milk thistle flour added to wheat flour + rye flour maintained rheological parameters within the recommended limits for good technological behavior and, consequently, good quality of bakery products. From all of the above data, it can be stated that, with regard to their baking characteristics, these flour mixtures fall into the category of flours suitable for bakery products.

The Synthesis Followed by Spectral and Calorimetric Evaluation of Stability of Human Milk Fat Substitutes Obtained from Thistle Milk and Lard

The central point of current investigations was the first time ever synthesis of modern substitutes of human milk fat followed by versatile evaluation of their oxidative properties. The enzymatic interesterification conducted at 70°C for 2, 4, and 6 hours, respectively, with milk thistle oil and lard blend as starting reactants was catalyzed by 1,3-specific lipase Lipozyme RM IM, obtained from Rhizomucor miehei. Pressure Differential Scanning Calorimetry (PDSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied to evaluate quality of products formed. Although PDSC curves showed lower oxidative stability of newly synthesized fats as compared to both starting materials separately, they can be considered adequate substitutes of human fat milk fat, as distribution of fatty acids in triacylglycerol molecules of substitutes obtained is much alike human milk fat itself, as resulted from analysis of GC data collected. Obvious changes in chemical structure of fats occurring during interesterification resulted in specific alterations in IR spectra of processed materials. Spectral data accompanied by PLS technique were successfully used for accurate determination of oxidative stability of new fats through indirect procedure, i.e., IR-PDSC-reference analysis of induction time. Additionally IR data exclusively, i.e., without any reference data, occurred powerfully in discrimination of human fat milk substitutes obtained.

Phyto-phospholipid complexes (phytosomes): A novel strategy to improve the bioavailability of active constituents

Although active constituents extracted from plants show robust in vitro pharmacological effects, low in vivo absorption greatly limits the widespread application of these compounds. A strategy of using phyto-phospholipid complexes represents a promising approach to increase the oral bioavailability of active constituents, which is consist of ‘‘label-friendly” phospholipids and active constituents. Hydrogen bond interactions between active constituents and phospholipids enable phospholipid complexes as an integral part. This review provides an update on four important issues related to phyto-phospholipid complexes: active constituents, phospholipids, solvents, and stoichiometric ratios. We also discuss recent progress in research on the preparation, characterization, structural verification, and increased bioavailability of phyto-phospholipid complexes.

Tunisian Milk Thistle: An Investigation of the Chemical Composition and the Characterization of Its Cold-Pressed Seed Oils

In this study, milk thistle seeds growing in different areas in Tunisia were cold pressed and the extracted oils were examined for their chemical and antioxidant properties. The major fatty acids were linoleic acid (C18:2) (57.0%, 60.0%, and 60.3% for the milk thistle seed oils native to Bizerte, Zaghouan and Sousse, respectively) and oleic acid (C18:1) (15.5%, 21.5%, and 22.4% for the milk thistle seed oils originating from Bizerte, Zaghouan and Sousse, respectively). High performance liquid chromatography (HPLC) analysis showed the richness of the milk thistle seed oils (MTSO) in α-tocopherol. The highest content was recorded for that of the region of Zaghouan (286.22 mg/kg). The total phenolic contents (TPC) of Zaghouan, Bizerte, and Sousse were 1.59, 8.12, and 4.73 Gallic Acid Equivalent (GAE) mg/g, respectively. Three phenolic acids were also identified (vanillic, p-coumaric, and silybine), with a predominance of the vanillic acid. The highest value was recorded for the Zaghouan milk thistle seed oil (83 mg/100 g). Differences in outcomes between regions may be due to climatic differences in areas. Zaghouan's cold-pressed milk thistle seed oil had a better quality than those of Bizerte and Sousse, and can be considered as a valuable source for new multi-purpose products or by-products for industrial, cosmetic, and pharmaceutical utilization.

Measurement and correlation study of silymarin solubility in supercritical carbon dioxide with and without a cosolvent using semi-empirical models and back-propagation artificial neural networks

The solubility data of compounds in supercritical fluids and the correlation between the experimental solubility data and predicted solubility data are crucial to the development of supercritical technologies. In the present work, the solubility data of silymarin (SM) in both pure supercritical carbon dioxide (SCCO₂) and SCCO₂ with added cosolvent was measured at temperatures ranging from 308 to 338 K and pressures from 8 to 22 MPa. The experimental data were fit with three semi-empirical density-based models (Chrastil, Bartle and Mendez-Santiago and Teja models) and a back-propagation artificial neural networks (BPANN) model. Interaction parameters for the models were obtained and the percentage of average absolute relative deviation (AARD%) in each calculation was determined. The correlation results were in good agreement with the experimental data. A comparison among the four models revealed that the experimental solubility data were more fit with the BPANN model with AARDs ranging from 1.14% to 2.15% for silymarin in pure SCCO₂ and with added cosolvent. The results provide fundamental data for designing the extraction of SM or the preparation of its particle using SCCO₂ techniques.

Supercritical CO₂ extraction of oil, fatty acids and flavonolignans from milk thistle seeds: Evaluation of their antioxidant and cytotoxic activities in Caco-2 cells

The optimal conditions of supercritical carbon dioxide (SC-CO2) (160-220 bars, 40-80 °C) technology combined with co-solvent (ethanol), to recover oil, flavonolignans (silychristin, silydianin and silybinin) and fatty acids from milk thistle seeds, to be used as food additives and/or nutraceuticals, were studied. Moreover, the antioxidant and cytotoxic activities of the SC-CO2 oil seeds extracts were evaluated in Caco-2 carcinoma cells. Pressure and temperature had a significant effect on oil and flavonolignans recovery, although there was not observed a clear trend. SC-CO2 with co-solvent extraction at 220 bars, 40 °C was the optimum treatment to recover oil (30.8%) and flavonolignans from milk thistle seeds. Moreover, linoleic (47.64-66.70%), and oleic (19.68-24.83%) acids were the predominant fatty acids in the oil extracts recovered from milk thistle under SC-CO2. In addition, SC-CO2 extract showed a high antioxidant activity determined by DPPH and ABTS tests. Cytotoxic activities of silychristin, silydianin and silybinin and the obtained SC-CO2 extract (220 bars, 40 °C) were evaluated against Caco-2 cells. The SC-CO2 extract inhibited the proliferation of Caco-2 cells in a dose-responsive manner and induced the highest percentage of mortality of Caco-2 cells (from 43 to 71% for concentrations from 10 up to 100 μg/ml of SC-CO2 oil seeds).