Subcritical water extraction of bioactive compounds from Radix Puerariae and optimization study using response surface methodology

Subcritical water extraction (SWE) of bioactive extracts from Radix Puerariae (RP) was firstly optimized by response surface methodology (RSM) and its extraction efficiency was compared with two traditional volatile isolation methods including hot water extraction (HWE) and ethanol reflux extraction (ERE). The optimal SWE parameters were as follows: extraction temperature of 141?°C, extraction time of 58?min, and liquid-solid ratio l of 23:1?mL/g. Under these conditions, yield of bioactive extracts was 28.9?±?0.2%, which was slightly higher than that obtained by ERE, and more than two-fold the value obtained by HWE respectively. Isoflavones and polysaccharide content in SWE was significantly higher than that of HWE and slight lower than that of ERE. The results indicated that SWE could be a productive and environmental friendly technique for extracting bioactive extracts from RP.     

Optimization of ultrasound-assisted extraction of bioactive compounds from B. forficata subsp. Pruinosa

Extracts containing bioactive compounds were obtained from Bauhinia forficata leaves by ultrasound-assisted extraction (UAE) with three different solvents (n-hexane, ethyl acetate, and ethanol) and were compared with those obtained by a conventional method (maceration). Box-Behnken experimental design was applied to examine and optimize the effect of the extraction temperature (40°C-60°C), power (20%-80%), and sample to solvent ratio (1:10 to 1:20 (w/v)) on the total phenolic content (TPC), total flavonoid content (TFC), and the ferric reducing antioxidant power (FRAP) of B. forficata leaf extracts. This experimental design generated second-order polynomial models, which accurately describe the experimental data, allowing the prediction of optimal conditions for the investigated responses. Optimal extraction was achieved under the following conditions: 80% power, temperature of 41°C, and a 1:20 sample to solvent ratio. Under these conditions, the experimental yield was 8.33 ± 0.32%, total phenolic content was 59.47 ± 0.71 mg GAE · g_extract⁻¹, total flavonoid content was 62.30 ± 3.38 mg QE · g_extract⁻¹, and the ferric reducing antioxidant power was 726.7 ± 15.7 μmol Fe(II)EQ · g_extract⁻¹, which were close to the predicted values, which validated the models. The major compounds found in B. forficata extracts were tocopherols, phytol, heneicosane, and β-Sitosterol.     

Extraction of Fatty Acids from <Emphasis Type="Italic">Boletus edulis</Emphasis> by Subcritical and Supercritical Carbon Dioxide

Mushrooms contain many valuable compounds such as fatty acids, carbohydrates, lycopene, lovastatin, trace elements etc. As they are currently valued for biologically active substances, and as high pressure carbon dioxide fluid extraction has been documented as an effective method for preparing bioactive products from plant materials, subcritical and supercritical carbon dioxide extraction of Boletus edulis mushroom was performed. In the extracts obtained, the fatty acids were determined. Response surface methodology (RSM) was applied to investigate the effect of pressure and extraction time on the extraction yield. The analysis of variance showed that pressure and extraction time had a significant effect on the extraction yield in both investigated process. The interaction between pressure and extraction time had a significant effect only in supercritical extraction process of B. edulis. Higher extraction yields have been obtained by subcritical carbon dioxide, and higher linoleic acid content has been determined in extracts obtained by supercritical carbon dioxide.     

Pressurized Liquid and Superheated Water Extraction of Active Constituents from Zingiber cassumunar Roxb. Rhizome

Active compounds, terpinene-4-ol and (E)-1-(3,4-dimethoxyphenyl) butadiene (DMPBD), displaying anti-inflammatory activity, were successfully extracted from the rhizome of Zingiber cassumunar Roxb. by pressurized liquid extraction (PLE) using methanol or ethanol and by superheated water extraction (SWE). Optimum conditions of both techniques were 1 mL/min flow rate and 5 min static time. The extraction temperature and dynamic time of the PLE and the SWE were 100°C 5 min and 140°C 20 min, respectively. Compared with water distillation, solvent sonication, and Soxhlet extraction, the PLE produced the highest amount of DMPBD and terpinene-4-ol, whereas the SWE and water distillation provided similar results.     

Impact of extraction parameters on chemical composition and antioxidant activity of bioactive compounds from Chinese licorice (Glycyrrhiza uralensis Fisch.) by subcritical water

An efficient extraction of bioactive compounds from licorice was developed using subcritical water. This study aimed at investigating the impacts of parameters on the composition and antioxidant property of the extract. It was found that total phenolics (TP), total flavonoids (TF), glycyrrhizic acid (GL), and antioxidant activity (TAA) were significantly affected by the time, pH, and temperature. The parameters of 20 min and pH 8 were preferred. The maximum values were obtained at 200°C (TF, TP), and 140°C (GL). At 280°C, TAA reached the highest level. Subcritical water extraction was confirmed to be an environmentally-friendly and efficient method.     

Antioxidant and Antimicrobial Activities of Echinacea (Echinacea purpurea L.) Extracts Obtained by Classical and Ultrasound Extraction

Antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by classical and ultrasound solvent extraction were compared. The dry aerial part of plant was extracted by 70% ethanol at a solid-to-liquid ratio of 1:10 (m/v) and 25°C. The extract obtained by classical solvent extraction contained 29% larger amounts of phenolic compounds and 20% higher content of flavonoids. 2,2-diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the values of EC50 were (34.16±0.65) μg·ml⁻¹ and (65.48±1.12) μg·ml⁻¹ for the extracts obtained by the classical and ultrasound extractions, respectively. The extracts, independent of the extraction technique applied, showed a considerable growth inhibition on Candida albicans and Saccharomyces cerevisiae, while no growth inhibition zones were observed for Aspergillus niger. The diameters of inhibition zone observed for all the microorganisms were larger for extracts obtained by classical extraction than those by ultrasound extraction.     

Subcritical water extraction of phenolic compounds from pomegranate (Punica granatum L.) seed residues and investigation into their antioxidant activities with HPLC–ABTS+ assay

Subcritical water extraction (SWE) of phenolic compounds from pomegranate seed residues (PSR) was performed. Total phenolic content (TPC) and antioxidant capacities of the extracts obtained at different temperatures were determined, and the individual antioxidant capacities were evaluated by coupling high performance liquid chromatography with ABTS radical reaction system (HPLC–ABTS⁺). The results showed that the optimum extraction time was 30 min, solid to water ratio was 1:40, and the highest TPC was obtained at 220 °C. The effect of extraction temperature on TPC was significant (p < 0.05), and TPC ranged from 651.7 to 4854.7 (mg/100 g DW) between 100 °C and 220 °C. HPLC–ABTS⁺ profiles revealed that nine compounds had antioxidant activity. Furthermore, the formation of Maillard reaction products during SWE was investigated, and the content of 5-hydroxymethylfurfural (5-HMF) was determined. The comparative study indicated that SWE was a promising technique for preparation of PSR phenolics.     

Optimization of subcritical water extraction of antioxidants from Coriandrum sativum seeds by response surface methodology

Subcritical water extraction (SWE) of antioxidants from Coriandrum sativum seeds (CSS) was optimized by simultaneous maximization of the total phenolics (TP) and total flavonoids (TF) yield and antioxidant activity, using IC₅₀ value. Box–Behnken experimental design (BBD) on three levels and three variables was used for optimization together with response surface methodology (RSM). Influence of temperature (100–200 °C), pressure (30–90 bar) and extraction time (10–30 min) on each response was investigated. Experimentally obtained values were fitted to a second-order polynomial model and multiple regression. Analysis of variance (ANOVA) was used to evaluate model fitness and determine optimal conditions. Moreover, three-dimensional surface plots were generated from employed mathematical model. The optimal SWE conditions obtained in simultaneous optimization were temperature of 200 °C, pressure of 30 bar and extraction time of 28.3 min, while obtained values of TP and TF yields and IC₅₀ value at this experimental point would be 2.5452 g GAE/100 g CSS, 0.6311 g CE/100 g CSS and 0.01372 mg/ml, respectively. Moreover, good and moderate linear correlation was observed between antioxidant activity (IC₅₀ value) and total phenolics content (R² = 0.965), and total flavonoids content (R² = 0.709) which indicated that these groups of compounds are responsible for antioxidant activity of C. sativum extracts.     

Fatty Acid Profile and Bioactive Compound Extraction in Purple Viper's Bugloss Seed Oil Extracted with Green Solvents

Oil extraction from seeds of purple viper's bugloss (Echium plantagineum) was carried out using different solvents (chloroform:methanol, n-hexane, ethanol, 2-propanol and ethyl acetate) at room temperature and also using Randall extraction. Extraction yields were calculated and oils were analyzed in terms of fatty acid profiles and distribution among lipid classes, total polyphenol content, oxygen radical absorbance capacity (ORAC) and phytosterol content. No considerable differences were found on fatty acid profiles and distribution in oils regardless of the solvent and temperature used for the extraction. However, ethanol combined with Randall extraction (85 °C for 1 hour) offered the best results in terms of total polyphenol content (20.9 mg GAE/100 g oil), ORAC (468.0 μmol TE/100 g oil), and phytosterol amount (437.2 mg identified phytosterols/100 g oil) among all assayed extraction methods. A higher extraction temperature led to significantly higher concentrations of bioactive compounds and ORAC values in the oil when ethanol or 2-propanol were used as extracting solvent, but that was not the case using n-hexane except for the concentrations of β-sitosterol and stigmasterol, which were significantly higher using Randall extraction than room temperature extraction with n-hexane. Ethanol is classified as a “green solvent,” and it could be considered a suitable option to produce oil from E. plantagineum seeds with a higher antioxidant capacity and bioactive compound concentration than the current commercial oil, which is usually extracted with n-hexane.     

Bioactive compounds and advanced processing technology: Phaleria macrocarpa (sheff.) Boerl,a review

Recent technological advances and the development of new methods has provided an opportunity to obtain highly purified natural bioactive compound extracts with potential for the treatment and prevention of human diseases. The use of hazardous and toxic solvents for the extraction and processing of bioactive compounds from plant materials is considered a problem for health, safety and environmental pollution. Advanced technology aims to increase production of the desired compounds and find an alternative to using toxic solvents in the extraction of bioactive compounds from plant materials. The ever growing interest in plant bioactive compounds and today's concerns about environment issues have led to an increased need for an efficient and green extraction method. This review is focused on the extraction of bioactive compounds from plants using advanced and environment‐friendly methods such as supercritical fluid extraction, microwave‐assisted extraction, ultrasound‐assisted extraction and similar techniques that can extract rapidly and free from organic residues. An updated overview of the bioactive compounds present in the plant Phaleria macrocarpa and its extraction, fractionation, purification and isolation is provided. The advantages and disadvantages of both conventional and non‐conventional extraction methods are also discussed in this review. © 2014 Society of Chemical Industry     

Optimizing Microwave‐Assisted Extraction Conditions to Obtain Phenolic‐Rich Extract from Chromolaena odorata Leaves

Phenolic compounds are secondary metabolites that are mainly responsible for different pharmacological activities of plant extracts. In this study, microwave‐assisted extraction (MAE) variables were optimized for the extraction of phenolic compounds from Chromolaena odorata leaves by using a Box‐Behnken design of response surface methodology. The concentration of polyphenols and functional characteristics of the extracts were identified by using liquid chromatography quadrupolar time‐of‐flight mass spectrometry and FTIR analyses, respectively. The obtained results indicated the MAE conditions for the optimal recoveries of the total phenolic content and total flavonoid content from C. odorata leaves. The results reveal that the C. odorata leaf is enriched with phenolic compounds.     

Recovery of water-soluble compounds from Ganoderma lucidum by hydrothermal treatment

The polypore fungus Ganoderma lucidum provides bioactive compounds containing several triterpenoids and polysaccharides that are reported to posses anti-cancerous and immunomodulatory properties. In this study, we determined the optimal conditions for extracting water-soluble polysaccharide compounds present in the ground form (3-mm particle size) of G. lucidum using water in subcritical conditions at distinct temperatures by two methods: batch-type subcritical water extraction and semi-continuous-type extraction. The optimal condition where solubility is higher to recover the maximum total amount of β-glucan from G. lucidum (0.44 mg/100 g dried sample) was determined to be 473 K at 10 MPa, with a water flow rate of 1 ml/min for 130 min. For batch-type and semi-continuous-type extractions, the best solubility was obtained at 473 K having efficiencies of 78.1% and 57.4%, and the highest extracted amounts of total WSOC were 328 and 241 mg WSOC/g dry sample, respectively.     

Effects of Different Drying Methods on Bioactive Compound Yield and Antioxidant Capacity of Phyllanthus amarus

Phyllanthus amarus (P. amarus) has been used as a herbal medicine, particularly for liver support, in many countries and its extracts have been shown to possess potent antioxidant and anticancer properties in vitro. The preparation of dried sample is crucial for further extraction and isolation of phytochemicals. In this study, the effects of six different drying methods (hot air, low-temperature air, infrared, microwave, sun, and vacuum drying) on the phytochemical yield and antioxidant capacity were determined to identify the optimal drying method for P. amarus. The results showed that different drying methods, as well as different drying conditions within each method, significantly affected phytochemical yield and antioxidant capacity of P. amarus extracts. Infrared drying at 30°C was the best method for both retention of bioactive compound yield and antioxidant capacity of P. amarus extract, with 12 compounds were identified. In contrast, low-temperature-air drying at 25°C not only required the longest drying time but also significantly reduced the levels of bioactive compounds and antioxidant capacity of P. amarus. Therefore, infrared drying at 30°C is suggested for drying P. amarus for subsequent assessment of bioactivity.     

Bioactive and Physicochemical Properties of Persimmon as Affected by Drying Methods

In this study, the effects of three different drying methods (freeze drying, oven drying, and vacuum oven drying) on bioactive (total phenolics, total flavonoids, condensed tannin and total hydrolyzable tannin contents, antiradical activity, and antidiabetic activity) and some physicochemical (dry matter, ash, water activity (a _w ), color, protein, hydroxymethylfurfural, glucose and fructose content) properties of persimmon fruit were investigated. Simplex lattice mixture design methodology was applied to determine the best solvent mixture for the extraction of phenolics from the samples. It was found that the mixture of acetone:water at the ratio of 50:50 % (v/v) was the best solvent mixture for the extraction. The persimmon powder sample obtained from freeze drying showed significantly (p <0.05) higher bioactivity values than oven- and vacuum-oven-dried samples. Antiradical activity changed significantly depending on the drying method employed and it was superior in freeze-dried samples than that of the other drying methods.     

Development of the ultrasonic conditions as an advanced technique for extraction of phenolic compounds from Eucalyptus robusta

This study is designed to develop ultrasonic conditions as an advanced technique for optimal recovery of phenolics and antioxidants from Eucalyptus robusta leaf and to evaluate the impact of solvents, temperature, sonication time and power on ultrasound-assisted extraction of these compounds. Temperature has the greatest impact on the total phenolic content (TPC) yield followed by time and power. A yield of 163.68 ± 2.13 mg GAE/g of TPC is observed using 250 W ultrasonic power for 90 min at 60°C with water. This study validates UAE as an efficient, green, and sustainable technique for extracting phenolics from E. robusta.     

超声强化亚临界水萃取脱脂葡萄籽中原花青素的动力学研究

根据质量衡算微分模型和运用Fick第一定律,建立了超声强化亚临界水萃取(USWE)和亚临界水萃取(SWE)原花青素的动力学模型,并通过对比这2个模型说明了超声对亚临界水萃取的强化作用。结果表明,Y=5.3974×(1-e~(-0.001 4t))和Y=5.2019×(1-e~(-0.001 2t))分别是USWE和SWE原花青素的动力学模型,并且这2个动力学模型都能很好地模拟萃取的过程;对比这2个模型方程的参数可知,超声能够加快葡萄籽内部原花青素的扩散及促进其解吸,因此能够对SWE起到强化作用。     

What defense doesSchouwia purpurea (Cruciferae) have against the desert locust?

A field study of the food eaten by solitary desert locusts was carried out in a winter breeding area in Mauritania. The food eaten, determined by the plant epidermis found in fecal pellets, was compared to the plant's availability in the habitat.Schouwia purpurea, well represented in the diets, was dominant at the study site. Adults had a preference forTribulus terrester. Growth and feeding on these two plants were compared. The high water content ofS. purpurea leaves limited the dry matter eaten and slowed down growth. Glucosinolates were separated and quantified by gas chromatography. There are 132mol/g dry matter in green leaves. In multiple choice tests, with paper disks, glucosinolate extracts were phagostimulant at a low concentration (21mol/g dry matter) and repulsive at a higher one (214mol/ g dry matter). Biting behavior onS. purpurea was recorded and analyzed on video. The importance ofSchouwia purpurea in desert locust habitats and its defenses is discussed.     

Extracts from pitanga (Eugenia uniflora L.) leaves: Influence of extraction process on antioxidant properties and yield of phenolic compounds

Different extraction processes were employed to extract the polyphenolic compounds from pitanga (Eugenia uniflora L.) leaves: a one-step process using water, ethanol or supercritical CO₂ as solvents, and a two-step process using supercritical CO₂ followed by either water or ethanol. The total polyphenolic compounds, total flavonoids and antioxidant activity were determined in all the extracts obtained. The process performance was evaluated with respect to three variables: global extraction yield, concentration and yield of both polyphenols and flavonoids in the extracts. For the one-step extraction, the results showed that the extraction yield increased with solvent polarity. For the two-step process, the results suggested that water was more efficient in extracting the phenolic compounds from E. uniflora when the matrix was previously extracted with scCO₂. With respect to the antioxidant activity, the ethanolic extracts obtained from both processes, using either the DPPH radical scavenging method or the β-carotene bleaching method, presented high antioxidant activities.     

亚临界水提取干花椒中精油的研究

采用亚临界水提取技术从干花椒中提取花椒精油.考察了原料颗粒度、提取时间、提取温度等因素对花椒精油提取得率的影响.确定亚临界水提取花椒精油的最佳工艺为:原料颗粒度0.5 mm、提取时间40 min、100～150℃的连续程序升温、压力5 Mpa,在此条件下花椒精油的提取得率为5.42%.同时,对亚临界水提取所得的花椒精油进行了抗氧化实验,并与常用抗氧化剂BHT和BHA进行了对比.结果表明,亚临界水提取所得的花椒精油具有较好的抗氧化性.用亚临界水提取技术提取花椒精油具有效率高、能耗低的优点.     

Extraction of phenolic compounds and anthocyanins from blueberry (Vaccinium myrtillus L.) residues using supercritical CO2 and pressurized liquids

This work explored the potential of subcritical liquids and supercritical carbon dioxide (CO₂) in the recovery of extracts containing phenolic compounds, antioxidants and anthocyanins from residues of blueberry (Vaccinium myrtillus L.) processing. Supercritical CO₂ and pressurized liquids are alternatives to the use of toxic organic solvents or extraction methods that apply high temperatures. Blueberry is the fruit with the highest antioxidant and polyphenol content, which is present in both peel and pulp. In the extraction with pressurized liquids (PLE), water, ethanol and acetone were used at different proportions, with temperature, pressure and solvent flow rate kept constant at 40 °C, 20 MPa and 10 ml/min, respectively. The extracts were analyzed and the highest antioxidant activities and phenolic contents were found in the extracts obtained with pure ethanol and ethanol + water. The highest concentrations of anthocyanins were recovered with acidified water as solvent. In supercritical fluid extraction (SFE) with CO₂, water, acidified water, and ethanol were used as modifiers, and the best condition for all functional components evaluated was SFE with 90% CO₂, 5% water, and 5% ethanol. Sixteen anthocyanins were identified and quantified by ultra performance liquid chromatography (UPLC).