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The subcritical water extraction of Undaria pinnatifida (blade, sporophyll, and root) was evaluated to determine its chemical properties and biological activities. The extraction was conducted at 180 °C and 3 MPa. Root extracts exhibited the highest phenolic content (43.32 ± 0.19 mg phloroglucinol/g) and flavonoid content (31.54 ± 1.63 mg quercetin/g). Sporophyll extracts had the highest total sugar, reducing sugar, and protein content, with 97.35 ± 4.23 mg glucose/g, 56.44 ± 3.10 mg glucose/g, and 84.93 ± 2.82 mg bovine serum albumin (BSA)/g, respectively. The sporophyll contained the highest fucose (41.99%) and mannose (10.37%), whereas the blade had the highest galactose (48.57%) and glucose (17.27%) content. Sporophyll had the highest sulfate content (7.76%). Key compounds included sorbitol, glycerol, L-fucose, and palmitic acid. Root extracts contained the highest antioxidant activity, with IC50 values of 1.51 mg/mL (DPPH), 3.31 mg/mL (ABTS+), and 2.23 mg/mL (FRAP). The root extract exhibited significant α-glucosidase inhibitory activity with an IC50 of 5.07 mg/mL, indicating strong antidiabetic potential. The blade extract showed notable antihypertensive activity with an IC50 of 0.62 mg/mL. Hence, subcritical water extraction to obtain bioactive compounds from U. pinnatifida, supporting their use in functional foods, cosmetics, and pharmaceuticals is highlighted. This study uniquely demonstrates the variation in bioactive compound composition and bioactivities across different parts of U. pinnatifida, providing deeper insights. Significant correlations between chemical properties and biological activities emphasize the use of U. pinnatifida extracts for chronic conditions. [ABSTRACT FROM AUTHOR]

The subcritical water extraction of Undaria pinnatifida (blade, sporophyll, and root) was evaluated to determine its chemical properties and biological activities. The extraction was conducted at 180 °C and 3 MPa. Root extracts exhibited the highest phenolic content (43.32 ± 0.19 mg phloroglucinol/g) and flavonoid content (31.54 ± 1.63 mg quercetin/g). Sporophyll extracts had the highest total sugar, reducing sugar, and protein content, with 97.35 ± 4.23 mg glucose/g, 56.44 ± 3.10 mg glucose/g, and 84.93 ± 2.82 mg bovine serum albumin (BSA)/g, respectively. The sporophyll contained the highest fucose (41.99%) and mannose (10.37%), whereas the blade had the highest galactose (48.57%) and glucose (17.27%) content. Sporophyll had the highest sulfate content (7.76%). Key compounds included sorbitol, glycerol, L-fucose, and palmitic acid. Root extracts contained the highest antioxidant activity, with IC50 values of 1.51 mg/mL (DPPH), 3.31 mg/mL (ABTS+), and 2.23 mg/mL (FRAP). The root extract exhibited significant α-glucosidase inhibitory activity with an IC50 of 5.07 mg/mL, indicating strong antidiabetic potential. The blade extract showed notable antihypertensive activity with an IC50 of 0.62 mg/mL. Hence, subcritical water extraction to obtain bioactive compounds from U. pinnatifida, supporting their use in functional foods, cosmetics, and pharmaceuticals is highlighted. This study uniquely demonstrates the variation in bioactive compound composition and bioactivities across different parts of U. pinnatifida, providing deeper insights. Significant correlations between chemical properties and biological activities emphasize the use of U. pinnatifida extracts for chronic conditions.

Jackfruit is one of the major fruits cultivated in many Asian countries. Jackfruit seeds are generally disposed of into the environment, which causes an environmental concern that leads to biowaste accumulation. The seeds have excellent nutritional value, such as carbohydrates, protein, fats, minerals, and bioactive compounds. Bioactive compounds, such as phenolic, can be recovered from jackfruit seeds that could add value to the food and pharmaceutical industry. Thus, this study focused on utilizing subcritical water to extract the phenolic compounds from jackfruit seeds and correlate them with antioxidant activity (AA). The extraction of phenolic compounds was studied at different temperatures and extraction times. The highest total phenolic compounds (TPC) and AA were obtained by treating the jackfruit seed powder at 210 °C, 30 min, and 15% solid loading under subcritical water extraction (SWE) with 1.84 mg GAE/100 g (TPC) and 86% (AA). High correlation between the extracted TPC and AA of the jackfruit seed extracts was obtained (R2 = 0.96), indicating a significant positive relationship between TPC and AA. A higher amount of TPC was obtained via SWE as compared to Soxhlet extraction (1 h:0.53 mg GAE/100 g and 4 h:1.20 mg GAE/100 g). More pores were detected on the surface of the sample treated by SWE than using Soxhlet extraction. Thus, jackfruit seed extracts can be potentially beneficial in the fortification of fermented dairy or meat products. [ABSTRACT FROM AUTHOR]

Aim: In this work, the development for the first time of a green and efficient method to obtain bioactive extracts from Mentha x rotundifolia leaves has been investigated. Methods: The efficiency of three techniques [microwave-assisted extraction (MAE), subcritical water extraction (SWE), and ultrasound-assisted extraction (UAE)] was compared in terms of total phenolic content (TPC) and antioxidant activity [1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzthioazoline-6-sulfonic acid) (ABTS) assays]. Results: Under similar operating conditions, SWE outperformed MAE and UAE for providing M. rotundifolia extracts with improved antioxidant activity. Further in-depth optimization of the SWE method by means of a Box-Behnken experimental design showed 120°C, 5 min, 0.08 g dry sample: 1 mL water and 2 extraction cycles as optimal experimental parameters to provide the maximum yield of phenolics and the highest bioactivity. The application of the developed SWE method to M. rotundifolia leaves collected in different annuities (2014–2017) showed, in general, no significant differences regarding both composition and antioxidant capacity, as expected from plant samples grown in field under drip irrigation conditions. Conclusions: The SWE method here optimized is shown as a sustainable and efficient alternative for providing bioactive M. rotundifolia extracts with application as functional ingredients, natural preservatives, etc. in the food industry, among others.

Mango seed kernel (MSK) extract contains phytochemicals, bioactives, and fatty acids that are of interest to food and nutritional scientists. The subcritical water extraction process (SCWE) can be effective in extracting valuable bioactives from MSK. In this study, SCWE was investigated and optimized for the extraction of bioactives from MSK using Box–Behnken experimental design. The extract yield was examined as a function of various process variables, namely, solvent-to-feed (L/S) ratio, extraction temperature (T), and extraction time (t). Analysis of variance (ANOVA) for experimental results showed that extraction temperature was the most significant variable that impacted the extract yield. A maximum yield of 52.3% was obtained at optimized extraction conditions of L/S ratio = 20.7, T = 116.5 °C, and t = 45 min. Antioxidant assessment of the SCWE extract obtained at the optimized conditions showed higher total phenolic content (19.2 mg GAE/g), and DPPH and ABTS radical scavenging activity (>91%), than the extracts obtained by conventional hot water extraction and ultra-sound assisted extraction. Furthermore, an assessment of the MSK extract as a natural preservative showed that its inclusion (20% v/v) improved the oxidative stability of cow ghee with a par performance to synthetic butylated hydroxyanisole antioxidant (0.02% w/v). Thus, the study demonstrated SCWE as an effective green method for the production of MSK extract that could be applied for the preservation of oxidative food products. [ABSTRACT FROM AUTHOR]

Rosmarinic acid (RA), an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, is a potent radical scavenger, a chelator of prooxidant ions, and an inhibitor of lipid peroxidation. RA-containing extracts are widely used natural antioxidants in food products, and many herbal preparations and food supplements, containing RA, are marketed with claims of beneficial health effects. The current study investigated the effectiveness of subcritical water extraction (SWE) for the recovery of RA from lemon balm (Melissa officinalis), as a "green" alternative to conventional hydro-alcoholic extraction. Different durations (10 min and 20 min) and extraction temperatures (100 °C and 150 °C) were applied. Subcritical water applied at a temperature of 100 °C was equally efficient as 50% ethanol in extracting RA. However, the further elevation of temperature to 150 °C decreased RA content by up to 20% due to thermal degradation. The content of RA in dried extracts was between 2.36% and 5.55% and the higher temperature of SWE increased extract yield by up to 41%. The higher extraction yield resulted from the degradation of plant material by subcritical water as evidenced by the increased extraction and degradation of proteins, pectin, and cellulose. These results reveal that SWE is an efficient technology for the extraction of RA and other antioxidants from lemon balm at reduced extraction time and without the use of toxic organic solvents. Furthermore, by modification of SWE conditions, dry extracts with different purity and content of RA are obtained. These extracts could be used in the food industry as food antioxidants, or in the development of food supplements and functional foods. [ABSTRACT FROM AUTHOR]

The chestnut tree (Castanea sativa, Mill.) is a widespread plant in Europe whose fruits and wood has a relevant economic impact. Chestnut wood (CW) is rich in high-value compounds that exhibit various biological activities, such as antioxidant as well as anticarcinogenic and antimicrobial properties. These metabolites can be mainly divided into monomeric polyphenols and tannins. In this piece of work, we investigated a sustainable protocol to isolate enriched fractions of the above-mentioned compounds from CW residues. Specifically, a sequential extraction protocol, using subcritical water, was used as a pre-fractionation step, recovering approximately 88% of tannins and 40% of monomeric polyphenols in the first and second steps, respectively. The optimized protocol was also tested at pre-industrial levels, treating up to 13.5 kg CW and 160 L of solution with encouraging results. Ultra- and nanofiltrations were used to further enrich the recovered fractions, achieving more than 98% of the tannin content in the heavy fraction, whilst the removed permeate achieved up to 752.71 mg GAE/gext after the concentration (75.3%). Samples were characterized by means of total phenolic content (TPC), antioxidant activity (DPPH· and ABTS·), and tannin composition (hydrolysable and condensed). In addition, LC-MS-DAD was used for semiqualitative purposes to detect vescalagin/castalagin and vescalin/castalin, as well as gallic acid and ellagic acid. The developed valorization protocol allows the efficient fractionation and recovery of the major polyphenolic components of CW with a sustainable approach that also evaluates pre-industrial scaling-up. [ABSTRACT FROM AUTHOR]

Jackfruit is one of the major fruits cultivated in many Asian countries. Jackfruit seeds are generally disposed of into the environment, which causes an environmental concern that leads to biowaste accumulation. The seeds have excellent nutritional value, such as carbohydrates, protein, fats, minerals, and bioactive compounds. Bioactive compounds, such as phenolic, can be recovered from jackfruit seeds that could add value to the food and pharmaceutical industry. Thus, this study focused on utilizing subcritical water to extract the phenolic compounds from jackfruit seeds and correlate them with antioxidant activity (AA). The extraction of phenolic compounds was studied at different temperatures and extraction times. The highest total phenolic compounds (TPC) and AA were obtained by treating the jackfruit seed powder at 210 °C, 30 min, and 15% solid loading under subcritical water extraction (SWE) with 1.84 mg GAE/100 g (TPC) and 86% (AA). High correlation between the extracted TPC and AA of the jackfruit seed extracts was obtained (R2 = 0.96), indicating a significant positive relationship between TPC and AA. A higher amount of TPC was obtained via SWE as compared to Soxhlet extraction (1 h:0.53 mg GAE/100 g and 4 h:1.20 mg GAE/100 g). More pores were detected on the surface of the sample treated by SWE than using Soxhlet extraction. Thus, jackfruit seed extracts can be potentially beneficial in the fortification of fermented dairy or meat products.

Bioactive compounds of cornelian cherry (Cornus mas L.) fruits were extracted by green extraction methods including ultrasound-assisted (with three solvents: water, water/ethanol 50:50 v/v, and ethanol), supercritical fluid, and subcritical water extraction. Evaluation of the flavonoid and tocopherol compounds, β-carotene/linoleic acid test, and oil oxidative stability index assay were used to quantify the antioxidant power of cornelian cherry extracts. In β-carotene/linoleic acid test, a strong antioxidant activity of 85.84% was observed in the water/ethanol (50:50, v/v) ultrasound assisted extract, which also had the highest extraction yield and total flavonoid and tocopherol contents achieved by this method. In oil oxidative stability index assay, cornelian cherry extracts had higher resistance to oxidation than the tert-butylhydroquinone (TBHQ) synthetic antioxidant. Among the extracts, the longest induction time of 4.50 h belonged to water/ethanol (50:50, v/v) ultrasound-assisted extract. High and significant correlation was found between the extracted components and antioxidant capacity. This research demonstrated that the cornelian cherry fruit can be used as a potential source of natural antioxidant in food industry. [ABSTRACT FROM AUTHOR]

Hemerocallis citrina Borani as a low-cost vegetable, has various health benefits. However, the industry of H. citrina Borani is in the state of primary processing, with poor economic benefits. This study aimed to investigate the physicochemical properties, and the antioxidant activity of H. citrina Borani polysaccharide (HCBP) using subcritical water extraction (SWE) at different temperatures, to expand the value of H. citrina Borani. HCBP mainly composed of nine monosaccharides (glucose, galactose, rhamnose, fucose, mannose, arabinose, xylose, galacturonic acid, and glucuronic acid), among which the content of neutral sugar was higher and uronic acid was lower. HCBP contained glycosidic bond of β-configurations and trace quantities protein. The molecular weight of HCBP decreased with increasing temperature. Shear thinning occurred in HCBP with the increase of shear rate (0.01–1 s−1), and the apparent viscosity of HCBP decreased at higher temperature (150–160°C) with the increase continuously of shear rate (1–10 s−1), but almost remained constant at lower temperature (130–140°C). Scanning electron microscope showed that HCBP had rough surface, loose structure, obvious particle gap, and irregular shape. In addition, HCBP extracted at 160°C had strong FRAP activity, and HCBP extracted at 130 and 140°C had better ABTS radical scavenging activity. This study suggests that HCBP extracted by SWE could provide a cheap raw material as food thickening agent and natural antioxidants.

Rosmarinic acid (RA), an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, is a potent radical scavenger, a chelator of prooxidant ions, and an inhibitor of lipid peroxidation. RA-containing extracts are widely used natural antioxidants in food products, and many herbal preparations and food supplements, containing RA, are marketed with claims of beneficial health effects. The current study investigated the effectiveness of subcritical water extraction (SWE) for the recovery of RA from lemon balm (Melissa officinalis), as a “green” alternative to conventional hydro-alcoholic extraction. Different durations (10 min and 20 min) and extraction temperatures (100 °C and 150 °C) were applied. Subcritical water applied at a temperature of 100 °C was equally efficient as 50% ethanol in extracting RA. However, the further elevation of temperature to 150 °C decreased RA content by up to 20% due to thermal degradation. The content of RA in dried extracts was between 2.36% and 5.55% and the higher temperature of SWE increased extract yield by up to 41%. The higher extraction yield resulted from the degradation of plant material by subcritical water as evidenced by the increased extraction and degradation of proteins, pectin, and cellulose. These results reveal that SWE is an efficient technology for the extraction of RA and other antioxidants from lemon balm at reduced extraction time and without the use of toxic organic solvents. Furthermore, by modification of SWE conditions, dry extracts with different purity and content of RA are obtained. These extracts could be used in the food industry as food antioxidants, or in the development of food supplements and functional foods.

Tea industry generates many by-products which could be used to produce and incorporate bioactive tea extracts (TE) into nutraceuticals, cosmetics and/or clinical applications. However, sensibility to external factors is a major disadvantage hindering its utilization. This study deals with the implementation and characterization of suitable biopolymer delivery systems based on starch, carrageenan or alginate, as microencapsulation, to stabilize and protect TE through innovative thin-carbohydrate-coated formulations. TE were spray-dried and microencapsulated in recycled carrier materials (alginate, carrageenan or starch). Product yields varied from 55 to 58%. High microencapsulation and loading efficiencies were achieved (60–93% and 65–84%, respectively). Antioxidant capacity varied from 32 to 46 g Trolox/100 g extract, within different carrier-systems; which also showed promising rheological and UV-protective properties when transformed into gels. Total phenolic content, particle-size distribution, HPSEC-analysis, SEM-analysis and FTIR-analysis were also performed. In sum, this paper characterizes and discusses the high potential of these recycled carbohydrate-coated microparticles for future applications. [ABSTRACT FROM AUTHOR]

In recent years, a growing number of studies have demonstrated that protein hydrolysates have interesting functional properties and a strong antioxidant capacity, amongst other important bioactivities. In this work, the potential of subcritical water (ScW) to efficiently extract bioactive protein hydrolysates contained in brown crab shell residues was evaluated. Aiming at maximizing the extraction of the target molecules, the impact of operating temperature (150, 200, and 250 °C), solid/liquid ratio (1:5, 1:10, and 1:15 g/mL), and heating rate (3 and 6 °C/min) on ScW extraction performance was assessed. Extracts were then evaluated in terms of total protein content, Maillard reaction products formation, free amino acid profile, and antioxidant potential through oxygen radical absorbance capacity assay. Results have shown that, although an increase in operating temperature allowed a significant increase in global extraction yields, there was a slight decrease (approximately 1.4-fold) in the extraction selectivity towards proteins. Nevertheless, higher temperatures enabled the production of extracts with a higher antioxidant potential, possibly due to an increase of smaller peptides/free amino acids and Maillard reaction products. Therefore, the study reported herein reinforces that ScW represents a viable sustainable alternative extraction media for the recovery of protein hydrolysates from shellfish biomass, with potential to be used as ingredients in industrial applications. [ABSTRACT FROM AUTHOR]

Soursop (Annona muricata L.) seeds, which is a residue obtained from juice agro-industries, were subjected to supercritical fluid extraction (SFE) and subcritical water extraction (SWE) in single or combined mode to extract the potential value-added compounds. Different extraction methods were evaluated in terms of the extraction yield, phenolics content, antioxidant activity (DPPH, ABTS, and FRAP), and Maillard reaction products. The extracts were analyzed using SEM, GC-MS, and LC-MS/MS techniques. The temperature and a combination of high-pressure techniques positively affected the overall results (SFE + SWE), affording nonpolar and polar extracts rich in phenolics and antioxidant compounds. SEM analysis showed that the use of SFE caused modifications in the cell wall, and the oil fraction was rich in fatty acids. Twenty-nine compounds associated with soursop seed extracts were detected for the first time using LC-MS/MS, showing the potential of the raw material as well as promoting resource re-utilization in circular economy.

Livestock manure solids have a significant content of protein which is not only underutilized, but prone to runoff and eventual breakdown to reactive nitrogen compounds, contributing to eutrophication. We have developed a novel subcritical water extraction process to extract protein from livestock manure solid without the use of any chemical. We demonstrate the versatility of our new process to control the molecular weight distribution of the extracted protein hydrolysate. The antioxidant activity of protein hydrolysate has been examined through Oxygen Radical Absorbance Capacity Assay. The results have shown that our protein hydrolysate had its antioxidant capacity against the peroxyl radical similar to that of vitamin E and exhibited almost 7 times as strong inhibition against the hydroxyl radical as vitamin E. We also evaluated the nutritional value of our PH by analyzing its amino acid composition and the MW distribution through amino acid analysis, SDS-PAGE, and MALDI-TOF mass spectroscopy.

In the present study, subcritical water was used for extraction of bioactive compounds of Symphytum officinale root. Temperature (120–200 °C), extraction time (10–30 min) and HCl concentration in extraction solvent (0–1.5%) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols, flavonoids and antioxidant activity of obtained extracts. The application of optimal conditions (200 °C, 25.6 min and 0.0075%) provided extracts rich in total phenols and flavonoids and high antioxidant activity. Results also demonstrated that subcritical water extraction showed significant advantages for recovery of comfrey root bioactive compounds comparing to maceration and ultrasound-assisted extraction techniques. In addition, subcritical water extracts of S. officinale root are the promising sources of compounds with antioxidant, ACE inhibition, and antiproliferative properties and could potentially be used for production of new pharmacologically-active formulations.

In this work valorization of the underexploited industrial solid residue generated after agar extraction from Gelidium sesquipedale was studied by using subcritical water in a semicontinuous fix-bed reactor. First, a complete characterization of this by-product was carried out, determining up to 21% (w/w) of protein content (for a nitrogen factor of 4.9) with high content of essential amino acids, 37% (w/w) of carbohydrate fraction and high amount of ash, 22% (w/w). The effect of temperature, in the range from 129 to 200 °C, and flow rate, in the range from 2 to 6 mL min−1, on protein and carbon fraction extraction/hydrolysis was studied. At constant flow rate of 2 mL min−1, a maximum in the protein extraction was achieved at 185 °C. Higher temperatures led to degradation of protein or its hydrolysis products. Free amino acids release followed the same trend as the protein fraction. The most temperature sensitive amino acids, as determined by gas chromatography (EZ:faast Phenomenex), were serine and aspartic and glutamic acids. As a consequence, the selectivity towards non-polar amino acids increased by working at high severity factors. A Pearson correlation between antioxidant capacity of the collected extracts with the bioactive compounds determined in the extracts (total polyphenolic compounds –TPC-, peptides and free amino acids) was established, being stronger for TPC. The ash content in the solid residue after treatment steadily increased with temperature due to non-solubilization being possible its application in agriculture as fertilizers. [ABSTRACT FROM AUTHOR]

Subcritical water extraction (SWE) was employed for the extraction of bioactive constituents from Crocus sativus corms. The extraction temperature and time, as the principal experimental variables, were investigated in the range of 100–180 °C and 10–30 min respectively. A central composite face-centered design (CCD) showed 180 °C and 21.99 min were the optimum conditions for maximizing the antioxidant activity and total phenolic content (TPC) of the extract. Under the optimized conditions, the amount of TPC, ferric reducing antioxidant power (FRAP) and the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) IC50 were 816.34 mg gallic acid/100 g dry matter, 1138.95 mM, and 61.67 mg kg−1, respectively. Gas chromatography–mass spectrometry (GC–MS) analysis showed dodecane (20.043%) is one of the main non-polar constituents in the saffron corm (SC) SWE extract (SC-SWE extract). Microdilution and disc diffusion methods revealed a degree of activity against Staphylococcus aureus and Escherichia coli. The results exhibited that SWE is a practical technique to extract bioactive constituents with antioxidant and antibacterial properties from Crocus sativus corms. [ABSTRACT FROM AUTHOR]

The efficient and green extraction of oil– and water–soluble essences from natural products is a key step in producing bioactive compounds and value–added chemicals. Herein, two components with different polarities from Semen richonsanthis were extracted using static subcritical water extraction technology at different temperatures (80–160°C), extraction times (5.0–30.0 min), and water loadings (2.0–6.0 mL). The oil–soluble and water–soluble components were measured by HPLC and phenol–sulfuric acid method, respectively. The optimum conditions of 3,29–dibenzoylkarounidiol (0.102±0.004%) and polysaccharides (0.462 ±0.021%) were obtained at 130°C, 10 min and 4.0 mL water loading. Compared with ultrasonic and heating reflux extraction, the three extracts were assessed by antioxidant activity against 2,2–diphenyl–1–picrylhydrazyl and the cytotoxicity towards HeLa cells. Overall results showed that the activities of subcritical water extracts are more promising than the other extracts and can be safely applied to pharmaceutical and nutraceutical products. Lastly, the morphological changes were evaluated by SEM which indicated subcritical water have a destructive effect on the cell wall. [ABSTRACT FROM AUTHOR]

Subcritical water extraction and molecular dynamics simulation were performed to investigate mangiferin and antioxidant extraction from Mahkota Dewa fruits at different operating temperatures. The mangiferin yield and antioxidant activity were analyzed using high‐performance liquid chromatography and 2‐diphenyl‐1‐picrylhydrazyl assay method, respectively. The diffusivity and intermolecular interactions were determined by mean squared displacement (MSD) and radial distribution function (RDF) analysis, respectively. The temperature exerts a momentous effect on mangiferin yield and antioxidant activity of the extract. The MSD result showed an increment in diffusivity coefficient of mangiferin with temperature. The RDF analysis revealed hydrogen bonding formations between mangiferin and water through OH2O••HMR4(OH1) interaction that plays a role in the extraction process. [ABSTRACT FROM AUTHOR]

In the present study, subcritical water was used for extraction of bioactive compounds of Symphytum officinale root. Temperature (120-200 °C), extraction time (10-30 min) and HCl concentration in extraction solvent (0-1.5%) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols, flavonoids and antioxidant activity of obtained extracts. The application of optimal conditions (200 °C, 25.6 min and 0.0075%) provided extracts rich in total phenols and flavonoids and high antioxidant activity. Results also demonstrated that subcritical water extraction showed significant advantages for recovery of comfrey root bioactive compounds comparing to maceration and ultrasound-assisted extraction techniques. In addition, subcritical water extracts of S. officinale root are the promising sources of compounds with antioxidant, ACE inhibition, and antiproliferative properties and could potentially be used for production of new pharmacologically-active formulations. [ABSTRACT FROM AUTHOR]

The present study was conducted to develop subcritical water extraction (SWE) of Echinacea purpurea flowers. The influence of temperature and extraction time on quality of extracts considering total phenols content, total flavonoids content, antioxidant capacity and extraction yield, was determined. Optimized extraction parameters for maximised investigated responses were as follows: 147.56 °C and 8.43 min. The experimental values agreed with the values predicted, thus indicating the adequacy of central composite experimental design for modelling the SWE of bioactive compounds from E. purpurea. Results of the study also highlighted the potential application of E. purpurea subcritical water extracts as a source of valuable bioactive compounds. [ABSTRACT FROM AUTHOR]

Essential of replacing natural compounds with synthetic ones has become more important. Participation of phenolic compounds in natural plant sources in antioxidant and antimicrobial activities caused to determine not only total phenolic and tocopherol compounds, but also antiradical capacity via three various methods such as free radical scavenging DPPH, ferric reducing power FRAP and beta carotene bleaching power of maceration (SO) and subcritical water extraction (SWE) methods of cinnamon extract further than antimicrobial properties of it on both gram negative and positive bacterium. Results proved various amounts with significant difference of total phenolic and tocopherol compounds of two various extraction methods. While SO-extract contained higher phenolic compounds, higher total tocopherol compounds were measured in SWE-extract. Results of all three antioxidant assays indicated that both extracts proved different antioxidant power comparing with TBHQ. The lowest concentration of SO-extract (500ppm) had a bactericide effect on all investigated bacterium in this work. Whereas, 500 ppm of SWE-extract was able to effect only Staphylococcusaureus as a gram positive bacteria, but not others. [ABSTRACT FROM AUTHOR]

We extracted and hydrolyzed bioactive flavonoids from C. unshiu peel using subcritical water (SW) in a semi-continuous mode. The individual flavonoid yields, antioxidant and enzyme inhibitory activities of the SW extracts were analyzed. The extraction yields of hesperidin and narirutin increased with increasing temperature from 145 °C to 165 °C. Hydrothermal hydrolysis products (HHP), such as monoglucosides (hesperetin-7-O-glucoside and prunin) and aglycones (hesperetin and naringenin) were obtained in the SW extracts at temperatures above 160 °C. The sum of hesperidin and its HHP in the SW extracts was strongly correlated with antioxidant activities, whereas the contents of hesperetin and naringenin were strongly correlated with enzyme inhibitory activities. Hesperetin exhibited the highest antioxidant activities (2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, ferric-reducing antioxidant power, and oxygen radical absorbance capacity), whereas hesperetin-7-O-glucoside exhibited the highest enzyme inhibitory activities (angiotensin-I converting enzyme (ACE) and pancreatic lipase (PL)). Naringenin exhibited the highest enzyme inhibitory activities (xanthine oxidase and α-glucosidase). PMFs (sinensetin, nobiletin, and tangeretin) also exhibited relatively high inhibitory activities against ACE and PL. This study confirms the potential of SW for extracting and hydrolyzing bioactive flavonoids from C. unshiu peel using an environmentally friendly solvent (water) and a shorter extraction time.

Lycium barbarum fruit (Goji or wolfberry) is widely used as a functional food as well as an herb in Chinese medicine. The polysaccharides of L. barbarum (LBPs) are well-known for immunomodulation and antioxidant activities. This study evaluated the yields, properties and bioactivities of LBPs extracted from L. barbarum fruit by different methods including hot water (HWE 100 °C), ultrasonic water (UWE 30–40 °C), subcritical water (SWE 110 °C), and ultrasound-enhanced subcritical water extraction (USWE 110 °C). The total LBP yield (80 min extraction followed by ethanol precipitation) was the highest from USWE (14% w/w) and the lowest from HWE (7.6%). The LBP from USWE also showed the highest protein (27.9%) and phenolic content (5.3%, w/w), and the highest antioxidant activities (scavenging radicals by DPPH and trolox equivalent antioxidant capacity assays; ferric reducing power). It also showed the highest immunoactivities in activating the phagocytosis and NO production of RAW264.7 macrophages. USWE was proven the most efficient method for extraction of LBPs. Temperature and ultrasound were two chief factors affecting the extraction yield, chemical properties and bioactivities of LBP.

In the present work, antioxidant compounds from Teucrium montanum were extracted by subcritical water. The influence of extraction temperature and pressure on antioxidant activity of extracts has been investigated in terms of extraction yield (EY), total phenolic content (TPC), and DPPH-radical scavenging activity (DPPH-RSA) and ferric reducing antioxidant power (FRAP). Additionally, the compounds responsible for the antioxidant activity were identified and quantified by high performance liquid chromatography (HPLC). The highest EY (42.63%), TPC (174.61 ± 4.09 mg GAE/g DE) and antioxidant activity by DPPH-RSA (176.23 ± 8.76 mg TE/g DE) and FRAP (141.71 ± 5.21 mg AAE/g DE) were seen in extracts obtained at temperature of 160 °C and pressure of 10 bar. HPLC analysis revealed that naringin and gallic acid were the principle antioxidant compounds in subcritical extracts. According to the results, SWE has a great potential in exploitation of natural sources of bioactive compounds and production of pharmacologically-active fractions. [ABSTRACT FROM AUTHOR]

Turkey is the world leader in hazelnut production and export. Large amount of wastes such as shell, husk and prunings are produced during the agriculture and processing of hazelnuts. Treatment of hazelnut wastes using an eco-friendly technology and production of valuable products can add value to those. In this study, total phenolic content (TPC) and total antioxidant activity (TAA) in the liquors of hazelnut wastes from subcritical water extraction at different temperature (150-200°C) and time (0-45 min.) values were analyzed. Generally, higher yields were obtained by subcritical water extraction compared to solvent extraction. As temperature increased, TPC and TAA obtained from shells increased. Increase in time did not have a statistically significant effect at 180°C; however, TPC increased significantly with time at 190°C (P <0.05). The combined effect of temperature and time on hazelnut shells was examined in a single variable by calculating logarithmic value of severity factor (log Ro). TPC (905.3-2115.7 mg GAE/100 g shell) and TAA (8163.9-12261.5 mg TE/100 g shell) increased with log Ro. Turkey is the world leader in hazelnut production and export. Large amount of wastes such as shell, husk and prunings are produced during the agriculture and processing of hazelnuts. Treatment of hazelnut wastes using an eco-friendly technology and production of valuable products can add value to those. In this study, total phenolic content (TPC) and total antioxidant activity (TAA) in the liquors of hazelnut wastes from subcritical water extraction at different temperature (150-200°C) and time (0-45 min.) values were analyzed. Generally, higher yields were obtained by subcritical water extraction compared to solvent extraction. As temperature increased, TPC and TAA obtained from shells increased. Increase in time did not have a statistically significant effect at 180°C; however, TPC increased significantly with time at 190°C (P <0.05). The combined effect of temperature and time on hazelnut shells was examined in a single variable by calculating logarithmic value of severity factor (log Ro). TPC (905.3-2115.7 mg GAE/100 g shell) and TAA (8163.9-12261.5 mg TE/100 g shell) increased with log Ro. [ABSTRACT FROM AUTHOR]

Subcritical water extraction (SWE) could be an eco-friendly excellent alternative to the traditional extraction method for extracting red ginseng ( Panax ginseng C.A. meyer). In this study, the bioactive components of red ginseng were analyzed by varying the temperature (150–200 °C) and extraction time (5–30 min) in SWE. The maximum yields of ginsenoside Rg3 and Rh2, which have 2 hydroxyl groups (200 °C), appeared at a higher temperature compared to ginsenoside Rg2 and Rh1, which have 3 hydroxyl groups (150 °C), in SWE. The antioxidative properties were maximized at 200 °C for 20 min (total phenolic content = 49.55 ± 1.03 mg gallic acid equivalent/g red ginseng, maltol content = 1.19 ± 0.01 mg/g red ginseng, the Maillard reaction product level = 1.14 ± 0.08, and the DPPH-free-radical scavenging activity = 39.97 ± 0.16%). Extracts of red ginseng from SWE all had higher ginsenoside concentrations and antioxidative properties compared to extracts prepared using traditional extraction methods, including ethanol, hot water, and methanol. [ABSTRACT FROM AUTHOR]

Subcritical water extraction (SWE) has become a popular green extraction technique for the isolation of different classes of compounds from natural matrices. Low price, safety and green character of water, good yields of target compounds and reduced energy consumption, make this technique favorable for potential industrial applications. The purpose of this study was to evaluate antioxidant, antimicrobial and cytotoxic activity of four medicinal plants traditionally used in folk medicine of Serbia. Black mulberry ( Morus nigra L.), wall germander ( Teucrium chamaedrys L.), wild geranium ( Geranium macrorrhizum L.) and comfrey ( Symphytum officinale L.) were extracted by subcritical water at different temperatures. Antioxidant activity of the extracts was defined by conventional spectrophotometric methods, such as the total phenolic content (TPC), DPPH-radical scavenging activity (DPPH-RSA), ferric reducing antioxidant power (FRAP) and total antioxidant capacity (TAC) assessed by a DNA-based sensor. Additionally, the main phenolic compounds contributing to the antioxidant activity of the produced extracts were also identified and quantified by high performance liquid chromatography with diode array detection (HPLC-DAD). Antimicrobial properties of extracts were evaluated against eight microbial strains. Furthermore, the cytotoxic activity was observed for two human cancer cell lines and a cell line derived from murine fibroblast. [ABSTRACT FROM AUTHOR]

Subcritical water extraction (SWE) was employed in order to obtain high valuable extracts from wild garlic ( Allium ursinum ). The influence of temperature (120–200 °C), extraction time (10–30 min) and added acidifier, HCl (0–1.5%) on extraction process was investigated. Analysis of variance was used to determine the fitness of the model and optimal process parameters for SWE, in order to maximize extraction yield, total phenolic compounds and total flavonoids content, and antioxidant activity. The optimal conditions for SWE were determined at temperature of 180.92 °C, extraction time of 10 min, and added acidifier at 1.09%. An insight into the development of Maillard reaction products during SWE was provided through measurement of 5-hydroximethylfurfural(5-HMF) and furfural (F)in all obtained extracts. No influence of 5-HMF and F on antioxidant activity was observed. Using HPLC-DAD, kaempferol derivates were identified as the major phenolic compounds in extract obtained at optimal condition. [ABSTRACT FROM AUTHOR]

Subcritical water extraction, also called green technology, is used to extract phytochemicals from different plants and foods. Orange peel, a valuable by-product in the food industry, is a rich source of antioxidant compounds such as phenolics, β-carotene and essential oils. In this study, determination of the relationship between antioxidant activities and phenolic compounds in subcritical water extracts from orange peel was aimed. For this aim, The Ferric Reducing Antioxidant Assay (FRAP), The Cupric Reducing Antioxidant Capacity (CUPRAC) and DPPH radical scavenging activity (IC50) of subcritical water extracts were measured. Total phenolic contents were statistically significant (P <0.01) correlated as r²=0.98 and 0.92 with FRAP and CUPRAC values in subcritical water extracts obtained from orange peel. Also, total flavonoid contents were statistically significant (P <0.01) correlated as r²=0.97 and 0.93 with FRAP and CUPRAC values in subcritical water extracts from orange peel. Besides, total phenolic and total flavonoid content in subcritical water extracts from orange peel were statistically significant (P <0.01) correlated as r²=-0.68 and -0.70 with IC50 value, respectively. [ABSTRACT FROM AUTHOR]

Mandarin peel, which discarded as by-product at large amounts during fruit juice production, is a valuable source of antioxidant compounds in the food industry. The aim of this study was to investigate the effect of extraction temperature and static extraction time on antioxidant activity and phenolic compounds during subcritical water extraction. The antioxidant activity of subcritical water extracts were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay as IC50, ferric ion reducing antioxidant power (FRAP) and total antioxidant potential assay using Cu(II) complex as an oxidant (CUPRAC). As the IC50 value of the subcritical water extracts obtained from mandarin peel decreased 40.8 times, FRAP and CUPRAC values increased 66.9 and 34.2 times with increasing extraction temperature from 50 to 180°C for 5 min, respectively. Besides, total phenolic content (TPC) of subcritical water extracts increased 4.9 and 5.0 times from 50 to 180°C for 5 and 15 min whereas, 9.6 and 9.9 times increase was obtained for total flavonoid content (TFC) in the subcritical water extracts, respectively. [ABSTRACT FROM AUTHOR]

Subcritical water extraction (SWE) and microwave-assisted water extraction (MAE) have been investigated for the effective recovery of antioxidant compounds from Plantago major and Plantago lanceolata . Subcritical water extractions were carried out at several temperatures ranging from 25 to 200 °C and two different extraction procedures have been used: individual and sequential extractions. For comparison purposes, microwave-assisted water extraction was carried out at the same extraction temperatures. The Plantago species’ extracts were characterized in terms of total phenol content by using the Folin-Ciocalteu assay. Antioxidant activity was measured using two different in vitro assays, namely DPPH radical scavenging and TEAC (trolox equivalents antioxidant capacity). The identification of bioactive components was carried out using liquid chromatography coupled to diode array and mass spectrometry (HPLC-DAD-MS). Results indicate the presence of various polyphenolic compounds such as plantamajoside, verbascoside and isoverbascoside and demonstrate that the extraction temperature had a positive influence on both extraction yield and antioxidant activity of the attained extracts. SWE and MAE demonstrated its usefulness as green extraction methods compared to traditional protocols and thus can be successfully employed to obtain bioactive extracts from Plantago species for their use in cosmetic and food industries. [ABSTRACT FROM AUTHOR]

The management of cashew nut shells in Vichada, Colombia, is a matter of deep concern for local farmers since this non-edible biomass accumulates in the farms and generates pollution. This study explores the valorization of cashew nut shells through supercritical fluid, subcritical water, and Soxhlet extraction techniques to recover valuable compounds for the formulation of a cosmetic cream. The profile of metabolites of the extracts was studied, and the cytotoxicity was determined. Supercritical fluid extraction showed high selectivity to phenolic compounds (134 ± 4.6 mg/mL). Soxhlet and subcritical water extractions recovered sugars and organic acids. It was demonstrated that including cashew extracts in the cream formulation resulted in similar rheology behavior compared to a commercial cream. The use of non-conventional extraction techniques to obtain natural compounds provides a novel perspective on the valorization of this biomass which could increase the circularity of the cashew agroindustry in Colombia. [Display omitted] • Cashew nut shell extracts contain phenols, fatty acids, organic acids, and sugars. • Supercritical fluid extraction showed a high affinity to phenolic compounds. • Cosmetic cream formulation with natural cashew extracts is a novel field of research. [ABSTRACT FROM AUTHOR]

[Display omitted] • Subcritical water extraction (SWE) of agroindustrial acerola by-product. • The temperature increase affected the results obtained by the SWE process. • UPLC untargeted analysis detected 16 metabolites in fresh and dry acerola by-product extracts. • SWE was able to extract ascorbic acid, kaempferol, quercetin, and isorhamnetin. • Strategy of studying different moisture contents in SWE showed promising results. The untargeted metabolomics approach was used to compare the chemical profiles of acerola (Malpighia emarginata DC.) pomace extracts. The effect of drying the raw material before subcritical water extraction (SWE) at different temperatures on the yield, phenolic content, and in vitro antioxidant activity was evaluated. The results were compared with those obtained via Soxhlet and the findings suggest that SWE saves time (15 min) and solvent for extracting valuable components as compared to Soxhlet (6 h). An increase in temperature significantly improved the extraction yield (23.9 to 33.4 %), phenolic content (119.1 to 362 mgGAEg−1), and antioxidant activity, and higher values were obtained with SWE as compared to Soxhlet. The most abundant compounds detected by UPLC-ESI-QTOF-MS were ascorbic acid, kaempferol, quercetin, and isorhamnetin. The investigation of different moisture contents in the SWE showed promising results for eliminating the drying operation, saving time and energy, and obtaining highly concentrated phenolic-rich by-products. [ABSTRACT FROM AUTHOR]

In this work, subcritical water extraction (SWE) of polyphenols from sage ( Salvia officinalis L.) herbal dust was optimized by simultaneous maximization of total phenols (TP) and total flavonoids (TF) yields, as well as maximized antioxidant activity, determined by DPPH, ABTS and reducing power assay. Sage herbal dust, discarded as by-product from filter tea factory, was used as raw material for extraction. Three level, three variables, Box-Behnken experimental design (BBD) with response surface methodology (RSM) was used for optimization of SWE. Temperature (X 1 : 120–220 °C), extraction time (X 2 : 10–30 min) and HCl concentration in extraction solvent (X 3 : 0–1.5%) were investigated as independent variables. Experimentally obtained values were fitted to a second-order polynomial model, and multiple regression analysis and analysis of variance (ANOVA) were used to determine model fitness and optimal conditions. The optimal SWE conditions for simultaneous maximization of TP, TF and antioxidant activity were temperature of 201.5 °C, extraction time of 15.8 min and pure water as extraction solvent, while predicted values of TP, TF, IC 50 , TEAC and EC 50 at this experimental point were 7.98 g GAE/100 g DW, 4.93 g CE/100 g DW, 13.38 μg/mL, 38.34 mM Trolox/100 g DW and 41.66 μg/mL, respectively. Results suggested that SWE provided significant advantages in terms of polyphenols yield, comparing to maceration, and that herbal dust from filter tea factory could be potentially utilized as good raw material for extraction of valuable bioactive compounds. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) was employed to optimize subcritical water extraction (SWE) of spent coffee grounds (SCG) with emphasis on the yield of total phenolics and radical scavenging capacities on 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS + ) and 1,1-diphenyl-2-picrylhydrazyl (DPPH + ). The analysis involved three variables: temperature (160–180 °C), time (35–55 min) and solid-to-liquid ratio (14.1–26.3 g/L). The optimal conditions for total phenolic compounds (86.23 mg GAE/g), antioxidant activity in terms of ABTS + (81.38 mmol TE/100 g) and DPPH + (42.13 mmol TE/100 g) scavenging activities were predicted to be in ranges of 160-180 °C/37.9–55.0 min/14.1 g/L. The verified TPC (88.34 mg GAE/g), antioxidant activity on ABTS + (88.65 mmol TE/100 g) and DPPH + (38.28 mmol TE/100 g) based on superimposing contour plots (179 °C, 36 min, and 14.1 g/L) were in good agreement with the predicted data obtained under optimal conditions. 3- O -caffeoylquinic acid, 4- O -caffeoylquinic acid and 5- O -caffeoylquinic acid were found to be the major contributor to the antioxidant activities of SCG extract. [ABSTRACT FROM AUTHOR]

Lycium barbarum fruit (Goji or wolfberry) is widely used as a functional food as well as an herb in Chinese medicine. The polysaccharides of L. barbarum (LBPs) are well-known for immunomodulation and antioxidant activities. This study evaluated the yields, properties and bioactivities of LBPs extracted from L. barbarum fruit by different methods including hot water (HWE 100 °C), ultrasonic water (UWE 30–40 °C), subcritical water (SWE 110 °C), and ultrasound-enhanced subcritical water extraction (USWE 110 °C). The total LBP yield (80 min extraction followed by ethanol precipitation) was the highest from USWE (14% w/w) and the lowest from HWE (7.6%). The LBP from USWE also showed the highest protein (27.9%) and phenolic content (5.3%, w/w), and the highest antioxidant activities (scavenging radicals by DPPH and trolox equivalent antioxidant capacity assays; ferric reducing power). It also showed the highest immunoactivities in activating the phagocytosis and NO production of RAW264.7 macrophages. USWE was proven the most efficient method for extraction of LBPs. Temperature and ultrasound were two chief factors affecting the extraction yield, chemical properties and bioactivities of LBP. [ABSTRACT FROM AUTHOR]

In this work, extracts of chamomile ( Matricaria chamomilla L.) ligulate flowers obtained by Soxhlet, microwave-assisted, ultrasound-assisted and subcritical water extraction were compared in respect to their bioactivity, more specifically antioxidant, antimicrobial and cytotoxic activity. In all obtained extracts, the content of total phenols and flavonoids was determined, indicating significant total extraction yields (49.70%) and total phenol content (151.45 mg ECA/ml) in water extracts obtained under moderate subcritical conditions. By applying DPPH and Reducing Power Test subcritical water extraction showed superior free-radical scavenging ability in comparison to other investigated extraction techniques. Microbial properties of extracts were examined using eight selected indicator strains and for all extracts minimum inhibitory concentrations were in the range between 19.53 and 312.50 μg/ml. Subcritical water extracts showed the highest activity against Escherichia coli (MIC = 39.10 μg/ml) and Aspergillus niger (MIC = 39.10 μg/ml). Cytotoxic effects of extracts were examined on human rhabdomyosarcoma cells (RD), cell line derived from human cervix carcinoma Hep2c (HeLa) and cell line derived from murine fibroblast (L2OB). On all three tested cell lines, subcritical water extracts demonstrated much better antitumor properties in comparison to extracts obtained by other techniques, with IC 50 values for Hep2c, RD and L2OB cells 30.54, 20.54 and 19.65 μg/ml, respectively. [ABSTRACT FROM AUTHOR]

Onion ( Allium cepa L.) peels were extracted by ethanol, hot water and subcritical water (SW) extraction and their antioxidant activities were evaluated. Extraction yields of SW extraction were 4-fold higher than ethanol extraction. However, the ethanol extraction increased the total phenolics contents (327.5 mg GAE/g extract) and flavonoids contents (183.95 mg QE/g extract) in the onion peel extract. The onion peel extracts by ethanol extraction showed greater DPPH radical scavenging activities and greater antioxidant activities determined by ferric thiocyanate assay than those by hot water extraction and SW extraction at 165°C. Antioxidant activity of onion peel extract by SW extraction at 110°C was similar to that of ethanol extraction. HPLC profiles revealed that SW extraction at lower temperature (110°C) increased the concentration of quercetin. These results demonstrated that the onion peel extracts produced by SW extraction technique have great potential as a source for useful antioxidant. [ABSTRACT FROM AUTHOR]