Comparison of microwave and ultrasound-assisted extraction techniques for leaching of phenolic compounds from nettle

Extraction of polyphenols and essential oils from herbs with green extraction methods - An insightful review

The demand for polyphenols and essential oils (EOs) on the food market is high and grows every year. Its partially the result of the fact that these compounds can be used in formulation of clean label foods, a fast growing food sector. A significant share of polyphenols and EOs are extracted from herbs. The quality of the extracts is determined mainly by the extraction method. Conventional extraction techniques of phytochemicals are time-consuming, operate at high temperatures, and require usage of organic solvents and energy in large quantities. According to the United Nations Sustainability Development Plan, chemical processes should be replaced by green alternatives that would reduce the use of solvents and energy. Ultrasound-Assisted Extraction (UAE), Microwave-Assisted Extraction (MAE) and Cold Plasma-Assisted Extraction (CPAE) meets these criteria. The review shows that each of these techniques seems to be a great alternative for conventional extraction methods ensuring higher yields of bioactive compounds.

Comparative study of polyphenol extraction using physical techniques and water as a solvent: a sustainable approach for the valorization of apple pomace

Apples are among the most commonly cultivated fruits globally. Approximately 65% of annual apple production is transformed into apple juice concentrate generating a large amount of waste material named apple pomace, which includes seeds, skin, and other components. Disposing of apple by-products directly into the environment constitutes a source of environmental pollution due to its high-water content and easily fermentable nature. Apple pomace is rich in polyphenols that can be utilized as active components in cosmetic, nutraceutical, or pharmaceutical products. The present study aims to describe and compare different physical methods for the extraction of polyphenols from apple pomace. Water was used as the extraction solvent in thermal-stirred extraction (TSE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE). The best extraction conditions were identified in terms of solid to solvent ratio, temperature, power, and time through a kinetic study. The best extraction parameters were compared environmentally on a pilot scale through a life cycle assessment (LCA). All the results demonstrated the MAE is the best technique to extract polyphenol from apple pomace in terms yield and environmental impact proving that it is possible to transform waste into a sustainable source of bioactive ingredients.

Impact of thermal and nonthermal process intensification techniques on yield and quality of virgin coconut oil

Virgin coconut oil (VCO) is valued for its nutraceutical potential. The focus of this research was to assess the effect of selected thermal and nonthermal pre-treatments on the yield and quality of subsequently wet-extracted VCO. The fresh coconut cream was subjected to microwave heating (450 W, 2 min), ohmic heating (180 V, 5 min), ultrasonication (350 W, 10 min), or a pulsed electric field (40 kV cm-1, 12.32 min). The thick cream was separated, and VCO was obtained after a freeze-thaw process. The highest VCO yields (>93%) were observed in the cases of ultrasonicated and pulsed electric field-treated samples. A range of oil quality parameters, total phenolic content, and antioxidants were evaluated. Further, the fatty acid composition of all oils was studied. Observations from this research indicate that ultrasonication pre-treatment resulted in the best VCO yield and quality.

Evaluation of maceration, microwave, ultrasound-assisted extraction methods on free, esterified and bound phenolic profile and antioxidant activity of black rice

Black rice (Oryza sativa L.) is a rich source of phenolics and anthocyanins. It was aimed to investigate the effect of different extraction methods such as conventional solvent extraction, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) on antioxidant activity and phenolic profiling of black rice free, esterified, and bound phenolics fractions. Spectrophotometric methods were used to evaluate antioxidant activity and HPTLC was used for phenolics profiling. The highest content of % yield, total anthocyanin (TAC), total phenolic (TPC), and total flavonoid (TFC) contents were detected in MAE. It was also observed that antioxidant activity based on DPPH, ABTS, superoxide radical-scavenging and ferric reducing antioxidant power (FRAP) assays showed highest activity in MAE. Eight phenolic compounds were identified and quantified by a validated HPTLC method. MAE showed most abundant phenolic compounds. A significant positive correlation was established between % yield, total phenolic content, and total flavonoid content (p < 0.05) where a significant negative correlation was established between % yield, TPC, and TFC with IC50 of antioxidant activity (p < 0.05). Diverse phenolic contents and antioxidant activity were studied with different forms of phenolics with the different extraction methods. It designates that the extraction techniques had effects on the bioactive compounds as well biological properties.

Effect of Microwave and Ultrasound-Assisted Extraction on the Phytochemical and In Vitro Biological Properties of Willow (Salix alba) Bark Aqueous and Ethanolic Extracts

White willow (Salix alba) is a medicinal plant used in folk medicine. In this study, aqueous and ethanolic willow bark extracts were obtained via ultrasonic-assisted extraction (UAE) and microwave-assisted extraction (MAE), and analyzed regarding their phytochemical (total phenolics, phenolic acids, flavonoids, and tannins) content and in vitro biological properties (antibacterial and antifungal activity, acetylcholinesterase AChE inhibitory activity and anti-inflammatory effects). The highest phenolic, tannin, and flavonoid contents were found for willow bark extracts obtained via microwave-assisted extraction using ethanol as a solvent (SA-ME). The polyphenol load of all MAE and UAE extracts was higher when conventional solid-liquid extraction was applied (ρ < 0.05). The antioxidant capacities were stronger for microwave-assisted ethanolic extracts, with the lowest IC₅₀ values of 12 μg/mL for DPPH^• and a value of 16 μg/mL for ABTS•+, whereas the conventional extraction had the highest IC₅₀ values (22 μg/mL and 28 μg/mL, respectively). Willow bark extract showed antibacterial activity against Gram-positive bacteria S. aureus and P. aeruginosa. AChE inhibitory activity was dependent on the extraction method and solvent used, and the highest inhibition among samples was observed for SA-ME. Taken altogether, our findings suggest that willow (Salix alba) bark extract obtained via ethanolic microwave-assisted extraction is a phytochemical-rich resource with in vitro, anti-inflammatory, and AchE inhibitory properties and, therefore, potential multiple medicinal end-uses.

Sonoprocessing improves phenolics profile, antioxidant capacity, structure, and product qualities of purple corn pericarp extract

For the first time, purple corn pericarp (PCP) was converted to polyphenol-rich extract using two-pot ultrasound extraction technique. According to Plackett-Burman design (PBD), the significant extraction factors were ethanol concentration, extraction time, temperature, and ultrasonic amplitude that affected total anthocyanins (TAC), total phenolic content (TPC), and condensed tannins (CT). These parameters were further optimized using the Box-Behnken design (BBD) method for response surface methodology (RSM). The RSM showed a linear curvature for TAC and a quadratic curvature for TPC and CT with a lack of fit > 0.05. Under the optimum conditions (ethanol (50%, v/v), time (21 min), temperature (28 °C), and ultrasonic amplitude (50%)), a maximum TAC, TPC, and CT of 34.99 g cyanidin/kg, 121.26 g GAE/kg, and 260.59 of EE/kg, respectively were obtained with a desirability value 0.952. Comparing UAE to microwave extraction (MAE), it was found that although UAE had a lower extraction yield, TAC, TPC, and CT, the UAE gave a higher individual anthocyanin, flavonoid, phenolic acid profile, and antioxidant activity. The UAE took 21 min, whereas MAE took 30 min for maximum extraction. Regarding product qualities, UAE extract was superior, with a lower total color change (ΔE) and a higher chromaticity. Structural characterization using SEM showed that MAE extract had severe creases and ruptures, whereas UAE extract had less noticeable alterations and was attested by an optical profilometer. This shows that ultrasound, might be used to extract phenolics from PCP as it requires lesser time and improves phenolics, structure, and product qualities.

Comparison of Different Extraction Techniques and Conditions for Optimizing an HPLC-DAD Method for the Routine Determination of the Content of Chlorogenic Acids in Green Coffee Beans

Chlorogenic acids (CGAs) are the main phenolic compounds found in green coffee beans. They are receiving more attention recently due to the proven health and nutrition benefits they offer, in addition to their role as markers for coffee quality. A relatively large number of studies are reported in the literature that are based on the analysis of these compounds. However, very limited research is dedicated to the evaluation of the performance of the analytical methods used, particularly the extraction procedures. Therefore, this work was dedicated to the comparison of different extraction techniques and conditions in order to evaluate their influence on the measured content of the three main CGAs in green coffee beans, namely, chlorogenic acid (5-CQA), neochlorogenic acid (3-CQA) and cryptochlorogenic acid (4-CQA). Five simple extraction techniques with affordable equipment were compared in order to develop a routine method suitable for most analytical and food analysis laboratories. The compared extraction techniques provided relatively similar extraction efficiency for the three compounds. However, due to the merits of ultrasonic-assisted extraction as a fast, effective, green, and economical technique, this was selected by comparing the extraction variables and developing an optimized routine method. The extraction solvent, temperature, time, solid-to-solvent ratio, and grinding treatments were the variables that were investigated. The extraction solvent and the solid-to-solvent ratio were found to be the most influencing variables that may improve the extraction efficiency to up to 50%. Based on this thorough investigation, an optimized method for the routine determination of the content of chlorogenic acids in green coffee beans was developed. The developed method is simple, fast, and efficient in the extraction of the three main CGAs.

Antioxidant Extracts of Nettle (Urtica dioica) Leaves: Evaluation of Extraction Techniques and Solvents

Nettle (Urtica dioica) is a great source of bioactive compounds. The objective of this study was to evaluate the extraction techniques (ultrasound, without stirring, and stirring), solvents (methanol, water, and ethanol), and extraction times (1–4 h) to maximize antioxidant capacity of the Urtica dioica extracts. In the case of total phenolic content (TPC) and ABTS^•+ (2,2-azino-bis(3-etilbenzotiazolin)-6-sulfonic acid) free radical scavenging values, ultrasound extraction was the most efficient method, while the best results of DPPH^• (1,1-diphenyl-2-picrylhydrazyl) assay in nettle extracts (91.08%) were obtained using stirring extraction, water as solvent, and 3 h of extraction time. Based on the obtained mathematical models, the optimization revealed that the best extraction conditions were ultrasound treatment with water as solvent and an extraction time of 3.15 h, obtaining values of 21.9 mg eq gallic acid/g dried nettle for TPC, 71.8% for %ABTS^•+ and 86.6% for %DPPH^•. This work proves that aqueous extract of nettle leaves through the ultrasound technique is an important source of natural antioxidants and can be considered a potential alternative to synthetic antioxidants.

Research progress on extraction technology and biomedical function of natural sugar substitutes

Improved human material living standards have resulted in a continuous increase in the rate of obesity caused by excessive sugar intake. Consequently, the number of diabetic patients has skyrocketed, not only resulting in a global health problem but also causing huge medical pressure on the government. Limiting sugar intake is a serious problem in many countries worldwide. To this end, the market for sugar substitute products, such as artificial sweeteners and natural sugar substitutes (NSS), has begun to rapidly grow. In contrast to controversial artificial sweeteners, NSS, which are linked to health concepts, have received particular attention. This review focuses on the extraction technology and biomedical function of NSS, with a view of generating insights to improve extraction for its large-scale application. Further, we highlight research progress in the use of NSS as food for special medical purpose (FSMP) for patients.

Determination of Phenolic Compounds and Bioactive Potential of Plum (Prunus salicina) Peel Extract Obtained by Ultrasound-Assisted Extraction

Ultrasound-assisted extraction (UAE) of bioactive compounds from black plum peels was optimized by response surface methodology (RSM). Temperature (35-55°C), time (15-45 min), and ethanol concentration (50-90%) were selected as independent extraction parameters, whereas total anthocyanin content (TAC), total phenolic content (TPC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition were kept as response variables. The optimized extraction conditions were determined by RSM as extraction at 49°C for 37 min with 68% ethanol, which corresponded to TAC, TPC, and DPPH inhibition values of 5.42 ± 0.61 mg/g, 6.217 ± 0.76 mg GAE/g, and 89 ± 2.13%, respectively. Fourier-transform infrared spectrometer (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography mass spectrometer (GCMS) were used for chemical characterization of optimized plum peel extract (PPE). Optimized PPE was further evaluated for antibacterial, antioxidant, anticancer, and food preservation potential. PPE showed 92.31% DPPH inhibition with IC₅₀ value of 360.6 μg/ml. Optimized PPE extract was effective in the inhibition of cancer cell proliferation and migration, and IC₅₀ values were in the range 1.85-3.96 mg/ml for different human cancer cell lines. Major phenolics identified in PPE were ferulic acid (47.87 mg/kg), sinapic acid (9.15 mg/kg), quercetin (7.44 mg/kg), gallic acid (3.24 mg/kg), m-coumaric acid (2.59 mg/kg), and vanillic acid (1.12 mg/kg). PPE extract inhibited the growth of various foodborne bacterial pathogens and increased the shelf life of PPE coated fresh grapes. PPE due to antibacterial, anticancer, antioxidant, and food preservation potential can be used in developing functional food and pharmaceutical products.

Compendium of naringenin: potential sources, analytical aspects, chemistry, nutraceutical potentials and pharmacological profile

Naringenin is flavorless, water insoluble active principle belonging to flavanone subclass. It exhibits a diverse pharmacological profile as well as divine nutraceutical values. Although several researchers have explored this phytoconstituent to evaluate its promising properties, still it has not gained recognition at therapeutic levels and more clinical investigations are still required. Also the neutraceutical potential has limited marketed formulations. This compilation includes the description of reported therapeutic potentials of naringenin in variety of pathological conditions alongwith the underlying mechanisms. Details of various analytical investigations carried on this molecule have been provided along with brief description of chemistry and structural activity relationship. In the end, various patents filed and clinical trial data has been provided. Naringenin has revealed promising pharmacological activities including cardiovascular diseases, neuroprotection, anti-diabetic, anticancer, antimicrobial, antiviral, antioxidant, anti-inflammatory and anti-platelet activity. It has been marketed in the form of nanoformulations, co-crystals, solid dispersions, tablets, capsules and inclusion complexes. It is also available in various herbal formulations as nutraceutical supplement. There are some pharmacokinetic issue with naringenin like poor absorption and low dissolution rate. Although these issues have been sorted out upto certain extent still further research to investigate the bioavailability of naringenin from herbal supplements and its clinical efficacy is essential.

Optimization of Microwave-Assisted Extraction of Polyphenols from Lemon Myrtle: Comparison of Modern and Conventional Extraction Techniques Based on Bioactivity and Total Polyphenols in Dry Extracts

The aromatic herb lemon myrtle is a good source of polyphenols, with high antioxidant and antimicrobial capacity. In this study, the green extraction technique microwave-assisted extraction (MAE) was applied and the extraction parameters were optimized using response surface methodology (RSM) to maximize the extraction yield of phenolic compound and antioxidant properties. Then, it was compared with other popular novel and conventional extraction techniques including ultrasound-assisted extraction (UAE) and shaking water bath (SWB) to identify the most effective technique for extraction of phenolic compounds from lemon myrtle. The results showed that the MAE parameters including radiation time, power, and sample to solvent ratio had a significant influence on the extraction yield of phenolic compounds and antioxidant capacity. The optimal MAE conditions were radiation time of 6 min, microwave power of 630 W, and sample to solvent ratio of 6 g/100 mL. Under optimal conditions, MAE dry extract had similar levels of total phenolic compounds (406.67 ± 8.57 mg GAE/g DW), flavonoids (384.57 ± 2.74 mg CE/g DW), proanthocyanidins (336.54 ± 7.09 mg CE/g DW), antioxidant properties, and antibacterial properties against (Staphylococcus lugdunensis and Bacillus cereus) with the other two methods. However, MAE is eight-times quicker and requires six-times less solvent volume as compared to UAE and SWB. Therefore, MAE is recommended for the extraction of polyphenols from lemon myrtle leaf.

The multiple-response modeling of heat-assisted, microwave-assisted and subcritical water extraction on selected phenolics from traditional plant species Teucrium montanum

The growing popularity of integration of functional compounds into food and pharmaceutical products has greatly influenced the intense investigation of aromatic plants as its notable sources. One of the insufficiently explored plant species-Mountain Germander (Teucrium montanum)-may represent a prominent source of biologically active components-polyphenols. Hence, to maximally enhance their recovery, conventional (HAE) and non-thermal extraction methods-microwave-assisted extraction (MAE) and subcritical water extraction (SWE) were employed by using multiple response surface methodology (RSM). Optimization of temperature, solid-to-solvent ratio, and extraction time was evaluated by measuring total phenolic content (TPC) and antioxidant capacity (DPPH and ABTS assays), with the further estimation of the extraction efficiency of two selected phenylethanoid glycosides present in final extracts-verbascoside and echinacoside determined by HPLC analysis. The optimum HAE, MAE, and SWE extraction conditions with the highest measured dependent variables were, as follows: 100 °C, 0.5 g/50 mL and 30 min, 90 °C, 0.5 g/50 mL and 9 min, 200 °C, 0.5 g/50 mL and 15 min, respectively. Regarding examined phenylethanoid glycosides, HAE extract showed to be its richest source (16.64 mg/g dw) while SWE was estimated as at least suitable extraction technique (5.42 mg/g dw). In conclusion, this study outlined the most appropriate extraction technique and conditions for the recovery of selected phenolic compounds using RSM and gave closely insight into the antioxidative potential of valuable ethnomedicinal plant from the Balkan peninsula-Teucrium montanum.

Phenolic Profile, Antioxidant Capacity and Antimicrobial Activity of Nettle Leaves Extracts Obtained by Advanced Extraction Techniques

Nettle is a widely known plant whose high biological activity and beneficial medicinal effects are attributed to various bioactive compounds, among which polyphenols play an important role. In order to isolate polyphenols and preserve their properties, advanced extraction techniques have been applied to overcome the drawbacks of conventional ones. Therefore, microwave-assisted extraction (MAE) has been optimized for the isolation of nettle leaves polyphenols and it was compared to pressurized liquid extraction (PLE) and conventional heat-reflux extraction (CE). The obtained extracts were analyzed for their individual phenolic profile by UPLC MS² and for their antioxidant capacity by ORAC assay. MAE proved to be the more specific technique for the isolation of individual phenolic compounds, while PLE produced extracts with higher amount of total phenols and higher antioxidant capacity. Both techniques were more effective compared to CE. PLE nettle extract showed antimicrobial activity against bacteria, especially against Gram-negative Pseudomonas fragi ATCC 4973 and Campylobacter jejuni NCTC 11168 strains. This suggests that PLE is suitable for obtaining a nettle extract with antioxidant and antimicrobial potential, which as such has great potential for use as a value-added ingredient in the food and pharmaceutical industry.

Identity confirmation of anthocyanins in berries by LC-DAD-IM-QTOFMS

Rugged analytical methods for the screening and identity confirmation of anthocyanins require a dedicated sample preparation, chromatographic setup, and the reliable generation of multiple identification points to confirm identity against the wide range of phenolic compounds typically present in food, beverage, and plant material samples. To this end, combinations of spectroscopic and mass spectrometric detection are frequently employed for this application to provide higher confidence in the absence of authentic standards. In the present work, low‐field drift tube ion mobility (DTIM) separation is evaluated for this task using a LC–DAD–DTIM–QTOFMS method. DTIM‐MS allows accurate determination of collision cross sections (^DTCCS) for all analysed compounds as well as a precise alignment tool for reconciling fragment and precursor ions in data independent acquisition mode. The presented approach thereby allows for an anthocyanin screening method taking true advantage of all dimensions of the analytical platform: relative retention (RPLC), UV/VIS absorption spectrum, accurate mass, ^DTCCS_N2, and confirmed high‐resolution fragment ions. From the analysis of authentic standards and several berry samples primarily from the Vaccinium genus, Level 1 confirmation data for six anthocyanins from the cyanidin family, and Level 2 confirmation for a further 29 anthocyanins confirmed in berry samples is provided. The method and accompanying dataset provided as part of this work provides a means to develop anthocyanin screening methods using the ion mobility dimension as an additional alignment and filtering parameter in data independent analysis acquisition across any LC–IM–MS platform.

Optimization of ultrasound-assisted extraction of anthocyanins and bioactive compounds from butterfly pea petals using Taguchi method and Grey relational analysis

Ultrasound-assisted extraction (UAE) was used to extract anthocyanins, antioxidants and phenolic compounds from butterfly pea petals, as an alternative to traditional methods. Taguchi method with three factors: extraction time (30, 45, 60 min), temperature (40, 60, 80 °C) and liquid-solid ratio (5, 7.5, 10 mL distilled water/mg butterfly pea) was used to obtain the high extraction yield. Grey relational analysis was employed to convert multi-response problem into single response optimization. The high extraction efficiency could be achieved at optimal parameter condition using 45 min of extraction time, 40 °C and 10 ml distilled water/mg butterfly pea. Liquid-solid ratio exhibited the highest contribution for anthocyanin and total phenolic content. A high temperature of ultrasonication resulted in a negative effect on antioxidant capacity and total phenolic content. The findings from this study indicated that the UAE process optimization would be an efficient and sustainable method for the preparation of bioactive compounds from medical plants with saving of reaction time and cost in which extraction yields of antioxidant capacity and total phenolic content were also increased. The color response analysis results suggested that the gelatin film incorporated with butterfly pea extract can be potentially used as pH-indicator for detecting food spoilage for intelligent packaging.

Asian bullfrog (Rana tigerina) skin gelatin extracted by ultrasound-assisted process: Characteristics and in-vitro cytotoxicity

Impact of ultrasound-assisted process (UAP) on yield and characteristics of Asian bullfrog (Rana tigerina) skin gelatin was studied and the in-vitro cytotoxicity of the resulting frog skin gelatin was evaluated using CaCo-2, Raw264.7 and L929 cell lines. Different ultrasonication modes (5 min on-time with 25 min off-time (5/25) and 10 min on-time with 50 min off-times (10/50)) were implemented for different total ultrasonication times (10-60 min) during gelatin extraction at 55 °C. UAP could effectively augment yield and recovery of frog skin gelatin, compared with the typical process (without UAP). Different UAPs used affected characteristics and properties of gelatin differently. Increased total ultrasonication time increased color changes and turbidity of resulting gelatin and induced protein fragmentation, regardless of modes used. At the same total ultrasonication time, mode of 10/50 provided gelatin with higher hydroxyproline content and higher gel strength than 5/25 mode. Gelatin extracted by UAP with 10/50 mode for 60 min (FU) possessed high yield and good gel property. Gelling and melting temperatures and FTIR-spectra of FU were similar to those of gel from typical process. Based on in-vitro cytotoxicity toward different cell lines, frog skin gelatin could be used as biocompatible material, which could be safe for human consumption.

Ultrasound-Assisted Extraction of Bioactive Compounds from Annatto Seeds, Evaluation of Their Antimicrobial and Antioxidant Activity, and Identification of Main Compounds by LC/ESI-MS Analysis

This study evaluated the antimicrobial activity (i.e., against Bacillus cereus and Staphylococcus aureus) and the antioxidant activity (i.e., ABTS, FRAP, and DPPH) of annatto seeds extract obtained by ultrasound-assisted extraction. A response surface design with three levels such as pH (2-11), solvent concentration (50-96 %), seed-to-solvent ratio (1:2–1:10), and treatment time (0-30 min) was employed to determine the optimal experimental conditions. Thus, a pH of 7.0, seed-to-solvent ratio of 1:7, and treatment time of 20 min were selected as optimal rendering an extract having a 0.62% of bixin, 3.81 mg gallic acid/mg equivalent of polyphenol compounds (ABTS 1035.7, FRAP 424.7, and DPPH 1161.5 μM trolox/L), and a minimal inhibitory concentration against Bacillus cereus and Staphylococcus aureus of 32 and 16 mg/L, respectively. Further, the main bioactive compounds identified by LC/ESI-MS were bixin and catechin, chlorogenic acid, chrysin, butein, hypolaetin, licochalcone A, and xanthohumol.

Combined impact of pulsed electric field and ultrasound on bioactive compounds and FT-IR analysis of almond extract

The aim of this paper is to investigate the combined impact of pulsed electric field (PEF) and ultrasound (US) to evaluate the physicochemical, bioactive compounds and chemical structure of almond extract. Almond extract was first treated with PEF and then with US. Combined treatment (PEF-US) has attained the highest value of total phenolics, total flavonoids, condense tannins, anthocyanin contents and antioxidant activity in DPPH, reducing power and metal chelating activity than all other treatments. Among all those treatments, there was slightly visible difference in the color. Moreover, FT-IR spectra indicate that the effect of PEF-US on almond extract did not produce new carbonyl compounds, but led to the higher concentration of these compounds. This study demonstrated that the PEF-US could be useful for the extraction of bioactive compounds as well as improving the stability of volatile compounds.

Ultrasound assisted extraction of antioxidative phenolics from cashew (Anacardium occidentale L.) leaves

Optimization of ultrasound-assisted extraction (UAE) of antioxidative phenolics from the leaves of cashew (Anacardium occidentale L.) was carried out by response surface methodology along with the central composite design. Two independent variables were considered: amplitude (30-77%) and time (7-31 min). The highest extraction yield was 23.61% when the optimal extraction condition (77% amplitude for 31 min) was implemented. The extract containing total phenolic content of 579.55 mg GAE/g dry extract possessed radical scavenging activities and reducing power. The experiment values were in line with the predicted counterparts. Extract contained gallic acid, isoquercetin, tannic acid, quercetin, catechin, apigenin, hydroquinin, eriodictyol, and rutin. The extract with increasing levels inhibited AAPH-induced DNA damage to a higher extent. Thus, UAE was demonstrated to potentially increase the extraction efficacy of phenolics from cashew leaves and the extract could be applied as a natural antioxidant.

Comparison of Bioactive Compounds of Matricaria recutita Extracted by Ultrasound and Maceration and their Effects on Preventing Sunflower Oil During Frying

Methods:

Bioactive compounds including phenolic, tocopherol, flavonoid and tannins and antioxidant activity of the extracts were evaluated. Moreover, extracts obtained from ultrasound and maceration methods were added to sunflower oil without any antioxidants at level of 200, 500 and 800 ppm, after that samples were heated at 180°C. Oxidation of the samples were evaluated after 0, 4, 8, 12, 16, 20 and 24 hours by measuring Peroxide Value (PV), Conjugated Diene (CD), Iodine Value (IV), Carbonyl Value (CV), Total Polar Compounds (TPC), Oil Stability Index (OSI), Color Index (CI) and acid value (AV).

Results:

The result showed total phenol (42.90 mg gallic acid/g extract), tocopherol (120.46 &#181;g &#945; - tocopherol/ml extract), flavonoid (2.64 mg/100 g extract) and tannins (3.89 mg gallic acid/g extract) of ultrasound extracts were higher than maceration extracts. Antioxidant activity of the extract was evaluated by DPPH assay which indicated 800 ppm of the Matricaria recutita extracted by ultrasound was the highest radical scavenging ability.

Conclusion:

Result indicated both ultrasound and maceration extracts could increase the oil oxidative stability but could not increase compared to BHA. In most cases, the extract samples by ultrasound had a better effect on stabilizing of sunflower oil during frying.

Advances in extraction and analysis of phenolic compounds from plant materials

Phenolic compounds, the most abundant secondary metabolites in plants, have received more and more attention in recent years because of their distinct bioactivities. This review summarizes different types of phenolic compounds and their extraction and analytical methods used in the recent reports, involving 59 phenolic compounds from 52 kinds of plants. The extraction methods include solid-liquid extraction, ultrasound-assisted extractions, microwave-assisted extractions, supercritical fluid extraction, and other methods. The analysis methods include spectrophotometry, gas chromatography, liquid chromatography, thin-layer chromatography, capillary electrophoresis, and near-infrared spectroscopy. After illustrating the specific conditions of the analytical methods, the advantages and disadvantages of each method are also summarized, pointing out their respective suitability. This review provides valuable reference for identification and/or quantification of phenolic compounds from natural products.

Characterization of phenolics, amino acids, fatty acids and antioxidant activity in pulp and seeds of high altitude Himalayan crab apple fruits (Malus baccata)

Phytochemicals in fruits and vegetables have achieved immense significance owing to the increasing evidence which signifying their activity for antioxidant and prevention of chronic diseases. The amount of phloretin (88.39 µg mg^-1) and phloridzin (83.03 µg mg^-1) were found to be higher among other phenolics determined using UPLC. DPPH, ABTS⁺, metal chelating and ·OH radical assays were used to evaluate antioxidant activity. Malus baccata pulp portion showed higher antioxidant activity than seed portion. HPLC analysis for free amino acids showed that serine (9.06 µg mg^-1), alanine (8.03 µg mg^-1), tyrosine (10.33 µg mg^-1), and cysteine (76.86 µg mg^-1) were only detected in pulp portion while seed comprised of histidine (3.96 µg mg^-1) only. Seed portion was also determined for their fatty acid composition including palmitic acid (0.89%), ethyl palmitate (0.56%), methyl petroselinate (0.90%) and linolein (3.93%) using GC-MS analysis. HPAEC technique detected fructose and sucrose in a fair amount of 21 and 17.3 mg g^-1 in pulp, while 9.4 and 4.24 mg g^-1 in seed portion, respectively. The present study suggested that M. baccata fruit is a rich source of phenolic and other chemical components which can be used in food products and nutraceutical formulations.

Extraction techniques and analysis of anthocyanins from food sources by mass spectrometry: An update

This article reviews recent developments in methods of sample preparation and analytical methodologies for the quantification of anthocyanins and their extraction from food sources. Various methods for sample extraction and purification are highlighted and evaluated. The use of UV-diode array, along with improved liquid chromatography (LC) and mass spectrometry (MS) and/or the combination of both methods have facilitated the identification of analytes. The use of one-dimensional and two-dimensional HPLC has significantly improved resolution with a shorter amount of time. Other LC × LC combinations to improve orthogonality are also discussed. The most efficient anthocyanin extraction method from food sources is pressurized liquid extraction. Moreover, electrospray ionization (ESI) and MS²/time-of-flight are currently the most popular instruments used for identification of anthocyanins; being positive mode of ESI the most widely used procedure for anthocyanin identification. Several databases for mass spectrometry polyphenol identification have been described for reference.

Mixture Design and Doehlert Matrix for the Optimization of the Extraction of Phenolic Compounds from Spondias mombin L Apple Bagasse Agroindustrial Residues

In this study, we have determined, using RSM (mixture design and Doehlert matrix), the optimum values of the independent variables to achieve the maximum response for the extraction of total phenolic compounds from Spondias mombin L bagasse agroindustrial residues in order to preserve their antioxidant activity. The extraction of phenolic compounds, as well as their antioxidant capacity and the capacity to scavenge ABTS, was determined by the modified DPPH method at different periods of time, temperature, velocity of rotation and solvents concentration. We observed that the optimum condition for the highest antioxidant yield was obtained using water (60.84%), acetone (30.31%), and ethanol (8.85%) at 30°C during 20 min at 50 rpm. We have also found that the maximum yield of total phenolics was 355.63 ± 9.77 (mg GAE/100 g), showing an EC₅₀ of 3,962.24 ± 41.20 (g fruit/g of DPPH) and 8.36 ± 0.30 (μM trolox/g fruit), which were measured using DPPH and ABTS assays. These results suggest that RSM was successfully applied for optimizing the extraction of phenolics compounds thus preserving their antioxidant activity.

Content Determination of Phenylpropanoids and Enhancing Exercise Ability of Effective Fractions in Pedicularis densispica

BACKGROUND

Most researches were focused on chemical constituents and bioactivities of Pedicularis. However, there were a few reports on simultaneous determination of the series phenylpropanoids compounds in Pedicularis by High Performance Liquid Chromatography (HPLC).

OBJECTIVE

To establish an HPLC method for simultaneous determination of salidroside, verbascoside, iso-verbascoside, leucoseptoside A, jionoside D and martynoside in Pedicularis densispica (PD), and to assess the enhancing exercise ability of effective fractions of phenylpropanoids (EFP).

MATERIALS AND METHODS

The separation was performed on C18 column with step-wise gradient elution with water (A)-methanol (B) as the mobile phase at a flow rate of 1.0 mL/min, with detection wavelength at 275 nm (0-4 min) and 330 nm (4-40 min). The EFP were obtained from extracts of PD by resin gradient dilution. The enhancing exercise ability of EFP was exerted in exhaustive swimming and anoxia endurance tests in vivo.

RESULTS

The contents of six marker compounds had good linear relationship in the ranges of 2.10-8.40, 13.60-54.40, 0.93-3.72, 0.53-2.12, 1.50-6.00, 0.37-1.28, respectively, and the average recoveries of the six phenylpropanoids were all in the range of 98-103%. Total contents of phenylpropanoids in EFP were more than 60%. Three medicine groups of exhaustive swimming and anoxia endurance time were higher than those of the water group.

CONCLUSION

The analytical method is reliable, simple and accurate, and can be used for the comprehensive quality control of PD. This experiment suggests that PD has the effect of promoting the recovery and elimination of fatigue and improving the exercise capacity.

SUMMARY

A simple, practical and low-cost RP-HPLC method has been developed for the simultaneous determination of six marker phenylpropanoids in Pedicularis densispica.Three effective fractions of phenylpropanoids groups of exhaustive swimming and anoxia endurance time were higher than those of the water group.The separation was performed on C18 column with stepwise gradient elution with water-methanol. The enhancing exercise ability was exerted in exhaustive swimming and anoxia endurance tests in vivo.This plant has the effect of promoting the recovery and elimination of fatigue and improving the exercise capacity. Abbreviation used: PD: Pedicularis densispica, EFP: Effective fractions of phenylpropanoids, DAD: Diode array detector, HPLC: High performance liquid chromatography, LOD: Limits of detection, LOQ: Limits of quantification, RSD: Relative standard deviation, BV: Bed volumes.

Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers

This research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70% aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95% confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70% aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50% aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15- to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.

Optimization of ultrasound-assisted extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant (Solanum melongena L.) peel

The present study describes the extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant peel using ultrasonic treatments and methanol and 2-propanol as extraction solvents. The extraction yields were optimized by varying the solvent concentration, ultrasonic frequency, temperature and time of ultrasonic treatment. Box-Behnken design was used to investigate the effect of process variables on the ultrasound-assisted extraction. The results showed that for TPC extraction the optimal condition were obtained with a methanol concentration of 76.6%, 33.88 kHz ultrasonic frequency, a temperature of 69.4 °C and 57.5 min extraction time. For TMA the optimal condition were the following: 54.4% methanol concentration, 37 kHz, 55.1 °C and process time of 44.85 min.

A powerful approach to explore the potential of medicinal plants as a natural source of odor and antioxidant compounds

In this study an efficient and reliable method based on dynamic headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-qMS), was developed to establish the volatile metabolomic pattern of Thymus vulgaris L., Rosmarinus officinalis L. and Ruta chalepensis L. medicinal plants. The HS-SPME influencing parameters were investigated and the results indicated that the best extraction capability, was obtained using DVB/CAR/PDMS coating fiber at 40 °C for 45 min. Under optimal conditions, a total of 99 volatile metabolites were identified, including 53 terpenoids, 19 carbonyl compounds, 7 esters, 6 alcohols, among others. The main volatile metabolites identified in T. vulgaris include thymol (67 %), 3-octanone (9 %) and 1-octen-3-ol (7 %), while in R. officinalis the most dominant volatiles were eucalyptol (40 %), 2-decanone (20 %) and bornyl acetate (10 %). 2-Undecanone (53 %), (E)-2-octenal (28 %) and 2-nonanone (10 %) were the most relevant volatile metabolites identified in R. chalepensis. The results suggested that the HS-SPME/GC-qMS methodology is a powerful approach to establish the volatile metabolomic fingerprint of medicinal plants and providing a reliable tool for the complete characterization of these biologically active medicinal plants.