Green extraction process of tannins obtained from Moroccan Acacia mollissima barks by microwave: Modeling and optimization of the process using the response surface methodology RSM

The effect of extraction conditions on polyphenols contents and condensed tannins by microwave-assisted extraction (MAE) was studied for the first time to our knowledge. Moroccan barks of Acacia mollissima was used to extract phenolic compounds. The variables studied are the following: power extraction, time extraction and solvent nature. Five powers extraction were tested: 150 W, 250 W, 300 W, 450 W and 600 W. A significant effect of power extraction on the extractable nature was proved by ANOVA and Student test. The yields were also affected by time extraction. Different solvent (water, ethanol, methanol and ethyl acetate) were tested to evaluate the best extraction solvent according to the extractable nature. Highest polyphenols contents were obtained with methanol. The proportion of this solvent, time extraction and power extraction were optimized using the response surface methodology (RSM). A face-centered composite design (FCCD) was applied to evaluate the effects of these variables on the polyphenols and condensed tannins contents. For each experiment, the extraction yield, the total polyphenolic contents and the condensed tannins contents were quantified using colorimetric essays. The extracts were characterized by their reactivity to formaldehyde and reverse phase high pressure liquid chromatography (RP-HPLC). The highest polyphenols content was obtained at 156 W using 80% of methanol during 5 min. For condensed tannins, the highest content of cyanidin was obtained at 182 W using 20% of methanol during 3.66 min. RSM applied in MAE, permitted to develop green extraction process of polyphenols and tannins extracted, using lower microwave power and methanol proportion with a shortest time extraction and in the same time improve the quantity of extractables obtained from renewable natural resource.     

Development of natural deep eutectic solvent (NADES) based on choline chloride as a green solvent to extract phenolic compound from coffee husk waste

Natural deep eutectic solvent (NADES) has been successfully used as a green alternative for the extraction of polyphenolic compounds (phenolic) from coffee husk waste. The NADES was produced by combining b the choline chloride compound with glycerol, glucose, citric acid, and proline. Furthermore, it was characterized using FTIR with the appearance of a widening hydroxyl peak at a wave number of 3277–3364 cm^?1, indicating the presence of hydrogen bond interactions. The results showed that the best composition of NADES solvent was choline chloride and proline ratio of 1:1, providing an extraction yield of 5.88 mg GAE g^?1 with a polyphenol concentration in NADES of 294.02 mg/L. Optimum extraction conditions were carried out with the addition of 50 % water, extraction time of 30 min, and the ratio of sample weight to solvent volume (1:10), obtaining a yield of 6.16 mg GAE g^?1 and the concentration of polyphenols in NADES of 307.81 mg/L. The effect of temperature on the extraction process can increase the extract yield under conditions at 80 °C with a yield of 10.07 mg GAE g^?1 and a polyphenol concentration of 671.4 mg/L. The chlorogenic acid group of polyphenolic compounds was identified using HPLC at a retention time of 3.454 min with a concentration of 63 mg/L. Based on the results, NADES can be use as a green solvent for extracting active compounds from coffee husk waste. These extract can safely be applied to various medicinal and food products.     

Ultrasound-assisted extraction of Cordyceps cicadae polyphenols: Optimization,LC-MS characterization,antioxidant and DNA damage protection activity evaluation

In this study, ultrasound-assisted extraction of polyphenols from C. cicadae was optimized by response surface methodology (RSM). The optimized conditions were determined as extraction time of 39 min, liquid-to-solid ratio of 1:29 g/mL, extraction temperature of 69 °C and ethanol concentration of 55% with a yield of 21.9 mg gallic acid equivalent/g dry weight. Four resins were used for polyphenol purification. D101 resin had the highest ratio of adsorption and was further applied in polyphenol purification test. A total of 19 different phenolic compounds were identified by LC-MS, including 12 phenolic acids and 7 organic acids. In addition, C. cicadae polyphenols displayed higher antioxidant activity in vitro and anti-aging activity of C. elegans in vivo. Lastly, C. cicadae polyphenols showed the potential to protect DNA from oxidative damage. Overall, our results suggest that polyphenols from C. cicadae may be considered as novel sources of anti-oxidation, anti-aging and recommended as reagents to protect DNA from oxidative damage in food and pharmaceutical industries.     

Thermal stability of total phenolic compounds and antioxidant activities of jaboticaba peel: Effect of solvents and extraction methods

The objective was to evaluate the effect of temperature on the degradation of total phenolic compounds (TPC) and antioxidant activities (AA), in addition to the effects of solvents (water, ethanol and methanol) and methods of maceration and ultrasound in the extraction of polyphenols from the jaboticaba peel powder (JPP). The thermal stability of the TPC and AA (DPPH, FRAP and ABTS) from JPP at different temperatures (90, 110 and 130 °C) was monitored over time (0–360 min). The effect of solvents (water, ethanol and methanol) and methods of maceration and ultrasound on the extraction of polyphenols from JPP was also evaluated. The best conditions for extracting polyphenols were quantified by HPLC. After extraction, the morphology of the powders was evaluated by scanning electron microscopy (SEM). The study of thermal stability showed that the ABTS radical presented a lower stability with time when compared to the other radicals. In addition, it was observed that the thermal degradation of TPC at the studied temperatures and that there is a positive correlation between TPC and AA. In the ultrasonic extraction using ethanol and methanol in the mass ratio of JPP/volume of solvent 1:20, the maximum TPC amounts were obtained. In the analysis by HPLC, a content of gallic acid (16.28 mg L⁻¹) and hesperidin (9.26 mg L⁻¹) were found for ethanol and methanol, respectively. The SEM images indicated that the changes in the structure favored the formation of pores contributing to the solubilization of TPC and consequently AA.     

A novel approach to bar adsorptive microextraction: Cork as extractor phase for determination of benzophenone,triclocarban and parabens in aqueous samples

This study describes the use of cork as a new coating for bar adsorptive microextraction (BAμE) and its application in determining benzophenone, triclocarban and parabens in aqueous samples by HPLC–DAD. In this study bars with 7.5 and 15 mm of length were used. The extraction and liquid desorption steps for BAμE were optimized employing multivariate and univariate procedures. The desorption time and solvent used for liquid desorption were optimized by univariate and multivariate studies, respectively. For the extraction step the sample pH was optimized by univariate experiments while the parameters extraction time and ionic strength were evaluated using the Doehlert design. The optimum extraction conditions were sample pH 5.5, NaCl concentration 25% and extraction time 90 min. Liquid desorption was carried out for 30 min with 250 μL (bar length of 15 mm) or 100 μL (bar length of 7.5 mm) of ACN:MeOH (50:50, v/v). The quantification limits varied between 1.6 and 20 μg L⁻¹ (bar length of 15 mm) and 0.64 and 8 μg L⁻¹ (bar length of 7.5 mm). The linear correlation coefficients were higher than 0.98 for both bars. The method with 7.5 mm bar length showed recovery values between 65 and 123%. The bar-to-bar reproducibility and the repeatability were lower than 13% (n = 2) and 14% (n = 3), respectively.     

Optimum extraction Process of polyphenols from the bark of Phyllanthus emblica L. based on the response surface methodology

Phyllanthus emblica L. is an economic plant used in Chinese medicine for the treatment of various diseases. The bark of P. emblica is rich in polyphenols and its extractions have shown strong antioxidative and radical scavenging activity. Response surface methodology (RSM) was used to assess the optimal extraction of polyphenols from P. emblica bark. Various extraction parameters including ethanol concentration, extraction time, temperature, solid–liquid ratio, and extraction times were chosen to identify their effects on polyphenols extraction. Among these parameters, extraction times and solvent concentration were found to have significant effect on polyphenols extraction. RSM was applied to obtain the optimal combination of solvent concentration, extraction time, temperature, and extraction time for maximum rate of extraction. The most suitable condition for the extraction of polyphenols was at ethanol concentration 75%, extraction time 25 min, extraction temperature 45°C, and extraction times 3. At these optimal extraction parameters, the maximum extraction of polyphenols obtained experimentally was found to be very close to its predicted value. The extraction rate of polyphenols was 19.78% at the optimum conditions. The mathematical model developed was found to fit with the experimental data of polyphenols extraction.     

A novel application of microwave-assisted extraction of polyphenols from brewer’s spent grain with HPLC-DAD-MS analysis

This paper reports a novel application of microwave-assisted extraction (MAE) of polyphenols from brewer’s spent grains (BSG). A 2⁴ orthogonal composite design was used to obtain the optimal conditions of MAE. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the extraction yield of ferulic acid was investigated through response surface methodology. The results showed that the optimal conditions were 15 min extraction time, 100 °C extraction temperature, 20 mL of solvent, and maximum stirring speed. Under these conditions, the yield of ferulic acid was 1.31 ± 0.04% (w/w), which was fivefold higher than that obtained with conventional solid–liquid extraction techniques. The developed new extraction method considerably reduces extraction time, energy and solvent consumption, while generating fewer wastes. HPLC-DAD-MS analysis indicated that other hydroxycinnamic acids and several ferulic acid dehydrodimers, as well as one dehydrotrimer were also present, confirming that BSG is a valuable source of antioxidant compounds.     

Optimization of Ultrasound-Assisted Extraction of Phenolics from Sideritis raeseri Using Response Surface Methodology

In this study we define the optimal conditions for ultrasound-assisted extraction of bioactive polyphenols from S. raeseri aerial parts using response surface methodology. The influence of ethanol concentration (10–90%), extraction temperature (20–80 °C), extraction time (10–60 min), and solid-to-solvent ratio (1:10–1:50) on total phenolic content as well as on content of individual flavonoids, and hypolaetin and isoscutellarein derivatives was studied. For the experimental design, a central composite design was chosen. In the obtained extracts, the following ranges of targeted compounds were detected: total phenol from 19.32 to 47.23 mg GAE/g dw, HYP from 1.05 to 11.46 mg/g dw, ISC 1 from 0.68 to 10.68 mg/g dw, and ISC 2 from 0.74 to 15.56 mg/g dw. The optimal extraction conditions were set as: ethanol concentration of 65%, extraction time of 50 min, extraction temperature of 63 °C, and solid-to-solvent ratio of 1:40. Contents of TP, HYP, ISC 1, and ISC 2 in optimal extracts were 47.11 mg GAE/g dw, 11.73 mg/g dw, 9.54 mg/g dw, and 15.40 mg/g dw, respectively. Experimentally set values were in good agreement with those predicted by the response surface methodology model, indicating suitability of the used model, as well as the success of response surface methodology in optimizing the conditions of the extraction.     

Extract with high 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibitory capability from pericarp and seed of mangosteen (Garcinia mangostana L.) using microwave-assisted extraction (MAE) two-phase solvent technique

The human body needs compounds that are antioxidants to prevent oxidative stress. Some parts of the mangosteen fruit (Garcinia mangostana L.) have been known as sources of bioactive compounds that have antioxidant properties. The pericarp and seeds of mangosteen were extracted using the MAE method to produce the extract with the greatest antioxidant activity. There are two types of solvent mixtures used in the extraction process: single-phase and two-phase solvents. The solvents used were ethanol (EtOH), ethyl acetate (EtOAc), isopropyl alcohol (IPA), and water. First, utilizing dried mangosteen pericarp powder as the raw material, a study was undertaken to determine the ideal operating conditions for the MAE process. A one-factor-at-a-time approach was used to find the best operating conditions. A mixture of solvents with varied ratios (mL/mL), extraction temperature (°C), extraction time (min), and solid to solvent ratio (g/mL) were applied as independent variables. Then, dried mangosteen seed powder extraction was carried out based on the best-operating conditions previously achieved. The DPPH scavenging activity, total phenolic content (TPC) value, and α-mangostin content of the two extracts were compared. It was discovered that the mangosteen pericarp extract showed higher antioxidant activity (IC₅₀ DPPH = 9.40 µg/mL) than the mangosteen seed extract (IC₅₀ DPPH = 37.54 µg/mL), even slightly better than ascorbic acid (IC₅₀ DPPH = 10.47 µg/mL). The best extract was produced from the bottom phase of two-phase solvent system (EtOAc:EtOH:Water 2:1:2), with an MAE temperature of 50 °C, a time of 4 min, and a solid-to-solvent ratio of 1:16. The TPC value of the best extract is 903.54 mgGAE/g extract, with a yield of 16.53 % and an α-mangostin concentration of 0.11 %.     

Evaluation of two membrane‐based microextraction techniques for the determination of endocrine disruptors in aqueous samples by HPLC with diode array detection

In this study, the viability of two membrane‐based microextraction techniques for the determination of endocrine disruptors by high‐performance liquid chromatography with diode array detection was evaluated: hollow fiber microporous membrane liquid–liquid extraction and hollow‐fiber‐supported dispersive liquid–liquid microextraction. The extraction efficiencies obtained for methylparaben, ethylparaben, bisphenol A, benzophenone, and 2‐ethylhexyl‐4‐methoxycinnamate from aqueous matrices obtained using both approaches were compared and showed that hollow fiber microporous membrane liquid–liquid extraction exhibited higher extraction efficiency for most of the compounds studied. Therefore, a detailed optimization of the extraction procedure was carried out with this technique. The optimization of the extraction conditions and liquid desorption were performed by univariate analysis. The optimal conditions for the method were supported liquid membrane with 1‐octanol for 10 s, sample pH 7, addition of 15% w/v of NaCl, extraction time of 30 min, and liquid desorption in 150 μL of acetonitrile/methanol (50:50 v/v) for 5 min. The linear correlation coefficients were higher than 0.9936. The limits of detection were 0.5–4.6 μg/L and the limits of quantification were 2–16 μg/L. The analyte relative recoveries were 67–116%, and the relative standard deviations were less than 15.5%.     

Bioactivity of Two Polyphenols Quercetin and Fisetin against Human Gastric Adenocarcinoma AGS Cells as Affected by Two Coexisting Proteins

It is recognized that minor dietary components polyphenols have anticancer effects on digestive tract, lung, leukemia, and other cancers, while polyphenols also can covalently or noncovalently interact with major dietary components proteins such as casein, soybean proteins, whey proteins, and bovine serum albumin. Thus, whether the noncovalent interaction between the molecules of two polyphenols (quercetin and fisetin) and two proteins (bovine serum albumin and casein) has positive or negative impact on anticancer activities of the polyphenols against human gastric adenocarcinoma AGS cells was assessed in this study. The two polyphenols had obvious anticancer activities to the cells, because dose levels as low as 20–160 μmol/L caused reduced cell viability of 30.0–69.4% (quercetin) and 24.6–63.1% (fisetin) (using a cell treatment time of 24 h), or 9.9–48.6% (quercetin) and 6.4–29.9% (fisetin) (using a cell treatment time of 48 h). However, the cell treatments by the polyphenols in the presence of the two proteins mostly caused lower polyphenol activity toward the cells, compared with those treatments by the polyphenols in the absence of the proteins. Specifically, the presence of the proteins led to reduced growth inhibition in the cells, because higher cell viability of 33.2–86.7% (quercetin) and 29.1–77.7% (fisetin) at 24 h, or 14.1–66.8% (quercetin) and 7.9–59.0% (fisetin) at 48 h, were measured in these treated cells. The two coexisting proteins also yielded the polyphenol-treated cells with less mitochondrial membrane potential loss, less formation of reactive oxygen species, and decreased cell apoptosis. Thus, it is highlighted that the noncovalent interaction between dietary polyphenols and proteins resulted in weakened anticancer ability for the polyphenols to the gastric cancer cells.     

Sponge-nested polymer monoliths: Versatile materials for the solid-phase extraction of bisphenols

Polymer monoliths are promising materials for sample preparation due to their high porosity, pH stability, and simple preparation. The use of melamine formaldehyde foams has been reported as an effective support to prepare highly robust silica and polymer monoliths. Herein, divinylbenzene monoliths based on a 50:50 (%, w/w) crosslinker/porogen ratio have been nested within a melamine-formaldehyde sponge, resulting in monoliths with a surface area higher than 400 m²/g. The extraction performance of these monoliths was evaluated for the extraction of endocrine-disrupting bisphenols from aqueous solutions. We evaluated for the first time the versatility of sponge-nested polymer monoliths by comparing three different extraction modes (vortex mixing, magnetic stirring, and orbital shaking). Vortex mixing showed a comparable recovery of bisphenols (39%–81%) in a shorter extraction time (30 min, instead of 2 h). In addition, the robustness of the sponge-nested polymer monoliths was demonstrated for the first time by reshaping a larger monolithic cube (0.125 cm³) into four smaller pieces (4 × 0.03125 cm³) leading to a 16%–21% increase in extraction efficiency. This effect was attributed to an increase in the effective contact area with the sample, obtaining a higher analyte extraction capacity.     

An ultrasound-based technique for the analytical extraction of phenolic compounds in red algae

Phenolic compounds are bioactive compounds that are also naturally found in red algae. To determine the level of these compounds in the red algae, spectroscopic or chromatographic determination was applied over the liquid extracts. Therefore, a prior extraction method is needed. The presented study aimed to develop the analytical ultrasound-assisted extraction (UAE) method to extract phenolic compounds from red algae. A Box–Behnken design (BBD) based on five factors included solvent composition (50–90% ethanol in water), extraction temperature (10–60 °C), ultrasonic power (20–100%), pulse duty-cycle (0.2–1.0 s^?1), and solvent-to-sample ratio (10:1 to 30:1) was used to evaluate the effects of the studied factors. Subsequently, response surface methodology (RSM) was performed to define the optimum extraction condition to recover phenolic compounds from the alga matrices. The UAE condition suggested by RSM was: ultrasonic power 100%, pulse duty-cycle 1 s^?1, temperature 52.5 °C, extraction solvent 50% ethanol in water, and solvent-to-sample ratio 30:1. Kinetic studies confirmed 10 min to provide comparable recovery (p > 0.05) than any longer extraction time. The acceptable values validated the developed method for repeatability (CV, 4.8%) and intermediate precision (CV, 5.7%). In addition, the accuracy of the method suggested a complete recovery for two extraction cycles. Furthermore, the method has successfully been applied for a number of samples covering three different red algae species. Fingerprints of each sample based on phenolic composition and levels characterize the type and origin of different red algae species.     

Bioguided extraction of polyphenols from grape marc by using an alternative supercritical-fluid extraction method based on a liquid solvent trap

The biological activity of polyphenols extracted from grape marc was studied with a view to finding a new use for this winery waste. Polyphenols were extracted by using an alternative supercritical-fluid extraction method based on the use of a liquid trap that allows extracted polyphenols to be retained in a saline buffer, thus avoiding the need for the organic solvent required to elute polyphenols from a solid trap. The major extraction variables influencing the performance of the liquid trap (viz. CO₂ modifier content, flow-rate, extraction time and trap volume) were optimized. The proposed method was applied to the supercritical-fluid extraction extraction of 0.3 g grape marc with CO₂ modified with 3% methanol at 350 bar at 50 °C (CO₂ density 0.9 g mL^-1) for 20 min, using a liquid flow-rate of 0.9 mL min^-1. The polyphenol extracts thus obtained exhibited cytotoxic effects that induced apoptosis in tumour cells.     

A novel silica supported chitosan/glutaraldehyde as an efficient sorbent in solid phase extraction coupling with HPLC for the determination of Penicillin G from water and wastewater samples

In this study, silica@chitosan-glutaraldehyde (Si@Cs-G) was synthesized as a novel adsorbent for extraction of Penicillin G (PG) from the synthetic and real samples followed by HPLC determination. The synthesized adsorbents were characterized by the scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM) and nitrogen adsorption–desorption techniques. The factors influencing the extraction efficiency including pH, sorbent dose, extraction time, extraction solvent type and its volume were investigated and optimized.Under the optimal conditions (sorbent dosage: 25 mg, desorption solvent (acetonitrile) with volume of 0.75 mL; pH: 6 and extraction time: 50 min), the Si@Cs-G demonstrated high efficiency and linearity (R² > 0.999) with the concentration of penicillin G ranging from 1 to 300 μg L⁻¹. Extraction recovery in synthetic samples was 98.977%, with LOD = 0.493 μg L⁻¹, LOQ = 1.638 μg L⁻¹ and RSD < 1.953%. The method was successfully applied for determination of PG in real water samples (tap, river, lake and well water) and wastewater samples (SH and SHB hospital effluent). The obtained relative recoveries were in the range of 91.31% -123.27% with RSD less than 6.34% for all the real samples. The dominant mechanism in the PG adsorption process was involved in the π-π interaction, hydrogen bonding, and electrostatic interaction.     

Biosensor immunoassay for traces of hazelnut protein in olive oil

The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins. To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils. The sample preparation was easy (extraction with buffer); the assay time was fast (4.5 min only) and the limit of detection was low (0.08 μg/g of hazelnut proteins in olive oil). Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Optimization of Portulaca oleracea L. extract using response surface methodology and artificial neural network and characterization of bioactive compound by high-resolution mass spectroscopy

The well-known medicinal plant Portulaca oleracea L. (PO) is used as a traditional medicine and culinary herb to treat various diseases. Fatty acids, essential oils, and flavonoids were extracted from PO seeds and leaves using ultrasonic, microwave, and supercritical fluid extraction with RSM techniques. However, investigations on the secondary metabolites and antioxidant capabilities of the aerial part of PO (APO) are scarce. In order to extract polyphenols and antioxidants from APO as effectively as possible, this study used heat reflux extraction (HRE), response surface methodology (RSM), and artificial neural network (ANN) modeling. It also used high-resolution mass spectrometry to identify the APO secondary metabolite. A central-composite design (CCD) was used to establish the ideal ethanol content, extraction time, and extraction temperature to extract the highest polyphenolic compounds and antioxidant activity from APO. According to RSM, the highest amount of TPC (8.23 ± 1.06 mgGAE/g), TFC (43.12 ± 1.15 mgCAE/g), DPPH-scavenging activity (43.01 ± 1.25 % of inhibition) and FRAP (35.98 ± 0.19 µM ascorbic acid equivalent) were obtained at 60.0 % ethanol, 90.2 % time, and 50 °C. Statistical metrics such as the coefficient of determination (R²), root-mean-square error (RMSE), absolute average deviation (AAD), and standard error of prediction (SEP) revealed the ANN's superiority. Ninety-one (91) secondary metabolites, including phenolic, flavonoids, alkaloids, fatty acids, and terpenoids, were discovered using high-resolution mass spectrometry. In addition, 21 new phytoconstituents were identified for the first time in this plant. The results revealed a significant concentration of phytoconstituents, making it an excellent contender for the pharmaceutical and food industries.     

Ultrasound-assisted extraction, HPLC analysis, and antioxidant activity of polyphenols from unripe apple

The polyphenols were extracted from the unripe apple assisted by a highly efficient and simple method of the ultrasound. Response surface methodology was used to investigate the effects of processing parameters, including ultrasound power, extraction time, temperature, and ethanol concentration on total polyphenols yield and polyphenols composition was analyzed by HPLC. Antioxidant activity of the polyphenols was evaluated as 2, 2-diphenyl-1-picrylhydracyl scavenging activity and inhibition activity of lipid peroxidation. The results showed that 10-100 times higher total polyphenols yield was obtained from the unripe apple than those from the reported apple pomace. The optimum extraction conditions were ultrasonic power of 519.39 W, extraction time of 30 min, extraction temperature 50°C, ethanol concentration of 50% gave the total polyphenols yield of 13.26 ± 0.56 mg GAE/g. HPLC analysis indicated that (-)-epicatechin, procyanidin B2, chlorogenic acid, and procyanidin B1 were the predominant polyphenols in unripe apple, which contributed to the higher antioxidant activity to 2, 2-diphenyl-1-picrylhydracyl of unripe apple polyphenols than other apple polyphenols. The extracted polyphenols had higher ability to inhibit lipid peroxidation than butylated hydroxy toluene, which demonstrated that the unripe apple polyphenols have the potential to be used as a substitute of some synthetic antioxidants.     

Solid-phase micro-extraction procedure for the determination of 1,3-dichloro-2-propanol in water by on-fibre derivatisation with bis(trimethylsilyl)trifluoroacetamide

The headspace solid-phase micro-extraction technique with on-fibre derivatisation followed by gas chromatography-tandem mass spectrometry has been evaluated for the analysis of 1,3-dichloro-2-propanol in water. An asymmetric factorial design has been performed to study the influence of five experimental factors: extraction time and temperature, derivatisation time and temperature and pH. The best extraction performance is achieved in the headspace mode, with 5 mL stirred water samples (pH 4) containing 1.3 g of NaCl, equilibrated for 30 min at 25 °C, using divinylbenzene-carboxen-polydimethylsiloxane as the fibre coating. On-fibre derivatisation has been used for the first time with 50 μL of bis(trimethylsilyl)trifluoroacetamide at 25 °C during 15 min, leading to effective yields. The proposed method provides high sensitivity, good linearity and repeatability (relative standard deviation of 5.1% for 10 ng mL⁻¹ and n = 5). The limits of detection and quantification were 0.4 and 1.4 ng mL⁻¹, respectively. Analytical recoveries obtained for different water samples were approx. 100%.     

Extraction and Study of Hypoglycemic Constituents from Myrica rubra Pomace

Myrica rubra pomace accounts for 20% of the fruit’s weight that is not utilized when it is juiced. The pomace contains bioactive phenolic substances such as anthocyanins and flavonoids. To improve the utilization value of Myrica rubra pomace, an optimized extraction method for the residual polyphenols was developed using response surface methodology (RSM). The resulting extract was analyzed by high performance liquid chromatography (HPLC), and the in vitro hypoglycemic activity and antioxidant activity of the polyphenolic compounds obtained were also investigated. The optimum extraction conditions (yielding 24.37 mg·g⁻¹ total polyphenols content) were: extraction temperature 60 °C, ultrasonic power 270 W, ethanol concentration 53%, extraction time 57 min, and solid to liquid ratio 1:34. Four polyphenolic compounds were identified in the pomace extract by HPLC: myricitrin, cyanidin-O-glucoside, hyperoside, and quercitrin. DPPH and hydroxyl radical scavenging tests showed that the Myrica rubra polyphenols extract had strong antioxidant abilities. It is evident that the residual polyphenols present in Myrica rubra pomace have strong hypoglycemic activity and the juiced fruits can be further exploited for medicinal purposes.