Far infrared-assisted extraction followed by capillary electrophoresis for the determination of bioactive constituents in the leaves of Lycium barbarum Linn

Development of an effective method based upon second-order overlapping repeated sample injections for isolation of carotenoids from Lycium barbarum L. fruits with elution-extrusion counter-current chromatography

Carotenoids are one of the main active components in Lycium barbarum L. fruit, which has a wide range of excellent biological activities. In this study, a novel second-order overlapping repeated injection method with elution-extrusion counter-current chromatography was developed for isolation and preparation of carotenoids from L. barbarum fruits. And three carotenoids were successfully separated using the solvent system composed of n-hexane/dichloromethane/acetonitrile (10:3.5:6.5, v/v) with the injection before equilibrium method. The entire separation process consisted of three complete elution-extrusion cycles with a total of 9 injections (80 mg crude extract per injection). Finally, three target compounds including zeaxanthin (28.5 mg), zeaxanthin monopalmitate (45.8 mg), and zeaxanthin dipalmitate (161.5 mg) with average purities of 87.9%, 88.9%, and 91.2% were successfully obtained in one complete second-order overlapping repeated elution-extrusion CCC process within 651 min. The result indicated that this second-order overlapping repeated method is efficient for large-scale preparation of carotenoids based on its advantages of large amount of sample injection and low solvent consumption. So this novel second-order overlapping repeated elution-extrusion counter-current chromatography separation method has enormous potential for largely preparative separation of natural bioactive compounds, such as carotenoids, which have good biological activity but possess unstable or other special chemical structure. It is worth noting that this overlapping repeated injections method requires target compounds to meet the requirements of elution-extrusion counter-current chromatography, and the normal implementation of this method is closely related to the sufficient interval of elution time between the target compounds.

Discrimination of Lycium chinense and L. barbarum Based on Metabolite Analysis and Hepatoprotective Activity

Lycii Fructus is a traditional medicine used to prevent liver and kidney diseases, which commonly derives from Lycium chinense and Lycium barbarum. Here, the extracts and ethyl acetate-soluble fractions of L. chinense fruits exhibited better hepatoprotective effects than those of L. barbarum, which was likely due to differences in their composition. Therefore, GC-MS and HPLC analyses were conducted to characterize the metabolite differences between L. chinense and L. barbarum. Based on amino acid (AA) and phenolic acid (PA) profiling, 24 AAs and 9 PAs were identified in the two species. Moreover, each species exhibited unique and readily distinguishable AA and PA star graphic patterns. HPLC analysis elucidated composition differences between the ethyl acetate-soluble layers of the two compounds. Further, NMR analysis identified their chemical structures as 4-(2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl)butanoic acid and p-coumaric acid. The higher content of 4-(2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl)butanoic acid was detected in L. chinense, whereas the content of p-coumaric acid was higher in L. barbarum. Therefore, the differences in the relative contents of these two secondary metabolites in the ethyl acetate-soluble layer of Lycii Fructus could be a good marker to discriminate between L. chinense and L. barbarum.

Environmentally Friendly Methods for Flavonoid Extraction from Plant Material: Impact of Their Operating Conditions on Yield and Antioxidant Properties

The flavonoids are compounds synthesized by plants, and they have properties such as antioxidant, anticancer, anti-inflammatory, and antibacterial, among others. One of the most important bioactive properties of flavonoids is their antioxidant effect. Synthetic antioxidants have side toxic effects whilst natural antioxidants, such as flavonoids from natural sources, have relatively low toxicity. Therefore, it is important to incorporate flavonoids derived from natural sources in several products such as foods, cosmetics, and drugs. For this reason, there is currently a need to extract flavonoids from plant resources. In this review are described the most important parameters involved in the extraction of flavonoids by unconventional methods such as ultrasound, pressurized liquid extraction, mechanochemical, high hydrostatic pressure, supercritical fluid, negative pressure cavitation, intensification of vaporization by decompression to the vacuum, microwave, infrared, pulsed electric field, high-voltage electrical discharges, and enzyme-assisted extraction. There are no unified operation conditions to achieve high yields and purity. Notwithstanding, progress has been achieved in the development of more advanced and environmentally friendly methods of extraction. Although in literature are found important advances, a complete understanding of the extraction process in each of the unconventional techniques is needed to determine the thermodynamic and kinetic mechanisms that govern each of the techniques.

Potential of galled leaves of Goji (Lycium chinense) as functional food

Background

Goji (Lycium) is a popular traditional health food, and its fruit and root extracts have been found to possess antioxidant, anti-inflammatory, and hypocholesterolemia-inducing abilities. Goji leaves also contain high amounts of phenolic compounds, similar to its fruit, and their extracts also exhibit several pharmaceutical effects. The induction of galls on Goji leaves reduces their photosynthetic ability and fruit yield, which raise their farming costs, thereby leading to economic loss. However, the defense mechanisms induced by infection may elevate the secondary metabolite content of the leaves, which might provide more nutritive compounds.

Method

Content of chlorophyll, carotenoids, polyphenols, and flavonoids in the extracts of normal and infected Goji leaves (L. chinense) were analyzed. The relative content of chlorogenic acid and rutin, two major phenolic compounds in Goji leaves, were determined by LC-MS/MS. Antioxidant activity was presented by demonstrating the DPPH scavenging percentage. The extract of Goji fruit (L. barbarum) was also analyzed to show a comparative result.

Results

In this study, we found that in infected Goji leaves, the polyphenol content was significantly increased. The level of chlorogenic acid was increased by 36% in galled leaves. The content of rutin in galled leaves was also elevated. Testing the antioxidant activities also showed that the extracts of galled leaves have higher DPPH scavenging abilities.

Conclusions

Our results demonstrated that galled Goji leaves have higher functional value, and may have potential as being consumed as health food.

Investigation of Chinese Wolfberry (Lycium spp.) Germplasm by Restriction Site-Associated DNA Sequencing (RAD-seq)

Chinese wolfberry (Lycium spp.) is an important edible and medicinal plant, with a long cultivation history. The genetic relationships among wild Lycium species and landraces have been unclear for a number of reasons, which has hindered the breeding of modern Chinese wolfberry cultivars. In this study, we collected 19 accessions of Chinese wolfberry germplasm, and constructed the genetic relationship based on RAD-seq markers. We obtained 30.32 Gb of clean data, with the average value of each sample being 1.596 Gb. The average mapping rate was 85.7%, and the average coverage depth was 6.76 X. The phylogeny results distinguished all accessions clearly. All the studied landraces shared their most recent common ancestor with L. barbarum, which indicated that L. barbarum may be involved in cultivation of these landraces. The relationship of some landraces, namely the ‘Ningqi’ series, ‘Qingqi-1’ and ‘Mengqi-1,’ has been supported by the phylogeny results, while the triploid wolfberry was shown to be based on a hybrid between ‘Ningqi-1’ and a tetraploid wolfberry. This study uncovered the genetic background of Chinese wolfberry, and developed the foundation for species classification, accession identification and protection, and the production of hybrid cultivars of wolfberry.

Quality evaluation of six bioactive constituents in goji berry based on capillary electrophoresis field amplified sample stacking

Goji berry, fruits of the plant Lycium barbarum L., has long been used as traditional medicine and functional food in China. In this work, a simple and easy-operation on-line concentration capillary electrophoresis (CE) for detection flavonoids in goji berry was developed by coupling of field amplified sample stacking (FASS) with an electroosmotic (EOF) pump driving water removal process. Due to the EOF pump and electrokinetic injection showing different influence on the concentration, the analytes injection condition should be systemically studied. Thereafter, the verification of the analytes injection conditions was achieved using response surface experimental design. Under the optimum conditions, 86-271 folds sensitivity enhancement upon normal capillary zone electrophoresis (CZE, 50 mbar × 5 s) were achieved for six flavonoids, and the detection limits ranged from 0.35 to 1.82 ng/mL; the LOQ ranged from 1.20 to 6.01 ng/mL. Eventually, the proposed method was applied to detect flavonoids in 30 goji berry samples from different habitats of China; and the results indicated that the flavonoids were rich in the eluent of 30-60% methanol, which provided a reference for extraction of goji berry flavonoids.

Characterization of the volatile components in green tea by IRAE-HS-SPME/GC-MS combined with multivariate analysis

In the present work, a novel infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of the volatile components in green tea. The extraction parameters such as fiber type, sample amount, infrared power, extraction time, and infrared lamp distance were optimized by orthogonal experimental design. Under optimum conditions, a total of 82 volatile compounds in 21 green tea samples from different geographical origins were identified. Compared with classical water-bath heating, the proposed technique has remarkable advantages of considerably reducing the analytical time and high efficiency. In addition, an effective classification of green teas based on their volatile profiles was achieved by partial least square-discriminant analysis (PLS-DA) and hierarchical clustering analysis (HCA). Furthermore, the application of a dual criterion based on the variable importance in the projection (VIP) values of the PLS-DA models and on the category from one-way univariate analysis (ANOVA) allowed the identification of 12 potential volatile markers, which were considered to make the most important contribution to the discrimination of the samples. The results suggest that IRAE-HS-SPME/GC-MS technique combined with multivariate analysis offers a valuable tool to assess geographical traceability of different tea varieties.

Application of CE-ICP-MS and CE-ESI-MS/MS for identification of Zn-binding ligands in Goji berries extracts

The identification of groups of ligands binding metals is a crucial issue for the better understanding of their bioaccessibility. In the current study, we have intended an approach for identification of Zn-binding ligands based on using capillary electrophoresis combined with inductively coupled plasma mass spectrometry (CE-ICP-MS) and tandem electrospray ionization mass spectrometry (CE-ESI-MS/MS). The approach, which featured the use of the coupling of capillary electrophoresis with inductively coupled plasma mass spectrometry allows to separate and observe zinc ions present in complexes with respect to their size and charge and to identify nine compounds with zinc isotopic profile. CE-ICP-MS provides us with information about presence of zinc species and elemental information about zinc distribution. CE-ESI-MS/MS provide us with information about the most favorable Zn binding ligands: amino acids, flavonols, stilbenoids, fenolic acids and carotenoids. The presented work is the continuation of previous studies based on using LC-ESI-MS/MS, though, now we presented a new solutions with the possibility of changing detectors without changing the separation techniques, what is important without re-optimizing the method. The new presented method allows to identify the zinc-binding ligands in shorter time.

Phytochemical characterization and bioactivity of Lycium europaeum: A focus on antioxidant, antinociceptive, hepatoprotective and nephroprotective effects

In this study, the antioxidant, antinociceptive, hepatoprotective, nephroprotective properties and the bioactive composition of Lycium europaeum were investigated. Polyphenols and total tannin contents were measured by colorimetric methods The antioxidant activity in vitro was evaluated using the reducing power, 2,2-diphenyl-1-picrylhydrazyl radical and phosphomolybdenum assays. The hepatotoxicity and nephrotoxicity effects were studied using carbon tetrachloride (CCl₄)-induced liver and renal injuries in mice. The analgesic activity was explored using the hot-plate and acetic acid tests in mice. Results showed that the methanol fraction of L. europaeum (LEM) had the highest level of total phenolic, total tannin, and flavonoid. HPLC-DAD analysis revealed the presence of twelve compounds among them caffeic acid was the major compound (140.18μg/g of extract). This fraction also showed the best antioxidant activity in vitro in the three used assays. In vivo, in the mice studies, CCl₄ administration induced hepatotoxicity and nephrotoxicity by a significant rise in the levels of serum liver biomarkers (gamma glutamyl transferase, lactate dehydrogenase, and aminotransferases) and serum renal biomarkers (urea, creatinine, and uric acid). Similarly, levels of lipid peroxidation (MDA) in both tissues were found increased by CCl₄ intoxication. Pretreatment with LEM and quercetin significantly restored the majority of these biological parameters to normal levels, as well as an improvement of histopathological changes. In addition, LEM showed an interesting analgesic activity. LEM decreased significantly the number of writhing induced by acetic acid and prolonged the reaction time in response to thermal stimulus in mice. Therefore, it was speculated that the obtained results highlighted the potential use of L. europaeum as a source of bioactive compounds with pharmacological advantages.

A simple and rapid infrared-assisted self enzymolysis extraction method for total flavonoid aglycones extraction from Scutellariae Radix and mechanism exploration

A new, simple, and fast infrared-assisted self enzymolysis extraction (IRASEE) approach for the extraction of total flavonoid aglycones (TFA) mainly including baicalein, wogonin, and oroxylin A from Scutellariae Radix is presented to enhance extraction yield. Extraction enzymolysis temperature, enzymolysis liquid-to-solid ratio, enzymolysis pH, enzymolysis time and infrared power, the factors affecting IRASEE procedure, were investigated in a newly designed, temperature-controlled infrared-assisted extraction (TC-IRAE) system to acquire the optimum analysis conditions. The results illustrated that IRASEE possessed great advantages in terms of efficiency and time compared with other conventional extraction techniques. Furthermore, the mechanism of IRASEE was preliminarily explored by observing the microscopic change of the samples surface structures, studying the main chemical compositions change of the samples before and after extraction and investigating the kinetics and thermodynamics at three temperature levels during the IRASEE process. These findings revealed that IRASEE can destroy the surface microstructures to accelerate the mass transfer and reduce the activation energy to intensify the chemical process. This integrative study presents a simple, rapid, efficient, and environmental IRASEE method for TFA extraction which has promising prospects for other similar herbal medicines. Graphical Abstract ᅟ.

Multivariate analysis of the volatile components in tobacco based on infrared-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry

A novel infrared-assisted extraction coupled to headspace solid-phase microextraction followed by gas chromatography with mass spectrometry method has been developed for the rapid determination of the volatile components in tobacco. The optimal extraction conditions for maximizing the extraction efficiency were as follows: 65 μm polydimethylsiloxane-divinylbenzene fiber, extraction time of 20 min, infrared power of 175 W, and distance between the infrared lamp and the headspace vial of 2 cm. Under the optimum conditions, 50 components were found to exist in all ten tobacco samples from different geographical origins. Compared with conventional water-bath heating and nonheating extraction methods, the extraction efficiency of infrared-assisted extraction was greatly improved. Furthermore, multivariate analysis including principal component analysis, hierarchical cluster analysis, and similarity analysis were performed to evaluate the chemical information of these samples and divided them into three classifications, including rich, moderate, and fresh flavors. The above-mentioned classification results were consistent with the sensory evaluation, which was pivotal and meaningful for tobacco discrimination. As a simple, fast, cost-effective, and highly efficient method, the infrared-assisted extraction coupled to headspace solid-phase microextraction technique is powerful and promising for distinguishing the geographical origins of the tobacco samples coupled to suitable chemometrics.

Anti-inflammatory Activity of Berry Fruits in Mice Model of Inflammation is Based on Oxidative Stress Modulation

BACKGROUND

Many fruits have been used as nutraceuticals because the presence of bioactive molecules that play biological activities.

OBJECTIVE

The present study was designed to compare the anti-inflammatory and antioxidant effects of methanolic extracts of Lycium barbarum (GOJI), Vaccinium macrocarpon (CRAN) and Vaccinium myrtillus (BLUE).

MATERIALS AND METHODS

Mices were treated with extracts (50 and 200 mg/kg, p.o.), twice a day through 10 days. Phytochemical analysis was performed by high-performance liquid chromatography. Antioxidant activity was determine by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, reducing power, lipid peroxidation thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and catalase (CAT) activity. Anti-inflammatory activity was evaluated by paw edema followed by determination of myeloperoxidase (MPO) and TBARS.

RESULTS

High amount of phenolic compounds, including rutin, were identified in all berries extracts. However, quercetin was observed only in BLUE and CRAN. GOJI presents higher scavenging activity of DPPH radical and reducing power than BLUE and CRAN. The extracts improved antioxidant status in liver; BLUE showed the largest reduction (75.3%) in TBARS when compared to CRAN (70.7%) and GOJI (65.3%). Nonetheless, CAT activity was lower in BLUE group. However, hepatic concentrations of GSH were higher in animals treated with GOJI rather than CRAN and BLUE. Despite all fruits caused a remarkable reduction in paw edema and TBARS, only BLUE and CRAN were able to reduce MPO.

CONCLUSION

These results suggest that quercetin, rutin, or other phenolic compound found in these berry fruits extracts could produce an anti-inflammatory response based on modulation of oxidative stress in paw edema model.

SUMMARY

Within fruits broadly consumed because of its nutraceuticals properties include, Lycium barbarum (Goji berry), Vaccinium myrtillus (Blueberry or Bilberry) and Vaccinium macrocarpon (Cranberry)The objectives of this study were the investigation and comparison of chemical composition, antioxidant activity "in vitro" and "in vivo" and anti inflammatory property of berry fruits bought dry form.In summary, two main findings can be addressed with this study: (1) Berry fruits presented antioxidant and anti inflammatory activities "in vitro" and "in vivo"; (2) the extracts of GOJI, CRAN, and BLUE modulate the inflammatory process by different mechanisms.

Infrared Irradiation: Toward Green Chemistry, a Review

This review provides a comprehensive overview of where infrared irradiation has been employed, mainly as regards activating green mode for natural products extractions, as well as to favor a reaction, highlighting its actual importance. It is also underlined that infrared irradiation heating has been around for a long time; however, only in the last eighteen years have many of its advantages been applied to satisfy a wide range of chemical processes, natural products extractions, and for the promotion of many kinds of reactions. In addition, it is brought to light that near infrared irradiation is more efficient than middle and far infrared irradiations, being easily controllable and with the quality of a fast responding heat source. Thus, the main objective of this review is to offer infrared irradiation as an alternative clean energy source to activate reactions, in addition to favor the selective extraction of natural products, all of which is within the Green Chemistry protocol. Some recent results from our laboratory are also included.

An electrochemical sensor for the sensitive detection of rutin based on a novel composite of activated silica gel and graphene

A novel sensor based on a silica gel–graphene composite for sensitive and selective detection of rutin.

Infrared-assisted extraction of salidroside from the root of Rhodiola crenulata with a novel ionic liquid that dissolves cellulose

Tetrabutylphosphonium hydroxide aqueous solution, a novel ionic liquid that could dissolve cellulose rapidly at ambient temperature, was used for the first time to develop an extraction method with infrared-assisted extraction.

Polyphenolic content, antioxidant and antimicrobial activities of Lycium barbarum L. and Lycium chinense Mill. leaves

This study was performed to evaluate the in vitro antioxidant and antimicrobial activities and the polyphenolic content of Lycium barbarum L. and L. chinense Mill. leaves. The different leave extracts contain important amounts of flavonoids (43.73 ± 1.43 and 61.65 ± 0.95 mg/g, respectively) and showed relevant antioxidant activity, as witnessed by the quoted methods. Qualitative and quantitative analyses of target phenolic compounds were achieved using a HPLC-UV-MS method. Rutin was the dominant flavonoid in both analysed species, the highest amount being registered for L. chinense. An important amount of chlorogenic acid was determined in L. chinense and L. barbarum extracts, being more than twice as high in L. chinense than in L. barbarum. Gentisic and caffeic acids were identified only in L. barbarum, whereas kaempferol was only detected in L. chinense. The antioxidant activity was evaluated by DPPH, TEAC, hemoglobin ascorbate peroxidase activity inhibition (HAPX) and inhibition of lipid peroxidation catalyzed by cytochrome c assays revealing a better antioxidant activity for the L. chinense extract. Results obtained in the antimicrobial tests revealed that L. chinense extract was more active than L. barbarum against both Gram-positive and Gram-negative bacterial strains. The results suggest that these species are valuable sources of flavonoids with relevant antioxidant and antimicrobial activities.

A review on plant-based rutin extraction methods and its pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Rutin is a common dietary flavonoid that is widely consumed from plant-derived beverages and foods as traditional and folkloric medicine worldwide. Rutin is believed to exhibit significant pharmacological activities, including anti-oxidation, anti-inflammation, anti-diabetic, anti-adipogenic, neuroprotective and hormone therapy. Till date, over 130 registered therapeutic medicinal preparations are containing rutin in their formulations. This article aims to critically review the extraction methods for plant-based rutin and its pharmacological activities. This review provides comprehensive data on the performance of rutin extraction methods and the extent of its pharmacological activities using various in vitro and in vivo experimental models.

MATERIALS AND METHODS

Literatures including journals, patents, books and leaflets reporting on rutin from natural resources are systematically reviewed, particularly in the aspect of its extraction methods and biological activities. Factors affecting the efficiency of rutin extraction such as extraction temperature, duration and solvent to sample ratio are presented based on the findings of previous studies. The observed biological activities followed by clear explanation are also provided accordingly.

RESULTS

The biological activities of rutin varied largely dependent on the geographical and plant origins. The complexity of natural rutin has impeded the development of rutin derived drugs. The detail mechanism of rutin in human body after consumption is still unclear. Therefore, studies are intensively carried out both in vitro and in vivo for the better understanding of the underlying mechanism. The studies are not limited to the pharmacological properties, but also on the extraction methods of rutin. Many studies have focused on the optimization of extraction method to increase the extraction yield of rutin. Currently, the performances of modern extraction approaches have also been compared to the conventional heat reflux method as a benchmark.

CONCLUSION

There are various extraction methods for plant-based rutin ranging from conventional method up to the use of modern techniques such as ultrasound, mechanochemical, microwave, infrared and pressurized assisted methods. However, proper comparison between the methods is very difficult because of the variance in plant origin and extraction conditions. It is important to optimize the extraction method in order to produce high yield and acceptable purity of rutin with a reasonable cost. Even though rutin has been proven to be effective in numerous pharmacological activities, the dosage and toxicity of rutin for such activities are still unknown. Future research should relate the dosage and toxicity of rutin for the ethnobotanical claims based on the underlying mechanisms.

Methods for Extraction and Determination of Phenolic Acids in Medicinal Plants: A Review

Phenolic acids constitute a group of potentially immunostimulating compounds. They occur in all medicinal plants and are widely used in phytotherapy and foods of plant origin. In recent years, phenolic acids have attracted much interest owing to their biological functions. This paper reviews the extraction and determination methods of phenolic acids in medicinal plants over the last 10 years. Although Soxhlet extraction and ultrasonic assisted extraction (UAE) are commonly used for the extraction of phenolic acids from plant materials, alternative techniques such as supercritical fluid extraction (SFE), and accelerated solvent extraction (ASE) can also be used. After extraction, phenolic acids are determined usually by liquid chromatography (LC) owing to the recent developments in this technique, especially when it is coupled with mass spectrometry (MS). Also detection systems are discussed, including UV-Vis, diode array, electrochemical and fluorimetric. Other popular techniques for the analysis of this group of secondary metabolites are gas chromatography coupled with mass spectrometry (GC-MS) and capillary electrophoresis (CE).

Quantitative analysis of betaine in Lycii Fructus by HILIC-ELSD

A rapid and simple high-performance liquid chromatography (HPLC) method with evaporative light scattering detection (ELSD) was developed for the determination of betaine from Lycii Fructus. Betaine was separated with an Atlantis hydrophilic interaction liquid chromatography silica column (4.6 × 150 mm, 5 μm, 100 Å) by isocratic elution using 30 mM ammonium acetate buffer and acetonitrile (20:80, v/v %) as the mobile phase. The flow rate was 1.0 mL/min, and the temperature for the spray chamber and drift tube was set at 30 and 50 °C, respectively. The method was fully validated with respect to linearity, precision, accuracy, stability and robustness. The HPLC/ELSD method was applied successfully to the quantification of betaine in the extract of Lycii Fructus. The HPLC analytical method for pattern recognition analysis was validated by repeated analysis of twenty-six L. barbarum L. from China (BC01-BC26), 3 L. barbarum L. (BJ27-BJ29) from Japan, 12 L. chinense Miller from China (CC30-CC41) and 51 L. chinense Miller samples (CK42-CK92) from Korea. The results indicate that the established HPLC/ELSD method is suitable for quality evaluation of Lycii Fructus.

Graphene/poly(ethylene-co-vinyl acetate) composite electrode fabricated by melt compounding for capillary electrophoretic determination of flavones in Cacumen platycladi

In this report, a graphene/poly(ethylene-co-vinyl acetate) composite electrode was fabricated by melt compounding for the amperometric detection of capillary electrophoresis. The composite electrode was fabricated by packing a mixture of graphene and melted poly(ethylene-co-vinyl acetate) in a piece of fused silica capillary under heat. The structure of the composite was investigated by scanning electron microscopy and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed in the composite to form an interconnected conducting network. The performance of this unique graphene-based detector has been demonstrated by separating and detecting rutin, quercitrin, kaempferol, and quercetin in Cacumen platycladi in combination with capillary electrophoresis. The four flavones have been well separated within 9 min in a 50-cm-long capillary at a separation voltage of 12 kV using a 50 mM sodium borate buffer (pH 9.2). The graphene-based detector offered significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, lower expense of operation, high resistance to surface fouling, and enhanced stability. It showed long-term stability and repeatability with relative standard deviations of <5% for the peak current (n = 15).

Electrochemical study and application on rutin at chitosan/graphene films modified glassy carbon electrode

Graphene (G) was dispersed into 0.5% chitosan (Chit) solution, then the composite films were coated on glassy carbon electrode (GCE), the electrochemical behavior of rutin on a Chit/G modified GCE was investigated and the electrochemical parameters of rutin were calculated. Rutin effectively accumulated on the Chit/G/GCE and caused a pair of redox peaks at around 408 mV and 482 mV (vs. SCE) in 0.1 M phosphate buffer solution (pH 4.0). Under optimized conditions, the anodic peak current was linear to the rutin concentration in the range of 5×10^-7-1.04×10^-5 M. The regression equation was: y=9.9219x-0.0025, r= 0.9958. The proposed method was successfully used for the determination of rutin content in tablet samples with satisfactory results.

Optimisation of infrared-assisted extraction of rutin from crude Flos Sophorae Immaturus using response surface methodology and HPLC analysis

INTRODUCTION

Rutin, one of main constituents in Flos Sophorae Immaturus, has been proven to possess several pharmacological properties such as anti-oxidant, anti-platelet, anti-inflammatory effects and so on. However, optimisation of the extraction of rutin from Flos Sophorae Immaturus has rarely been reported. Thus, it is important to develop an effective method to obtain maximum yields of rutin from Flos Sophorae Immaturus.

OBJECTIVE

To develop an infrared-assisted extraction method for maximum rutin yield from crude Flos Sophorae Immaturus using response surface methodology and HPLC analysis.

METHODOLOGY

Through single factor experiments, ranges of the main variables (including methanol concentration, liquid:solid ratio, extraction time and infrared power) affecting the extraction yield of rutin were confirmed. A Box-Behnken design consisting of 24 experimental runs and five replicates at zero point was then applied and a regression model was obtained to predict the optimal extraction yield.

RESULTS

The ANOVA analysis indicated that the regression equation fits very well with the actual situation. The optimal conditions were as follows: infrared power 204.90 W, liquid:solid ratio 30.00 mL/g, methanol concentration 70.00% and extraction time 4.80 min. Under optimal conditions the predicted maximum yield (125.70 mg rutin/0.5 g raw material) was consistent with the experimental value (126.32 ± 0.67 mg rutin/0.5 g raw material) (n = 3).

CONCLUSION

The application of response surface methodology was reliable and feasible in the optimisation of infrared-assisted extraction of rutin from crude Flos Sophorae Immaturus.

Recent progress for capillary electrophoresis with electrochemical detection

Capillary electrophoresis (CE) is an attractive technique in separation science because of its high separation performance, short analysis time and low cost. Electrochemical detection (EC) is a powerful tool for CE because of its high sensitivity. In this review, developments of CE-EC from 2008 to August, 2011 are reviewed. We choose papers of innovative and novel results to demonstrate the newest and most important progress in CE-EC.

Determination of carbohydrates in Folium Lysium Chinensis using capillary electrophoresis combined with far-infrared light irradiation-assisted extraction

In this work, a method based on capillary electrophoresis with amperometric detection and far-infrared-assisted extraction has been developed for the determination of mannitol, sucrose, glucose and fructose in Folium Lysium Chinensis, a commonly used traditional Chinese medicine. The water-soluble constituents in the herbal drug were extracted with double distilled water with the assistance of far-infrared radiations. The effects of detection potential, irradiation time, and the voltage applied on the infrared generator were investigated to acquire the optimum analysis conditions. The detection electrode was a 300-μm-diameter copper disk electrode at a detection potential of +0.65 V. The four carbohydrates could be well separated within 18 min in a 50-cm length fused-silica capillary at a separation voltage of 9 kV in a 50-mM NaOH aqueous solution. The relation between peak current and analyte concentration was linear over about three orders of magnitude with detection limits (S/N=3) ranging from 0.66 to 1.15 μM for all analytes. The results indicated that far infrared significantly enhanced the extraction efficiency of the carbohydrates in Folium Lysium Chinensis. The extraction time was significantly reduced to 7 min compared with several hours for conventional hot solvent extraction.

Highly efficient proteolysis accelerated by electromagnetic waves for Peptide mapping

Proteomics will contribute greatly to the understanding of gene functions in the post-genomic era. In proteome research, protein digestion is a key procedure prior to mass spectrometry identification. During the past decade, a variety of electromagnetic waves have been employed to accelerate proteolysis. This review focuses on the recent advances and the key strategies of these novel proteolysis approaches for digesting and identifying proteins. The subjects covered include microwave-accelerated protein digestion, infrared-assisted proteolysis, ultraviolet-enhanced protein digestion, laser-assisted proteolysis, and future prospects. It is expected that these novel proteolysis strategies accelerated by various electromagnetic waves will become powerful tools in proteome research and will find wide applications in high throughput protein digestion and identification.