Targeted delivery of food functional ingredients in precise nutrition: design strategy and application of nutritional intervention.

With the high incidence of chronic diseases, precise nutrition is a safe and efficient nutritional intervention method to improve human health. Food functional ingredients are an important material base for precision nutrition, which have been researched for their application in preventing diseases and improving health. However, their poor solubility, stability, and bad absorption largely limit their effect on nutritional intervention. The establishment of a stable targeted delivery system is helpful to enhance their bioavailability, realize the controlled release of functional ingredients at the targeted action sites in vivo, and provide nutritional intervention approaches and methods for precise nutrition. In this review, we summarized recent studies about the types of targeted delivery systems for the delivery of functional ingredients and their digestion fate in the gastrointestinal tract, including emulsion-based delivery systems and polymer-based delivery systems. The building materials, structure, size and charge of the particles in these delivery systems were manipulated to fabricate targeted carriers. Finally, the targeted delivery systems for food functional ingredients have gained some achievements in nutritional intervention for inflammatory bowel disease (IBD), liver disease, obesity, and cancer. These findings will help in designing fine targeted delivery systems, and achieving precise nutritional intervention for food functional ingredients on human health.

Determination of L-Ergothioneine in Cosmetics Based on Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry.

A new method was developed for the identification and determination of L-ergothioneine in cosmetics based on ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pretreatment method, chromatographic column, chromatographic conditions, and mass spectrometric conditions of cosmetic samples were optimized. Methanol was chosen as the extraction solvent, 85% acetonitrile with 0.1% FA was selected as the mobile phase, and the Waters CORTECS UPLC hydrophilic interaction liquid chromatography (HILIC) column was chosen for the separation. The sample was extracted with methanol and filtered, then separated by HILIC and detected by triple-quadrupole mass spectrometry. The quantitation was done under the matrix calibration curve using the external standard method. The results showed good linear relationships in the range of 5-200 ng/mL, and the correlation coefficient was greater than 0.999 in cosmetic samples. The limit of detection was in the range of 25-50 µg/kg and the limit of quantitation was in the range of 50-100 µg/kg. The recoveries of the method spiked ranged from 85.3% to 96.2% and the relative standard deviation (RSD) was in the range of 0.84%-2.08% (n = 6). The method is simple, quick, and accurate for the determination of L-ergothioneine in cosmetics, and has great practical value.

Synthesis of Novel Indole Schiff Base Compounds and Their Antifungal Activities.

A series of novel indole Schiff base derivatives (2a-2t) containing a 1,3,4-thiadiazole scaffold modified with a thioether group were synthesized, and their structures were confirmed using FT-IR, 1H NMR, 13C NMR, and HR-MS. In addition, the antifungal activity of synthesized indole derivatives was investigated against Fusarium graminearum (F. graminearum), Fusarium oxysporum (F. oxysporum), Fusariummoniliforme (F.moniliforme), Curvularia lunata (C. lunata), and Phytophthora parasitica var. nicotiana (P. p. var. nicotianae) using the mycelium growth rate method. Among the synthesized indole derivatives, compound 2j showed the highest inhibition rates of 100%, 95.7%, 89%, and 76.5% at a concentration of 500 µg/mL against F. graminearum, F. oxysporum, F.moniliforme, and P. p. var. nicotianae, respectively. Similarly, compounds 2j and 2q exhibited higher inhibition rates of 81.9% and 83.7% at a concentration of 500 µg/mL against C. lunata. In addition, compound 2j has been recognized as a potential compound for further investigation in the field of fungicides.

Rapid determination of 103 common veterinary drug residues in milk and dairy products by ultra performance liquid chromatography tandem mass spectrometry.

A multi-residue method has been developed for the identification and quantification of 103 common veterinary drug residues in milk and dairy Products. This method was based on QuEChERS with dispersive solid-phase where C18 sorbent and anhydrous sodium sulfate were used to sample purification. After evaporation and reconstitution, the samples were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. The mean recovery results were all higher than 60% except ampicillin, pipemidic acid, enoxacin, and estriol, and the relative standard deviation was <20.0%. The limit of quantification ranged between 0.1 and 5 µg/kg for milk and between 0.5 and 25 µg/kg for milk powder. It was successfully used to detect residues of veterinary drug in real samples. This study proposes a simple and fast analytical method for monitoring multi-class veterinary drug residues to ensure food safety.

Rapid Screening of 22 Polycyclic Aromatic Hydrocarbons Residues in Vegetable Oils by Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry.

A method for simultaneous determination of 22 polycyclic aromatic hydrocarbons (PAHs) residues in vegetable oils by gas chromatography-electrostatic field orbitrap high resolution mass spectrometry (Orbitrap GC-MS) was established. The samples were vortexed with acetonitrile, centrifuged at 8,000 r/min for 5 min, and frozen at -70°C for 10 min. The extracts of upper layer were poured out, dried with nitrogen at 40°C, redissolved in dichloromethane, and measured by Orbitrap GC-MS. The matrix interference in vegetable oil could be effectively removed by determining the accurate mass number of target compounds under the full scan mode. Six typical vegetable oil samples (soybean oil, sesame oil, peanut oil, olive oil, rapeseed oil, sunflower oil) were used for method validation. The calibration curve displayed good linearity in the range of 1-100 ng/mL, with correlation coefficients > 0.9950. The limits of detection (LODs) were in the range of 0.10-0.60 µg/kg, and the limits of quantification (LOQs) were in the range of 0.35-2.00 µg/kg. The average spiked recoveries of 22 PAHs in 6 matrices at 5, 50 and 100 µg/kg levels were 76.4-115.4%, and the average relative standard deviations (RSDs) were 1.8-10.8%. The results showed that 22 PAHs were detected in 6 types of 90 edible vegetable oil samples in the Chinese market by this method. Meanwhile, the abundance of light PAHs (LPAHs) was higher than that of heavy PAHs (HPAHs), and its relative contribution of LPAHs to the total PAHs was higher. All levels of BaP conformed to the Chinese requirement of upper limit, 10 µg/kg. However, 13.3 and 11.1% of the samples exceeded the maximum limits of BaP and PAH4 set by EU, 2 and 10 µg/kg, respectively. The total concentrations of 22 PAHs (defined as PAH22) varies greatly among different oil species, and the average PAH22 contents were listed in descending order as follows: peanut oil > sesame oil > olive oil > rapeseed oil > soybean oil > sunflower seed oil. The established method effectively avoided interference from large amounts of lipids and pigments. Therefore, the method is simple, sensitive and suitable for rapid screening and confirmation of PAHs in vegetable oil.

Rapid Screening of 352 Pesticide Residues in Chrysanthemum Flower by Gas Chromatography Coupled to Quadrupole-Orbitrap Mass Spectrometry with Sin-QuEChERS Nanocolumn Extraction.

To analyze pesticide residues, GC coupled with quadrupole-Orbitrap MS (GC-Orbitrap-MS) has become a powerful tool because of its unique characteristics of accurate mass full-spectrum acquisition, high resolution, fast acquisition rates, and overcoming matrix interference. This paper presents an efficiency evaluation of GC-Orbitrap-MS for identification and quantitation in the 352 pesticide residues analysis of chrysanthemum flowers in full-scan mode. A streamlined pretreatment approach using one-step extraction and dilution was used, which provided high-throughput processing and excellent recovery. The samples were extracted using acetonitrile. The extracted solution was purified by a Sin-QuEChERS Nano column to suppress the matrix in chrysanthemum flowers and determined by GC-Orbitrap-MS. The calibration curves for the 352 pesticides obtained by GC-Orbitrap-MS were linear in the range of 0.5-200 µg·kg-1, with the correlation coefficients higher than 0.99. The limits of detection (LODs) and the limits of quantification (LOQs) for the 352 pesticide residues were 0.3-3.0 µg·kg-1 and 1.0-10.0 µg·kg-1, respectively. The average recoveries in chrysanthemum flower at three levels were 95.2%, 88.6%, and 95.7%, respectively, with relative standard deviations (RSDs) of 7.1%, 7.5%, and 7.2%, respectively. Lastly, the validated method and retrospective analysis was applied to a total of 200 chrysanthemum flower samples bought in local pharmacies. The proposed method can simultaneously detect multipesticide residues with a good performance in qualitative and quantitative detection.

Determination of Tropomyosin in Shrimp and Crab by Liquid Chromatography-Tandem Mass Spectrometry Based on Immunoaffinity Purification.

A UPLC-MS/MS method was developed for the detection of tropomyosin (TM) in shrimp and crab. After simple extraction, the samples were purified by immunoaffinity column and then digested by trypsin. The obtained sample was separated by Easy-nLC 1000-Q Exactive. The obtained spectrums were analyzed by Thermo Proteome Discoverer 1.4 software and then ANIQLVEK with high sensitivity was selected as the quantitative signature peptide. Isotope-labeled internal standard was used in the quantitative analysis. The method showed good linearity in the range of 5-5,000 µg/L with a limit of quantification (LOQ) of 0.1 mg/kg. The average recoveries were 77.22-95.66% with RSDs ≤ 9.97%, and the matrix effects were between 88.53 and 112.60%. This method could be used for rapid screening and quantitative analysis of TM in shrimp and crab. Thus, it could provide technical support for self-testing of TM by food manufacturers and promote further improvement of allergen labeling in China.

Antrodia cinnamomea exerts an anti-hepatoma effect by targeting PI3K/AKT-mediated cell cycle progression in vitro and in vivo.

Antrodia cinnamomea is extensively used as a traditional medicine to prevention and treatment of liver cancer. However, its comprehensive chemical fingerprint is uncertain, and the mechanisms, especially the potential therapeutic target for anti-hepatocellular carcinoma (HCC) are still unclear. Using UPLC‒Q-TOF/MS, 139 chemical components were identified in A. cinnamomea dropping pills (ACDPs). Based on these chemical components, network pharmacology demonstrated that the targets of active components were significantly enriched in the pathways in cancer, which were closely related with cell proliferation regulation. Next, HCC data was downloaded from Gene Expression Omnibus database (GEO). The Cancer Genome Atlas (TCGA) and DisGeNET were analyzed by bioinformatics, and 79 biomarkers were obtained. Furtherly, nine targets of ACDP active components were revealed, and they were significantly enriched in PI3K/AKT and cell cycle signaling pathways. The affinity between these targets and their corresponding active ingredients was predicted by molecular docking. Finally, in vivo and in vitro experiments showed that ACDPs could reduce the activity of PI3K/AKT signaling pathway and downregulate the expression of cell cycle-related proteins, contributing to the decreased growth of liver cancer. Altogether, PI3K/AKT-cell cycle appears as the significant central node in anti-liver cancer of A. Cinnamomea.

Determination of 35 Free Amino Acids in Tea Using Ultra-Performance Liquid Chromatography Coupled With Quadrupole Time-of-Flight Mass Spectrometry.

The purpose of this research was to develop a simple, sensitive, and accurate method for simultaneous determination of 35 free amino acids using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Tea samples were extracted with boiling water bath, and then separated by XBridge BEH Amide column by gradient elution. The exact mass and MS/MS spectra of the target compound was detected under the TOF-MS and Information dependent acquisition (IDA)-MS/MS mode. The results demonstrated good linearity (R 2 > 0.9980) in the range of 0.5-1,000 ng/mL. The limits of detection (LODs) were 0.13-25.00 mg/kg and the limits of quantitation (LOQs) were 0.25-50.00 mg/kg. The recovery rate ranged from 70.1 to 105.1% with relative standard deviations (RSDs) <11% (n = 6). This research provides a targeted strategy for developing an analysis method for amino acids in tea.

Rapid Screening of 350 Pesticide Residues in Vegetable and Fruit Juices by Multi-Plug Filtration Cleanup Method Combined with Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry.

A new method for screening pesticide residues in vegetable and fruit juices by the multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-electrostatic field orbitrap high resolution mass spectrometry(GC-Orbitrap/MS) was developed. The samples were extracted with acetonitrile, purified with m-PFC and determined by GC-Orbitrap/MS. Qualitative analysis was confirmed by retention time, accurate molecular mass and quantitative analysis were performed with the matrix standard calibration. It could eliminate matrix interference effectively. Eight kinds of typical samples (orange juice, apple juice, grape juice, strawberry juice, celery juice, carrot juice, cucumber juice, tomato juice) were evaluated. The linear ranges of the 350 pesticides were from 5 to 500 µg/kg, with good correlation coefficients greater than 0.990. The limits of detection (LODs) were 0.3-3.0 µg/kg and the limits of quantification (LOQs) were 1.0-10.0 µg/kg. The average recoveries at three spiked levels of 10, 100, 200 µg/kg were in the range of 72.8-122.4%, with relative standard deviations (RSDs) of 2.0-10.8%. The method has effectively improved the determination efficiency of pesticide residue screening by high-resolution mass spectrometry in vegetable and fruit juices.

Surface plasmon resonance biosensor for the detection of phenylethanolamine A in swine urine.

In the present study, an antibody against phenylethanolamine A (PEA) was produced, confirmed, and used in a surface plasmon resonance (SPR)-based measurement. Bovine serum albumin (BSA)-conjugated PEA was linked to nano-gold particles bound to l-cysteine modified on the surface of a Au-NP sensor chip. The concentrations of antigen and antibody were optimized, and the designed biosensor chip was investigated to examine the stability and accuracy of the proposed method. The recovery of PEA ranged from 80.4-93.4% in swine urine samples with spike levels of 5, 10 and 20 ng mL-1, and the relative standard deviations of PEA were less than 2%. PEA analogues, such as clenbuterol, ractopamine, and salbutamol, did not influence the PEA measurement. The developed method could be used to measure PEA in swine urine samples.

[Determination of 10 pyrethroid pesticide residues in tea by gas chromatography-tandem mass spectrometry coupled with multi-plug filtration cleanup].

A method for the determination of 10 pyrethroid pesticide residues in tea was established by multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Different extraction solvents (acetonitrile, acetone and ethyl acetate) and extraction methods (immersion without water and immersion with water) were compared. The effect of two kinds of QuEChERS pipes and m-PFC column on the purification of tea extracts and the pesticide recoveries were compared. The results showed that the tea samples could be extracted most efficiently when using acetonitrile without immersion in water. The m-PFC column had a good purification effect on the tea extract and could guarantee a high recovery rate. Good linear relationships were observed for the 10 pyrethroid pesticides, and the correlation coefficients (R2) were greater than0.9980. The average recoveries for the 10 pyrethroid pesticides were in the range of 87.5%-111.3% at four spiked levels, and the RSDs were in the range of 2.1%-8.9%. The LODs and LOQs were 0.001-0.015 mg/kg and 0.003-0.05 mg/kg, respectively. The method was applied to the determination of the 10 pyrethroid pesticides in 50 tea samples. The detection rate of the pyrethroid pesticides was 48%, but all the pesticide residues were below the national standard limits. Compared with the traditional QuEChERS and solid phase extraction methods, this method has the advantages of operational simplicity as well as high accuracy and good precision. The establishment of this method provides a new strategy for the rapid detection of pyrethroid pesticide residues in tea.

[Determination of ten alkaloids in cosmetics by high performance liquid chromatography-tandem mass spectrometry].

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the determination of ten alkaloids in cosmetics. Extraction conditions, purification methods and instrumental parameters were optimized. The samples were ultrasonically extracted with 80% (v/v) methanol aqueous solution. The extracts were separated and filtered after centrifugation. The analytes were separated on a Waters BEH C18 column, and detected in the selected reaction monitoring mode. Ten alkaloids were quantified by the external standard method. The ten alkaloids showed good linearity with correlation coefficients (R2) greater than 0.9900. The limits of detection (LODs) and the limits of quantification (LOQs) of the ten alkaloids were in range of 5.0-12.5 µg/kg and 12.5-50.0 µg/kg, respectively. The average spiked recoveries in the cosmetics ranged from 70.91% to 116.75%, and the relative standard deviations (RSDs) ranged from 0.49% to 9.98%. The method can be used for the rapid screening and quantitative analysis of ten alkaloids in cosmetics.

[Determination of 50 pesticide residues in fruits by gas chromatography-tandem mass spectrometry].

A method for the determination of 50 pesticides in fruits by gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. The three QuEChERS methods (the original one without buffer, the one with acetate buffer and the one with citrate buffer) were compared. The purification effects of primary secondary amine (PSA) and SinChERS-Nano column were also investigated. The results showed that the acetate buffer and the citrate buffer had positive influence on the extraction compared to the original method without buffer, and there was no significant difference between the two methods using buffers. Finally, the QuEChERS method using acetate buffer was chosen as the extraction method. By comparing the purification effect images and the total ion current (TIC) chromatograms, SinChERS-Nano column was revealed to have a better cleaning effect, and was chosen for cleanup. The recoveries of methamidophos, acephate, omethoate, chlorothalonil and dicofol were in ranged of 71.2%-129.2%, the other 45 pesticides were ranged from 79.1% to 122.3%. The limits of detection (LODs) were 0.3-3.0 µ g/kg and the limits of quantification (LOQs) were 1.0-10.0 µ g/kg. The method is rapid and suitable for the screening of the 50 pesticide residues in citrus, grapes and other fruit samples.

Synthesis, characterization and antifungal activity of coumarin-functionalized chitosan derivatives.

Four novel coumarin-functionalized chitosan derivatives 4a-4d were synthesized via condensation reactions of thiosemicarbazide chitosan with coumarin derivatives. Their structures were confirmed by FT-IR, 13C NMR, XRD and elemental analysis. Their antifungal activities against three kinds of phytopathogens, Alternaria solani sorauer (A. solani), Fusarium oxysporum f.sp. vasinfectum (F. oxysporum) and Fusarium moniliforme (F. moniliforme), were tested using the mycelial growth rate in vitro at 0.1, 0.5, and 1.0mg/mL. The degree of substitution for 4a-4d ranged from 40 to 60%. At 1mg/mL, 4a inhibited F. moniliforme growth by 58.1%, and had an inhibitory index against F. Moniliforme of 77.2%. Derivative 4a was more effective than unmodified chitosan whose antifungal index was 9.7%. The fungicidal tests showed that the synthesized chitosan derivatives have higher activity against the tested fungi compared to unmodified chitosan. Moreover, the introduction of halogen atoms into the chitosan derivatives causes an increase in antifungal activity.

Rapid determination of 18 glucocorticoids in serum using reusable on-line SPE polymeric monolithic column coupled with LC-quadrupole/orbitrap high-resolution mass spectrometer.

A simple, rapid and sensitive method for the simultaneous determination of 18 glucocorticoids in serum was developed by coupling on-line solid-phase extraction (SPE) polymeric monolithic column to a liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometer. A simple poly(ethylene glycol dimethacrylate) monolith column (10mm×2.1mm i.d.) was fabricated, and the morphology, surface area and extraction performance of the monolithic column were characterized. Serum samples were extracted by acetonitrile (ACN). Then, online SPE was achieved on the synthesized monolithic column using a 10mmol/L ammonium acetate solution as the loading solvent. After the transfer from the monolith into analytical column (Capcell Pak ADME column) using ACN, the adsorbed analytes were separated on the analytical column and detected with a high-resolution hybrid quadrupole/orbitrap mass spectrometer with full scan/ddMS2 scan mode Under optimized conditions, the method was linear with target linear correlation coefficient (R2) higher than 0.995. Detection limits were in range of 0.1-0.6ng/mL, and the quantification limits were 0.3-1.5ng/mL. The recovery was between 71.9% and 89.2% in three spike levels with precision (n=5) of 5.40-12.1%. The serum sample was directly analyzed after a simple extraction procedure, and the on-line SPE and determination were achieved within only 16min. The method was used to analyze the dynamic contents variation of cortisone and hydrocortisone in serum before and after the surgery.

Rapid Detection of Small Molecule Metabolites in Serum of Hepatocellular Carcinoma Patients Using Ultrafast Liquid Chromatography-Ion Trap-Time of Flight Tandem Mass Spectrometry.

A method was developed for analyzing broad spectrum small molecule metabolites in the serum of hepatocellular carcinoma (HCC) patients based on ultrafast liquid chromatography-ion trap-time of flight tandem mass spectrometry (UFLC-IT-TOF MS). Serum samples were collected from 80 HCC patients and healthy persons. After pretreatment process for protein precipitation, the supernatant was analyzed with the UFLC-IT-TOF MS to obtain information on the metabonomics of small molecules. The eight compounds of glycocholic acid, choline glycerophosphate, acetyl-L-phenylalanine, oleamide, tetradecanamide, acetylcarnitine, lysolecithin and glycochenodeoxycholic acid in the HCC group were identified with significant differences from those in the health group (P <0.01). By using multidimensional analysis of variation coefficient and principal component analysis for the repeatability and 48 h stability, the method was demonstrated to have good repeatability, excellent precision, and high stability, which can satisfy the metabonomics research requirement. The high throughput and practical usability of the method further shows perspective for metabonomic analysis of large-batch serum samples.

Synergistic effects and related bioactive mechanism of Potentilla fruticosa L. leaves combined with Ginkgo biloba extracts studied with microbial test system (MTS).

BACKGROUND: Potentilla fruticosa, also called "Jinlaomei" and "Gesanghua", is widely used as folk herbs in traditional Tibetan medicine in China to treat inflammations, wounds, certain forms of cancer, diarrhoea, diabetes and other ailments. Previous research found P. fruticosa leaf extract (C-3) combined with Ginkgo biloba extracts (EGb) showed obvious synergistic effects in a variety of oxidation systems. The aim of the present study was to further confirm the synergy of P. fruticosa combined with EGb viewed from physiological bioavailability and explore the related bioactive mechanism behind the synergism. METHODS: The microbial test system (MTS) was adopted to evaluate the related bioactive mechanism. The synergistic effects were evaluated by isobolographic analysis. The H2O2 production rate and antioxidant enzyme (Catalase (CAT), Peroxidase (POD), Superoxide dismutase (SOD), Glutathione peroxidase (GSH-PX)) activities were determined by the colorimetric method. Enzyme gene (CAT, SOD) expression was measured by real time-PCR. RESULTS: The MTS antioxidant activity results showed the combination of C-3 + EGb exhibited synergistic effects especially at the ratio 5:1. Components of isorhamnetin and caffeic acid in C-3 and EGb displayed strong antioxidant activities on MTS and their combination also showed significant synergy in promoting H2O2 production. The combinations of C-3 + EGb and isorhamnetin + caffeic acid promoted CAT and SOD enzyme activities and the ratio 1:1 exhibited the strongest synergy while no obvious promotion on POD and GSH-PX enzyme activities was found. Both combinations above promoted gene expression of CAT and SOD enzymes and the ratio 1:1 exhibited the strongest synergy. CONCLUSIONS: Antioxidant activity results in MTS further confirmed the significant synergy of C-3 combined with EGb and isorhamnetin combined with caffeic acid. The synergy of C-3 combined with EGb may be attributed to the combination of isorhamnetin + caffeic acid, which promoted CAT and SOD enzyme gene expression and further promoted the enzyme activities in E. coli. This study could further provide rational basis for optimizing the physiological bioavailability of P. fruticosa by using natural and safe antioxidants in low doses to produce new medicines and functional products.

Chemical composition, antibacterial activity and related mechanism of the essential oil from the leaves of Juniperus rigida Sieb. et Zucc against Klebsiella pneumoniae.

ETHNOPHARMACOLOGICAL RELEVANCE: Juniperus rigida is used as Tibetan and Mongolian medicine in China for the treatment of rheumatoid arthritis, nephritis, brucellosis and other various inflammatory diseases. AIM OF THE STUDY: To evaluate antibacterial potential of essential oils from J. rigida leaves against Klebsiella pneumoniae and to examine its possible related mechanisms. The study was undertaken in order to scientifically validate the traditional use of J. rigida. MATERIALS AND METHODS: The essential oil was extracted from the leaves of J. rigida by supercritical CO2 fluid extraction technology. Chemical composition of essential oils was analyzed by gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was evaluated against 10 bacteria by the paper disc diffusion method. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of the essential oil were estimated by agar dilution method. The antibacterial mechanism was evaluated by growth curve, the integrity of cell membrane, the SDS-PAGE of protein patterns and scanning electron microscope (SEM). RESULTS: 61 components were identified from the essential oil. Caryophyllene (13.11%) and α-Caryophyllene (11.72%) were found to be the major components. The antibacterial activities of the essential oil were screened and compared against 10 bacteria. The essential oil showed good antibacterial activity against K. pneumoniae, with the biggest diameters of inhibition zones (DIZ) (16.00±0.25mm) and the lowest MIC and MBC values of 3.125mg/mL. The increase in proteins, 260nm absorbing materials of bacterial cells suspension indicated that the cytoplasmic membranes were broken by the essential oil. The SDS-PAGE of bacterial proteins demonstrated that the essential oil could damage bacterial cells through the destruction of cellular proteins. Scanning electron microscopy (SEM) showed that the essential oil damaged the morphology of cell wall and membrane. CONCLUSIONS: The essential oil of J. rigida has potential antibacterial activities against K. pneumoniae. The antibacterial mechanism is the essential oil causing the irreversible damage to the cell wall and membrane, leading to the leakage of proteins and 260nm absorbing materials (DNA and RNA). Further phytochemical and pharmacological studies are required for proper scientific validation of the folk use of this plant species.

[Determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd by modified QuEChERS method and liquid chromatography-tandem mass spectrometry].

A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method followed by liquid chromatography-tandem mass spectrometric analysis was developed for the determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd. Yuba and dried beancurd samples were soaked by deionized water, then acetonitrile was added to extract the analytes. Sodium chloride and anhydrous magnesium sulfate were added for liquid-liquid separation. The extracts were cleaned-up by dispersive solid-phase using N-propyl diethylamine. The analytes were separated by liquid chromatography and determined by mass spectrometry. External standard method was used for quantification. The recoveries of dimethyl yellow were in the range of 73.5%-84.5% at spiked levels of 0.3, 1 and 10 kg/kg and the recoveries of diethyl yellow were in range of 70.5%-81.2% at spiked levels of 0.1,1 and 10 µg/kg; relative standard deviations of the method were lower than 11%. The limit of detection and the limit of quantification of dimethyl yellow were 0.1 µg/kg and 0.3 µg/kg, respectively; the limit of detection and the limit of quantification of diethyl yellow were 0.05 µg/kg and 0.1 µg/kg, respectively. This method can be used in rapid screening and quantitative analysis of dimethyl yellow and diethyl yellow in yuba and dried beancurd.