Magnetic-stirring-enhanced mechanical amorphous dispersion extraction for the hydrophobic phytochemical constituents using an aqueous solution from a medicinal plant.

A method involving chitosan-assisted magnetic-stirring-enhanced mechanical amorphous dispersion extraction was developed and utilized to extract hydrophobic anthraquinones from Rhei Radix et Rhizoma prior to ultrahigh performance liquid chromatography analysis. Incorporating natural chitosan as a dispersant facilitated the extraction of hydrophobic anthraquinones using purified water, considerably enhancing the eco-friendliness of the extraction methodology. To optimize extraction efficiency, an extensive evaluation of the crucial parameters influencing rhubarb yield was conducted. Furthermore, a response surface methodology was applied to optimize the extraction conditions. Under these optimized conditions, the method exhibited linearity ranges of 0.1-100 µg/mL, with correlation coefficients between 0.9990 and 0.9998. The method's intraday (n = 6) and interday (n = 6) precision levels were maintained at ≤3.58%, which was considered to be within acceptable limits. The computed detection and quantification limits were 16.54-24.60 and 54.91-82.04 ng/mL, respectively. Consequently, this optimized method was effectively employed to extract five specific compounds (aloe-emodin, emodin, rhein, chrysophanol, and physcion) from Rhei Radix et Rhizoma, achieving recoveries ranging from 86.43% to 102.75%.

Nontargeted metabolomics and enzyme inhibitory and antioxidant activities for chemical and biological characterization of jujube (Ziziphus jujuba) extracts.

The chemical and biologically active characterization of jujube samples (fruits, cores, and leaves) were carried out by the integrated nontargeted metabolomics and bioassay. Firstly, collision cross-section values of active compounds in jujubes were determined by ultrahigh-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry. Then, a multidimensional statistical analysis that contained principal component analysis, partial least squares-discriminant analysis and hierarchical clustering analysis was employed to effectively cluster different tissues and types of jujubes, making identification more scientific. Furthermore, angiotensin-converting enzyme (ACE) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) were used to evaluate the quality of jujubes from a double activity dimension. The analytical results obtained by using ACE and DPPH to evaluate the quality of jujube were different from multivariate statistics, providing a reference for the application of jujube. Therefore, integrating chemical and biological perspectives to evaluate the quality of jujube provided a more comprehensive evaluation and effective reference for clinical needs.

The function role of HIGD1A in nonalcoholic steatohepatitis from chronic hepatitis B.

BACKGROUND: Accompanied by the growing prevalence of nonalcoholic fatty liver disease (NAFLD), the coexistence of chronic hepatitis B (CHB) and NAFLD has increased. In the context of CHB, there is limited understanding of the factors that influence the development of NASH. METHODS: We enrolled CHB combined NAFLD patients who had liver biopsy and divided them to NASH vs. non-NASH groups. A whole transcriptome chip was used to examine the expression profiles of long noncoding RNAs (lncRNAs) and mRNA in biopsied liver tissues. The function analysis of HIGD1A were performed. We knocked down or overexpressed HIGD1A in HepG2.2.15 cells by transient transfection of siRNA-HIGD1A or pcDNA-HIGD1A. In vivo investigations were conducted using hepatitis B virus (HBV) transgenic mice. RESULTS: In 65 patients with CHB and NAFLD, 28 were patients with NASH, and 37 were those without NASH. After screening 582 differentially expressed mRNAs, GO analysis revealed differentially expressed mRNAs acting on nicotinamide adenine dinucleotide phosphate (NADPH), which influenced redox enzyme activity. KEGG analysis also shown that they were involved in the NAFLD signaling pathway. The function analysis revealed that HIGD1A was associated with the mitochondrion. Then, both in vivo and in vitro CHB model, HIGD1A was significantly higher in the NASH group than in the non-NASH group. HIGD1A knockdown impaired mitochondrial transmembrane potential and induced cell apoptosis in HepG2.2.15 cells added oleic acid and palmitate. On the contrary, hepatic HIGD1A overexpression ameliorated free fatty acids-induced apoptosis and oxidative stress. Furthermore, HIGD1A reduced reactive oxygen species (ROS) level by increasing glutathione (GSH) expression, but Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/Acetyl-CoA carboxylase (ACC) pathway was not involved. CONCLUSION: Both in vivo and in vitro CHB model, an upward trend of HIGD1A was observed in the NASH-related inflammatory response. HIGDIA played a protective role in cells against oxidative stress. Our data suggested that HIGD1A may be a positive regulator of NASH within the CHB context.

On-line concentration and separation of multiple derivatized monosaccharides from edible fruit with cyclodextrin-encapsulated sweeping by micellar electrokinetic chromatography.

An on-line enrichment and separation of multiple derivatized monosaccharides with cyclodextrin-encapsulated sweeping (CDES) by micellar electrokinetic chromatography (MEKC) was presented. Five monosaccharides (L-(-)-Mannose, D-(+)-Glucose, D-(-)-Ribose, D-(+)-Xylose, and L-(+)-Rhamnose) were derivatized with 1-phenyl-3-methyl-5-pyrazolone, subsequently concentrated and separated by MEKC. The optimized conditions were as follows: 50 mM phosphoric acid (PA), 100 mM sodium dodecyl sulfate (SDS), and 30 % (v/v) methanol in background solution; 140 s injection of sample solution containing 50 mM CD and 100 mM PA, followed by 90 s injection of 40 mM SDS solution. Under the optimized conditions, the correlation coefficients ≥ 0.9953, and the limits of detection ranged from 4.2 to 7.4 ng/mL. Relative standard deviation values ranged from 0.24-4.23 %, and sensitivity enrichment factors were in the range of 53-82 compared with typical injection (50 mbar, 3 s). The CDES-MEKC method was successfully applied to Jujube with good recoveries of 84.22-104.33 %. The method provides new ideas for the on-line enrichment and detection of trace monosaccharides and even other target analytes in foods with complex matrices.

Two-step pressure injection-assisted online enrichment of herbicides from foods with affinity micelle sweeping by micellar electrokinetic chromatography.

A novel online two-step pressure injection-assisted stacking preconcentration method, which involves sweeping and affinity micelles in micellar electrokinetic chromatography was developed to simultaneously measure various organic anions. The micellar solution was a mixed solution that contained 0.3 mM didodecyldimethylammonium bromide and 20 mM borax. After the micellar solution was injected for 60 s, the tested analytes prepared in 20 mM borax were introduced into the capillary for 150 s. The key experimental factors that influenced the separation and sensitivity were investigated and optimized, including the concentration and injection time of the micellar solution, the concentration of borax in the sample solution, the concentration of sodium dodecyl sulfate and borax in the background electrolyte (BGE), the content of acetonitrile in the BGE and the injection time of the sample solution. Compared with typical injection methods, this method achieved sensitivity enhancement factors ranging from 85 to 97 under optimized conditions. Good linearity for matrix-matched calibration was established for all analytes with R2 values of 0.9986-0.9996. The intraday (n = 6) and interday (n = 6) precisions of the method were less than 2.85% when expressed as relative standard deviations. When the method was applied to analyze rice and dried ginger samples, analyte recoveries ranged from 85.81% to 106.59%. Through sweeping and affinity micelles, stacking preconcentration method was successfully employed to analyze trace amounts of fenoprop and 2,4-dichlorophenoxyacetic acid in rice and dried ginger samples.

Chemometrics and antioxidant activity assisted nontargeted metabolomics for the identification of ginger species.

An ultrahigh-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry method was developed for the separation and identification of phenols, organic acids, flavonoids and curcumin in different species of ginger. The parameters affecting the separation and response of liquid chromatography, including the stationary phase and mobile phase, were systematically investigated and optimized. To further identify the differential metabolites in the six types of samples, a chemometric approach was introduced. Principal component analysis, cluster analysis and partial least squares discriminant analysis were used to identify the major components in the samples and to compare the compositional differences between the various samples. In addition, antioxidant experiments were designed to investigate the differences in antioxidant activity among the six ginger samples. The method showed good linearity (R2 ≥0.9903), satisfactory precision (RSD% ≤ 4.59 %), low LOD (0.35-25.86 ng/mL) and acceptable recovery (78-109 %) and reproducibility (RSD% ≤ 4.20 %). Therefore, the method has great potential for application in the compositional analysis and quality control of ginger.

Clinical Features of Non-Alcoholic Fatty Liver Disease in the Non-Lean Population.

INTRODUCTION: The prevalence of non-alcoholic fatty liver disease (NAFLD) in non-lean patients is significantly increased, and obesity significantly increases the risk of cirrhosis and HCC in NAFLD patients. However, whether there is a difference in clinical manifestations of NAFLD between overweight and obesity remains unclear. The objective of this study was to assess the clinical and histological features of NAFLD among a non-lean population. METHODS: Current study enrolled consecutive non-lean (body mass index [BMI] >23 kg/m2) patients with NAFLD and available liver biopsy results. Patients were stratified by BMI into two groups for the comparison of their clinical and histological variables, which included the overweight (BMI 23∼<28 kg/m2) and the obese (BMI ≥28 kg/m2). Risk factors for moderate to severe fibrosis (stage >1) were also analyzed through the logistic regression model. RESULTS: Among 184 non-lean patients with metabolic-associated fatty liver disease enrolled, 65 and 119 were overweight and obese, respectively. Patients in the obesity group had a significantly lower level of gamma-glutamyl transpeptidase, higher levels of platelet, glucose, prothrombin time, and more common of moderate to severe inflammatory activity when compared to those in the overweight group. However, a significant low frequency of moderate to severe fibrosis was found in the obesity group versus the overweight group (19.33% vs. 40.00%, p = 0.002). Binary logistics regression analysis of fibrosis found that aspartate transaminase (AST), BMI, alanine transaminase (ALT), and cholesterol (CHOL) were independent predictors for moderate to severe fibrosis in non-lean patients with NAFLD. Compared with the traditional fibrosis-4 (AUC = 0.77) and aminotransferase to platelet ratio index (AUC = 0.79) indexes, the combined index based on AST, BMI, ALT, and CHOL was more accurate in predicting moderate to severe fibrosis in non-lean patients with NAFLD (AUC = 0.87). CONCLUSIONS: Clinical and histological features differed between obesity and overweight patients with NAFLD. When compared to the traditional serum markers, the combination index including AST, BMI, ALT, and CHOL provided a better model to predict moderate to severe fibrosis in non-lean patients with NAFLD.

Nanographite-assisted matrix solid phase dispersion microextraction of active and toxic compounds from complex food matrices using cyclodextrin aqueous solution as elution solvent.

In this study, a cyclodextrin aqueous solution was used as an environmentally friendly eluent to simultaneously extract active and toxic compounds from food matrices with the aid of nanographite-assisted matrix solid phase dispersion microextraction (NG-MSPDM). The NG-MSPDM procedure was optimized by single-factor experiments and response surface methodology to obtain optimum conditions. The proposed method achieved excellent linearity at 0.10-20 µg/mL for all target analytes with a coefficient of correction (R2) ≥ 0.9909, limits of detection < 52.01 ng/mL, satisfactory reproducibility below 3.21 %, and acceptable recoveries of 82.0-112 %. To accurately determine the target components in the complex matrix, collision cross-section values of the analytes were obtained using ion mobility quadrupole time-of-flight mass spectrometry (IM-Q-TOF/MS). Results indicated that the NG-MSPDM method successfully achieved the simultaneous extraction of flavonoids and phenoxyacetic herbicides from Alpinia officinarum.

A highly sensitive method (supercritical fluid chromatography coupled with ion mobility mass spectrometry) for determination of multiple compounds in radix curcumae.

A highly sensitive method was developed for simultaneously separating and identifying multiple compounds in radix curcumae. The determination of these compounds was achieved by combining supercritical fluid chromatography with drift tube ion mobility quadrupole time-of-flight MS. Related parameters were optimized: the RX-SIL column was used as the stationary phase, methanol was selected as the organic modifier, back pressure was 120 bar, back temperature was 60°C, the mobile phase flow rate was 1.75 mL/min, the makeup solvent was 0.2% formic acid/methanol with a flow rate of 0.7 mL/min. Under optimal conditions, multipolar compounds were separated. Furthermore, these compounds were identified by the values of collision sectional areas. The established method was verified by related parameters and exhibited good linearity, sensitivity, precision and accuracy. It could be extended to analyze other curcuminoids and sesquiterpenoids in natural products.

Sorafenib triggers ferroptosis via inhibition of HBXIP/SCD axis in hepatocellular carcinoma.

Sorafenib, which inhibits multiple kinases, is an effective frontline therapy for hepatocellular carcinoma (HCC). Ferroptosis is a form of iron-dependent programmed cell death regulated by lipid peroxidation, which can be induced by sorafenib treatment. Oncoprotein hepatitis B X-interacting protein (HBXIP) participates in multiple biological pro-tumor processes, including growth, metastasis, drug resistance, and metabolic reprogramming. However, the role of HBXIP in sorafenib-induced ferroptotic cell death remains unclear. In this study, we demonstrated that HBXIP prevents sorafenib-induced ferroptosis in HCC cells. Sorafenib decreased HBXIP expression, and overexpression of HBXIP blocked sorafenib-induced HCC cell death. Interestingly, suppression of HBXIP increased malondialdehyde (MDA) production and glutathione (GSH) depletion to promote sorafenib-mediated ferroptosis and cell death. Ferrostatin-1, a ferroptosis inhibitor, reversed the enhanced anticancer effect of sorafenib caused by HBXIP silencing in HCC cells. Regarding the molecular mechanism, HBXIP transcriptionally induced the expression of stearoyl-CoA desaturase (SCD) via coactivating the transcriptional factor ZNF263, resulting in the accumulation of free fatty acids and suppression of ferroptosis. Functionally, activation of the HBXIP/SCD axis reduced the anticancer activity of sorafenib and suppressed ferroptotic cell death in vivo and in vitro. HBXIP/SCD axis-mediated ferroptosis can serve as a novel downstream effector of sorafenib. Our results provide new evidence for clinical decisions in HCC therapy.

Analysis of iodinated amino acids by microemulsion electrokinetic chromatography using aliphatic amine as a cosurfactant.

A novel microemulsion electrokinetic chromatography (MEEKC) was established for the separation and determination of iodinated amino acids using n-butylamine as a novel cosurfactant. By optimizing the type of oil phase, the type and concentration of surfactant, the concentration of cosurfactant and the type and concentration of buffer in the microemulsion system, the optimal conditions for the separation of organic iodines were determined to be 0.5% ethyl acetate, 0.6% SDS, 1.2% n-butylamine and 10 mM sodium borate. The efficient and rapid separation of the five analytes (3-iodo-L-tyrosine (MIT), 3, 5-Diiodo-L-tyrosine (DIT), 3, 5-Diiodo-L-thyronine (T2), 3, 3', 5-Triiodo-L-thyronine (T3) and L-Thyroxine (T4)) was achieved under the optimal conditions. The reliability of the method was verified by measuring the precision, LOD, LOQ and recovery. The practicality of the MEEKC method was demonstrated by applying it to the determination of two iodotyrosines, MIT and DIT, in kelp. The analytical method established in this experiment will provide a reference for the study of iodotyrosines in other natural plants and food.

Recent advances on discovery of enzyme inhibitors from natural products using bioactivity screening.

The essence of enzymes is to keep the homeostasis and balance of humans by catalyzing metabolic responses and modulating cells. Suppression of an enzyme slows the progress of some diseases, making it a therapeutic target. Therefore, it is important to develop enzyme inhibitors by proper bioactivity screening strategies for the future treatment of some major diseases. In this review, we summarized the recent (2015-2020) applications of several screening strategies (electrophoretically mediated microanalysis, enzyme immobilization, affinity chromatography, and affinity ultrafiltration) in finding enzyme inhibitors from certain species of bioactive natural compounds of plant origin (flavonoids, alkaloids, phenolic acids, saponins, anthraquinones, coumarins). At the same time, the advantages and disadvantages of each strategy were also discussed, and the future possible development direction in enzyme inhibitor screening has been prospected. To sum up, it is expected to help readers select suitable screening strategies for enzyme inhibitors and provide useful information for the study of the biological effects of specific kinds of natural products.

Phase â and phase â ¡ metabolic studies of Citrus flavonoids based on electrochemical simulation and in vitro methods by EC-Q-TOF/MS and HPLC-Q-TOF/MS.

The oxidation products and metabolic pathways of five Citrus flavonoids were studied by online electrochemical/quadrupole time-of-flight mass spectrometry (EC/Q-TOF/MS). The simulated oxidation metabolism of target compounds in phase I and phase Ⅱ was carried out at boron-doped diamond (BDD) working electrode. The results obtained by EC-MS were compared with the conventional metabolism of rats and humans reported in previous literatures. In addition, the method of incubating the target compounds with rat liver microsomes in vitro was established, the target compounds and their metabolites were analyzed by high performance liquid chromatography coupled mass spectrometry. The structures of the metabolites were determined by accurate mass measurements and previous in vivo metabolite results. The results showed that the electrochemical oxidation metabolites were consistent with the results of in vitro incubation of liver microsomes, and also with the results reported in other literatures. As a consequence, EC/Q-TOF/MS is a promising and effective tool for studying metabolic transformation of different complex food components.

The modulation of PD-L1 induced by the oncogenic HBXIP for breast cancer growth.

Programmed death ligand-1 (PD-L1)/PD-1 checkpoint extensively serves as a central mediator of immunosuppression. A tumor-promoting role for abundant PD-L1 in several cancers is revealed. However, the importance of PD-L1 and how the PD-L1 expression is controlled in breast cancer remains obscure. Here, the mechanisms of controlling PD-L1 at the transcription and protein acetylation levels in promoting breast cancer growth are presented. Overexpressed PD-L1 accelerates breast cancer growth in vitro and in vivo. RNA-seq uncovers that PD-L1 can induce some target genes affecting many cellular processes, especially cancer development. In clinical breast cancer tissues and cells, PD-L1 and HBXIP are both increased, and their expressions are positively correlated. Mechanistic exploration identifies that HBXIP stimulates the transcription of PD-L1 through co-activating ETS2. Specifically, HBXIP induces PD-L1 acetylation at K270 site through interacting with acetyltransferase p300, leading to the stability of PD-L1 protein. Functionally, depletion of HBXIP attenuates PD-L1-accelerated breast tumor growth. Aspirin alleviates breast cancer via targeting PD-L1 and HBXIP. Collectively, the findings display new light into the mechanisms of controlling tumor PD-L1 and broaden the utility for PD-L1 as a target in breast cancer therapy.

The identify role and molecular mechanism of the MALAT1/hsa-mir-20b-5p/TXNIP axis in liver inflammation caused by CHB in patients with chronic HBV infection complicated with NAFLD.

BACKGROUND/AIMS: To identify the inflammatory damage caused by chronic hepatitis B (CHB) in patients of chronic hepatitis B virus (HBV) infection complicated with non-alcoholic fatty liver disease (NAFLD), then guiding clinicians to carry out antiviral treatment. METHODS: According to the pathological features of liver biopsy, treatment-naïve obese patients of chronic HBV infection complicated with NAFLD who had elevated alanine transaminase (ALT) were divided into CHB group and NASH group. Transcriptome chips were used to analyze the expression profiles of long non-coding RNA (lncRNA) and mRNA in liver puncture tissues from the two groups. The chip data of CHB and NASH groups were analyzed for differential expression analysis, gene function analysis, signal pathway analysis, target gene prediction and competing endogenous RNAs (ceRNA) network analysis. RESULTS: By comparing CHB group with NASH group, a total of 44 differentially expressed lncRNAs and 567 differentially expressed mRNAs were screened. GO analysis predicted that the differentially expressed mRNAs may affect monooxygenase activity and oxidoreductase activity. KEGG analysis predicted that the differentially expressed mRNAs may be related to signaling pathways involved in oxidative phosphorylation, phagosomes, and NAFLD. Differential analysis of lncRNA shown that the expression of metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) in CHB group was significantly upregulated. Subsequently, through target gene prediction and ceRNA network analysis, we found thioredoxin interacting protein (TXNIP), which was significantly upregulated in the CHB group and had a ceRNA relationship with MALAT1. It is predicted that there may be a ceRNA regulation relationship of MALAT1/hsa-miR- 20b-5p/TXNIP. CONCLUSION: The MALAT1/hsa-miR-20b-5p/TXNIP axis may mediate CHB-induced inflammatory damage in chronic HBV infection complicated with NAFLD, and the mechanism may be related to the activation of NLRP3 inflammatory bodies and downstream inflammatory responses.

Ligand fishing based on bioaffinity ultrafiltration for screening xanthine oxidase inhibitors from citrus plants.

Citrus plants are valuable medicinal plants with abundant flavonoids content in the parts of fruits and peels, which exhibit potential hypouricemic effect. In the present study, a ligand fishing assay was performed based on bio-affinity ultrafiltration for rapidly screening and identifying xanthine oxidase inhibitors from citrus plants. Under the optimal experimental conditions, five potential ligands were fished out when xanthine oxidase acted as the targeted protein. Subsequently, the chemical structures of all five compounds were identified by quadrupole time-of-flight mass spectrometry. Among them, hesperidin and naringin were confirmed as high-efficiency xanthine oxidase inhibitors. The half maximal inhibitory concentration values of hesperidin and naringin were 0.15 and 1.82 µM, respectively. Compared with the clinical antigout drug, allopurinol (half maximal inhibitory concentration = 8.03 µM), lower half maximal inhibitory concentration values indicated higher enzyme inhibitory activity. The Lineweaver-Burk plots indicated that the two compounds inhibited xanthine oxidase in a noncompetitive manner. The results demonstrate that the bioaffinity ultrafiltration method is a powerful tool for screening out xanthine oxidase inhibitors from natural products.

Cucurbituril and zwitterionic surfactant-based matrix solid-phase dispersion microextraction to simultaneously determine terpenoids from Radix Curcumae.

A rapid, efficient, and environmentally friendly matrix solid-phase dispersion microextraction was established to determine and quantify terpenoids in Radix Curcumae using ultra-high-performance liquid chromatography with a diode array detector. Various parameters affecting the extraction were investigated in detail, such as the grinding time, amount of adsorbent, type and concentration of elution solvent, and pH. The optimization of single-factor and response surface methodology was performed to confirm the best conditions in this procedure. The final optimized conditions were obtained by applying 70 mg of cucurbituril as adsorbent, 149 s as the optimum grinding time, and 228 mM of 3-(N,N-dimethylpalmitylammonio)propanesulfonate aqueous solution (pH 6.5) as the optimal elution solvent. The validated method showed a satisfactory linear range of 0.10-10 µg/mL for curdione and furanodiene, 0.01-10 µg/mL for isocurcumenol and germacrone, and 0.05-10 µg/mL for furanodienone, while the correlation coefficients ranged from 0.9945 to 0.9970. The recoveries of the investigated analytes at two spiked concentration levels (0.1 and 1.0 µg/mL) ranged from 96.53 to 104.60%. In addition, this method displayed acceptable reproducibility (relative standard deviation ≤ 3.66%). The results showed that the newly proposed matrix solid-phase dispersion microextraction method was successfully applied to analyze curdione, isocurcumenol, furanodienone, germacrone and furanodiene in Radix Curcumae samples.

Screening of ß-secretase inhibitors from Dendrobii Caulis by covalently enzyme-immobilized magnetic beads coupled with ultra-high-performance liquid chromatography.

In the present study, to effectively discover potential ß-secretase inhibitors from Dendrobii Caulis, ß-secretase was immobilized on magnetic beads via direct covalent connection and coupled with ultra-high-performance liquid chromatography. Mechanochemical-assisted extraction was used to extract active ingredients from Dendrobii Caulis. The main reaction conditions, including screening enzyme inhibitors, were evaluated, and the most important enzyme kinetic parameters were also investigated across the UV-vis spectrophotometer. Five compounds (rutin, scoparone, naringenin, dendrophenol, and erianin) with high binding affinity to magnetic beads were removed from the extract. The results indicated that ß-secretase was successfully immobilized and screened out five potential inhibitor compounds by ligand fishing. The lowest IC50 values were noted for rutin (5.437 µM) and erianin (2.039 µM). This is the first report on immobilized ß-secretase on magnetic beads for the identification of potential active compounds against Alzheimer's disease from complex biological mixtures.

In situ antioxidation-assisted matrix solid-phase dispersion microextraction and discrimination of chiral flavonoids from citrus fruit via ion mobility quadrupole time-of-flight high-resolution mass spectrometry.

A simple and sensitive in situ antioxidation process assisted with a matrix solid-phase dispersion method for extracting chiral flavonoids in citrus fruit was established, and samples were further analyzed using ion mobility quadrupole time-of-flight high-resolution mass spectrometry. The collision cross-sections of the target compounds were studied using single-field and stepped-field methods. The optimal conditions were obtained using 30 mg of C18 as a dispersant, methanol as an elution solvent and 0.6 mM 1,1-diphenyl-2-picrylhydrazyl (DPPH) as a radical solution. Additionally, the method showed satisfactory limits of detection (3.70-6.52 ng/mL) and good recoveries (96.78-104.67%) for four flavonoids in citrus fruit. The IC50 values of DPPH radical-scavenging activities ranged from 817.8 to 981.55 µg/mL for tested samples. The method was a good alternative for the microextraction and determination of antioxidant capacity and chiral differentiation of narirutin, naringin, hesperidin and neohesperidin in citrus fruit.

Electrochemical microreactor combined with mass spectrometry for online oxidation and real-time detection of alkaloids.

The main purpose of the present study was to investigate the prototypes and oxidation products of alkaloids with the use of an online electrochemistry/quadrupole time-of-flight mass spectrometry system. The metabolism of oxidative phase I and II was simulated in an electrochemical reaction cell. The metabolic processes for coptisine and jatrorrhizine were simulated in a thin-layer cell fitted with a glassy carbon working electrode, while the metabolic processes for berberine and palmatine were simulated by using a boron-doped diamond working electrode. By using the new experimental system, dehydrogenation, demethylation, methylation, hydroxylation, and the formation of two hydroxylation adducts were detected by applying different potentials to the electrochemical cell. The online reaction with glutathione yielded different covalent glutathione adducts. The results obtained from the electrochemical simulation were found to be in good accordance with those reported previously in vivo, showing that electrochemistry/mass spectrometry is an effective tool for studying metabolic reactions for various complex components. Moreover, analysis of alkaloids in liver microsomes by liquid chromatography coupled with mass spectrometry confirmed the possibility of using an electrochemistry technique to simulate the metabolism of target compounds.