In-depth characterization of cycloartane triterpenoids and discovery of species-specific markers from three Cimicifuga species guided by a strategy that integrates in-source fragment elimination, diagnostic ion recognition, and feature-based molecular networking.

Characterization studies of the plant metabolome are crucial for revealing plant physiology, developing functional foods, and controlling quality. Mass spectrometry-based metabolite profiling allows unprecedented qualitative coverage of complex biological extract composition. However, the electrospray ionization used in metabolite profiling generates multiple artifactual signals for a single analyte, which makes it challenging to filter out redundant signals and organize the signals corresponding to abundant constituents. This study proposed a strategy integrating in-source fragments elimination, diagnostic ions recognition, and feature-based molecular networking (ISFE-DIR-FBMN) to simultaneously characterize cycloartane triterpenoids (CTs) from three medicinal Cimicifuga species. The results showed that 63.1 % of the measured ions were redundant. A total of 184 CTs were annotated, with 27.1 % being reported for the first time. It presents a promising approach to assess the composition of natural extracts, thus facilitating new ingredient registrations or natural-extracts-based drug discovery campaigns. Besides, chemometrics analysis of the three Cimicifuga species identified 32 species-specific markers, highlighting significant differences among them. The valuable information can enhance the sustainable utilization and further development of Cimicifuga resources. The codes involved in ISFE-DIR-FBMN are freely available on GitHub (https://github.com/LHJ-Group/ISFE-DIR-FBMN.git).

Integration of untargeted and pseudotargeted metabolomics reveals specific markers for authentication and adulteration detection of Fritillariae Bulbus using tandem mass spectrometry and chemometrics.

Authentication and adulteration detection of closely related herbal medicines is a thorny issue in the quality control and market standardization of traditional Chinese medicine. Taking Fritillariae Bulbus (FB) as a case study, we herein proposed a three-step strategy that integrates mass spectrometry-based metabolomics and multivariate statistical analysis to identify specific markers, thereby accurately identifying FBs and determining the adulteration level. First, an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based untargeted metabolomics method was employed to profile steroid alkaloids in five sorts of FB and screen potential differential markers. Then, the reliability of the screened markers was further verified by the distribution in different FB groups acquired from ultra-high performance liquid chromatography triple quadrupole mass spectrometry-based pseudotargeted metabolomics analysis. As a result, a total of 16 compounds were screened out to be the specific markers, which were successfully applied to distinguish five FBs by using discriminant analysis model. Besides, partial least squares regression models based on specific markers allowed accurate prediction of three sets of adulterated FBs. All the models afforded good linearity and good predictive ability with regression coefficient of prediction (R2p) > 0.9 and root mean square error of prediction (RMSEP) < 0.1. The reliable results of discriminant and quantitative analysis revealed that this proposed strategy could be potentially used to identify specific markers, which contributes to rapid chemical discrimination and adulteration detection of herbal medicines with close genetic relationship.

An integrated strategy combining network toxicology and feature-based molecular networking for exploring hepatotoxic constituents and mechanism of Epimedii Folium-induced hepatotoxicity in vitro.

Epimedii Folium (EF), a commonly used herbal medicine to treat osteoporosis, has caused serious concern due to potential hepatotoxicity. Until now, its intrinsic hepatotoxic mechanism and hepatotoxic ingredients remain unclear. Here, a novel high-throughput approach was designed to investigate the intrinsic hepatotoxic of EF. High-content screen imaging (HCS) and biochemical tests were first performed to obtain the cytotoxicity parameter matrix of 17 batch EF samples. EF-treated alpha mouse liver 12 (AML12) cells showed increased reactive oxygen species (ROS), reduced glutathione (GSH) and mitochondrial membrane potential (MMP), and apoptosis and cholestasis were further observed. Network toxicology predicted that EF-triggered hepatotoxiciy was involved in transcription factor (TF) activity. The FXR expression, screened by a TF PCR array, exhibited down-regulation following EF extract administration. Moreover, EF inhibited bile acid (BA) metabolism pathway in an FXR-dependent manner. Pearson correlation between the cytotoxicity parameter matrix and quantification feature table obtained from UHPLC-QTOF data of EF suggested 7 prenylated flavonoids possessed potent hepatotoxicities and their cytotoxicity order was further summarized. The transcriptional repression effects of them on FXR were also verified. Collectively, our findings indicate that FXR is probably responsible for EF-induced hepatotoxicity and prenylated flavonoids may be a major class of hepatotoxic constituents in EF.

Revealing active components and action mechanism of Fritillariae Bulbus against non-small cell lung cancer through spectrum-effect relationship and proteomics.

BACKGROUND: Fritillariae Bulbus (FB) is widely used as a traditional medicine for the treatment of lung meridian diseases. It has been proved that FB has good anti-non-small cell lung cancer (NSCLC) activity. However, the active components and potential mechanism are still not clear. PURPOSE: To reveal the bioactive components of FB against NSCLC and potential mechanism through spectrum-effect relationship and proteomics. METHOD: First, the FB extract was chemically profiled by UHPLC-QTOF-MS and the inhibitory effect of FB extract on A549 cell viability was evaluated by Cell Counting Kit-8 assay. Second, orthogonal-partial least squares-regression analysis was applied to screen potential active compounds through correlating the chemical profile with corresponding inhibitory effect. Third, the anti-NSCLC activities of potential active components were further investigated in terms of cell proliferation, cell cycle and cell apoptosis in vitro and tumor growth in vivo. Finally, proteomics was utilized to reveal the underlying anti-NSCLC mechanism. RESULTS: Six potential active components including verticine, verticinone, zhebeirine, ebeiedinone, yibeissine and peimisine were screened out by spectrum-effect relationship. Among them, zhebeirine showed higher inhibitory effect on A549 cell viability with IC50 value of 36.93 µM and dosage-dependent inhibition of A549 xenograft tumor growth in nude mice. Proteomics and western blotting assays indicated that zhebeirine could arrest cell cycle by down-regulating the expressions of CDK1, CDK2, Cyclin A2, Cyclin B2 and inhibiting the phosphorylation of p53. Moreover, the proteins participating in p53 signaling pathway including PCNA, 14-3-3σ, CHEK1 were significantly decreased, which suggested that zhebeirine affected cell cycle progression through p53 signaling pathway. CONCLUSION: This study not only provides scientific evidence to support the clinical application of FB against NSCLC, but also demonstrates that zhebeirine is a promising anti-NSCLC lead compound deserving further studies.

RNA interference of vATPase subunits A and E affects survival of larvae and adults in Plagiodera versicolora (Coleoptera: Chrysomelidae).

Vacuolar-type H+-ATPases (vATPases) are ATP-driven proton pumps and play essential roles in many physiological functions. Plagiodera versicolora (Coleoptera: Chrysomelidae) is a leaf-eating forest pest found in salicaceous trees worldwide. RNA interference (RNAi) is a powerful tool for functional identify and pest control. In this study, we used RNAi as an approach to knock down subunits A and E of the vATPase gene. The phylogenetic analysis showed that vATPase-A and vATPase-E from the same order were clustered together to form Coleoptera subclades, respectively. The expression levels of vATPase-A and vATPase-E were higher in gut, Malpighian tubules and 1st instar larvae. Ingest the dsvATPase-A and dsvATPase-E significantly inhibited the development of 1st to 3th instar larvae, incapacitated of mating and oviposition in adults. In addition, knockdown of vATPase subunit genes caused higher mortality in larvae and adults. The results demonstrate that RNAi efficiencies both vATPase-A and vATPase-E genes at various larvae stages and adults. Moreover, this research suggested that silencing of two vATPase subunits A and E offers a potential strategy to control P. versicolora.

Chemometrics integrated with in silico pharmacology to reveal antioxidative and anti-inflammatory markers of dandelion for its quality control.

BACKGROUND: Dandelion is an herb with high nutritional and medicinal values, which has been listed in Chinese Pharmacopeia, European Pharmacopoeia and British Pharmacopoeia, gaining increasing acceptance around the world. However, the current quality control of dandelion is lagging behind. Only in Chinese Pharmacopeia, cichoric acid is used as a marker compound for its quality evaluation, whereas, it can not comprehensively reflect the bioactivity of dandelion. METHODS: This study developed a strategy by integrating chemometrics with in silico pharmacology to reveal the bioactive markers of dandelion for its quality control. Firstly, the major chemicals in dandelion were characterized using HPLC-DAD-MS/MS, and the corresponding antioxidant and anti-inflammatory activities were evaluated in vitro. Subsequently, the active components were screened by relating the chemicals and bioactivity of dandelion via grey relational assay and partial least squares regression analysis. The potential active components were then subjected to a validation for their activities. Moreover, in silico pharmacology was utilized to evaluate the contribution of active components to efficacy. RESULTS: A total of 22 phenolic compounds were characterized. Among them, cichoric acid, caffeic acid and luteolin were identified as quality markers owing to their good correlations with the bioactivities of dandelion. These three markers were quantified in frequently-used dandelion species, viz. Taraxacum mongolicum Hand.-Mazz. (TAM) and T. officinale F. H. Wigg. (TAO). TAM, with acceptably higher content of cichoric acid and caffeic acid, showed better antioxidant activity than TAO. While TAO included higher content of luteolin, presenting slightly more effective in anti-inflammation. CONCLUSION: An useful strategy for the quality marker discovery was successfully designed. And the results provided more knowledge for the quality evaluation of dandelion.

Long-term oral administration of Epimedii Folium induced cholestasis in mice by interfering with bile acid transport.

ETHNOPHARMACOLOGICAL RELEVANCE: Epimedii Folium (EF) is a common traditional Chinese medicine that functions as a tonifying kidney yang to strengthen bones and muscles and dispel wind dampness (limb pain, lethargy, nausea, anorexia, and loose stools). Several studies have reported the potential risk of cholestatic liver damage from EF use; however, there have been few investigations of EF-induced cholestasis, particularly the underlying mechanisms. AIMS OF THE STUDY: The purpose of this study was to evaluate the risk of EF-induced cholestasis in vivo and to explore the mechanisms of action. MATERIALS AND METHODS: ICR mice were orally administered a water extract of EF (WEF) in doses of 6.5 and 19.5 g/kg/day for 14 weeks. Liver-to-body weight ratios, body weight, histopathological examination, and biochemical analyses were performed to assess WEF-induced cholestasis in the mice. Genes associated with bile acid (BA) metabolism and transport, including sodium taurocholate cotransporting polypeptide (NTCP), cytochrome P450 8B1 (CYP8B1), bile-salt export pump (BSEP), multidrug resistance P-glycoproteins 1 (MDR1), and farnesoid X receptor (FXR), were measured at the transcript and protein levels to investigate the potential mechanisms through which cholestasis is aroused by EF. RESULTS: After administration of WEF for 14 weeks, mice in the high-dose WEF group showed poor health with an increased liver-to-body weight ratio as well as higher serum aminotransferase, alkaline phosphatase, direct bilirubin, and total BA levels. Compared with the control group, mRNA expression of NTCP and cholesterol 7a-hydroxylase (CYP7A1) increased, and levels of BSEP, MDR1, multidrug resistance-associated protein 2, and multidrug resistance-associated protein 3 decreased in the WEF-treated group. NTCP, BSEP, MDR1, and CYP8B1 showed similar mRNA and protein expression trends. CONCLUSION: We demonstrated that the long-term oral administration of WEF causes cholestatic liver injury in mice, which is consistent with reported clinical cases. Furthermore, we found that the destruction of BA metabolism and transport is involved in WEF-induced cholestasis. The fine-scale molecular mechanisms of WEF-induced cholestasis and the active compounds of EF need further study.

Molecular-networking-guided discovery of species-specific markers for discriminating five medicinal Paris herbs.

BACKGROUND: Paridis Rhizoma (PR) is a famous traditional herbal medicine. Apart from two officially recorded species, viz. Paris polyphylla Smith var. yunnanensis (Franch.) Hand. - Mazz. (PPY) and P. polyphylla Smith var. chinensis (Franch.) Hara (PPC), there are still many other species used as folk medicine. It is necessary to understand the metabolic differences among Paris species. PURPOSE: To establish a strategy that can discover species-specific steroidal saponin markers to distinguish closely-related Paris herbs for quality and safety control. METHODS: A new strategy of molecular-networking-guided discovery of species-specific markers was proposed. Firstly, the ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was applied to obtain the MS and MS/MS data of all samples. Then, molecular networking (MN) was created using MS/MS data to prescreen the steroidal saponins for subsequent analysis. Next, the principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA) models were established to discover potential markers. Finally, the verification, identification and distribution of chemical markers were performed. RESULTS: A total of 126 steroidal saponins were screened out from five species using MN. Five species were classified successfully by OPLS-DA model, and 18 species-specific markers were discovered combining the variable importance in the projection (VIP) value, P value (one-way ANOVA) and their relative abundance. These markers could predict the species of Paris herbs correctly. CONCLUSION: These results revealed that this new strategy could be an efficient way for chemical discrimination of medicinal herbs with close genetic relationship.

A strategy for rapid discovery of traceable chemical markers in herbal products using MZmine 2 data processing toolbox: A case of Jing Liqueur.

Objective: The quality evaluation of herbal products remains a big challenge. Traceable markers are the core concept of the authentication of herbal products. However, the discovery of traceable markers is labor-intensive and time-consuming. The aim of this study is to develop a convenient approach to rapidly screen the traceable markers for herbal product authentication. Methods: Commercial Jing Liqueur and its 22 species of herbal ingredients were analyzed using HPLC-QTOF-MS and GC-MS to characterize nonvolatile and volatile chemicals. The acquired data were imported into MZmine 2 software for mass detection, chromatogram building, deconvolution and alignment. The aligned data were exported into a csv file and then traceable markers were selected using the built-in filter function in Excel. Finally, the traceable markers were identified by searching against online databases or publications, some of which were confirmed by reference standards. Results: A total of 288 chemical features transferred from herbal materials to Jing Liqueur product were rapidly screened out. Among them, 52 markers detected by HPLC-QTOF-MS were annotated, while nine volatile markers detected by GC-MS were annotated. Moreover, 30 of these markers were confirmed by comparing with reference standards. A chemical fingerprint consisting of traceable markers was finally generated to ensure the authentication and quality consistency of Jing Liqueur. Conclusion: A strategy for rapid discovery of traceable markers in herbal products using MZmine 2 software was developed.

Diagnostic fragmentation-assisted mass spectral networking coupled with in silico dereplication for deep annotation of steroidal alkaloids in medicinal Fritillariae Bulbus.

Fully understanding the chemicals in an herbal medicine remains a challenging task. Molecular networking (MN) allows to organize tandem mass spectrometry (MS/MS) data in complex samples by mass spectral similarity, which yet suffers from low coverage and accuracy of compound annotation due to the size limitation of available databases and differentiation obstacle of similar chemical scaffolds. In this work, an enhanced MN-based strategy named diagnostic fragmentation-assisted molecular networking coupled with in silico dereplication (DFMN-ISD) was introduced to overcome these obstacles: the rule-based fragmentation patterns provide insights into similar chemical scaffolds, the generated in silico candidates based on metabolic reactions expand the available natural product databases, and the in silico annotation method facilitates the further dereplication of candidates by computing their fragmentation trees. As a case, this approach was applied to globally profile the steroidal alkaloids in Fritillariae bulbus, a commonly used antitussive and expectorant herbal medicine. Consequently, a total of 325 steroidal alkaloids were discovered, including 106 cis-D/E-cevanines, 142 trans-D/E-cevanines, 29 jervines, 23 veratramines, and 25 verazines. And 10 of them were confirmed by available reference standards. Approximately 70% of the putative steroidal alkaloids have never been reported in previous publications, demonstrating the benefit of DFMN-ISD approach for the comprehensive characterization of chemicals in a complex plant organism.

Untargeted metabolomics coupled with chemometric analysis reveals species-specific steroidal alkaloids for the authentication of medicinal Fritillariae Bulbus and relevant products.

Authentication of original species is embedded in the quality control system of herbal medicines. In this work, ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based untargeted metabolomics coupled with chemometric analysis was utilized for the precise authentication of the Fritillaria species for both raw materials and commercial products. First, a stepwise difference-enlarging chemometric analysis strategy was proposed to analyze eight medicinal Fritillaria species. Subsequently, 21 species-specific markers were discovered and the specificity was investigated under different sample preparation methods. Finally, the obtained species-specific markers were successfully utilized to identify the Fritillaria species in commercially relevant products. This work is the first to report robust and specific markers for authentication of Fritillaria products, showing promise for tracking the supply chain of herbal suppliers.

Metabolomic-transcriptomic landscape of 8-epidiosbulbin E acetate -a major diterpenoid lactone from Dioscorea bulbifera tuber induces hepatotoxicity.

Studies have shown that 8-epidiosbulbin E acetate (EEA), a major diterpenoid lactone in the tuber of Dioscorea bulbifera, can induce hepatotoxicity in vivo. However, the underlying mechanisms remain unknown. Using the integrated transcriptomic and metabolomics method, in this study we investigated the global effect of EEA exposure on the transcriptomic and metabolomic profiles in mice. The abundance of 7131 genes and 42 metabolites in the liver, as well as 43 metabolites in the serum were altered. It should be noted that EEA mainly damaged hepatic cells through the aberrant regulation of multiple systems primarily including bile acid metabolism, and taurine and hypotaurine metabolism. In addition, an imbalance of bile acid metabolism was found to play a key pat in response to EEA-triggered hepatotoxicity. In summary, these findings contributed to understanding the underlying mechanisms of EEA hepatotoxicity.

A novel liquid-liquid-solid microextraction strategy for bio-sample preparation by in situ self-assembly of zeolitic imidazolate framework 8 on hollow fiber membrane.

A novel liquid-liquid-solid membrane microextraction (LLSMME) method which integrates hollow fiber liquid phase microextraction (HF-LPME) and solid phase microextraction (SPME) was developed for bio-sample preparation. The homogeneous zeolitic imidazolate framework 8 mixed matrix membrane (ZIF-8-MMM) was prepared by in situ self-assembly of ZIF-8 on the inner surface of hollow fiber membrane and employed as a flexible LLSMME device. Incorporating the advantages of both HF-LPME and SPME, the as-fabricated ZIF-8-MMM exhibited excellent performance on the extraction and preconcentration of small molecule drugs of different polarity from complex biological matrices. As a case study, ZIF-8-MMM-based LLSMME coupled with UPLC-MS/MS were developed and validated for determination of ibuprofen, simvastatin and ranitidine at trace levels in rat plasma. The method showed good linearity (r2 > 0.99) and repeatability (RSD < 15%), low limits of detection (2-3 ng mL-1) and high relative recoveries (97.42-103.8%). The enrichment factors were between 87.3 and 112.6. Our study provided a promising strategy for developing more efficient, cost-effective and environmentally friendly technique for bio-sample pretreatment.

A pair of cyclopeptide epimers from the seeds of Celosia argentea.

Two cyclopeptides, celogentin L (1) and its epimer lyciumin A (2) were firstly isolated from Celosia argentea L.. The planar structures of the two compounds were fully determined by spectroscopic data, including 1D-, 2D-NMR, and HR-ESI/MS. The absolute configurations of amino acid components were assigned via chiral-phase HPLC analyses after acid hydrolysis. Furthermore, the configuration of C-N linkage at the glycine Cα was elucidated by extensive analyses of 2D-NMR and comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Cytotoxicity of the two compounds against human alveolar epithelial A549, hepatocellular carcinoma HepG2, and cervical cancer Hela cell lines was assayed. Although both of them were inactive in these cells, the present findings add new facets for the chemistry of Celosia argentea.

Dereplication-guided isolation of novel hepatoprotective triterpenoid saponins from Celosiae Semen by high-performance liquid chromatography coupled with electrospray ionization tandem quadrupole-time-of-flight mass spectrometry.

Although natural products (NPs) from ethnomedical plants have played a vital role in modern drug discovery, separation and purification of bioactive compounds from plant extract is still challenging. In this study, a dereplication strategy using HPLC-QTOF-MS was employed to rapidly discover and highly targeted isolate the novel hepatoprotective triterpenoid saponins from the methanol extract of Celosiae Semen. Firstly, four known saponins, i.e. celosin H, celosin I, celosin J, and pseudoginsenoside RT1 were selected as model compounds, and their fragmentation patterns in ESI-QTOF-MS/MS were characterized. Secondly, an HPLC-QTOF-MS/MS method was applied to chemically screen the saponins of interest, and thereby to guide the subsequent fraction and isolation procedure. Thirdly, the targeted isolation of desired compounds afforded two new triterpenoid saponins namely celosin K (1) and celosin L (2), which were structurally elucidated by combination of extensive NMR spectroscopic and chemical analyses. Finally, the protective effects of compounds 1 and 2 against APAP-induced hepatotoxicity in HepG2 cells were evaluated. These results indicate that the HPLC-QTOF-MS-guided isolation is an efficient methodology for isolating new NPs from medicinal plants through improving selectivity in separation and purification process.

Dispersive solid-phase microextraction and capillary electrophoresis separation of food colorants in beverages using diamino moiety functionalized silica nanoparticles as both extractant and pseudostationary phase.

In this work, a new method for the determination of food colorants in beverage samples is developed, using diamino moiety functionalized silica nanoparticles (dASNPs) as both adsorbents in dispersive solid-phase microextraction (dSPME) and pseudostationary phases (PSPs) in capillary electrophoresis (CE) separation. dASNPs were firstly used as adsorbents for the preconcentration of four colorants by the dSPME process. After that, colorants were efficiently separated by CE using 30 mM phosphate buffer (pH 6.0) containing 2 mM ß-CD and 0.9 mg/mL dASNPs as additives. All factors influencing dSPME and CE separations were optimized in detail. The investigated analytes showed good linearities with correlation coefficients (R(2)) higher than 0.9932. The limits of detection for the four food colorants were between 0.030 and 0.36 mg/L, which are lower than those reported previously. The established method was also used to analyze four colorants in beverage samples with recoveries ranging from 82.7% to 114.6%. To the best of our knowledge, this is the first time to use NPs both as extractants in dSPME and pseudostationary phases in CE for the analytical purpose.

Simultaneous separation and determination of five organic acids in beverages and fruits by capillary electrophoresis using diamino moiety functionalized silica nanoparticles as pseudostationary phase.

A kind of novel diamino moiety functionalized silica nanoparticles with the diameter of ~110 nm was successfully prepared and characterised by transmission electron microscope (TEM) and elemental analysis. Capillary electrophoresis (CE) with this kind of nanoparticles as pseudostationary phase was developed for the simultaneous analysis of five organic acids in beverage and fruit samples. The effects of pH, buffer concentration, and nanoparticles concentration on separation were carefully investigated. Five organic acids were baseline separated in 5 min under optimum experimental conditions. The precisions for five replicate separations of a standard mixture solution were 2.71-6.13% for peak area and 1.22-1.93% for migration time respectively. The detection limits were 7.5, 0.15, 0.23, 0.33 and 10.0mg/L for citric acid, salicylic acid, benzoic acid, sorbic acid and ascorbic acid, respectively. The developed method was applied to the simultaneous analysis of five analytes in beverage and fruit samples and certified reference materials with satisfactory results.

Water-compatible surface molecularly imprinted silica nanoparticles as pseudostationary phase in electrokinetic chromatography for the enantioseparation of tryptophan.

A novel approach based on surface molecularly imprinted technique is demonstrated for the synthesis of surface molecularly imprinted silica nanoparticles (MI-SiNPs) in aqueous media, using l-tryptophan (l-Trp) as template molecule. The MI-SiNPs were fully characterized by transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and atomic force microscopy (AFM), and the results showed MI-SiNPs thus prepared were uniform in particle size (∼87nm) with a distinct core-shell structure with shell thickness of ∼7nm. The terminal carboxyl groups endowed the MI-SiNPs with good water-compatibility, and so good suspension stability for MI-SiNPs in water-rich buffer solutions can be easily achieved without the addition of any other reagents. When MI-SiNPs were used as pseudostationary phases (PSPs) in electrokinetic chromatography (EKC) for the enantioseparation of Trp, a resolution of 2.73 can be achieved in less than 10min with symmetric peaks. These excellent separation features are mainly attributed to the fast mass transfer and good accessibility of the interaction sites locating at the surface of the MI-SiNPs. The effects of some important separation factors, e.g., pH and concentration of buffer solution, content of MI-SiNPs added, content of organic modifier in buffer solution, on the enantioseparation of Trp were studied, and an optimum separation condition of 30% (v/v) acetonitrile in 20mmolL(-1) phosphate buffer (pH 7.0), with 0.50mgmL(-1) MI-SiNPs added was ultimately selected.

[Epidemiological analysis of maternal death in Beijing from 1995 to 2010].

OBJECTIVE: To analysis the trend of maternal death time and explore the impact of the variety of death causes and birth place to maternal death time. METHODS: According to the data provided by Beijing Maternal and Children Health Hospital, the 372 death cases of pregnant and lying-in women from 1995 to 2010, a retrospective study was performed to analyze the death causes, maternal death time and the influencing factors. RESULTS: The MMR declined from 27.9 per 100 000 live births from 1995 to 2000 to 14.8 per 100 000 live births from 2006 to 2010, with a decline of 46.9%. Among the maternal death within 24 hours of delivery, 79.7% (106/133) died of obstetric hemorrhage, hypertensive disorder complicating pregnancy and amniotic fluid embolism. It took up 47.8% (64/134) from 1995 to 2000, reduced to 37.5% (45/120) from 2006 to 2010. At the same time, the maternal mortality ratio within 24 hours reduced from 40.2%(54/134) to 28.3% (34/120), the variation of death time was consistent with the causes of maternal mortality (χ² = 59.109, P < 0.05). Indirect obstetric causes increased significantly from 2006 to 2010, 53.2% (33/62) of pregnant women with heart disease, cerebrovascular disease and pulmonary embolism died in prenatal or more than 120 hours postnatal. Among the maternal death delved in hospital, 29.0% (29/100) died within 24 hours, 52 cases delved at home or in private clinics, 43 cases (82.6%) died within 24 h postnatal. There were significant differences between birth place and death time (χ² = 24.500, P < 0.05). CONCLUSION: Maternal death time changed from 24 hours of delivery to prenatal or postnatal a long time. The maternal mortality causes and hospital delivery is an important factor affecting maternal time.