Syringic acid attenuates acute lung injury by modulating macrophage polarization in LPS-induced mice.

BACKGROUND: Acute lung injury (ALI) is a continuum of lung changes caused by multiple lung injuries, characterized by a syndrome of uncontrolled systemic inflammation that often leads to significant morbidity and death. Anti-inflammatory is one of its treatment methods, but there is no safe and available drug therapy. Syringic acid (SA) is a natural organic compound commonly found in a variety of plants, especially in certain woody plants and fruits. In modern pharmacological studies, SA has anti-inflammatory effects and therefore may be a potentially safe and available compound for the treatment of acute lung injury. PURPOSE: This study attempts to reveal the protective mechanism of SA against ALI by affecting the polarization of macrophages and the activation of NF-κB signaling pathway. Trying to find a safer and more effective drug therapy for clinical use. METHODS: We constructed the ALI model using C57BL/6 mice by intratracheal instillation of LPS (10 mg/kg). Histological analysis was performed with hematoxylin and eosin (H&E). The wet-dry ratio of the whole lung was measured to evaluate pulmonary edema. The effect of SA on macrophage M1-type was detected by flow cytometry. BCA protein quantification method was used to determine the total protein concentration in bronchoalveolar lavage fluid (BALF). The levels of Interleukin (IL)-6, IL-1ß, and tumor necrosis factor (TNF)-α in BALF were determined by the ELISA kits, and RT-qPCR was used to detect the expression levels of IL-6, IL-1ß and TNF-α mRNA of lung tissue. Western blot was used to detect the expression levels of iNOS and COX-2 and the phosphorylation of p65 and IκBα in the NF-κB pathway in lung tissue. In vitro experiments were conducted with RAW267.4 cell inflammation model induced by 100 ng/ml LPS and A549 cell inflammation model induced by 10 µg/ml LPS. The effects of SA on M1-type and M2-type macrophages of RAW267.4 macrophages induced by LPS were detected by flow cytometry. The toxicity of compound SA to A549 cells was detected by MTT method which to determine the safe dose of SA. The expressions of COX-2 and the phosphorylation of p65 and IκBα protein in NF-κB pathway were detected by Western blot. RESULTS: We found that the pre-treatment of SA significantly reduced the degree of lung injury, and the infiltration of neutrophils in the lung interstitium and alveolar space of the lung. The formation of transparent membrane in lung tissue and thickening of alveolar septum were significantly reduced compared with the model group, and the wet-dry ratio of the lung was also reduced. ELISA and RT-qPCR results showed that SA could significantly inhibit the production of IL-6, IL-1ß, TNF-α. At the same time, SA could significantly inhibit the expression of iNOS and COX-2 proteins, and could inhibit the phosphorylation of p65 and IκBα proteins. in a dose-dependent manner. In vitro experiments, we found that flow cytometry showed that SA could significantly inhibit the polarization of macrophages from M0 type macrophages to M1-type macrophages, while SA could promote the polarization of M1-type macrophages to M2-type macrophages. The results of MTT assay showed that SA had no obvious cytotoxicity to A549 cells when the concentration was not higher than 80 µM, while LPS could promote the proliferation of A549 cells. In the study of anti-inflammatory effect, SA can significantly inhibit the expression of COX-2 and the phosphorylation of p65 and IκBα proteins in LPS-induced A549 cells. CONCLUSION: SA has possessed a crucial anti-ALI role in LPS-induced mice. The mechanism was elucidated, suggesting that the inhibition of macrophage polarization to M1-type and the promotion of macrophage polarization to M2-type, as well as the inhibition of NF-κB pathway by SA may be the reasons for its anti-ALI. This finding provides important molecular evidence for the further application of SA in the clinical treatment of ALI.

Metformin Increases the Response of Cholangiocarcinoma Cells to Gemcitabine by Suppressing Pyruvate Kinase M2 to Activate Mitochondrial Apoptosis.

BACKGROUND: Cholangiocarcinoma (CCA) is a malignant tumor with a high mortality rate. Resistance to chemotherapy remains a major challenge related to cancer treatment, and increasing the sensitivity of cancer cells to therapeutic drugs is a major focus of cancer treatment. AIMS: We purposed to explore the role of Metformin in CCA involved in chemotherapeutic sensitivity and Pyruvate kinase M2 (PKM2) through regulating mitochondrial apoptosis in the present study. METHODS: CCA cell lines of HCC9810 and RBE were treated with Metformin companied with antagonists or agonists of PKM2, cells sensitivity to Gemcitabine, cell migration and invasion along with apoptosis, which is mediated by JC-1 and LDH were assayed. RESULTS: Our results indicated that Metformin and Gemcitabine exhibit synergistic effect on inhibition of cholangiocarcinoma cell viability, cell migration and invasion as well as promotion apoptosis of cholangiocarcinoma cells. In vivo, Metformin combined with Gemcitabine has cooperation in inhibiting the growth of cholangiocarcinoma cell-derived tumors. Moreover, Metformin and Gemcitabine inhibited expression of PKM2 and PDHB in HCC9810 and RBE. CONCLUSION: Our study suggested that Metformin may increase the response of cholangiocarcinoma cells to Gemcitabine by suppressing PKM2 to activate mitochondrial apoptosis.

Investigations of Electronic, Structural, and In Silico Anticancer Potential of Persuasive Phytoestrogenic Isoflavene-Based Mannich Bases.

Isoflavenes have received the greatest research attention among the many groups of phytoestrogens. In this study, various isoflavene-based Mannich bases were selected for their theoretical studies. The purpose of this research was to discover the binding potential of all the designated Mannich bases acting as inhibitors against cancerous proteins EGFR, cMet, hTrkA, and HER2 (PDB codes: 5GTY, 3RHK, 6PL2, and 7JXH, respectively). For their virtual screening, DFT calculations and molecular docking studies were undertaken using in silico software. Docking studies predicted that ligands 5 and 15 exhibited the highest docking score by forming hydrogen bonds within the active pocket of protein 6PL2, ligands 1 and 15 both with protein 3RHK, and 7JXH, 12, and 17 with protein 5GTY. Rendering to the trends in polarizability and dipole moment, the energy gap values (0.2175 eV, 0.2106 eV) for the firm conformers of Mannich bases (1 and 4) replicate the increase in bioactivity and chemical reactivity. The energy gap values (0.2214 eV and 0.2172 eV) of benzoxazine-substituted isoflavene-based Mannich bases (9 and 10) reflect the increase in chemical potential due to the most stable conformational arrangements. The energy gap values (0.2188 eV and 0.2181 eV) of isoflavenes with tertiary amine-based Mannich bases (14 and 17) reflect the increase in chemical reactivity and bioactivity due to the most stable conformational arrangements. ADME was also employed to explore the pharmacokinetic properties of targeted moieties. This study revealed that these ligands have a strong potential to be used as drugs for cancer treatment.

Sinomenine ameliorates collagen-induced arthritis in mice by targeting GBP5 and regulating the P2X7 receptor to suppress NLRP3-related signaling pathways.

Sinomenine (SIN) is an isoquinoline alkaloid isolated from Sinomenii Caulis, a traditional Chinese medicine used to treat rheumatoid arthritis (RA). Clinical trials have shown that SIN has comparable efficacy to methotrexate in treating patients with RA but with fewer adverse effects. In this study, we explored the anti-inflammatory effects and therapeutic targets of SIN in LPS-induced RAW264.7 cells and in collagen-induced arthritis (CIA) mice. LPS-induced RAW264.7 cells were pretreated with SIN (160, 320, 640 µM); and CIA mice were administered SIN (25, 50 and 100 mg·kg-1·d-1, i.p.) for 30 days. We first conducted a solvent-induced protein precipitation (SIP) assay in LPS-stimulated RAW264.7 cells and found positive evidence for the direct binding of SIN to guanylate-binding protein 5 (GBP5), which was supported by molecular simulation docking, proteomics, and binding affinity assays (KD = 3.486 µM). More importantly, SIN treatment markedly decreased the expression levels of proteins involved in the GBP5/P2X7R-NLRP3 pathways in both LPS-induced RAW264.7 cells and the paw tissue of CIA mice. Moreover, the levels of IL-1ß, IL-18, IL-6, and TNF-α in both the supernatant of inflammatory cells and the serum of CIA mice were significantly reduced. This study illustrates a novel anti-inflammatory mechanism of SIN; SIN suppresses the activity of NLRP3-related pathways by competitively binding GBP5 and downregulating P2X7R protein expression, which ultimately contributes to the reduction of IL-1ß and IL-18 production. The binding specificity of SIN to GBP5 and its inhibitory effect on GBP5 activity suggest that SIN has great potential as a specific GBP5 antagonist.

Design, Synthesis, Characterization and Computational Studies of Mannich Bases Oxadiazole Derivatives as New Class of Jack Bean Urease Inhibitors.

Mannich bases consisting of 1,3,4-oxadiazole-2-thione (3 a-3 l) bearing various substituents were synthesized and found potent jack bean urease inhibitors. The prepared compounds showed significantly good inhibitory activities with IC50 values from 9.45±0.05 to 267.42±0.23 µM. The compound 3 k containing 4-chlorophenyl (-R) and 4-hydroxyphenyl (-R') was most active with IC50 9.45±0.05 µM followed by 3 e (IC50 22.52±0.15 µM) in which -R was phenyl and -R' was isopropyl group. However, when both -R and -R' were either 4-chlorophenyl groups (3 l) or only -R' was 4-nitrophenyl (3 i), both compounds were found inactive. The detailed binding affinities of the produced compounds with protein were explored through molecular docking and data-supported in-vitro enzyme inhibition profiles. Drug likeness was confirmed by in silico ADME investigations and molecular orbital analysis (HOMO-LUMO) and electrostatic potential maps were got from DFT calculations. ESP maps exposed that there are two potential binding sites with the most positive and most negative parts.

Aqueous extract of Platycodon grandiflorus attenuates lipopolysaccharide-induced apoptosis and inflammatory cell infiltration in mouse lungs by inhibiting PI3K/Akt signaling.

BACKGROUND: Acute lung injury (ALI), an acute inflammatory lung disease, can cause a rapid inflammatory response in clinic, which endangers the patient's life. The components of platycodon grandiflorum, such as platycodins have a wide range of pharmacological activities such as expectorant, anti-apoptotic, anti-inflammatory, anti-tumor and anti-oxidant properties, and can be used for improving human immunity. Previous studies have shown that aqueous extract of platycodon grandiflorum (PAE) has a certain protective effect on ALI, but the main pharmacodynamic components and the mechanism of action are not clear. METHODS: The anti-inflammatory properties of PAE were studied using the lipopolysaccharide (LPS)-induced ALI animal model. Hematoxylin and eosin stains were used to assess the degree of acute lung damage. Changes in RNA levels of pro-inflammatory cytokines in the lungs were measured using quantitative RT-qPCR. The potential molecular mechanism of PAE preventing ALI was predicted by lipidomics and network pharmacology. To examine the anti-apoptotic effects of PAE, TdT-mediated dUTP nick-end labelling (TUNEL) was employed to determine apoptosis-related variables. The amounts of critical pathway proteins and apoptosis-related proteins were measured using Western blotting. RESULTS: Twenty-six chemical components from the PAE were identified, and their related pathways were obtained by the network pharmacology. Combined with the analysis of network pharmacology and literature, it was found that the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signaling pathway is related to ALI. The results of lipidomics show that PAE alleviates ALI via regulating lung lipids especially phosphatidylinositol (PI). Finally, the methods of molecular biology were used to verify the mechanism of PAE. It can be found that PAE attenuates the inflammatory response to ALI by inhibiting apoptosis through PI3K/Akt signaling pathway. CONCLUSION: The study revealed that the PAE attenuates lipopolysaccharide-induced apoptosis and inflammatory cell infiltration in mouse lungs by inhibiting PI3K/Akt signaling. Furthermore, our findings provide a novel strategy for the application of PAE as a potential agent for preventing patients with ALI.

Selective enrichment of microbiota-derived tryptophan metabolites in mouse faeces based on molecularly imprinted solid-phase extraction for HPLC analysis.

Gut microbiota-derived tryptophan (TRP) metabolites, especially the indole derivatives, function as critical modulators of intestinal immune function and integrity via modulating the aryl hydrocarbon receptor pathway. Selective enrichment of these indole metabolites in biological samples is important for quantitative determination by routine methods such as HPLC. Here, we report a molecularly imprinted polymer (MIP) for solid-phase extraction (SPE) of TRP-derived indole metabolites from faeces of mice. The MIP was synthesized by surface polymerization by using indole-3-acetic acid (IAA) and acrylamide after cross-linking by ethylene glycol dimethacrylate (EGDMA) and initialed by 2',2-azobisisobutyronitrile (AIBN). The MIPs were then characterized by transmission electron microscope (TEM) and fourier transform infrared spectroscopy (FTIR), and the adsorption capacity, selectivity and reusability of MIPs were systematically evaluated. Results showed that IAA-MIPs showed a uniformly distributed nanoshell layer with a thin shell thickness of 26 nm. The IAA-MIPs could selectively adsorb IAA, indole-3-propionic acid (IPA), and indole-3-lactic acid (ILA) in a mixed solution that also contains TRP and tyrosine. The adsorption capacity of IAA-MIPs only slightly decreased with the increase of recycling use. As purification material for SPE, the IAA-imprinted polymers (IAA-MIPs) were successfully applied to extract IAA, IPA, and ILA from normal and colitis mice for HPLC determination. Collectively, these surface molecularly imprinted polymers could find extensive use to selective enrichment of microbiota-derived indole metabolites in biological samples.

Novel computer-assisted separation prediction strategy for online-enrichment-HPLC-FLD in simultaneous monitoring of bisphenols in children's water bottles.

An on-line enrichment-liquid chromatography-fluorescence detection (LC-FD) method was developed for simultaneous determination of nine bisphenols (BPs). In this process, we predicted the separation based on an in-house developed software allowing for calculating both retention time (tR) and half-peak width (W1/2) of the solute by mobile phase fraction (φ) under gradient conditions. The proposed strategy was applied to separation prediction of BPs with high accuracy. Under the optimized conditions, good linearity was obtained with the correlation coefficients (R2) ranging from 0.998 to 1.000. The recoveries in spiked samples were 91.3-110.7% with the intra-day and inter-day relative standard deviation ranging 0.4-9.6% and 0.5-10.2%, respectively. The limits of detection and quantification were 0.13-66.7 ng L-1 and 0.40-200 ng L-1. The developed approach was used to monitor the nine BPs in 28 children's water bottles. The developed method provides an effective way for monitoring bisphenols in other similar matrix.

[Determination of nine bisphenols in children's water bottle by online enrichment coupled with high performance liquid chromatography-fluorescence detection].

A method was developed for the rapid determination of bisphenol A (BPA) and eight structural analogs in children's plastic water bottles by online enrichment coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD). The correlation coefficients of the nine bisphenols were greater than 0.998. The limits of detection (LOQs) ranged from 0.13 ng/L to 66.7 ng/L. The recoveries ranged from 90.7% to 112.4% (RSD<11.3%, n=6). This method was applied to monitor nine bisphenols in children's water bottles. The results showed that except 4,4'-(9H-fluoren-9-ylidene)bisphenol (BPFL), all the remaining eight bisphenols were detected in different water bottles. The amounts of bisphenols leached increased with the increase of soaking time, and decreased after washing several times at 100℃. The proposed strategy is rapid, sensitive, reliable and eco-friendly, and is suitable for the simultaneous analysis of new bisphenols in water samples.

FÖrster resonance energy transfer (FRET)-based biosensors for biological applications.

FÖrster resonance energy transfer (FRET)-based biosensors have achieved great success for biological applications. However, what is not extensively appreciated is the growing role as versatile FRET biosensors within a similar biological context. This review provides a brief introduction of recent advances in principle, the designing strategies and kinds of applications of FRET biosensors. For each FRET biosensor, the appropriate background and fabrication is explained before studying their related applications. The prominent roles of nanomaterials are present in the development of more sensitive and specific FRET biosensors. Finally, the challenges and outlooks of FRET biosensors are emphasized.

[Simultaneous determination of six estrogens in dairy products by high performance liquid chromatography-triple quadrupole-ion trap mass spectrometry coupled with matrix solid-phase dispersion and solid phase extraction].

Matrix solid-phase dispersion (MSPD) and solid-phase extraction (SPE) were respectively developed for the pretreatment six estrogens in milk powder and liquid milk. It was implied that MSPD was suitable for the treatment of milk powder, while SPE was suitable for liquid milk treatment. Based on the optimized pretreatment procedures, the method for the simultaneous determination of the six estrogens in different dairy products was established by high performance liquid chromatography-triple quadrupole-ion trap mass spectrometry (HPLC-Q-TRAP-MS). The proposed method provided low limits of detection (LODs, 0.01-0.05 mg/L) and limits of quantification (LOQs, 0.05-0.10 mg/L), wide linearity range of 0.1-200 mg/L (except for estriol of 0.1-20 mg/L) with excellent correlation coefficients (R2)> 0.99. The average recoveries of the six estrogens in milk powder pretreated by MSPD ranged from 71.8% to 106.0% with RSD of 1.6%-9.2% (n=3), while the corresponding average recoveries in liquid milk pretreated by SPE ranged from 70.3% to 108.4% with RSD of 2.0% and 11.0% (n=3) with spiking levels of 1.0, 5.0, and 10 mg/kg, respectively. This sensitive and reliable method meets the demand for the analysis of trace estrogen residues in complex matrices.

Simultaneous determination of sulfur compounds from the sulfur pathway in rat plasma by liquid chromatography tandem mass spectrometry: application to the study of the effect of Shao Fu Zhu Yu decoction.

A sensitive, accurate, and time-saving approach was developed for the simultaneous quantification of eight sulfur compounds in the sulfur pathway, which could reflect the status of an organism, including oxidative stress, signal transduction, enzyme reaction, and so on. In order to overcome the instability of highly reactive sulfhydryl compounds, N-ethylmaleimide derivatization was adopted to effectively protect sulfhydryl-containing samples. Using isotope-labeled glutathione (GSH-13C2, 15N), the validated method was demonstrated to offer satisfactory linearity, accuracy, and precision. Separation was done by UHPLC, using a BEH amide column. Accordingly, 0.1% formic acid acetonitrile was selected as the precipitant. A tandem mass spectrometer was coupled to the chromatographic system and afforded a detection limit of 0.2 ng/mL. Good linearity was maintained over a wide concentration range (r2 > 0.994), and the accuracy was in the range of 86.6-114% for all the studied compounds. The precision, expressed in RSD%, ranged from 1.1% to 9.4% as intraday variability and less than 13% as interday precision for all of the analytes. The approach was applied to study the potential therapeutic mechanism of a well-known traditional Chinese medicine, Shao Fu Zhu Yu decoction. The results suggested that Shao Fu Zhu Yu decoction might protect against oxidative damage by increasing the concentrations of sulfhydryl compounds. Graphical abstract An approach to quantitatively determining sulfur compounds in the sulfur pathway simultaneously wasestablished and applied to the study of the effect of Shao Fu Zhu Yu decoction.

The stochastic resonance algorithm with the direct current signal as external force and its application to the detection of weak chromatographic peaks.

As a potential tool for amplifying weak chromatographic peaks, the stochastic resonance algorithm was developed based upon a counterintuitive physical phenomenon. Therefore, the essential step, parameter optimization, was perplexing and difficult for analysts. In order to avoid optimizing the system parameters on a case-by-case basis, an improved algorithm was proposed by introducing a constant or direct current signal into the signal to be measured as the external force. The weak chromatographic peak can be amplified and detected by the new algorithm using the same set of parameters. Two sets of our previous experimental data were reanalyzed by using the developed algorithm and the results were satisfactory. A generalized solution was expected to come into being on account of the new algorithm.

Development and application of a comprehensive lipidomic analysis to investigate Tripterygium wilfordii-induced liver injury.

Lipid metabolic pathways play pivotal roles in liver function, and disturbances of these pathways are associated with various diseases. Thus, comprehensive characterization and measurement of lipid metabolites are essential to deciphering the contributions of lipid network metabolism to diseases or its responses to drug intervention. Here, we report an integrated lipidomic analysis for the comprehensive detection of lipid metabolites. To facilitate the characterization of untargeted lipids through fragmentation analysis, nine formulas were proposed to identify the fatty acid composition of lipids from complex MS (n) spectrum information. By these formulas, the co-eluted isomeric compounds could be distinguished. In total, 250 lipids were detected and characterized, including diacylglycerols, triacylglycerols, glycerophosphoethanolamines, glycerophosphocholines, glycerophosphoserines, glycerophosphoglycerols, glycerophosphoinositols, cardiolipins, ceramides, and sphingomyelins. Integrated with the targeted lipidomics, a total of 27 inflammatory oxylipins were also measured. To evaluate the aberrant lipid metabolism involved in liver injury induced by Tripterygium wilfordii, lipid network metabolism was further investigated. Results indicated that energy lipid modification, membrane remodeling, potential signaling lipid alterations, and abnormal inflammation response were associated with injury. Because of the important roles of lipids in liver metabolism, this new method is expected to be useful in analyzing other lipid metabolism diseases.

Pharmacokinetics, intestinal absorption and microbial metabolism of single platycodin D in comparison to Platycodi radix extract.

BACKGROUND: Platycodi radix, the dried root of Platycodon grandiflorum A. DC, has been widely used as food and herb medicine for treating cough, cold and other respiratory ailments, and platycodin D (PD) is one of the most important compounds in Platycodi Radix. OBJECTIVE: The purpose of this study was to compare the pharmacokinetic characteristics, intestinal absorption and microbial metabolism of PD in monomer with that in Platycodi radix extract (PRE). MATERIALS AND METHODS: In the pharmacokinetic study, the concentrations of PD in rat plasma were determined by ultra-performance liquid chromatography-tandem mass spectrometry and the main pharmacokinetic parameters were calculated by data analysis software (DAS). Besides, in vitro Caco-2 cells and fecal lysate were performed to investigate the intestinal absorption and metabolism, respectively. RESULTS: The results from pharmacokinetics showed that the area under the curve, the peak concentration the time to reach peak concentration and mean residence time of PD in PRE were enhanced significantly compared with that in single PD. Caco-2 cells transport study indicated that the absorption of PD both in monomer and in PRE were poor owning that the permeability of PD were <1/10(6) cm/s. The hydrolysis degree of PD in PRE was significantly lower than that in monomer PD in fecal lysate, which might be illustrated by the other ingredients in PRE influenced the hydrolysis of PD via gut microbiota. CONCLUSION: These findings indicated that the difference of microbial metabolism, not apparent absorption in intestine for PD between in monomer and in PRE contributed to their pharmacokinetic difference.

Determination of sparstolonin B by ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry: application to pharmacokinetic study of sparstolonin B in rat plasma.

Sparstolonin B (SsnB), a spontaneous isocoumarin compound isolated from the tuber of Scirpus yagara Ohwi. (Cyperaceae), possesses potent anti-inflammatory and antitumor activity. In the present study, a rapid and simple UHPLC/MS/MS method for determination of SsnB in rat plasma was developed and validated. Plasma samples were pretreated by liquid-liquid extraction with ethyl acetate containing rhein as an internal standard and separated on a C18 column at 35 °C, with a gradient mobile phase consisting of acetonitrile and water containing 0.2% (v/v) formic acid within 2.1 min. MS/MS detection was accomplished in multiple reaction monitoring mode with negative electrospray ionization. The precursor-product ion transitions were m/z 266.9 [M-H](-) → m/z 211.0 for SsnB and m/z 283.2 [M-H](-) → m/z 239.0 for IS. The intra- and inter-day precision (RSD) was <8.98% and the accuracy (RE) ranged from -7.40 to 4.50%. The extraction recoveries ranged from 96.28 to 97.30%. The pharmacokinetic parameters were calculated using Win Nonlin53 software. The absolute bioavailability of SsnB was estimated to be 6.98%. The proposed method was successfully applied to a pharmacokinetic study of SsnB in rats after intravenous administration with a dose of 0.5 mg/kg and oral administration at a dose of 5 mg/kg.

The application of multiobjective genetic algorithm to the parameter optimization of single-well potential stochastic resonance algorithm aimed at simultaneous determination of multiple weak chromatographic peaks.

Simultaneous determination of multiple weak chromatographic peaks via stochastic resonance algorithm attracts much attention in recent years. However, the optimization of the parameters is complicated and time consuming, although the single-well potential stochastic resonance algorithm (SSRA) has already reduced the number of parameters to only one and simplified the process significantly. Even worse, it is often difficult to keep amplified peaks with beautiful peak shape. Therefore, multiobjective genetic algorithm was employed to optimize the parameter of SSRA for multiple optimization objectives (i.e., S/N and peak shape) and multiple chromatographic peaks. The applicability of the proposed method was evaluated with an experimental data set of Sudan dyes, and the results showed an excellent quantitative relationship between different concentrations and responses.

Modeling of autocatalytic hydrolysis of adefovir dipivoxil in solid formulations.

The stability and hydrolysis kinetics of a phosphate prodrug, adefovir dipivoxil, in solid formulations were studied. The stability relationship between five solid formulations was explored. An autocatalytic mechanism for hydrolysis could be proposed according to the kinetic behavior which fits the Prout-Tompkins model well. For the classical kinetic models could hardly describe and predict the hydrolysis kinetics of adefovir dipivoxil in solid formulations accurately when the temperature is high, a feedforward multilayer perceptron (MLP) neural network was constructed to model the hydrolysis kinetics. The build-in approaches in Weka, such as lazy classifiers and rule-based learners (IBk, KStar, DecisionTable and M5Rules), were used to verify the performance of MLP. The predictability of the models was evaluated by 10-fold cross-validation and an external test set. It reveals that MLP should be of general applicability proposing an alternative efficient way to model and predict autocatalytic hydrolysis kinetics for phosphate prodrugs.

Application of the stochastic resonance algorithm to the simultaneous quantitative determination of multiple weak peaks of ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry.

The stochastic resonance algorithm (SRA) has been developed as a potential tool for amplifying and determining weak chromatographic peaks in recent years. However, the conventional SRA cannot be applied directly to ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOFMS). The obstacle lies in the fact that the narrow peaks generated by UPLC contain high-frequency components which fall beyond the restrictions of the theory of stochastic resonance. Although there already exists an algorithm that allows a high-frequency weak signal to be detected, the sampling frequency of TOFMS is not fast enough to meet the requirement of the algorithm. Another problem is the depression of the weak peak of the compound with low concentration or weak detection response, which prevents the simultaneous determination of multi-component UPLC/TOFMS peaks. In order to lower the frequencies of the peaks, an interpolation and re-scaling frequency stochastic resonance (IRSR) is proposed, which re-scales the peak frequencies via linear interpolating sample points numerically. The re-scaled UPLC/TOFMS peaks could then be amplified significantly. By introducing an external energy field upon the UPLC/TOFMS signals, the method of energy gain was developed to simultaneously amplify and determine weak peaks from multi-components. Subsequently, a multi-component stochastic resonance algorithm was constructed for the simultaneous quantitative determination of multiple weak UPLC/TOFMS peaks based on the two methods. The optimization of parameters was discussed in detail with simulated data sets, and the applicability of the algorithm was evaluated by quantitative analysis of three alkaloids in human plasma using UPLC/TOFMS. The new algorithm behaved well in the improvement of signal-to-noise (S/N) compared to several normally used peak enhancement methods, including the Savitzky-Golay filter, Whittaker-Eilers smoother and matched filtration.

[Analysis of metabolites of daphnetin in the intestinal wall of rats by liquid chromatography and quatrupole-time of flight mass spectrometry].

In this study, daphnetin and its major metabolites in the intestinal wall of rats were identified by liquid chromatography and quatrupole-time of flight mass spectrometry. Perfusion fluid of duodenum, jejunum, ileum and colon were collected separately for 2 hours from the rat intestine following perfusion with daphnetin. The metabolites of daphnetin in the perfusion fluid of different intestine segments were analyzed by the liquid chromatography and quatrupole-time of flight mass spectrometry. It is shown that the parent drug daphnetin and four metabolites were found in the perfusion fluid of duodenum, jejunum and ileum. However, no metabolites were found in the colon. Among the four metabolites, two daphnetin sulfates (m/z 257) were first discovered as the phase II metabolites of daphnetin in rats, which revealed a new way of daphnetin metabolism in rats.