Simultaneous determination of naringenin and hesperetin in rats after oral administration of Da-Cheng-Qi decoction by high-performance liquid chromatography-tandem mass spectrometry

To quantify naringenin and hesperetin in rat plasma after oral administration of Da-Cheng-Qi decoction, a famous purgative traditional Chinese medicine, a high-performance liquid chromatography-tandem mass spectrometry method was developed and validated. The HPLC separation was carried out on a Zorbax SB-C(18) column using 0.1% formic acid-methanol as mobile phase and estazolam as internal standard after the sample of rat plasma had been cleaned up with one-step protein precipitation using methanol. Atmospheric pressure chemical ionization in the positive ion mode and selected reaction monitoring method was developed to determine the active components. This method was validated in terms of recovery, linearity, accuracy and precision (intra- and inter-batch variation). The recoveries of naringenin and hesperetin were 72.8-76.6 and 75.7-77.2%, respectively. Linearity in rat plasma was observed over the range of 0.5-250 ng/mL (r2 > 0.99) for both naringenin and hesperetin. The accuracy and precision were well within the acceptable range and the relative standard deviation of the measured rat plasma samples was less than 15% (n = 5). The validated method was successfully applied for the evaluation of the pharmacokinetics of naringenin and hesperetin administered to six rats.     

Determination of caudatin-2,6-dideoxy-3-O-methy-beta-d-cymaropyranoside in rat plasma using liquid chromatography-tandem mass spectrometry

A selective, sensitive and rapid liquid chromatography-tandem mass spectrometry method has been developed for the determination of caudatin-2,6-dideoxy-3-O-methy-beta-d-cymaropyranoside (CDMC) in rat plasma. This method involves a plasma clean-up step using liquid-liquid extraction, followed by LC separation and positive electrospray ionization mass spectrometry detection (LC/ESI-MS/MS). Chromatographic separation of the analytes was achieved using a C(18) column with a mobile phase of acetonitrile and water (70:30, v/v) at a flow rate of 1.0 mL/min. Low energy collision tandem mass spectrometric analysis (CID-MS/MS) using the multiple reaction monitoring (MRM) mode was used for analyte quantification. For the MRM analysis of CDMC, the following transition at m/z 658.4 --> 529.6 derived from the protonated molecule [M + Na](+). A calibration curve was linear in the 5-500 ng/mL range for CDMC, and the limit of detection was 5 ng/mL. The inter- and intra-day precisions (RSD) were 相似文献   

Facile synthesis of spherical covalent organic frameworks for enrichment and quantification of aryl organophosphate esters in mouse serum and tissues

Here, an imine-linked-based spherical covalent organic framework (COF) was prepared at room temperature. The as-synthesized spherical COF served as an adsorbent in dispersive solid-phase extraction (dSPE), by its virtue of great surface area (1542.68 m²/g), regular distribution of pore size (2.95 nm), and excellent stability. Therefore, a simple and high-efficiency dispersive solid phase extraction method based on a spherical COF coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established to determine aryl organophosphate esters in biological samples. This approach displayed favorable linearity in the range of 10.0–1000.0 ng/L (r > 0.9989), a high signal enhancement factor (58.8–181.8 folds) with low limits of detection (0.3–3.3 ng/L). Moreover, it could effectively eliminate complex matrix interference to accurately extract seven aryl organophosphate esters from mouse serum and tissue samples with spiked recoveries of 82.0%–117.4%. The as-synthesized spherical COF has been successfully applied in sample preparation. The dSPE-HPLC-MS/MS method based on a spherical COF has potential application to study the pollutants' metabolism in vivo.     

Quantification and antioxidant and anti-HCV activities of the constituents from the inflorescences of Scabiosa comosa and S. tschilliensis

To investigate the bioactive constituents of the inflorescences of Scabiosa comosa and S. tschilliensis, which are used traditionally for liver diseases, we tested the antioxidant activity using 2,2′-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), ferric reducing antioxidant potential (FRAP), and DPPH-ultra high performance liquid chromatography-mass spectrometer (UPLC-MS) assay. In addition, cell-based anti-HCV activity of the major compounds were evaluated. The plant extracts showed strong antioxidant activity. For the first time, 3,4-dicaffeoylquinic acid (DCQA), 3,5-DCQA and 4,5-DCQA were identified from genus Scabiosa. A UPLC-MS method in multiple reaction monitoring (MRM) mode was established to quantify 18 constituents in the inflorescences of Scabiosa. The 3,5-DCQA, chlorogenic acid and some glycosides of luteolin or apigenin were found to be the most abundant constituents. Chlorogenic acid and 3,5-DCQA showed excellent radical scavenging activity and demonstrated anti-HCV activity. These findings provided scientific evidences for the clinic use of this herbal medicine for liver diseases.     

First approach to radionuclide mixtures quantification by using plastic scintillators. Influence of the diameter of the plastic beads

Recent studies have evaluated the capability of plastic scintillation (PS) as an alternative to liquid scintillation (LS) in radionuclide activity determination without mixed waste production. In order to complete the comparison, we now assess the extent to which PS can be used to quantify mixtures of radionuclides and the influence of the diameter of the plastic scintillation beads in detection efficiency.

The results show that the detection efficiency decreases and the spectrum shrink to lower energies when the size of the plastic scintillation beads increases, and that the lower the energy of the beta particle, the greater the variation takes place. Similar behaviour has been observed for beta–gamma and alpha emitters.

Two scenarios for the quantification of mixtures are considered, one including two radionuclides (¹⁴C and ⁶⁰Co) whose spectra do not overlap significantly, and the other including two radionuclides (¹³⁷Cs and ⁹⁰Sr/⁹⁰Y), where the spectra of one the isotopes is totally overlapped by the other The calculation has been performed by using the conventional window selection procedure and a new approach in which the selected windows correspond to those with lower quantification errors. Relative errors obtained using the proposed approach (less than 10%) are lower than those of the conventional procedure, even when a radionuclide is completely overlapped, except for those samples with extreme activity ratios that were not included in the window optimization process.     

Time-Domain Quantification of Multiple-Quantum-Filtered Na Signal Using Continuous Wavelet Transform Analysis

The application of continuous wavelet transform (CWT) analysis technique is presented to analyze multiple-quantum-filtered (MQF) ²³Na magnetic resonance spectroscopy (MRS) data. CWT acts on the free-induction-decay (FID) signal as a time-frequency variable filter. The signal-to-noise ratio (SNR) and frequency resolution of the output filter are locally increased. As a result, MQF equilibrium longitudinal magnetization and the apparent fast and slow transverse relaxation times are accurately estimated. A developed iterative algorithm based on frequency signal detection and components extraction, already proposed, was used to estimate the values of the signal parameters by analyzing simulated time-domain MQF signals and data from an agarose gel. The results obtained were compared to those obtained by measurement of signal height in frequency domain as a function of MQF preparation time and those obtained by a simple time-domain curve fitting. The comparison indicates that the CWT approach provides better results than the other tested methods that are generally used for MQF ²³Na MRS data analysis, especially when the SNR is low. The mean error on the estimated values of the amplitude signal and the apparent fast and slow transverse relaxation times for the simulated data were 2.19, 6.63, and 16.17% for CWT, signal height in frequency domain, and time-domain curve fitting methods, respectively. Another major advantage of the proposed technique is that it allows quantification of MQF ²³Na signal from a single FID and, thus, reduces the experiment time dramatically.     

Inference on COVID-19 Epidemiological Parameters Using Bayesian Survival Analysis

The need to provide accurate predictions in the evolution of the COVID-19 epidemic has motivated the development of different epidemiological models. These models require a careful calibration of their parameters to capture the dynamics of the phenomena and the uncertainty in the data. This work analyzes different parameters related to the personal evolution of COVID-19 (i.e., time of recovery, length of stay in hospital and delay in hospitalization). A Bayesian Survival Analysis is performed considering the age factor and period of the epidemic as fixed predictors to understand how these features influence the evolution of the epidemic. These results can be easily included in the epidemiological SIR model to make prediction results more stable.     

Quantification of Caffeine and Chlorogenic Acid in Green and Roasted Coffee Samples Using HPLC-DAD and Evaluation of the Effect of Degree of Roasting on Their Levels

Chlorogenic acid and caffeine are among the important components in coffee beans, determining the taste and aroma. In addition, phenols and antioxidants content possess vital health values. The main aim of this study is to determine the levels of caffeine and chlorogenic acid in several coffee samples of different origins and degrees of roasting. The coffee samples were extracted using hot water. The levels of caffeine and chlorogenic acid were quantified using high-performance liquid chromatography (HPLC) equipped with a diode array detector, a reverse phase system, and an ODS column (C18). Total phenol and antioxidant contents were previously determined for the same samples. The results showed that the highest content of caffeine was found in the medium roasted coffee (203.63 mg/L), and the highest content of chlorogenic acid content was found in the green coffee (543.23 mg/L). The results demonstrated a negative correlation between the chlorogenic acid levels with the degree of roasting, while it showed a positive correlation between the caffeine levels with the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. The origin of coffee samples did not show any effect on any of the measured variables. Antioxidant effects of coffee samples were largely determined by chlorogenic acid content.     

Network Dynamics in Elemental Assimilation and Metabolism

Metabolism and physiology frequently follow non-linear rhythmic patterns which are reflected in concepts of homeostasis and circadian rhythms, yet few biomarkers are studied as dynamical systems. For instance, healthy human development depends on the assimilation and metabolism of essential elements, often accompanied by exposures to non-essential elements which may be toxic. In this study, we applied laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to reconstruct longitudinal exposure profiles of essential and non-essential elements throughout prenatal and early post-natal development. We applied cross-recurrence quantification analysis (CRQA) to characterize dynamics involved in elemental integration, and to construct a graph-theory based analysis of elemental metabolism. Our findings show how exposure to lead, a well-characterized toxicant, perturbs the metabolism of essential elements. In particular, our findings indicate that high levels of lead exposure dysregulate global aspects of metabolic network connectivity. For example, the magnitude of each element’s degree was increased in children exposed to high lead levels. Similarly, high lead exposure yielded discrete effects on specific essential elements, particularly zinc and magnesium, which showed reduced network metrics compared to other elements. In sum, this approach presents a new, systems-based perspective on the dynamics involved in elemental metabolism during critical periods of human development.