A validated assay by liquid chromatography–tandem mass spectrometry for the simultaneous quantification of elvitegravir and rilpivirine in HIV positive patients

Because of the large variability in the pharmacokinetics of anti‐HIV drugs, therapeutic drug monitoring in patients may contribute to optimize the overall efficacy and safety of antiretroviral therapy. An LC–MS/MS method for the simultaneous assay in plasma of the novel antiretroviral agents rilpivirine (RPV) and elvitegravir (EVG) has been developed to that endeavor. Plasma samples (100 μL) extraction is performed by protein precipitation with acetonitrile, and the supernatant is subsequently diluted 1:1 with 20‐mM ammonium acetate/MeOH 50:50. After reverse‐phase chromatography, quantification of RPV and EVG, using matrix‐matched calibration samples, is performed by electrospray ionization–triple quadrupole mass spectrometry by selected reaction monitoring detection using the positive mode. The stable isotopic‐labeled compounds RPV‐¹³C6 and EVG‐D6 were used as internal standards. The method was validated according to FDA recommendations, including assessment of extraction yield, matrix effects variability (<6.4%), as well as EVG and RPV short and long‐term stability in plasma. Calibration curves were validated over the clinically relevant concentrations ranging from 5 to 2500 ng/ml for RPV and from 50 to 5000 ng/ml for EVG. The method is precise (inter‐day CV%: 3–6.3%) and accurate (3.8–7.2%). Plasma samples were found to be stable (<15%) in all considered conditions (RT/48 h, +4°C/48 h, ?20°C/3 months and 60°C/1 h). Selected metabolite profiles analysis in patients' samples revealed the presence of EVG glucuronide, that was well separated from parent EVG, allowing to exclude potential interferences through the in‐source dissociation of glucuronide to parent drug. This new, rapid and robust LCMS/MS assay for the simultaneous quantification of plasma concentrations of these two major new anti‐HIV drugs EVG and RPV offers an efficient analytical tool for clinical pharmacokinetics studies and routine therapeutic drug monitoring service. Copyright © 2013 John Wiley & Sons, Ltd.     

Chemical analysis of sulfur species in geothermal waters

Analytical methods have been developed to determine sulfur species concentrations in natural geothermal waters using Reagent-Free™ Ion Chromatography (RF™-IC), titrations and spectrophotometry. The sulfur species include SO₄²⁻, S₂O₃²⁻, and ∑S²⁻ with additional determination of SO₃²⁻ and S_xO₆²⁻ that remains somewhat semiquantitative. The observed workable limits of detections were ≤0.5 μM depending on sample matrix and the analytical detection limits were 0.1 μM. Due to changes in sulfur species concentrations upon storage, on-site analyses of natural water samples were preferred. Alternatively, the samples may be stabilized on resin for later elution and analysis in the laboratory. The analytical method further allowed simultaneous determination of other anions including F⁻, Cl⁻, dissolved inorganic carbon (DIC) and NO₃⁻ without sample preservation or stabilization. The power of the newly developed methods relies in routine analysis of sulfur speciation of importance in natural waters using techniques and facilities available in most laboratories doing water sample analysis. The new methods were successfully applied for the determination of sulfur species concentrations in samples of natural and synthetic waters.     

Square‐Micrometer‐Sized,Free‐Standing Organometallic Sheets and Their Square‐Centimeter‐Sized Multilayers on Solid Substrates

Oligofunctional terpyridine‐based monomers are spread at an air/water interface, where they are connected with transition metal salts such as Fe(II) into mechanically coherent monolayer sheets of macroscopic dimension. The conversions of these processes are determined by XPS for several monomer/metal ion combinations. The sheets are transferred onto TEM grids, the 20 × 20 square micrometer sized holes of which can be spanned. AFM indentation experiments provide in‐plane elastic moduli which are compared with naturally occurring sheets such as graphene. The new organometallic sheets are also used to create multilayer assemblies on square centimeter length scales on solid substrates. Finally some directions are provided where this research can lead to in future and where its application potential lies.

     

Characterization of poly(ethylene oxide) modified with different phenyl hepta isobutyl polyhedral oligomeric silsesquioxanes

Journal of Thermal Analysis and Calorimetry - Poly(ethylene oxide)/polyhedral oligomeric silsesquioxanes (PEO/POSSs) composites were prepared by the melting method. The investigation of their...     

Frequency-resolving spatiotemporal wave-front sensor

We report on a high-resolution wave-front sensor that measures the complete spatial profile of any frequency component of a laser field containing multiple frequencies. This probe technique was developed to address the necessity of measuring the spatial overlap of the carrier field with each sideband component of the field exiting the output port of a gravitational-wave interferometer. We present the results of an experimental test of the probe, where we were able to construct the spatial profile of a single radio-frequency sideband at the level of -50 dBc.     

Brown Macroalgae Sargassum cristaefolium Extract Inhibits Melanin Production and Cellular Oxygen Stress in B16F10 Melanoma Cells

The brown macroalgae Sargassum has been reported for its anti-UV and photoprotective potential for industrial applications. This study evaluated the melanin inhibition activity of Sargassum cristaefolium (SCE) ethanol extract. Melanogenesis inhibition by SCE was assessed in vitro with B16-F10 melanoma cell models and in silico against melanin regulatory proteins Tyrosinase (TYR) and Melanocortin 1 Receptor (MC1R). The regulatory properties evaluated were the melanin content, intracellular tyrosinase activity and cellular antioxidant activities. In addition, the bioactive compounds detected in SCE were subjected to molecular docking against TYR and MC1R. Based on the results, 150 µg/mL SCE effectively inhibited the production of melanin content and intracellular tyrosinase activity. Cellular tyrosinase activity was reduced by SCE-treated cells in a concentration-dependent manner. The results were comparable to the standard tyrosinase inhibitor kojic acid. In addition, SCE effectively decreased the intracellular reactive oxygen species (ROS) levels in B16-F10 cells. The antioxidant properties may also contribute to the inhibition of melanogenesis. In addition, LCMS UHPLC-HR-ESI-MS profiling detected 33 major compounds. The results based on in silico study revealed that the bioactive compound putative kaurenoic acid showed a strong binding affinity against TYR (−6.5 kcal/mol) and MC1R (−8.6 kcal/mol). However, further molecular analyses are needed to confirm the mechanism of SCE on melanin inhibition. Nevertheless, SCE is proposed as an anti-melanogenic and antioxidant agent, which could be further developed into cosmetic skin care products.     

Multivariate Analysis Revealed Ultrasonic-Assisted Extraction Improves Anti-Melanoma Activity of Non-Flavonoid Compounds in Indonesian Brown Algae Ethanol Extract

Indonesia has high biodiversity of algae that are under-utilised due to limitations in the processing techniques. Here, we observed the effect of two different extraction methods (cold maceration and ultrasonic-assisted extraction (UAE)) on multiple variables of Indonesian brown algae ethanol extracts (Sargassum polycystum, Sargassum cristaefolium, Sargassum aquifolium and Turbinaria ornata). The variables observed included metabolites screening by untargeted metabolomics liquid chromatography-high-resolution mass spectrometry (LC-HRMS), observation of total phenolic content (TPC), total flavonoid content (TFC), anti-oxidant and B16-F10 melanoma cells cytotoxicity. UAE extracts had higher extraction yield and TPC, but no TFC difference was observed. UAE extract had more lipophilic compounds, such as fatty acids (Palmitic acid, Oleamide, Palmitoleic acid, Eicosapentaenoic acid, α-Linolenic acid, Arachidonic acid), lipid-derived mediators (11,12-Epoxyeicosatrienoic acid ((±)11(12)-EET)), steroid derivatives (Ergosterol peroxide), lipophilic metabolite (Fucoxanthin), and lipid-soluble vitamins (all-trans-retinol). Principle component analysis (PCA) revealed that TPC, not TFC, in the UAE extracts was correlated with the anti-oxidant activities and cytotoxicity of the extracts towards B16-F10 melanoma cells. This means other non-flavonoid phenolic and lipophilic compounds may have contributed to its bioactivity. These results suggest that out of the two methods investigated, UAE could be a chosen method to extract natural anti-melanogenic agents from brown algae.     

Magnetically polymeric nanocarriers for targeting delivery of curcumin and hyperthermia treatments toward cancer cells

Magnetically polymeric nanocarriers, Cur‐FA‐SAMN, were designed and synthesized for targeting, therapeutic treatments to cancer cells. Amine‐group immobilized iron oxides, Fe₃O₄‐NH₂, were attached on the surface of self‐assembled tri‐block copolymer, poly[(acrylic acid)‐block‐(N‐isopropylacrylamide)‐block‐(acrylic acid)] synthesized via reversible addition‐fragmentation chain‐transfer polymerization. For the purpose of targeting effect, folic acid was grafted on the surface of Fe₃O₄‐NH₂ attached nanoparticles. The nanocarriers were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, and UV‐Vis spectral analysis. Therefore, a hydrophobic anti‐cancer drug, curcumin, gained water dispersity, and stable storage via encapsulating into and on the magnetically polymeric nanocarriers, and the release behaviors were studied in vitro, with and without high frequency magnetic field. Biocompatibility and cytotoxicity of inherent and curcumin‐loaded nanocarriers were investigated by MTT assay. Results displayed that our nanocarriers have no cytotoxicity while curcumin‐loaded nanocarriers offered significant death to MCF‐7, human breast camcer cells. Intracellular‐uptake experiments demonstrated tremendous uptake and the destroying effect to MCF‐7 cells, most of the cancer cells were killed and the surviving ones were surrounded by the curcumin‐loaded nanocarriers. According to the aforementioned characteristics, these magnetically polymeric nanocarriers will be able to apply as a potential device for practical therapy. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2706–2713