Submicellar liquid chromatography with fluorescence detection improves the analysis of naproxen in plasma and brain tissue

Rapid, simple, and sensitive submicellar liquid chromatography with fluorescence detection was developed and validated to quantify naproxen in plasma and brain samples after oral administration of Naproxen formulations. The method used tramadol as an internal standard. Different submicellar mobile phases with organic phases ranging from 40 to 60% were studied to improve the native fluorescence of the Naproxen and decrease retention times. Separation was done in a Zorbax SB C8 column (250 × 4.6 mm, 5 μm) with a mobile phase containing acidic 0.007 M sodium dodecyl sulfate/acetonitrile (50:50, v/v) at a flow rate of 1 mL/min. Detection was performed with an excitation wavelength of 280 nm and emission of 310 nm and 360 nm for internal standard and Naproxen, respectively. The method was validated by International Conference of Harmonization standards. The method is specific, accurate, and precise (relative standard deviation <3%). Limits of detection and quantification were 0.08 and 0.25 μg/mL, respectively, for biological samples. This method was applied to analyze brain/plasma ratios in mice that had received oral administrations of Naproxen micellar formulations containing 10% w/w of sodium dodecyl sulfate, Cremophor RH 40, or Tween 80. The sodium dodecyl sulfate micelles were faster and more widely distributed in the mouse brains.     

Carbon Paste Composite with Co3O4 as a New Electrochemical Sensor for the Detection of Allura Red by Reduction

The detection of Allura red (AR) by electrochemical reduction using a different electrode from the conventional mercury electrode is presented. A carbon paste with cobalt (II, III) oxide composite electrode (CoO_x/CPE) is reported for the first time for the detection of AR. Moreover, others dyes such as tartrazine (TZ), sunset yellow (SY), amaranth (AM), Ponceaut 4‐R (P‐4R), and Sudan (SD) as well as pharmaceutical agents such as paracetamol (PMC) that are present in samples that contained AR did not show a reduced signal between 0.0 and ?0.3 V, which is the potential range where AR reduction was observed. The surface electroactivity was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The presence of CoO_X increased the cathodic peak current for AR by more than 50 % and 65 % via CV and square wave voltammetry (SWV), respectively, compared with an unmodified carbon paste electrode. Under the optimal parameters, (pH=3.0, accumulation time (t_ACC)=60 s and accumulation potential (E_ACC)=0.50 V), the detection limit for AR was 0.05 μmol L^?1. The new sensor was sensitive and stable for the detection of AR. Moreover, it was easily manufactured and very convenient for food samples such as soft and isotonic drinks as well as chili sauce.     

Determination of Bismuth in Bottled and Mineral Water Samples at Trace Levels by T-Shaped Slotted Quartz tube-Atom Trap-Flame Atomic Absorption Spectrometry

An accurate and reliable analytical method for the determination of bismuth at trace levels in bottled and mineral water samples has been developed based on hydrogen assisted T-shape slotted quartz tube-atom trap-flame atomic absorption spectrometry (T-SQT-AT-FAAS). Conventional FAAS is not sufficiently sensitive to measure trace and ultra-trace levels of metals due to the low nebulization efficiency and short residence time of atoms in the light path. To overcome this problem, atom trapping with a T-shaped slotted quartz tube was coupled to the FAAS system. Bismuth atoms were trapped on the surface of T-SQT and released by hydrogen gas, which provided a reducing environment. All of the system parameters such as flame type, hydrogen flow rate, the height of T-SQT from the burner head, and trapping period were optimized to enhance the analytical signal to attain low detection limits. After obtaining the optimum conditions, the limit of detection and limit of quantitation of the developed method were found to be 0.95 and 3.2?µg L^?1, respectively. Recovery values were obtained between 90% and 104% that showed good accuracy and applicability of the proposed method to the analysis of bottled and mineral water samples.     

Incorporation of Baccharis dracunculifolia DC (Asteraceae) leaf extract into phosphatidylcholine-cholesterol liposomes improves its anti-inflammatory effect in vivo

The aerial parts of Baccharis dracunculifolia (BdE) is used in the Brazilian folk medicine to treat inflammatory conditions. Here we examined the ability of free and liposomal BdE to modulate reactive oxygen species generation in human neutrophils in vitro and zymosan-induced acute joint inflammation in Wistar rats. We prepared biocompatible liposomes of soya phosphatidylcholine and cholesterol with low diameter, homogeneous size distribution, and neutral surface charge. Free BdE decreased joint swelling, total leucocyte and neutrophil infiltration, and the synovial levels of tumour necrosis factor-α and interleukins 6 and 1β. Incorporation of BdE into liposomes preserved its capacity to inhibit the neutrophil superoxide anion and total reactive oxygen species generation, and improved its anti-inflammatory effect in vivo by decreasing the effective BdE dose by nearly sixfold. The same liposome type lowered the effective dose of caffeic acid by nearly sixteenfold. Therefore, incorporation of BdE into phosphatidylcholine-cholesterol liposomes improves its anti-inflammatory effect.     

Synthesis of benzaldehyde-functionalized LewisX trisaccharide analogs for glyco-SAM formation

LewisX (Le^x) antigen based carbohydrate–carbohydrate interactions are mediated by complexation of metal ions. Although theoretical studies about the influence of participating hydroxyl groups in the Le^x trisaccharide head group (Galβ(1-4)[Fucα(1-3)]GlcNAc) could gave same rudimental information about the basic mechanism behind this interaction, a little is known about orientation and configuration of the hydroxyl groups required for the specific interaction mediated by Ca²⁺ complexation. Therefore, there is a need of non-natural derivatives to provide detailed information about the requirements for hydroxyl group arrangement in Le^x head group surface plasmon resonance and gold nanoparticle techniques have shown to be powerful tools to investigate carbohydrate–carbohydrate interactions. Benzaldehyde-functionalized glycans can be used for attachment to both gold nanoparticles and surface plasmon resonance sensor surfaces. Therefore, seven benzaldehyde equipped Le^x analogs including the natural trisaccharide were synthesized utilizing convergent approach. The derivatives were applied in ongoing carbohydrate–carbohydrate interaction studies by surface plasmon resonance experiments to prove theoretical postulate about the structural requirements of hydroxyl group arrangements in Le^x trisaccharides.     

Concise synthesis of orthogonally diprotected l-glyceraldehyde

Orthogonally diprotected l-glyceraldehyde was efficiently prepared from readily available starting materials, allowing to obtain a highly stable and synthetically versatile chiral building block compared to known symmetrically protected derivatives.     

An efficient and convenient synthesis of unsymmetrical disulfides from thioacetates

We have developed convenient methods for the synthesis of functionalized unsymmetrical dialkyl disulfides under mild conditions in very good yields. The designed method is based on the reaction of (5,5-dimethyl-2-thioxo-1,3,2-dioxaphosphorinan-2-yl)-disulfanyl derivatives 1 with functionalized alkyl thiolate anions, generated in situ from thioacetates 2 and sodium methoxide or butylamine. The developed method allows the preparation of unsymmetrical disulfides bearing additional hydroxy, carboxy, amino, azido, biotin, or maleimide functionalities.     

Synthesis and molecular modeling study of Cu(Ⅱ) complexes derived from 2-(diphenylmethylene)hydrazinecarbothioamide derivatives with cholinesterase inhibitory activities

Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone（L¹-L⁴） have been synthesized and their Cu（Ⅱ） complexes（1-4） were afforded via coordination with cupric chloride.All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis.NMR spectroscopy was also applied to characterize the ligands.In vitro chohnesterase inhibitory assays for the complexes（1-4） showed IC₅₀ values less than 10μmol/L,with complex 1 exhibiting the most activity,IC₅₀=2.15μmol/L and 2.16μmol/L for AChE and BuChE,respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors.In DPPH assay,the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.     

An efficient synthesis of 2-(guaiazulen-1-yl)furan derivatives via intramolecular Wittig reactions

An efficient and mild synthesis of 2-(guaiazulen-1-yl)furans,starting from easily accessible 1-(3-aryl-2-cyanopropenoyl) guaiazulenes,tributylphosphine and acyl chlorides,is described.The strategy employs the intramolecular Wittig protocol as a key step to append the crticial furan ring,leading to the highly functional furans in good yields.